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1
Yun, Hee Sun. "An Orchestral Approach to Johannes Brahms' "Variationen und Fuge über ein Thema von Händel," Op. 24: Orchestral Transcription as an Interpretive Tool." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1752377/.
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This dissertation provides an interpretive guide to Variationen und Fuge über ein Thema von Händel, Op. 24, written in 1861 by Johannes Brahms (1833–1897), in orchestral terms, using as basis the orchestral transcription by Edmund Rubbra (1901–1986), published as his Op. 47 in 1938. Not only does Brahms' Variationen present players with considerable pianistic difficulties, its intense harmonic and polyphonic structures make the music sound symphonic. The English composer Edmund Rubbra, a great Brahms enthusiast, transcribed the work for orchestra. The transcription in effect represents Rubbra's interpretation of the piano work as well as his respect for it. When both orchestra and piano versions of a composition exist, pianists may obtain essential musical ideas from studying the orchestral version, just as it is advisable for conductors to study the piano versions of symphonic works, not only those arranged by the composer. Brahms himself was not only a composer but also a pianist and conductor. It is possible that he imagined orchestral sound when composing large-scale piano works such as his Variationen. New experiments in interpretation can offer a refreshing perspective. This study focuses on elements from Rubbra's orchestral version of Variationen that can inform pianists' interpretation.
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Perkins, Tedrow Lewis. "British Pastoral Style and E.J. Moeran's Fantasy Quartet: A Lecture Recital, Together with Three Recitals of Selected Works of J.S. Bach, B. Britten, L. Foss, G. Handel, A. Marcello, E. Rubbra, C. Saint-Saens, and Others." Thesis, North Texas State University, 1986. https://digital.library.unt.edu/ark:/67531/metadc331812/.
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British musical style changed dramatically after 1880 primarily due to factors which may be subsumed under the general heading of nationalism. This change from an essentially Germanic style has been termed the British musical renaissance by many writers on the subject. Within this new musical language, several distinctive substyles arose. One of these, British pastoral style, has been alluded to by Frank Howes and others, but these allusions do not contribute to an understanding of the works purportedly belonging to that style. It is the purpose of this study to define British pastoral style and examine its relation to the British musical renaissance. The method employed for defining style will be that of Jan LaRue's as described in his Guidelines for Style Analysis. What is British pastoral style? Judging from the literature, British pastoral style is a type of British music written between 1900 and 1950 which evokes pastoral images, especially those associated with the British landscape. A stylistic analysis of selected works will define British pastoral style through enumeration and discussion of the style's musical constituents. A more refined definition of British pastoral style is achieved by an in-depth analysis of E. J. Moeran's Fantasy Quartet, which represents a large portion of British pastoral music, that is, works featuring the oboe. Finally, an examination of British pastoral style's relation to the British musical renaissance will reveal reasons for this particular manifestation of British musical style.
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Goodall, John W. (John Williams). "A Stylistic Analysis of Charles Martin Loeffler's Deux Rapsodies for Oboe, Viola and Piano, L'étang and La cornemuse, After Poems by Maurice Rollinat: A Lecture Recital, Together with Three Recitals of Selected Works by E. Rubbra, D. Beaty, B. Britten, W.A. Mozart, and Others." Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc332159/.
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At the turn of this century, Charles Martin Loeffler (1861-1935) was considered to be among the finest of the handful of well-known American composers of the time. His music was often performed by major symphony orchestras, chamber groups and solo artists.
Deux rapsodies for Oboe, Viola and Piano: L'Etang and La Cornemuse, after poems by Maurice Rollinat (1846-1903), show Loeffler's affinity for programmatic concepts. These works, completed in 1901, are revisions of settings of 1898 for low voice, clarinet, viola and piano, and are now, unfortunately, out of print; but the oboe, viola and piano setting has been published (originally as Deux rapsodies by G. Schirmer, 1905; the latest edition, Two Rhapsodies, is by McGinnis and Marx, N.Y., 1979) and recorded several times.
Loeffler has reflected Rollinat's poetry in his settings by means of melodic, rhythmic and harmonic devices unique to his style. Formal and articulative devices also tend to point to his dependence on the poetry as a source of inspiration and as means for defining the final musical product. Indeed, the music seems incapable of existence independent of its source in the richly imagistic poetry of Rollinat.
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Mikrut, Marek. "Low surface energy rubber materials relationship between network architecture and tack of silicone rubbers /." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/58028.
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Intharapat, Punyanich. "Thermoplastic natural rubbers based on natural rubber (NR) and ethylene vinyl acetate copolymer (EVA) with natural rubber-graft- poly(dimethyl(methacryloyloxymethyl)phosphonate) (NR-g-PDMMMP) as compatibilizer." Le Mans, 2009. http://cyberdoc.univ-lemans.fr/theses/2009/2009LEMA1005.pdf.
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Des copolymères greffés à base de caoutchouc naturel (NR) et de poly(acryloyloxyméthylphosphonate de diméthyle) (NR-g-PDMAMP), de poly(méthacryloyloxyéthylphosphonate de diméthyle) (NR-g-PDMMEP) et de poly(méthacryloyloxyméthylphosphonate de diméthyle) (NR-gPDMMMP), ont été synthétisés en milieu latex selon la méthode dite « grafting from » à partir de sites amorceurs photosensibles N ,Ndiéthyldithiocarbamate préalablement introduits le long des chaînes 1,4-polyisoprène du caoutchouc naturel. Des études de compatibilisation des mélanges caoutchouc naturel (NR) / copolymère d'éthylène - acétate de vinyle (EV A) ont par la suite été envisagées avec le copolymère NR-gPDMMMP, choisi comme agent compatibilisant. Elles ont été effectuées sur des mélanges simples 50/50 NR/EV A, mais aussi des mélanges dynamiquement vulcanisés 40/60 NR/EVA. Dans les deux cas,les influences du taux de greffage du NR-g-PDMMMP (71, 80, 89, et 95%) et du taux de chargement en compatibilisant (0, 1,3,5,7,9,12, et 15 % en poids par rapport au NR) sur les propriétés rhéologiques, dynamiques, mécaniques, morphologiques, et thermiques, ont été étudiées. Les meilleurs effets de compatibilisation ont été observées avec un copolymère NR-g-PDMMMP ayant un taux de greffage de 80 %, pour un taux de chargement de 7 % dans le cas du mélange simple 50/50 NR/EV A et de 9 % dans celui du mélange dynamiquement vulcanisé 40/60 NR/EV A. Les études microscopiques par SEM des mélanges ont montré une réduction de la taille des domaines. Il a aussi été noté que la stabilité thermique du mélange NR/EVA se trouve renforcée avec l'incorporation du NR-g-PDMMMPGraft copolymers of natural rubber and poly(dimethyl(acryloyloxymethyl)phosphonate) (NR-g-PDMAMP), natural rubber and poly(dimethyl(methacryloyloxyethyl)phosphonate) (NR-g-PDMMEP), and natural rubber and poly(dimethyl(methacryloyloxymethyl)phosphonate) (NR-g-PDMMMP), were prepared in latex medium via a "grafting from" methodology based on the photopolymerization of vinyl monomers initiated from N,N-diethyldithiocarbamate groups previously bound in side position of the 1,4-polyisoprene chains of natural rubber. Thereafter, compatibilization studies of natural rubber (NR) / ethylene vinyl acetate copolymer (EV A) blends were considered using NR-g-PDMMMP as a blend compatibilizer. The investigations were carried out on two categories of blends : uncured 50/50 and dynamically cured 40/60 NR/EV A blends. Ln the two cases, the influences of NR-g-PDMMMP grafting rates (i. E. , 71, 80, 89, and 95 %) and of loading level in compatibilizer (i. E. , 0, 1,3,5,7,9,12, and 15 wt% compared to NR) on rheological, dynamical, mechanical, morphological, and thermal properties, were studied. The best compatibilization effects were observed with a NR-g-PDMMMP having a grafting rate equal to 80 %, at a loading level of 7 wt% for 50/50 uncured blend and 9 wt% for 40/60 dynamically cured blend. In these conditions, the highest complex viscosity (positive deviation), tensile strength, and elongation at break, as well as the lowest values of tension set and tan d (damping factor), were observed. SEM micrographs of compatibilized blends showed a size decrease of the domains. It was also noted that the thermal stability of NR/EV A blends was improved by incorporating NR-g-PDMMMP
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Gartshore, James. "Biodegradation of plasticizers by rhodotorula rubra." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33968.
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The degradation of plasticizers by the yeast Rhodotorula rubra J-96-1 (ATCC 9449) was studied in the presence of a water-soluble substrate (glucose). The plasticizers studied included bis 2-ethylhexyl adipate (B(EH)A), dioctyl phthalate (DOP) and terephthalate (DOTP), which are in widespread use. In addition, the degradation of two less common plasticizers, di-propylene glycol dibenzoate (D(PG)DB) and di-ethylene glycol dibenzoate (D(EG)DB), were studied. It has been proposed that the latter plasticizers be used as alternatives to the commonly used plasticizers, which have been associated with negative environmental impacts.The degradation of D(PG)DB or D(EG)DB led to a significant increase in solution toxicity. This increase in toxicity was associated with the production of metabolites resulting from the incomplete breakdown of the original plasticizers. The metabolites responsible for the acute toxicity in the D(PG)DB system were identified as isomers of di-propylene glycol monobenzoate. A mechanism for the formation of this metabolite was proposed. Although the metabolite observed when D(EG)DB was being degraded was not isolated, it was tentatively identified as di-ethylene glycol monobenzoate by analogy to the D(PG)DB system. This same metabolite was observed when D(EG)DB was degraded by the fungus, Aspergillus niger ATCC 9642-U.
In contrast, there were no observable metabolites nor increases in toxicity in the media during the degradation of B(EH)A, DOP, or DOTP by R. rubra. These observations also differ from those of earlier work in which it was reported that the degradation of all three of these plasticizers by bacteria resulted in the production of toxic metabolites.
Collectively, these results do not support the use of D(PG)DB and D(EG)DB as environmentally safe alternatives to B(EH)A, DOP or DOTP.
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Lewan, Michael Victor. "Crosslink density distributions in natural rubber/nitrile rubber blends." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/32972.
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An NMR technique has recently been developed to determine the crosslink density in each phase of a polymer blend. This work uses the NMR method to study natural rubber (NR)/acrylonitrile butadiene rubber (NBR) blends, in order that the cure system used to vulcanize such blends can be optimized. A standard injection moulding cure system for NR/Perbunan N1807 (18% acrylonitrile content) gave much more crosslinking in the NBR phase. To reduce this imbalance a less polar analogue of the accelerator was used, resulting in a more even distribution of crosslinks but still with a bias towards the NBR.
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Choi, Jaesun. "Ultrasonically Aided Extrusion of Rubber Nanocomposites and Rubber Blends." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1362747207.
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Lacroix, Christian 1962. "Floral development of Basella rubra L. (Basellaceae)." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65495.
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Arlett, Megan J. "Rubble & Honey." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3271.
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RUBBLE & HONEY is a collection of poems unified by its use of language driven lyricism to recount personal narratives in the life of the poet. The poems in this manuscript depict the landscapes of California, Florida, Mississippi, the South Downs of England, and Anglesey off the northwest coast of Wales. The manuscript engages with these physical spaces, how the speaker reacts to the natural world and how these locations can reflect the internal. The collection is broken into four sections: the first two explore parting, firstly from a relationship and then revisiting the poet’s childhood landscape of Sussex, England; the third is a rebirth of sorts after the exploration of these losses, a joyous look at the world that is tentative but hopeful; and the fourth section revisits the themes of the first from a more distanced perspective.
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Buffham, Timothy M. D. "Isotropic rubber moulding." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/27907.
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The current work was initiated to develop, understand and optimise a novel computer controlled, automated, flexible compression moulding system primarily for the production of fluid seals. A prototype moulding system was designed and built for the study. It was used to process a range of rubber compounds for process evaluation.
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Sakulkaew, Kartpan. "Tearing of rubber." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8616.
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There have been several studies on the tearing of rubber materials since the seminal paper on rupture of rubber was published by Rivlin and Thomas (1953).The behaviour is typically characterised using a fracture mechanics approach whereby the rubber has a geometrically independent relationship between crack growth rate during tearing versus strain energy release rate. This approach works well under conditions of steady tearing as the crack growth rate is easy to measure. However, this approach is much harder to interpret under the condition where the rubber exhibits discontinuous crack growth behaviour such as knotty tearing or stick slip tearing. Unfortunately, these are common tearing conditions observed in practice for filled rubbers as well as for some unfilled rubbers, especially those such as natural rubber that are capable of strain-induced crystallisation. Under these conditions it is not clear what the actual crack growth rate is as the value typically given results from the average of a very rapid tearing rate and a zero velocity tearing rate. The aim of this work is to develop a new approach to characterise the unsteady tearing behaviour of rubber in terms of the relationship between the rate of increase in the strain energy at the crack tip just immediately prior to the onset of the tearing which is quantified directly as the time derivative of the strain energy release rate · T , and the critical strain energy release rate T* required to propagate the crack. The approach adopted in this study is then evaluated using a range of different crystallising and non-crystallising rubbers as well as crystallising rubbers that have been modified to alter their crystallisation over a range of different test temperatures. Additionally, a new elastic-viscous transition diagram in association with the rate of change in the strain energy release rate at the tip of the crack is presented.
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Thai, Hwee Tatz. "Biodeterioration of rubbers." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/15625.
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The standard agar plate technique was found to be a good method for screening the presence of leachable antimicrobial additives in rubber compounds. However, this technique restricts the growth of microorganisms to the perimeter of the samples and is less satisfactory as a long term test. In a liquid medium, there should not be any problem for the microorganisms to gain access to the inorganic and organic nutrients as well as oxygen. Many experimental trials were carried out in liquid media under dynamic and static conditions with Streptomyces lipmanii NCIMB 9841 as test organism. This led to the development of the modified batch processes. The modified tests allowed experiments to be performed over a long period of time without concern of accumulation of toxins from the leachable antimicrobial additives in the rubber samples and the metabolites from the utilisation of carbon sources by the microorganisms. The test procedure developed proved to be very reproducible and repeatable. The use of neutral chemically defined media with no added carbon source, the absence of strong oxidation catalysts coupled with the use of proper control samples defined the least vigorous conditions for biodeterioration of rubber compounds. On the other hand, the degradation of the rubber compounds under field and semi-field tests is likely to be a combined effect of biodeterioration, hydrolytic degradation, leaching and oxidation of samples. Five strains of fungi and four strains of actinomycetes were tested against five carbon black-filled seal compounds. The types of rubbers used were based on natural, styrene/butadiene, peroxide-cured EPDM, sulphur-cured EPDM and acrylonitrile /butadiene rubbers. Among all the species tested, Nocardia was found to be the most aggressive group of microorganisms in affecting the rubber samples. The strains NCIMB 12811 and 12814 had activity towards vulcanised gum NR samples, whilst Nocardia asteriodes NCIMB 12082 was very capable of utilizing rubber additives. It was found that besides the physical dimensions, types and formulations of rubber compounds; test conditions such as temperature, agitation speed, pH; amount of rubber sample used per unit volume of test medium, and renewal or non-renewal of test media also played an important role in affecting the activities of microorganisms towards rubber compounds.
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Kapgate, Bharat P., Chayan Das, Debdipta Basu, Amit Das, and Gert Heinrich. "Rubber composites based on silane-treated stöber silica and nitrile rubber: Interaction of treated silica with rubber matrix." Sage, 2015. https://tud.qucosa.de/id/qucosa%3A35602.
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Role of silane-treated stöber silica as reinforcing filler for nitrile rubber (NBR) has been studied. Stöber silica is synthesized by sol–gel method, and the surface of silica is modified with the treatment of silane-coupling agent viz. γ-mercaptopropyltrimethoxysilane (γ-MPS) in varying proportions. Average particle size of stöber silica of spherical shape in the range of 200 to 400 nm is evident from scanning electron microscopy (SEM). Surface modification of silica particle with silane-coupling agents decreases surface energy and reduces agglomeration of silica particles in rubber matrix. Stress–strain study and dynamic mechanical analysis of silica-filled composites are compared with the unfilled ones. Analysis of cross-linking density, mechanical properties, and storage moduli indicates a strong rubber–filler interaction in the silane-treated, silica-filled NBR composites. Silane treatment is found to be effective in uniform dispersion of silica in rubber matrix and in improving the mechanical properties of rubber composite. Different functionalities of organosilane at its both end improve the compatibility of silica with rubber matrix and offer better rubber–filler interaction.
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Cagatay, Onur. "Rubber Toughening Of Phenolic Resin By Using Nitrile Rubber And Amino Silane." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606281/index.pdf.
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The aim of this study was to investigate rubber toughening of resol type phenol-formaldehyde resin. For this purpose, phenolic resin was first modified by only acrylonitrile butadiene rubber, and then by using nitrile rubber together with 3-aminopropyltriethoxysilane.
Test specimens were prepared by mixing and casting of liquid phenolic resin in three groups. In the first one, neat phenolic resin specimens were produced. In the second group, phenolic resin was modified with 0.5, 1, 2, and 3 wt.% nitrile rubber, while in the last group modification was carried out by using 0.5 wt.% nitrile rubber together with 1, 2, and 4wt.% amino silane (with respect to nitrile rubber). All specimens were heat cured in the oven.
In order to observe behaviors of the specimens, Three-Point Bending, Charpy Impact, Plane-Strain Fracture Toughness, and Dynamic Mechanical Analysis tests were conducted according to the related ISO standards for all specimens groups. Scanning Electron Microscopy was also used for the fractographic analysis of some samples.
It can be concluded that, although there were problems in mixing and casting of liquid resol type phenolic resin, its toughness could be improved by using nitrile rubber and amino silane. Modification by using nitrile rubber and amino silane together was much more effective than by using only nitrile rubber. In this synergistic case for instance, Charpy impact strength and fracture toughness values of the neat phenolic specimens were increased 63% and 50%, respectively. SEM studies indicated that the main rubber toughening mechanism was shear yielding observed as deformation lines especially initiated at the domains of nitrile rubber and amino silane.
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Lowe, David James. "Natural rubber/organoclay nanocomposites." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2971.
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Natural rubber (NR)/organoclay nanocomposites were prepared using organomontmorillonite (OMMT) and organo-sepiolite (OSEP). Both were found to improve modulus significantly more than equivalent amounts of conventional fillers such as carbon black for strains up to 100%. OSEP was found to increase modulus more than OMMT for a given filler content, and NR/OSEP nanocomposites also had potentially anisotropic physical properties. OMMT had more effect on vulcanisation than OSEP, although both produced considerable acceleration. The tensile stress-strain behaviour of NR/OMMT and NR/OSEP nanocomposites were studied using a number of different micromechanical models. Some models were found to give a good empirical fit with experimental data, with the best results given by the Halpin-Tsai model. Furthermore, by analysis of the vulcanisation behaviour using rheometry, and particle morphology using transmission electron microscopy (TEM), it was possible to accurately estimate the Young's modulus of a nanocomposite from knowledge of the cure onset time and the shape factor of the particles. It was discovered that unmodified montmorillonite and sepiolite clays could undergo organic modi cation in situ during mixing into NR following the addition of a suitable modifier. This resulted in vulcanisates with very similar physical properties to those found when using pre-modified OMMT or OSEP. TEM and X-ray diffraction showed that the exfoliation state of the clay modified in situ was also similar to that of pre-modified organoclay. Silane coupling agents were also used with NR/OMMT and NR/OSEP nanocomposites, producing significant increases in modulus. However, the increased modulus was only observed above 40% strain for OMMT and above 25% for OSEP. The coupling agents strengthens the rubber- ller interface preventing interfacial slippage and cavitation in the nanocomposite, and these mechanisms only begin to operate when the interfacial stress reaches a significant level. The most effective coupling agent used was bis[triethoxysilylpropyl] tetrasulfide due to its relatively high reactivity.
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Kawamoto, Jiro. "Fatigue of rubber composites." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14566.
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Mullins, Michael Bryan. "Hildegard On Rubble Mountain." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3328/.
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Hildegard On Rubble Mountain is a cinema verité documentary about Hildegard Modinger's childhood. She grew up in Stuttgart, Germany during World War II and immigrated to the United States at the age of nineteen. This video follows her back to her childhood neighborhood as she recalls memories of that time in her life. The accompanying production book explains the production process: preproduction, production, postproduction, theoretical approaches, style used and a self-evaluation.
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Thompson, W. C. "Analysis of rubber vulcanisates." Thesis, Aston University, 1987. http://publications.aston.ac.uk/9713/.
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A study has been made, using High Pressure Liquid Chromatography, of the migration of TMQ (a quinoline type) and 6PPD (a paraphenylenediamine type) antidegradants from a tyre sidewall compound into adjacent casing and liner compounds containing no antidegradant. Migration takes place at a rapid rate, even during the vulcanisation of the composite. After 4000 hours ageing in nitrogen at 100oC, there is a higher level of antidegradants in the casing than in the sidewall. An equilibrium distribution is not obtained. After 114 days at 50oC in 95% relative humidity, the level of solvent extractable 6PPD fell to zero, but subsequent ageing for 2 years in 50 pphm ozone showed no evidence of sidewall cracking. It is suggested that the antidegradant is still active but linked to the polymer chain. An analytical method, for the type and amount of sulphenamide accelerators in vulcanised rubber compounds, has been developed. During the vulcanisation process, the accelerators decay, liberating specific amines which have been solvent extracted, derivatised with 1-chloro-2,4-dinitrobenzene and the yellow coloured zwitter ion analysed using High Pressure Liquid Chromatography. The decay of the accelerator and sulphur during the vulcanisation process, has been studied. It has been demonstrated that the sulphur crosslinking with a styrenebutadiene polymer is a first order reaction, after an initial period during which the accelerator content falls to zero. Variations in sulphur to accelerator ratios gave consistent rate constants for the crosslinking, except for a sulphur level of less than 1% by weight and a ratiio of accelerator to sulphur of 1:1.3. The retention time of the reaction product between sulphur and accelerator from an HPLC column changes with cure time, showing that the precurser to crosslinking is an ever changing material. One of these reaction products has been analysed.
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Suttipong, Angthong. "Role of the Rubber Cooperatives in Thailand in Improving Smallholders' Incomes: Empirical Study in Traditional and Non-traditional Rubber Production Areas." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263768.
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Brown, Daniel. "Investigating the biosynthesis of natural rubber through the characterisation of rubber associated proteins." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/88568/.
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Natural rubber from the para rubber tree Hevea brasiliensis is one of world’s most important natural resources. Despite its use in the manufacture of a wide range of essential items the mechanisms by which natural rubber is synthesised is poorly understood. Natural rubber is a long chain cis-polyisoprene, composed of units of isopentenyl pyrophosphate (IPP) which is contained within rubber particles. Rubber particles consist of a hydrophobic polyisoprene interior surrounded by a monolayer membrane. Due to the insoluble nature of rubber the only place that polymerisation could occur is on this membrane by a hypothetical membrane bound rubber transferase. Whether this is a single enzyme or complex is currently unknown. Cis-prenyltransferases (CPTs) are a group of enzymes responsible for the polymerisation of cis-polyisoprene. The first plant CPTs were identified in Arabidopsis which paved the way for the identification of two Hevea CPTs, HRT1 and HRT2. HRT2 is able catalyse the formation of long chain polyisoprene products in the presence of rubber particles and is the focus of this thesis. Hevea takes at least 4 years to reach maturity. Its long life cycle coupled with the difficulty of genetic transformation meant that direct study on Hevea was not feasible for this project. Instead transient expression in N. benthamiana as well as some preliminary work in L. sativa was used to characterise rubber associated proteins. HRT2 was found to be a cytosolic protein and in theory incapable of polymerising natural rubber on the surface of rubber particles. The scope of the project was therefore widened to include possible interactors that could act to bring it to a membrane. These interactors were identified and cloned based on existing literature and included small rubber particle protein (SRPP), rubber elongation factor (REF), rubber biosynthesis stimulator protein (RBSP) and a newly characterised cis-prenyltransferase like (CPTL) protein, HevNogo. Whilst HRT2 on its own was unable to associate with a membrane, expression with HevNogo induced its subsequent localisation to the plasma membrane. This interaction initially took place on the endoplasmic reticulum. The HRT2/HevNogo complex may be part of a rubber transferase complex, however it is likely that additional components are required.
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Egodage, Shantha M. "The development of rubber-thermoplastic blends from ground tyre rubber and waste polypropylene." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/36154.
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The aim of this thesis was to develop and process viable rubber-thermoplastics blends from ground tyre rubber (GTR) and waste polypropylene (WPP). The use of WPP with waste rubber in blends is novel, although limited studies have been carried out on virgin polypropylene (PP)-waste rubber blends. The Delink pretreatment for the GTR is also a novel technique used for property enhancement. To achieve the aim, a number of GTR/WPP blends were prepared, in different blend compositions (from 0 to 100 wt% of each polymer), at different processing parameters, and with two compatibilizing systems. One system called dimaleimide contained N-N' meta-phenylene dimaleimide (HVA-2) as the compatibilizer and either di(tert-butylperoxyisopropyl) benzene (DTBPIB) or 2-2'-dithiobenzothiazole (MBTS) as an activator. The other system contained phenolic resin compatibilizer (SP 1045H resin) and stannous chloride (SnCl2) activator in two forms: anhydrous and dihydrated. The compatibilizer level varied from 0 to 5 pphp, while the activator level varied from 0 to 1 pphp.
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Ren, Xianjie ren. "Improving sustainability of rubber composites with renewable additives and epoxidized guayule natural rubber." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574440536318129.
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Barnett, Oliver Edward. "The population genetics of Festuca rubra on park grass." Thesis, Open University, 2005. http://oro.open.ac.uk/54484/.
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An explanation for the ubiquity of sexual reproduction remains elusive although it is commonly suggested that sex and recombination facilitate a more rapid response to environmental change than clonal reproduction. If this suggestion is true then one would expect the frequency of sexual reproduction within populations to increase with rate of environmental change. The study described here investigates the potential correlation between mode of reproduction and rate of environmental change in red fescue, Festuca rubra, a clonal/sexual species of perennial grass. Populations are identified that have experienced contrasting histories of change over the past 138 years, and within which the ratios of clonally to sexually derived individuals have been determined. From these ratios the selection pressures on mode of reproduction in each of the Festuca rubra populations investigated are inferred. The unexpected discovery that Festuca rubra is represented by two sub-species at the main study site has also prompted investigations into the factors governing their relative frequencies and distributions. Since the sub-species represent different cytotypes within the red fescue aggregate, this has allowed for inferences to be made relating to their observed coexistence and the apparent overcoming of minority cytotype exclusion by the subspecies found at lower frequencies.
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Rubbo, Louis Joseph. "Gravitational wave astronomy using spaceborne detectors." Diss., Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/rubbo/RubboL0805.pdf.
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Euchler, Eric, Radek Stocek, Michael Gehde, Jörg-Michael Bunzel, Wolfgang Saal, and Reinhold Kipscholl. "Fracture behavior of rubber powder modified rubber blends applied for conveying belt top covers." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-198136.
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The aim of this study is concentrated on the experimental investigation of wear resistance of rubber powder modified rubber blends. Styrene-Butadiene-Rubber (SBR) blends applied for conveying belt top covers have been modified by ground rubber (rubber powder) based on SBR. We theoretically described the rubber wear mechanism due to loading conditions occurring at conveyor belts in the field, to simulate wear behavior of top cover rubber materials. An own developed testing equipment based on gravimetric determination of mass loss of rubber test specimen was used investigating dynamic wear with respect to fracture properties of top cover materials. Furthermore we investigated fatigue crack growth (FCG) data over a broad range of tearing energy by Tear Analyzer to characterize crack propagation behavior of rubber powder modified rubber blends. Thus, we demonstrate the influence of rubber powder on resistance against occurrence of fracture as well as dynamic wear as a function of the rubber powder content in rubber blends applied for conveying belt top covers.
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Euchler, Eric, Radek Stocek, Michael Gehde, Jörg-Michael Bunzel, Wolfgang Saal, and Reinhold Kipscholl. "Fracture behavior of rubber powder modified rubber blends applied for conveying belt top covers." Technische Universität Chemnitz, 2014. https://monarch.qucosa.de/id/qucosa%3A20409.
Full textAbstract:
The aim of this study is concentrated on the experimental investigation of wear resistance of rubber powder modified rubber blends. Styrene-Butadiene-Rubber (SBR) blends applied for conveying belt top covers have been modified by ground rubber (rubber powder) based on SBR. We theoretically described the rubber wear mechanism due to loading conditions occurring at conveyor belts in the field, to simulate wear behavior of top cover rubber materials. An own developed testing equipment based on gravimetric determination of mass loss of rubber test specimen was used investigating dynamic wear with respect to fracture properties of top cover materials. Furthermore we investigated fatigue crack growth (FCG) data over a broad range of tearing energy by Tear Analyzer to characterize crack propagation behavior of rubber powder modified rubber blends. Thus, we demonstrate the influence of rubber powder on resistance against occurrence of fracture as well as dynamic wear as a function of the rubber powder content in rubber blends applied for conveying belt top covers.
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GOKHALE, PUSHKAR M. "PARAMETRIC STUDY OF 1/24 SCALE LAMINATED RUBBER BEARINGS AND LEAD CORE RUBBER BEARINGS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155084414.
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Boyce, Annemè. "Devulcanization of model compounds by a variety of diphenyldisulfides." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/14730.
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Improvements to the properties of recycled rubber, by developing a more selective breakdown process, is an important issue and a global challenge. Devulcanization is the most promising way to achieve this. It is a process which aims to totally or partially cleave monosulfidic (C-S-C), disulfidic (C-S-S-C) and polysulfidic (C-Sx-C) crosslinks of vulcanized rubber. In this study, the devulcanization of sulfur-vulcanized natural rubber with a variety of diphenyldisulfides has been studied using 2,3-dimethyl-2-butene and squalene as model compounds, vulcanized by sulfur and 2-bisbenzothiazole-2,2’-disulfide. 2-aminodiphenyldisulfide; 4-amino-diphenyldisulfide; bis(2-benzamido-)diphenyldisulfide and 2,2’-bithiosalicylic acid were used as aromatic disulfides devulcanization agents. Thermal analysis was used to investigate interactions between various combinations of curatives in the vulcanization systems in the absence of model compounds. Thermogravimetric analysis was used to detect mass changes during vulcanization and whether the samples decompose/evaporate so as not to contaminate differential scanning calorimetry instrumentation. Differential scanning calorimetry was used to investigate reactions occurring between curatives. Comparison of reversing and non-reversing signals in modulated experiments are suggestive of reactions between devulcanization agents and sulfur, and accelerators Vulcanization of the model compounds were performed in 10m evacuated sealed glass ampoules placed in an oil bath at 160 °C and agitated for the duration of vulcanization. After 60 min the ampoules were removed and quenched. These were then devulcanized by exposure to a devulcanization agent in a sealed ampoule at 180 for 60 min. Crosslinked 2,3-dimethyl-2-butene species were isolated and analysed by reversed phase high performance liquid chromatography. Particular attention was paid to changes in the number of sulfur atoms in the crosslinks. Results indicate that of the devulcanization agents tested 4-amino-diphenyldisulfide was the most effective. No detrimental effect on devulcanization efficiency was caused by the substitution of a basic amino group with an acidic carboxylic acid group Gel permeation chromatography was performed on devulcanized squalene crosslinks using a tetrahydrofuran eluent. GPC investigations with squalene were less effective than HPLC experiments with 2,3-dimethyl-2-butene at evaluating the relative efficiency of individual devulcanization agents. Results were, however, consistent with 4-amino-diphenyldisulfide again being the most efficient devulcanization agent.
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Huynh, Anh Nhut Materials Science & Engineering Faculty of Science UNSW. "Rubber-polymer blends: a thesis in polymer engineering." Awarded by:University of New South Wales. Materials Science & Engineering, 2007. http://handle.unsw.edu.au/1959.4/40833.
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This study examines composite materials prepared from ground recycled tires (tire crumb) and post-consumer recycled high density polyethylene (HDPE). An initial set of composites was prepared from as-received tire crumb and HDPE recyclate containing 040% tire crumb in 10% increments, using injection moulding. The elastic modulus and tensile strength were found to decrease linearly with increasing tire crumb content. Addition of tire crumb to recycled HDPE caused produced an immediate reduction in the strain to failure with a progressively more modest decrease as the tire crumb content was increased. The impact toughness decreased more linearly with increasing tire crumb fraction. Cross sections of the composites showed that the tire crumb particles were in intimate contact with the matrix but post mortem examination of the fracture surface of the impact test specimens indicated that the level of bonding had been poor. A second set of composites was a prepared from 10% tire crumb. The tire crumb was first given an oxidative treatment in hot aqueous copper chloride at concentrations from 0-5 wt% Cu Ch at 50 or 100??C for 6 or 12 hours. The composites were injection moulded with an addition of 0.5 wt% dicumyl peroxide (DCP). These composites showed good bonding between the tire crumb and the recycled HDPE even at concentrations of 0% of the Cu 2+ oxidation catalyst. The addition of DCP was found to substantially reduce the modulus of neat HDPE and this reduction was reflected in the modulus of the composites. It was found that the DCP concentration could be reduced to 0.02% without adversely affecting the composites.
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South, Joseph Thomas. "Mechanical Properties and Durability of Natural Rubber Compounds and Composites." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/26306.
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The focus of this research was to investigate the effect of thermal degradation upon the mechanical properties of natural rubber compounds and apply those effects to the life prediction of off axis 2-ply cord rubber laminates. The work examined both the quasi-static and dynamic mechanical properties of two natural rubber vulcanizates, which had been subjected to isothermal anaerobic aging. Thermal aging was performed on two different natural rubber vulcanizates. The thermal aging was conducted between the temperatures of 80 and 120°C for times ranging from 3 to 24 days. The effect of thermal degradation was measured from the changes in the chemical composition of the vulcanizates as functions of time at temperature. A master curve relationship between the changes in the chemical composition of the vulcanizates due to thermal degradation and their static and dynamic mechanical properties has been developed. This relationship allowed for the prediction of the vulcanizate mechanical properties after thermal aging. It was found that the mechanical properties correlated with the percentage of poly and monosulfidic crosslinks, where in general higher levels of polysulfidic crosslink gave rise to the highest mechanical properties.
Crack propagation in an aged and unaged natural rubber vulcanizate was measured using a double cantilever beam, DCB. This type of testing arrangement exhibits a plane strain condition and resulted in crack growth rates two orders of magnitude faster than traditional plane stress testing geometries. To validate the DCB specimens, an investigation into the potential cavitation inside the rubber of the DCB specimens was performed. It was found that no cavitation occurred due to the high speed of the fracture. DCB samples were thermally aged to determine the effect of thermal aging upon the crack growth rate. It was found that crack growth rates increase with thermal aging.
Life prediction of the aged 2-ply laminates was performed using a finite element analysis. In order to verify the finite element models used in the life prediction, the fatigue failure and crack growth characteristics of off axis 2-ply cord-rubber laminates were examined with a delamination analysis. This analysis allowed for the determination of the modulus of off axis 2-ply laminates in the presence of damage as well as the calculation of the crack growth rates of the laminate. The failure of unaged and thermally aged 2-ply laminates was evaluated and compared to the crack growth rates of thermally aged DCB specimens. The trend due to thermal aging between the two types of testing specimens was consistent.
The finite element analysis was sectioned into two approaches: crack initiation and crack propagation. The former utilized a residual strength approach, while the latter applied a fracture mechanics approach. The predicted stress versus cycles, S-N, curves were not in complete agreement with the experimental data. The error between the predicted and the experimental is discussed and future work to correct that error is suggested. While there was not complete agreement between the predicted and the experimental data, this dissertation outlines a comprehensive approach to track the effects of thermal degradation and apply those effects to a real world application.Ph. D.
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Qin, Feng. "Thermocatalytic decomposition of vulcanized rubber." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4781.
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Used vulcanized rubber tires have caused serious trouble worldwide. Current disposal and recycling methods all have undesirable side effects, and they generally do not produce maximum benefits. A thermocatalytic process using aluminum chloride as the main catalyst was demonstrated previously from 1992 to 1995 in our laboratory to convert used rubber tire to branched and ringed hydrocarbons. Products fell in the range of C4 to C8. Little to no gaseous products or fuel oil hydrocarbons of lower value were present. This project extended the previous experiments to accumulate laboratory data, and provide fundamental understanding of the thermocatalytic decomposition reaction of the model compounds including styrene-butadiene copolymers (SBR), butyl, and natural rubber. The liquid product yields of SBR and natural rubber consistently represented 20 to 30% of the original feedstock by weight. Generally, approximately 1 to 3% of the feedstock was converted to naphtha, while the remainder was liquefied petroleum gas. The liquid yields for butyl rubber were significantly higher than for SBR and natural rubber, generally ranging from 30 to 40% of the feedstock. Experiments were conducted to separate the catalyst from the residue by evaporation. Temperatures between 400 ðC and 500 ðC range are required to drive off significant amounts of catalyst. Decomposition of the catalyst also occurred in the recovery process. Reports in the literature and our observations strongly suggest that the AlCl3 forms an organometallic complex with the decomposing hydrocarbons so that it becomes integrated into the residue. Catalyst mixtures also were tested. Both AlCl3/NaCl and AlCl3/KCl mixtures had very small AlCl3 partial pressures at temperatures as high as 250 ðC, unlike pure AlCl3 and AlCl3/MgCl2 mixtures. With the AlCl3/NaCl mixtures, decomposition of the rubber was observed at temperatures as low as 150 ðC, although the reaction rates were considerably slower at lower temperatures. The amount of naphtha produced by the reaction also increased markedly, as did the yields of aromatics and cyclic paraffin. Recommendations are made for future research to definitively determine the economic and technical feasibility of the proposed thermocatalytic depolymerization process.
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Lokander, Mattias. "Performance of Magnetorheological Rubber Materials." Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31.
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Magnetorheological (MR) rubber materials are the solid analogue of magnetorheological fluids; i.e. their rheological properties can be controlled continously, rapidly, and reversibly by an applied magnetic field. They consist of magnetically polarisable particles in an elastomer matrix and they can be made to respond to changes in their environment; hence, they are considered as "smart" materials. Examples of potential applications for these materials are adaptive tuned vibration absorbers, stiffness-tuneable mounts and suspensions, and automotive bushings.
The purpose of this work was to increase the knowledge relating to magnetorheological materials for damping applications. The materials should exhibit a large response to an applied magnetic field, and have good mechanical and long-term properties.
MR rubber materials were made from nitrile, natural and silicone rubber, with irregularly shaped iron particles several micrometres in size. The particles were not aligned by a magnetic field prior to the vulcanisation; hence, the materials can be considered to be isotropic. These materials show a large MR effect, i.e. an increase in the shear modulus when a magnetic field is applied, although the particles are not aligned within the material. This is explained by the low critical particle volume concentration (CPVC) of such particles. Similar behaviour can be obtained with materials containing carbonyl iron, if the particles are aggregated so that they behave like large irregular particles. The iron particle concentration must be very close to the CPVC in order to obtain a large MR effect without alignment of the particles.
The absolute MR effect (MPa) in an isotropic MR rubber material with large irregular iron particles is independent of the matrix material, and the relative MR effect (%) can thus be increased by the addition of plasticisers. However, the obtainable effect is limited by the reinforcement of the particles and by friction between the particles. Therefore, it is very difficult, if not impossible, to achieve an MR effect larger than 60%.
Other ways of increasing the MR effect are to increase the strength of the magnetic field, although the materials saturate magnetically at high field strengths, or to use small strain amplitudes. The strong strain amplitude dependence of the MR effect suggests that MR rubber materials are most suitable for low amplitude applications, such as sound and vibration insulation. Measurements at frequencies within the audible frequency range show that this is a promising application for MR rubber materials.
The incorporation of large amounts of iron into the rubber matrix decreases the oxidative stability dramatically. This is probably due to iron oxides on the surface of the particles, and to the fact that the oxidation rate is enhanced by iron ions, which are able to diffuse into the matrix. Standard antioxidants do not provide sufficient stabilisation for MR rubbers. Thus, proper stabilisation systems have to be found in order for these materials to be successful in applications.
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Canevarolo, Sebastiao V. "Melt behaviour of thermoplastic rubbers." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/27871.
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Thermoplastic rubbers have been shown to have unusual solid state properties which must derive from the structure of the melt prior to solidification. The melt phase has been studied in some detail. The molecular architecture of these block copolymers comprises of hard segments (usually polystyrene) connected by a flexible rubbery chain (polybutadiene or polyisoprene) in a linear or radial structure. Their flow characteristics have been studied and the results correlated with measurements in the solid state. They have been modelled mathematically based on two particular theoretical models. A liquid phase transition was recorded for both models, with appreciable reduction in the apparent activation energy of flow above this temperature. The quality of the domain structure depends on the continuity of the polystyrene phase and has been measured by the stress at yield and by the optical birefringence. A change in response was associated with the liquid-liquid transition.
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Anderson, H. J. "Isotropic and reinforced rubber analysis." Thesis, Swansea University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.635781.
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Samsuri, A. B. "Tear strength of filled rubbers." Thesis, London Metropolitan University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234798.
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Gough, Julia. "Stress-strain behaviour of rubber." Thesis, Queen Mary, University of London, 2000. http://qmro.qmul.ac.uk/xmlui/handle/123456789/28819.
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Several aspects of the stress-strain behaviour of rubber, important for evaluating its properties for finite element analysis and engineering applications, are investigated. Measurements of the deformation behaviour of an elastomer containing a compressible filler are used to assess theoretical equations for the compression modulus of rubber pads bonded to rigid endplates. The volume fraction of filler is estimated from a simple model. The first cycle stress-strain behaviour of filled and unfilled rubbers is characterised from uniaxial tests and by measuring both non-zero principal stresses with a novel pure shear technique. Various theoretical forms for the strain energy density function are assessed. The results support the assumption that the strain energy of filled natural rubber is a function only of the first strain invariant. Finite element modelling of the behaviour of a hyperelastic material in simple shear reveals that the proximity of the free edges in conventional simple shear testpieces strongly influences the stresses and deflections in the thickness direction. These finding are qualitatively supported by experiment. The effect of free edges on the shear modulus is also assessed. Deviations from hyperelastic behaviour are investigated through experimental studies of stress relaxation, cyclic stress softening and the superposition of a torsion on a uniaxial extension. Anisotropic deformations can result in corresponding differences in the amounts of stress relaxation or stress softening in different directions. Isotropic models cannot model these features but may be adequate for most practical applications. The relationship between the modulus and crystallinity of partially crystalline rubber is determined experimentally. The reinforcing effect of the crystals is found to be approximately independent of their morphology and of the modulus of the amorphous rubber. Studies of yielding of partially crystalline rubber show that the yield stress increases with increasing amounts of crystallization whereas the yield strain remains roughly constant.
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Wu, Guangchang. "The mechanisms of rubber abrasion." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25986.
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Rubber abrasion is one of the most important properties for rubber products, such as tyres. However, due to its complexity rubber abrasion is still a very challenging topic in rubber research. Rubber abrasion is not governed by a single mechanism. Different mechanisms can dominate the abrasion behaviour depending on the rubber compound, base polymer type, loading severity, contact conditions, testing temperature and chemical environment. This study investigates the different mechanisms for rubber abrasion and the transition between these mechanisms using two types of abrasion apparatus, a blade abrader and a surface abrader, respectively. Blade abrasion was used to generate the abrasion pattern. Once the abrasion pattern was formed on the rubber surface under unidirectional sliding, the underlying mechanism was primarily one of fatigue crack growth, which is referred as "fatigue wear" in the literature. An independent pure shear fatigue test with various loading profiles was conducted to predict the crack growth rate using a fracture mechanics approach during these abrasion tests. The tearing energy during blade abrasion was calculated using a fracture mechanics approach. A Finite Element Analysis (FEA) technique using the Virtual Crack Closure Technique (VCCT) was adopted. The VCCT approach was a simpler, faster and more reliable approach to derive the tearing energy under these complicated large strain contact conditions. The prediction of the abrasion rate using this independent measurement of the crack growth resistance of materials worked best for unfilled SBR material. A bespoke surface contact abrasion machine was used to investigate rubber abrasion on silicon carbide sandpaper under both dry and wet conditions. Depending on the materials, contact conditions and sliding velocity, two different mechanisms were observed. The first being a mechanochemical degradation, during which a sticky layer was generated on the rubber surface. This behaviour is also called "smearing wear". The second failure mode resulted from a purely mechanical fracture named "abrasive wear". It seemed that the carbon black filled rubber was more susceptible to smearing wear than the silica filled one. Higher sliding velocities promoted smearing wear, possibly due to higher temperatures being generated at the interface. Alternatively, water lubrication was seen to promote abrasive wear. Therefore, the abrasion mechanism changed to more rapid abrasive wear under wet conditions, which resulted in a significant increase in the rate of weight loss. Finally, the sticky debris generated during the smearing wear was characterised using various different techniques. This revealed that the sticky debris had more oxygen and lower carbon and sulphur content. It contained a greater amount volatiles and generated more char formation during its degradation in the air. The molecular weight of the sticky debris was much lower when compared to the original uncured rubber. It seemed that in the sticky debris the filler network can slowly recover and the degraded polymer chains can re-absorb back onto filler surface forming "bound rubber", which leads to faster rates of weight loss.
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Ella, Samantha. "Rubber snow interface and friction." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/17941.
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Tyres are used in everyday life for a variety of practical and recreational tasks. Frictional behaviour of tyres on any surface is important for vehicle safety and control; this behaviour becomes more important when that surface is snow. The interaction of rubber and a snow surface is complex and a deeper understanding of both is needed in order to help develop better tyres. Outdoor full scale tyre test results were compared to results from indoor laboratory tests using a linear tribometer and a surface of compacted artificial snow; these were in excellent correlation allowing a systematic and comprehensive study of rubber friction on snow to be conducted in the laboratory. Rubber samples of varied rubber compositions and geometries were used to gain an understanding of friction on snow. Samples with varying glass transition temperature (Tg), dynamic rigidity (G*) and Payne effect (dependence of the dynamic moduli on the amplitude of the applied strain) were investigated along with samples with and without sipes. The rubber friction coefficient (μ) was measured as a function of velocity and temperature. The siped samples exhibited a higher μ than those without sipes. FE simulations, rubber friction tests for varying contact pressures and steel blade force tests were performed to evaluate contributions from ‘surface’ friction and ploughing separately. The increased μ was attributed to the ploughing force from the front edges of the ‘subblocks’ created by the sipes. Although it is well known in the industry that siped tyres grip well, this is the first time it has been explained how sipes grip effectively through a combination of ploughing and rubber snow interaction. A comprehensive study of varying rubber properties (Tg, G* and Payne effect) was conducted to better understand their impact on snow friction. The findings were evaluated using the WLF shift factor to account for the running frequency of the rubber from the snow surface roughness. G* was found to be the dominant parameter for rubber μ when considering running frequency. Increased μ values were exhibited by rubbers with a lower G*. The decreased G* makes the rubber more compliant, thus increasing the contact area between the rubber and the snow, in turn increasing μ. A better knowledge of the surface roughness of snow will aid the understanding of the interaction between rubber and snow for tyres. A method was developed to characterise the artificial snow surface utilising sectioning and imaging of chemically stabilised snow samples. From images of the snow surface before friction testing the average indentor size can be found, this is used to analyse the running frequency of the rubber. Qualitatively comparing the surfaces before and after rubber friction testing shows a decrease in surface profile aggressivity after a test; this is attributed to melting of the snow from frictional heating and snow grain fracture. Friction tests were conducted to directly compare rubber friction on snow and ice using round edged samples. Again it was found that the rubber with the decreased G* exhibited higher friction; this was seen on both snow and ice confirming G* as the dominant rubber property for both surfaces, regardless of the surface roughness change. It was found that at low temperatures ice had a higher μ than snow, while at high temperatures snow exhibited a higher μ than ice. It is hypothesised that this intriguing switch is due to the surface roughness change leading to differing contact areas both with and without melt water. This switch is not seen when a simple heat transfer model is used, confirming the effect as a surface roughness change. The use of a modified Hertz model shows that indentation is the dominant mechanism at low velocities on snow. It is hypothesised that at high velocities melt water dominates on both snow and ice while adhesion may have a more significant role on ice at low velocities. These findings provide knowledge that can be used in the design of tyres for snow and ice in the future.
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Abd, Karim Yahya. "Modelling the rubber tree system." Thesis, Imperial College London, 2006. http://hdl.handle.net/10044/1/49915.
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An effort is made to develop a model that aims to predict the growth and production of rubber under different environmental conditions as well as different agroforestry options. The work begins with the development of the simple static model, namely Hevea Version 1.0, which acts as a precursor for development of a dynamic model. The dynamic model, which was developed using STELLA Research Software Environment and Microsoft EXCEL is then linked to the current agroforestry model WaNuLCAS (Water, Nutrients, and Light Capture in Agroforestry Systems). STELLA is the software for building system models while Microsoft EXCEL provides data analysis, list keeping, calculations as well as presentation tools. Two sub-models were added, namely a Tapping sub-model and a Tapping Panel sub-model, as a part of process to improve the efficiency of the overall model predictions. The model was run for 20 years, representing the economics life of rubber, and the outputs of the simulation were compared with observed data for validation purposes. Results from the statistical analysis showed that the model was able to simulate the girth, latex production, above-ground biomass, leaf and twigs and wood production with efficiencies (EF) of 0.83, 0.97, 0.70, -0.15 and -4.90 respectively. EF measures the accuracy of the model in performing simulation as compared to experimental data. An optimum value of EF is 1. The negative value for leaf and twigs and wood production indicated that the observed mean value is better than predicted value. An economic analysis, based on the output of the dynamic model for different rubber agroforestry system options, showed that the option of planting maize as an intercrop with rubber before tapping, followed by selling rubber wood at the end of a 20-year of rotation gave the highest Net Present Value, Internal Rate of Return, Benefit-Cost Ratio and Annual Equivalent Value compared with the option of planting rubber as monocrop.
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Sun, Yu. "VULCANIZATION AND DEVULCANIZATION OF RUBBER." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1594830138675509.
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Uliarczyk, Jan. "Stanovení hodnoty společnosti Rubena, a.s." Master's thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-74705.
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The aim of this paper is to determine the market value of company Rubena, a.s. as of April 30, 2011 based on publicly available information. The paper begins with the theoretical part which explains basic relations and different pricing models. Such information is then applied in the practical part which begins with the introduction of the company. The market appraisal is based on the theoretical recommendations. A crutial part is therefore the strategic analysis, which is followed by the analysis of financial health. The deduction of the paper features a statement about the company value.
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Frobel, Ronald K., R. A. Jimenez, C. Brent Cluff, and Gene R. Morris. "Asphalt-Crumb Rubber Waterproofing Membrane." Water Resources Research Center. The University of Arizona, 2014. http://hdl.handle.net/10150/314283.
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No date on item. Authors' manuscript.This report is concerned with laboratory testing and field investigations of a water seepage barrier consisting of asphalt cement and reclaimed crumb-rubber tire peel. The test methods that were utilized and evaluated included the following: water vapor transmission (ASTM E96 -72, Procedure BW), water absorption (ASTM 570-72), ductility (ASTM D113-74), viscosity, toughness, and brittleness /impact resistance (ASTM 0994-72). The test results showed that the asphalt-rubber as a membrane is relatively impermeable and absorbs an insignificant amount of water. The crumb rubber effectively increases the viscosity of the asphalt cement while decreasing the ductility value. The asphalt-rubber combination exhibits a tough, impact resistant membrane with excellent waterproofing properties.
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De, Venny Alan S. "Recycling of demolished masonry rubble." Thesis, Edinburgh Napier University, 1999. http://researchrepository.napier.ac.uk/Output/6043.
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The recycling of demolished masonry rubble as the coarse aggregate in new concrete represents an interesting possibility at a time when the cost of dumping such material is on the increase. With growing concerns over the environmental impact of aggregate extraction and the continued rise in aggregate demand in the UK, it is clear that the market is now there for recycled and secondary aggregates. The present investigation consists of experimental and theoretical studies into the effects of using recycled aggregates to produce concrete instead of virgin aggregates. The aggregates used have been recycled from construction and demolition waste. The recycled aggregates were predominately made up of crushed bricks but the aggregates did contain impurities such as timber and mortar. New bricks were crushed to form an aggregate in order to investigate the properties of brick as a material without impurities. The physical properties of the various aggregates were firstly examined and compared with granite aggregate, an aggregate proven in the production of good quality concrete. Concrete was then produced with the aggregates and all the physical and mechanical properties of the concretes were examined in some detail. The results showed that recycled masonry aggregates can be used successfully to produce· concrete of an acceptable standard. New test methods were presented in this investigation to determine brick porosity and water absorption. This involved the testing of broken brick fragments under vacuum, rather than the testing of whole brick units by 5hrs boiling or 24hrs submersion in cold water. The new test methods proved to be easy to perform and provided accurate results. A new test method for estimating the strength of bricks was presented. This involved point-loading of masonry specimens to obtain strength index values. From the pointload results, equations were presented relating the strength index values of brick fragments to the compressive strength of whole brick units. This involved the development of shape factors for different masonry specimens. The point-load test is easy to perform, presents a cheaper alternative to heavy compression machines and can be used on site to determine the suitability of recycled bricks as the aggregate in new concrete.
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Al-Bermani, Abdul-Karim Khudiyer Abbas. "Taxonomic, cytogenetic and breeding relationships of Festuca rubra sensu lato." Thesis, University of Leicester, 1991. http://hdl.handle.net/2381/35431.
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Work involving morphological, anatomical, ecological, distributional, cytological and hybridization studies has been carried out on F. rubra s.l. and has led to a reclassification of this complex group. Two subgroups, F. rubra subgroup and F. trichophylla subgroup, have been recognized. In the latter subgroup, FT pseudotrichophylla, F. cyrnea, F. paucispicula and F. rubra var. iberica are scarcely distinct from each other, and they are treated as synonyms of trichophylla. F. rubra ssp. asperifolia was found to be closer to F. trichophylla than to F. rubra, so it is treated as a subspecies of F. trichophylla. In the former subgroup, F. nigrescens, F. richardsonii, F. rivularis and F. diffusa cannot be satisfactorily separated from F. rubra at species level, and are therefore treated as subspecies commutata, arctica, rivularis and megastachys respectively, along with the type subspecies and three others (litoralis, scotica and juncea). F. rubra sspp. megastachys and multiflora (together treated as F. diffusa in Flora Europaea) cannot be maintained as separate entities and are treated under the former (earlier) subspecies name. Similarly F. rubra ssp. pruinosa and F. rubra ssp. juncea have been amalgamated under the latter name. F. junci folia and F_ rubra ssp. arenaria cannot be kept separate even as subspecies, yet they are distinct from F. rubra at species level and are treated under the earlier species name F. arenaria. F. rubra ssp. scotica is recognised as a new taxon. Over 30000 intra- and inter-specific crosses within F. rubra s.l. and between F. rubra s.l. and F. ovina s.l. were carried out. The results show that within F. rubra s.l. crosses were relatively easily achieved, and that the crossability in general is positively correlated with the ploidy level of the female parent. Crosses with F. ovina s.l. were most successful between hexaploid taxa; diploid taxa were more successful as female than as male parents. Natural hybridization was shown to occur in some cases, but seems to be very rare. The inheritance of morphological and anatomical characters is presented. The course of meiosis, including an analysis of chromosome configuration of the parents and their hybrids, suggests that hexaploid, octoploid and decaploid taxa of F. rubra s.l. are segmental alloploids with a multivalent suppressor system, since both homogenetic and heterogenetic pairing commonly occurs The evolution of F. rubra s.l. and the mode of allopatric speciation are discussed.
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Miltner, Stanislav. "Pěstování dubu červeného (Quercus rubra L) v podmínkách České republiky." Doctoral thesis, Česká zemědělská univerzita v Praze, 2016. http://www.nusl.cz/ntk/nusl-259677.
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The study analyses growth and development of Northern red oak stands in the Czech Republic. The Northern red oak stands under study have the age span between 17 to 159 years. The study also investigated the influence of the species on soil upper horizons. The results show the high wood production potential of red oak when compare to sessile oak being at the same or higher quality and health. Data show slower decomposition of biomass in upper soil horizons under red oak causing acid reaction of soils. The data propose the red oak to be a good additional species in lowland stands and it could be a species which substitutes domestic oaks where tracheomycosis diseases can occur
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Chumeka, Wannapa. "Improvement of compatibility of poly(lactic acid) blended with natural rubber by modified natural rubber." Phd thesis, Université du Maine, 2013. http://tel.archives-ouvertes.fr/tel-01018026.
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The aim of this research work was to improve the compatibility of polymer blends made from poly(lactic acid) and natural rubber (PLA/NR blends) by using modified natural rubber as a compatibilizer. Natural rubber was chemically modified into two categories: natural rubber grafted poly(vinyl acetate) copolymer (NR-g-PVAc) and block copolymers (PLA-NR diblock copolymer and PLA-NR-PLA triblock copolymer). PLA/NR blends were prepared by melting blending in a twin screw extruder and compression molded to obtain a 2-mm thick sheet. The blends contained 10-20 wt% of NR and modified NR, and the impact strength and tensile properties were investigated. The compatibilization effect was determined by DMTA, DSC and SEM. NR-g-PVAc was synthesized by emulsion polymerization to obtain different PVAc graft contents (1%, 5% and 12%). Characterization by DMTA showed an enhancement in miscibility of the PLA/NR-g-PVAc blends. NR-g-PVAc could be used as a toughening agent of PLA and as a compatibilizer of the PLA/NR blend. The block copolymers were synthesized following two routes: (1) hydroxyl telechelic natural rubber (HTNR) and lactide and (2) HTNR and PLA prepolymer. In the former route, lactide was in situ polymerized via a ring opening polymerization to be a PLA block segment during block copolymerization. In the latter route PLA prepolymer was synthesized by a condensation polymerization of L-lactic acid prior to block copolymerization. Both block copolymers acted as good compatibilizers for the PLA/NR blend by increasing the impact strength and decreasing the NR particle size. Triblock copolymers provided higher impact strength than diblock copolymers, and they were a less effective compatibilizer than NR-g-PVAc. In contrast to NR and NR-g-PVAc, the block copolymer was not a good toughening agent for PLA.
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Euchler, Eric, Gert Heinrich, Hannes Michael, Michael Gehde, Radek Stocek, Ondrej Kratina, Reinhold Kipscholl, Jörg-Michael Bunzel, and Wolfgang Saal. "Fundamental studies on dynamic wear behavior of SBR rubber compounds modified by SBR rubber powder." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-198870.
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The aim of this study is focused on the experimental investigation of dynamic wear behavior of carbon black filled rubber compounds comprising pristine styrene butadiene rubber (SBR) together with incorporated SBR ground rubber (rubber powder). We also analyzed and described quantitatively the service conditions of some dynamically loaded rubber products, which are liable to wear (e.g. conveyor belts, tires). Beside the well-known standard test method to characterize wear resistance at steady-state conditions, we used an own developed testing equipment based on gravimetric determination of mass loss of rubber test specimen to investigate the influence of rubber powder content on dynamic wear depending on varying impact energy levels. Incorporation of SBR rubber powder in SBR rubber compounds increases wear. With increasing rubber powder content the wear at steady-state conditions progressively increases. However, the level of wear at dynamic loading conditions increases only once, but stays constant subsequently even with contents of incorporated rubber powder.
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Euchler, Eric, Gert Heinrich, Hannes Michael, Michael Gehde, Radek Stocek, Ondrej Kratina, Reinhold Kipscholl, Jörg-Michael Bunzel, and Wolfgang Saal. "Fundamental studies on dynamic wear behavior of SBR rubber compounds modified by SBR rubber powder." Deutsche Kautschuk-Gesellschaft e.V, 2015. https://monarch.qucosa.de/id/qucosa%3A20419.
Full textAbstract:
The aim of this study is focused on the experimental investigation of dynamic wear behavior of carbon black filled rubber compounds comprising pristine styrene butadiene rubber (SBR) together with incorporated SBR ground rubber (rubber powder). We also analyzed and described quantitatively the service conditions of some dynamically loaded rubber products, which are liable to wear (e.g. conveyor belts, tires). Beside the well-known standard test method to characterize wear resistance at steady-state conditions, we used an own developed testing equipment based on gravimetric determination of mass loss of rubber test specimen to investigate the influence of rubber powder content on dynamic wear depending on varying impact energy levels. Incorporation of SBR rubber powder in SBR rubber compounds increases wear. With increasing rubber powder content the wear at steady-state conditions progressively increases. However, the level of wear at dynamic loading conditions increases only once, but stays constant subsequently even with contents of incorporated rubber powder.
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Wysocki, Clare L. "Reinforcement of Ethylene Propylene Rubber (EPR) and Ethylene Propylene Diene Rubber (EPDM) by Zinc Dimethacrylate." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145038716.
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