Littérature scientifique sur le sujet « Latex compounding »

This article describes how a hospital pharmacy department provided total parenteral nutrition (TPN) fora known latex-allergic patient to safely meet the patient's nutritional needs and maintain proper aseptic technique during the compounding process. After numerous attempts to feed the patient enterally failed, total parenteral nutrition was recommended. It was decided that preparation and administration of parenteral nutrition for this patient should follow the recently initiated Pharmacy policy for the preparation of sterile products for latex-allergic patients as closely as possible. After reviewing the compounding process, it was determined that a base solution of protein and dextrose could be safely prepared by making sure that the products we used did not contain latex and that the process did not involve puncturing of latex-containing ports or stoppers. All other ingredients would be added manually. Prior to discharge, enteral feeding was reintroduced and the TPN solution was discontinued.

This study has developed an alternative compounding formulation and process for natural rubber latex (NRL) foams for hand exercising application. Deprotenized natural rubber latex was used as raw material and a combination of DIXP and TBzTD, which were fugitive and high molecular weight accelerators, respectively, was used to lower allergenic potential and harmful nitrosamines. The NRL foams were prepared to various densities, characterized by Scanning Electron Microscopy (SEM) and tested for hardness index, accelerated ageing and compression set in comparison to the foams with conventional compounding formulation. With the same processes, the foams with these two different formulations were found to have similar densities and hardness indices. However, the foams using DIXP and TBzTD accelerators performed better in compression set and accelerated ageing tests.

The reduced graphene oxide (rGO) modified natural rubber composite (NR) filled with high contents of silica was prepared by a wet compounding and latex mixing process using a novel interface modifier cystamine dihydrochloride (CDHC) with coagulation ability. CDHC acts as a coagulation agent through electrostatic interaction with rGO, SiO2, and latex rubber particles during the latex-based preparation process, while in the obtained silica/graphene/natural rubber composites, CDHC acts as an interface modifier. Compared with the composites prepared by the conventional mechanical mixing method, the dispersion of both rGO and SiO2 in the composites made by a wet compounding and latex mixing process is improved. As a result, the obtained silica/graphene/natural rubber composite prepared by this new method has good comprehensive properties. A Dynamic Mechanical Test suggests that the tan δ values of the composites at 60 °C decrease, indicating a low rolling resistance with increasing the graphene content at a low strain, but it increases at a higher strain. This unique feature for this material provides an advantage in the rubber tire application.

ABSTRACT Carbon nanohorn (CNH)–filled elastomer hybrid nanocomposites were prepared based on NBR. Three different CNH types were analyzed, each featuring various characteristics such as aggregate structure, specific surface area, surface energy distribution, and electrical conductivity and resulting in different potentials regarding the properties of the developed elastomers. For the CNH types, a high tendency of agglomeration was observed in the pristine state, indicating the need for an effective strategy to break up the agglomerates during the mixing or the compounding procedure to realize their incorporation and sufficient dispersion in a polymer matrix. In addition to the melt mixing technology by means of an internal lab mixer, a discontinuous static and a continuous dynamic latex compounding process were used. Carbon nanotubes and a highly conductive carbon black (Printex) were used as hybrid fillers in the compounds mixed by melt mixing, whereas two different types of carbon black (Printex and Derussol) were also incorporated in the latex experiments. Hybrid nanocomposites with low content of CNHs (≤1 wt%) show an improvement in dynamic-mechanic and physical properties due to distinctive polymer–filler interactions. Dealing with higher amounts of CNHs leads to filler reagglomeration, resulting in deterioration of the elastomer properties. For the electric conductivity assessment, addition of CNH indicates no synergistic effects and no significant increase of the hybrid compounds, which is demonstrated in dielectric measurements, although pristine CNHs are conductive themselves. Elastomer compounds processed via the latex method show enhanced material performance by using the continuous dynamic latex compounding, which is mainly attributed to the dispersion of the hybrid filler.

This study showed the effect of different compounding methods on the impact resistance and tensile properties of poly(lactic acid) blended with cassava starch and natural rubber latex. Poly(ethylene glycol) was used as a plasticizer. It was found that the compounding method was important for the derived mechanical properties of the blend. Furthermore, cooling method of the extrudate also affected the mechanical properties of the blends. The air cooling in the extrusion process provided higher mechanical properties than the water cooling. This work also showed the effect of the natural rubber in the PLA/starch blend.

L’industria degli pneumatici si prefigge di indagare possibili strategie sintetiche per ridurre l’impatto ambientale durante tutto il ciclo di vita dello pneumatico, attraverso l’uso di materiali sostenibili e lo sviluppo di tecniche innovative che riducano il consumo di energia e le emissioni di CO2. In questo contesto, questa progetto di dottorato è focalizzato sulla preparazione di nanocompositi eco-sostenibili attraverso l’uso di un approccio colloidale per aumentare la dispersione di filler idrofilici, in linea con i nuovi requisiti di sostenibilità delle politiche europee. L’approccio colloidale punta a produrre nanocompositi con filler idrofilici, la cui efficiente dispersione attraverso tecniche di miscelazione tradizionali rimane difficoltosa a causa della scarsa compatibilità con la matrice organica. Questa tecnica si focalizza sull’incremento della dispersione di filler senza alcuna modifica superficiale, con l’eliminazione delle poveri prodotte durante il mescolamento con significativi benefici per l’ambiente e i lavoratori. Due diversi approcci colloidali sono stati utilizzati: i) una tecnica di miscelazione in lattice e ii) una in situ polimerizzazione in emulsione per la produzione di nanocompositi altamente caricati contenenti filler come silice e sepiolite (Sep), questi ultimi sono considerati filler promettenti nell’ambito del rinforzo dei polimeri grazie alla loro struttura fibrosa e all’elevato rapporto di forma. La concentrazione, la carica, la forma dei nanofiller a base silicea sono stati studiati come parametri rilevanti per la stabilizzazione e destabilizzazione di lattici a base di poliisoprene naturale e sintetico. Una efficiente procedura di miscelazione in lattice è stata messa a punto per produrre compositi eco-sostenibili, chiamati masterbatches (MBs), attraverso l’incorporazione di silice o Sep nel lattice di gomma naturale (emulsione in acqua di cis-1,4-poliisoprene), attraverso la flocculazione (aggregazione risultante dalla coesione di particelle di polimero) di una miscela acquosa di nanofiller a base silicea e gomma. La tecnica di miscelazione in lattice ha dimostrato di favorire una omogenea dispersione di fibre di sepiolite idrofilica in matrice di gomma. La principali caratteristiche fisico-chimiche che controllano i processi di aggregazione in acqua come il pH, il potenziale Z, la concentrazione, assieme alle caratteristiche morfologiche del MB Sep-gomma naturale, sono state prese in considerazione allo scopo di investigare le interazioni Sep-gomma naturale. E’ stato proposto un meccanismo di flocculazione basato su attrazioni elettrostatiche e depletive, connesso all’elevato contenuto di filler (50% in peso) e alla peculiare anisotropia delle particelle di Sep. Inoltre, i MBs sono stati utilizzati per preparare compositi sostenibili attraverso la combinazione di miscelazione in lattice e mescolazione meccanica. Questo approccio combinato sfrutta la buona distribuzione del filler e previene il rilascio di polveri durante il processo. Una polimerizzazione Pickering in situ è stata considerata come alternativa per la produzione di nanocompositi eco-sostenibili. Particelle poliisoprene/filler a base silicea sono state sintetizzate sfruttando dell’effetto stabilizzante di filler inorganici che agiscono come tensioattivi riducendo la tensione superficiale e stabilizzando l’emulsione. Sulla base dei nostri risultati, viene suggerito un possibile meccanismo di polimerizzazione in emulsione stabilizzata da particelle solide. In conclusione, l’approccio colloidale, basato su miscelazione in lattice e polimerizzazione Pickering in situ, può essere considerato un metodo sostenibile, semplice ed efficace adatto per applicazioni tecnologiche altamente performanti. I risultati indicano che le strategie utilizzate sono adatte per produrre nanocompositi altamente caricati di filler a base silicea.
Sustainability has become a field of great interest in the world industry. For the scientific community the challenge lies in the identification of green synthetic approaches and new alternatives to petroleum-based materials. In the case of the tyre industry, the challenge is to identify possible design strategies and alternatives to reduce the environmental impact throughout the life cycle of tyres, by means of both the use of environmentally friendly materials and the development of innovative products, having reduced energy consumption and CO2 emissions. In this context, this PhD thesis is focused on the preparation of eco-friendly silica-based nanocomposites by using a colloidal approach to increase the dispersion of hydrophilic fillers in line with the new requirements of sustainability from the EU policies. The colloidal approach aims at compounding nanocomposites with hydrophilic fillers, whose efficient dispersion through traditional mixing still remains a challenging issue, due to their poor compatibility with the organic matrix. This technique aims at increasing the filler dispersion without any expensive surface modification, with the elimination of the volatile component released during mixing, producing significant benefits for environment and workers. Two different colloidal approaches were applied: i) latex compounding technique (LCT) and ii) in situ emulsion polymerization to prepare highly-loaded nanocomposite rubber materials containing silica-based fillers, silica and sepiolite (Sep) clay, considered a promising filler candidate for the polymer strengthening due to its fibrous structure and high particle aspect ratio (AR). The concentration, the charge and the shape of silica-based nanofillers were studied as relevant parameters on stabilization and destabilization of natural and synthetic polyisoprene latexes. An effective LCT procedure was established to produce eco-friendly composites, namely masterbaches (MBs), by incorporating silica or Sep into natural rubber latex (i.e. emulsion in water of cis-1,4-polyisoprene), through the flocculation (i.e. aggregation resulting from the bridging of polymer particles) of the silica-based nanofillers/rubber mixed aqueous system. LCT showed to favour a homogeneous dispersion of hydrophilic Sep fibers in the rubber matrix. The main physicochemical parameters which control aggregation processes in the aqueous medium, i.e. pH, -potential, concentration, as well as the morphological features of the final Sep-natural rubber MBs, were comprehensively investigated helping to figure out the Sep-NR interactions and to propose a flocculation mechanism, based on electrostatic and depletion attraction forces, remarkably connected both to the high content (50 wt.%) and to the peculiar anisotropy of Sep fibers. Furthermore, the MBs with high filler loadings were used to produce environmentally friendly composites, by combining LTC and melt mixing. This combined approach could take advantage of the good filler distribution and prevents dust from floating in the air during processing. In situ Pickering polymerization was considered as an alternative colloidal approach to produce eco-friendly nanocomposites. Polyisoprene/silica-based structured particles were synthesized on the base of the stabilizing effects of inorganic fillers which act like surfactants lowering the interfacial tension and stabilizing the emulsion. On the basis of our results, we suggested a possible mechanism for emulsion polymerizations stabilized by solid particles. In conclusion, the colloidal approach, based on both LTC and in situ Pickering emulsion polymerization, can be considered as green, simple and effective method suitable for high-performance technological applications. The outcomes indicate the suitability of the adopted strategies as a sustainable procedure for the production of high-loaded silica based-rubber nanocomposites.

The present study used a discounting task to evaluate how weight gain and weight loss aredifferentially discounted across successively greater lengths of time. Two surveys wereadministered to twenty participants that included hypothetical discounting questions. Questions included the following format, “Would you rather eat food item A for X amount of days and gainY pounds or eat food item B for X amount of days and gain 0 pounds.” The questions consisted offood item A being a high calorie/high preferred food and food item B being a moderate calorie/moderately preferred food, the X value equaled days ranging from 1 day to 600 days, and the Y value equaled the amount of weight ranging from 0.01 to 0.1 multiplied by X. Each survey was preceded with a different hypothetical scenario where unhealthy foods, moderately healthy foods, or health foods were available to eat and were incorporated into the following food choices the participants were asked to select based on preference. The results showed a difference in the levels of discounting across the two conditions, where the greatest discounting occurred when healthy foods resulted in losing weight. Exponential decay functions provided a strong fit for the two conditions (R² = 0.059, R² = 0.47, respectively), and relationships between the data in each loss or gain condition was analyzed.

In this chapter the case is made that while Hopkins studied Anglo-Saxon poetry too late for it to have a direct influence on his idiosyncratic prosody, nevertheless the poet learned much about the Anglo-Saxon language through the work of nineteenth-century philologists. In particular Hopkins’s knowledge of the writer George Marsh is investigated in detail, and applied to read several of his poems etymologically as the products of ‘fossil poetry’, including close studies of ‘The Starlight Night’ and ‘Harry Ploughman’. Hopkins’s word-compounding practice is re-examined, in view of his reading of Marsh, with particular reference to ‘The Loss of the Eurydice’, and this word-compounding practice is then brought to bear on a reconsideration of ‘sprung rhythm’.

This chapter focuses on Type 2 (lexical aspectual) compound verbs, which appear to occupy a unique position in the systems of V-V complexes in Asian languages because they make up lexical combinations with desemanticized verbs in V2. Based on diachronic data, it is suggested that this marked class of compound verbs arose in Late Middle or Early Modern Japanese via two paths: (i) reanalysis and lexicalization of aspectual auxiliary constructions in Old and Early Middle Japanese and (ii) constructionalization of a special compounding schema where V2 specifies the manner and other adverbial meanings of V1. The latter path is characterized by the desemanticization of V2s in Type 1 thematic compounds or by spontaneous coinage of new V2s with adverbial meanings. The multifaceted development of Type 2 compounds, which does not readily fit in with the standard view of item-by-item grammaticalization, presents a motivation for viewing grammaticalization as creation of a novel morphological construction.

Entrepreneurship is the impetus for development of any nation. Entrepreneurship is a revolution to ignite the minds of low spirited youth and would be considered as a means to revolutionize enterprises. Industrialization and entrepreneurship go on same lines as the former created foundation for current modernized Indian enterprises, so does later. ‘Ideas are many but execution is a cup of few'. There are many people who come up with different ideas at every point, but entrepreneurs are the one who pull off rabbit out of the magic hat. In today's world, entrepreneurship has become an act of inspiration which eventually have a compounding effect on society, benefiting the mankind. India is going through a new phase where one is going to witnesses old wine in a new bottle i.e., start-ups, which is nothing but an act of entrepreneurship, being the vantage point to all businesses. The purpose of the chapter is to articulate the potential importance the word entrepreneurship holds and the tools of IT used in entrepreneurial development.

Forced migration and disability often are ignored in the research literature. In spite of the equalities legislation for the rights of disabled people, often the responses to disabled migrants are not helpful. In theory, the UK’s National Health Service is founded on the basic principle of universalism. The theoretical hegemonic commitment to universal human rights has often been most overtly broken in relation to migrant rights. In contrast to official condemnation of racism and disablism, successive governments of different political persuasions have continued to, and indeed competed to, prove their hostility towards migrants, whether they are disabled or not. The British asylum system itself is disabling by design. Some people are disabled on arrival in the UK; others become disabled later on. Disabled asylum seekers often describe the system as psychological torture. Therefore, ongoing mental distress can create difficulties in further adjustment, thus compounding problems. Using case histories, this chapter illustrates some of the difficulties faced by migrants with disabilities. A fundamental systemic change is needed to address the injustice encountered by disabled asylum seekers.

Abstract For over two decades multilateral technology has extended the production life of fields in the North Sea by continuing to evolve to meet the demands of increasingly complex deepwater applications. The use of multilateral technology delivers a higher recovery factor supported by the cumulative production of the multiple laterals. Over this history, multilateral applications have evolved from dual-laterals with standalone screens and commingled flow to the subject well of this paper whose slot has been kept active for over two decades through the use of re-entry multilateral systems. The well was originally completed as a dual-lateral and has since been recompleted twice to produce reserves previously left behind. As investment and availability of new fields decline, operators face challenges to extend the production life of mature fields while also working to reduce overall development cost, cycle times, and carbon footprint. Further challenges include delivery of wells and facility systems using less in-field construction hours at a lower baseline cost. The expectation is that the projects will also reduce typical greenhouse gas emissions compared with traditional pads. This paper will focus on the evolution of a mature field in a region that has been installing multilateral wells for over two decades. Wells originally drilled as dual-laterals have several years later been re-drilled as tri-lateral installations. As the wells once again reached the end of their expected production life, the use of re-entry multilateral technology has been utilized to extend field life for further economic production. This paper discusses three multilateral installations on the same subsea well over a 20-year period. It highlights the technology used to keep this well slot active for over two decades and the benefits of expanding the use of this technology as fields become slot restricted. It also highlights the benefits this technology delivers in enhancing reservoir exposure and the time savings brought by drilling new lateral legs in existing subsea wells without spending significant time having to first retrieve the xmas tree or tieback liner. The case study will include discussion of workover operations, completions, isolation methods, and lateral creation systems. Through three separate multilateral installations in one subsea slot, the production life has been extended beyond 20 years. The paper focuses on a particular multilateral well and the technology used to extend its production life past two decades. The paper also provides insight as to methodology for continually improving reliability of multilateral installations to maximize efficiencies.

Abstract For over two decades multilateral technology has extended the production life of fields in the North Sea by continuing to evolve to meet the demands of increasingly complex deepwater applications. The use of multilateral technology delivers a higher recovery factor supported by the cumulative production of the multiple laterals. Over this history, multilateral applications have evolved from dual-laterals with standalone screens and commingled flow to the subject well of this paper whose slot has been kept active for over two decades through the use of re-entry multilateral systems. The well was originally completed as a dual-lateral and has since been recompleted twice to produce reserves previously left behind. As investment and availability of new fields decline, operators face challenges to extend the production life of mature fields while also working to reduce overall development cost, cycle times, and carbon footprint. Further challenges include delivery of wells and facility systems using less in-field construction hours at a lower baseline cost. The expectation is that the projects will also reduce typical greenhouse gas emissions compared with traditional pads. This paper will focus on the evolution of a mature field in a region that has been installing multilateral wells for over two decades. Wells originally drilled as dual-laterals have several years later been re-drilled as tri-lateral installations. As the wells once again reached the end of their expected production life, the use of re-entry multilateral technology has been utilized to extend field life for further economic production. This paper discusses three multilateral installations on the same subsea well over a 20-year period. It highlights the technology used to keep this well slot active for over two decades and the benefits of expanding the use of this technology as fields become slot restricted. It also highlights the benefits this technology delivers in enhancing reservoir exposure and the time savings brought by drilling new lateral legs in existing subsea wells without spending significant time having to first retrieve the xmas tree or tieback liner. The case study will include discussion of workover operations, completions, isolation methods, and lateral creation systems. Through three separate multilateral installations in one subsea slot, the production life has been extended beyond 20 years. The paper focuses on a particular multilateral well and the technology used to extend its production life past two decades. The paper also provides insight as to methodology for continually improving reliability of multilateral installations to maximize efficiencies.

In many industrial gas turbine compressor designs, the compressors later stage blade angles are reduced in a constant flow area section as a means to even out the per stage workload. Most compressors use NACA 65 series type airfoils, which are good for high subsonic and supersonic flow, but are poor for middle or low subsonic flows. The temperature increases as the compression ratio increases; which cause the Mach number to drop. With reduced blade cascade overlaps, a reduction in axial blade solidity results. The compounding effect of low solidity and a low Mach number can cut the stalling angle by several degrees. This recent study found that compressor stall more or less is linked to the change of moment coefficient Cm, rather than lift coefficient Cl. Designing the airfoil, by extending the constant moment coefficient to a higher angle of attack region can delay the trailing edge upper surface separation to a higher angle of attack, the main source of rotating stall. This separated flow exhibits itself more clearly on the moment coefficient, but is obscured by an increase in lift coefficient before “aerodynamic” stall. This new design is based on the second order derivative of the camber line, with a low drag symmetrical airfoil thickness. Numerical simulation of a single airfoil and cascade of the new airfoil is compared with other shapes. The results show that the trailing edge flow separation begins at a 9.5-degree angle of attack for the NACA 65 series airfoils. The NACA 0012 separation (i.e. change in Cm) starts at 5 degrees (total stall occurs at 11 degrees). The new airfoil CFS18-0010 exhibits no separation for a single airfoil of up to 12 degrees. The cascade results showed no flow separation up to an angle of 15 degrees, which is enough to eliminate most of the rotating stall.

The effect of directional orientation of Chopped steel wool fiber in a friction material matrix / Brake pads that influences Friction, Wear and Mechanical properties of the Brake pads have been evaluated in a phenolic resin-based asbestos-free semi-metallic friction material composition. </p><p>Brake pad compositions widely use chopped steel wool fibers having a nominal length of less than 10 mm; diameter of about 500 microns; carbon content between 0.05 – 0.15 % as reinforcement. During compounding and mixing of friction material formulation, chopped Steel wool fibers along with dozen other raw materials are mixed/homogenized using plough shear mixer resulting in the steel fibers dispersed and oriented randomly in different plan and direction in the mixture and so over the final brake pad matrix too. </p><p>Trials have been carried out in Fricmart’s prototype Lab to orient chopped steel wool fiber in an uni directional plan in various semi-metallic formulations and progress has been achieved only in a medium- steel brake pad formulation that contains about 25% chopped steel fibers. Fricmart’s S-428 grade Steel wool fiber conforming to the above said specification has been used in the experiments. Fibers were initially classified using a set of sieves to remove the fines having diameter and length less than 200 microns and 3 mm respectively to meet the desired loose density / bulk density limit of 0.55 – 0.70 gm/cc to support the process of orientation. Further, a brake pad model that has rectangular geometry ( Merc. W-123 Pad) with an area of about 50 sq. cm was chosen to conduct the trials and to support the process of orientation. Brake pads were molded using conventional compression molding process at temp. of 150 deg. C with specific pressure of 250 bar and 6 minutes curing followed by 4 hours step curing ( post-baking ) to max. temp. of 180 deg. C in an air oven . Preparation of Samples: Sample 1 -By employing bi-directional magnetic field coupled with other special charging chute and dispersing techniques, the desired orientation of chopped steel wool fiber that was targeted to be parallel to the sliding direction of the brake (pad) was achieved to a level of more than 90% evenly oriented throughout the layer and matrix of the brake pad. Fricmart’s PLM – Stereo Microscope surveillance facility is used to ascertain percentage orientation during trials. Sample - 2: Brake pads processed as above by “parallel orientation to sliding direction’’ have later been used to study the effect of “orientation in perpendicular to the sliding direction’’ just by “inverting the new sample” specimen at the time of testing. Sample - 3: One set of brake pads were processed as per industries standard using the same batch/composition of raw materials with a random distribution of chopped steel wool fiber under identical process condition without carrying out directional orientation. Testing & Evaluation:The samples were cut from the brake pad and tested in Chase Type Friction Tester as per SAE J661 – small sample testing and the following are the observations. Internal shear measured as per ISO 6311 of sample -1 was significantly higher than sample – 2 & least in the case of sample 3 Faster bedding or faster adaptability to the disc in case of the sample- 1. 80% bedding achieved within 10 minutes of burnishing as compared to 20 minutes in case of samples- 2 & 3. The coefficient of friction is also dependent on the fiber orientation and µ for the developed pad ranges between 0.35 and 0.40. Fade resistance for samples 1 & 2 is superior when compared to sample 3.</p><p>Further, it was observed that as temperature increases, initially there was abrasion/plowing and on a further rise in temperature, a transfer film was developed making the steady-state friction. The wear rates decreased if the sliding path/direction changes from parallel to the perpendicular direction. The worn surface morphology was studied using FESEM and found that wear resistance is found to relate to the stability of the developed film. Sample 1 with the fibers oriented parallel to the sliding direction exhibited smoother running whereas sample 2 created undesirable judder noise. Hence it can be concluded that the Orientation of fibers with respect to sliding direction is preferable to the randomly oriented fibers towards frictional characteristics.