Tesi sul tema "Grafted silica nanoparticle"
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1
Tang, Saide. "Self-Assembly of Polymer Brush-Grafted Silica Nanoparticles". Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1451396345.
2
Issa, Sébastien. "Synthèse et caractérisation d'électrolytes solides hybrides pour les batteries au lithium métal". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0046.
Abstract (sommario):
Les problématiques engendrées par l’extraction et l’utilisation intensives des ressources fossiles ont forcé l’humanité à se tourner vers le développement d’énergies renouvelables et de véhicules électriques. Cependant, ces technologies doivent être couplées à des moyens de stockage de l’énergie efficaces pour exploiter leur potentiel. Les systèmes embarquant une anode de lithium métallique sont particulièrement intéressants car ils présentent une densité d’énergie élevée. Cependant, cette technologie souffre de la formation de dendrites pouvant déclencher des courts-circuits provoquant l’explosion du dispositif. Ainsi, de nombreux efforts ont été consacrés à l’élaboration d’électrolytes solides polymères (SPE) à base de POE permettant de constituer une barrière qui bloque la croissance dendritique tout en préservant les propriétés de conduction ionique. Cependant, la conductivité ionique des SPE à base de POE décroît fortement avec la température. A l’heure actuelle, les meilleurs SPE de la littérature nécessiteraient de fonctionner à 60 °C, ce qui signifie qu’une partie de l’énergie de la batterie sera détournée de son utilisation pour maintenir cette température. Ainsi, l’objectif principal de ce travail de thèse est de concevoir un SPE permettant le fonctionnement de la technologie de batterie au lithium métal à température ambiante. Ces SPE doivent présenter une conductivité ionique élevée à température ambiante (≈ 10-4 S.cm-1) et des propriétés mécaniques permettant l’inhibition du phénomène de croissance dendritique. Pour cela, les objectifs du projet sont focalisés sur le développement de nouveaux SPE nanocomposites et hybridesThe problems caused by the intensive extraction and use of fossil fuels have forced humanity to turn to the development of renewable energies and electric vehicles. However, these technologies need to be coupled with efficient energy storage means to exploit their potential. Lithium metal anode systems are particularly interesting because they have a high energy density. However, this technology suffers from the formation of dendrites that can trigger short circuits causing the device to explode. Thus, many efforts have been devoted to the development of POE-based solid polymer electrolytes (SPEs) that provide a barrier that blocks dendritic growth while preserving ionic conduction properties. However, the ionic conductivity of POE-based SPEs decreases strongly with temperature. Currently, the best SPEs in the literature would require operation at 60 °C, which means that some of the energy in the battery will be diverted from its use to maintain this temperature. Thus, the main objective of this thesis work is to design an SPE that allows the operation of lithium metal battery technology at room temperature. These SPEs must exhibit high ionic conductivity at room temperature (≈ 10-4 S.cm-1) and mechanical properties that allow the inhibition of the dendritic growth phenomenon. For this, the objectives of the project are focused on the development of new nanocomposite and hybrid SPEs
3
Khlifa, Moussa Abrahim Saleh. "Synthesis of polymer grafted silica nanoparticles : effect of grafting on mechanical reinforcement". Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2691.
Abstract (sommario):
A series of polymer-silica nanocomposites were prepared by grafting poly(methyl methacrylate), poly(butyl acrylate), polystyrene and poly(styrene-co-acrylonitrile) from both aggregated silica nanoparticles and colloidally dispersed silica using atom-transfer radical polymerisation (ATRP). Cross-linking and macroscopic gelation were minimised by using a miniemulsion system. The grafted polymers silica nanoparticles were characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM), gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), fourier transform infrared spectroscopy (FTIR) and elemental analysis. The thermal and mechanical behaviour of the nanocomposites have been examined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Grafting polymers chains from the surface of the nanoparticles gave materials with a 10 oC higher glass transition temperature Tg (according to DSC and DMTA) compared to the pure polymers. DMTA measurements revealed that chain grafted nanocomposites showed an increased modulus and significantly lower high-temperature damping over the neat polymers. In contrast, samples prepared from colloidally dispersed silica nanoparticles exhibited a much less pronounced reinforcement effect than aggregated silica and also showed little change in Tg. Further information on the temperature dependence of the relaxation process was obtained using time temperature superposition. A fast and efficient microwave-assisted method for ring-deuteration of polystyrene and poly(4-hydroxystyrene) using “superheated” C6D6 or D2O in sealed microwave reaction vials has also been developed. The optimised procedure will make future work using neutron scattering possible.
4
Samaratunga, Ashani Rangana. "Efficacy and Recovery of Cellulases Immobilized on Polymer Brushes Grafted on Silica Nanoparticles". Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27212.
Abstract (sommario):
Cellulosic biofuels can be more economical if cellulases are recovered and reused.
Cellulase and ?-glucosidase were immobilized on poly(acrylic acid) brush particles. Impact of brush enzyme density on efficacy and recovery was tested. Use of free enzymes led to higher
sugar concentrations than the attached for both the enzymes. Increasing cellulase density on the
brushes did not impact efficacy. Higher proportions of cellobiose in hydrolyzates suggest
differential attachment or efficacy of attached enzymes. Higher ?-glucosidase density on brushes led to increased glucose concentrations. Density on brushes did not impact ?-glucosidase recovery and [approximately] 66% was recovered. Effect of pH and temperature on hydrolysis rates and enzyme recovery was modeled. Free ?-glucosidase was more stable with temperature than attached. Optimal pH for attached cellulase and ?-glucosidase was 4.98 and 4.39, respectively. Recovery of ?-glucosidase decreased with increasing pH and was not impacted by temperature.National Science Foundation (NSF)
5
Fashina, Adedayo, Edith Amuhaya e Tebello Nyokong. "Photophysical studies of newly derivatized mono substituted phthalocyanines grafted onto silica nanoparticles via click chemistry". Elsevier, 2015. http://hdl.handle.net/10962/d1020287.
Abstract (sommario):
This work reports on the synthesis, characterization and photophysical studies of newly derived phthalocyanine complexes and the phthalocyanine–silica nanoparticles conjugates. The derived phthalocyanine complexes have one terminal alkyne group. The derived phthalocyanine complexes showed improved photophysical properties (ФF, ФT, ΦΔ and τT) compared to the respective phthalocyanine complexes from which they were derived. The derived phthalocyanine complexes were conjugated to the surface of an azide functionalized silica nanoparticles via copper (1) catalyzed cyclo-addition reaction. All the conjugates showed lower triplet quantum yields ranging from 0.37 to 0.44 compared to the free phthalocyanine complexes. The triplet lifetimes ranged from 352 to 484 μs for the conjugates and from 341 to 366 μs for the free phthalocyanine complexes.
6
Duda, Radek. "Analýza nanostruktur metodou ToF-LEIS". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234584.
Abstract (sommario):
The presented thesis deals with the utilization of TOF-LEIS analytical method in the area of nanostructure analysis. A new procedure for depth profiling of the elemental composition of the sample, based on the alternate measurement with the DSIMS method, was established. The TOF-LEIS method is able to detect the interface between the layers before its mixing by the ion beam of the DSIMS method. Furthermore, a procedure of TOF-LEIS spektra modification was established to obtain the actual concentration of elements in the sample by reduction of a multiple collision contribution. By comparison of TOF-LEIS spectra with the results received by the DSIMS method the ratio of molybdenum and silicon ion yields was obtained. In the next section advantages of the TOF-LEIS method in combination with XPS during analysis of thermal stability of gold nanoparticles are presented. The mutual complementarity of both methods is shown and final conclusions are supported by electron microscopy images. The final section deals with a newly assembled apparatus for the TOF-SARS analytical method and shows its possibilities regarding the detection of hydrogen on the graphene.
7
Huang, Hao-Kuan, e 黃豪寬. "Synthesis of nano-scale colloidal silica from elemental silicon by hydrolysis, and synthesis of polymer-grafted silica nanoparticle, polymer-grafted graphene oxide, and polymer-grafted exfoliated graphene nanoplatelet with core-shell structure as low-profile additives and tougheners for unsaturated polyester and vinyl ester resins by RAFT living free radical solution polymerizations". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/29945158148023952847.
Abstract (sommario):
碩士國立臺灣科技大學
化學工程系
103
Synthesis of nano-scale inorganic/organic core-shell particle (CSP) as low-profile additives (LPA) and toughenors for thermoset resins, and their effects on the cured sample morphology, volume shrinkage characteristics and mechanical properties for low-shrink vinyl ester resins (VER) during the cure were investigated. These CSP designated as SiO2-polymer or GO-polymer, the former of which contained silica nanoparticle (SNP) as the core and the latter of which contained graphite oxide(GO) as the cure and both of them with organic polymer as the shell, were synthesized by the Z supported reversible addition-fragmentation chain transfer (RAFT) graft polymerization using silica-supported or graphite oxide-supported 3-(benzylsulfanylthiocarbonylsulf- anl) propionic acid (SiO2-BSPA or GO-BSPA) as the chain transfer agent (CTA). The silica nanoparticle with a diameter of 15 nm was synthesized by size-controllable hydrolysis of elemental silicon, and the graphite oxide(GO) was synthesized from natural graphites with average particle size of 2 to 15μm. The grafted polymer as the shell of the SiO2-polymer or GO-polymer was made from poly(methyl acrylate)(PMA), copolymer of MA and glycidyl methacrylate(poly(MA-co-GMA)),poly(butylacrylate)-block-poly(methyl acrylate) (PBA-b-PMA) or PBA-block-poly(MA-co-GMA). Structure characterizations of BSPA, SiO2-BSPA, SiO2-polymer, GO-BSPA and GO-polymer have been performed by using FTIR, 1H-NMR, 13C-NMR, GPC and DSC. In this work, the effects of SiO2-polymer and GO-polymer on the volume shrinkage characteristics and mechanical properties of the styrene(St)/ vinyl ester(VER)/ SiO2-polymer or (GO-polymer) ternary systems during the cure have also been explored.
8
Chung, Wan-lun, e 鍾宛倫. "Synthesis of nano-scale colloidal silica from elemental silicon by hydrolysis, and synthesis of polymer-grafted silica nanoparticle and polymer-grafted monomorillonite clay with core-shell structure as low-profile additives and tougheners for unsaturated polyester, vinyl ester, and epoxy resins by RAFT living free radical solution polymerizations". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/58613975785769985529.
Abstract (sommario):
碩士國立臺灣科技大學
化學工程系
102
Synthesis of nano-scale inorganic/organic core-shell particle (CSP) as low-profile additives (LPA) and toughenors for thermoset resins, and their effects on the cured sample morphology, volume shrinkage characteristics and mechanical properties for low-shrink vinyl ester resins (VER) during the cure were investigated. These CSP designated as SiO2-polymer, which contained silica nanoparticle (SNP) as the core and organic polymer as the shell, were synthesized by the Z supported reversible addition-fragmentation chain transfer (RAFT) graft polymerization using silica-supported 3-(benzylsulfanylthiocarbonylsulf- anl) propionic acid (Si-BSPA) as the chain transfer agent (CTA). The silica nanoparticle with a diameter of 15 nm was synthesized by size-controllable hydrolysis of elemental silicon, whereas the grafted polymer as the shell of the SiO2-polymer was made from poly(methyl acrylate) (PMA), copolymer of MA and glycidyl methacrylate (poly(MA-co-GMA)), poly(butyl acrylate)-block-poly(methyl acrylate) (PBA-b-PMA) or PBA-block-poly(MA-co-GMA). Depending on the molecular weight of the VER resin matrix employed, the content of CSP, and the shell composition of CSP, the CSP could lead to a reduction of cyclization reaction for VER resins during the cure, and the microgel structure during the cure would be less compact, and, in turn, be favorable for the decrease of intrinsic polymerization shrinkage after the cure. It was found that with the adjustment of VER molecular weight to prevent the phase separation of the St/VER/SiO2-polymer ternary system prior to cure, adding a higher content of SiO2-polymer as an LPA in the VER resin may result in a lower volume shrinkage after cure, and adding 10% of 15 nm size of SiO2- polymer can lead to a decrease of volume shrinkage by 80%. Also, adding 10% of 15 nm size of SiO2- polymer can result in an increase of impact strength and Young’s modulus, by 80% and 25%, respectively, but a decrease of tensile strength by 30%.
9
Lin, Hsiao-chien, e 林曉倩. "Nitroxide Polymer Brushes Grafted onto Silica Nanoparticles as Cathodes for Organic Radical Batteries". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/80141698288157113057.
Abstract (sommario):
碩士國立中山大學
化學系研究所
100
Nitroxide polymer brushes grafted on silica nanoparticles as binder-free cathode for organic radical battery have been investigated. Scanning electron microscopy, transmission electron microscopy, infrared spectroscopy and electron spin resonance confirm that the nitroxide polymer brushes are successfully grafted onto silica nanoparticles via surface-initiated atom transfer radical polymerization. The thermogravimetric analysis results indicate that the onset decomposition temperature of these nitroxide polymer brushes is found to be ca. 201 ◦C. The grafting density of the nitroxide polymer brushes grafted on silica nanoparticles is 0.74–1.01 chains nm−2. The results of the electrochemical quartz crystal microbalance indicate that the non-crosslinking nitroxide polymer brushes prevent the polymer from dissolving into organic electrolytes. Furthermore, the electrochemical results show that the discharge capacity of the polymer brushes is 84.9–111.1 mAh g−1 at 10 C and the cells with the nitroxide polymer brush electrodes have a very good cycle-life performance of 96.3% retention after 300 cycles.
10
Yang, Jian-jhe, e 楊建哲. "Synthesis and applications of nitroxide radical polymer brushes grafted onto silica nanoparticles and Fe3O4@SiO2 core-shell nanoparticles". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/88968600508672208541.
Abstract (sommario):
碩士國立中山大學
化學系研究所
100
Nitroxide radical groups grafted on silica have been synthesized. The catalytic oxidation of alcohols to aldehydes and ketones using the nitroxide radical groups as a catalyst was also investigated. The results of scanning electron microscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy confirmed that the nitroxide radical groups are successfully grafted onto silica. The yield of the catalytic oxidation using the catalysts is higher than 99%. The catalysts are easily recovered. Furthermore, the reused catalysts still keep high performance in the catalytic oxidation.
11
Lin, Wei-Ching, e 林暐靜. "Synthesis of Nano-scale Colloidal Silica from Elemental Silicon by Hydrolysis, and Effects of Silane-grafted Silica Nanoparticles, Reactive Microgel Particles, and Silane-grafted and Polymer-grafted Graphene Oxide and Thermally Reduced Graphene Oxide on the Cure Kinetics, Glass Transition Temperatures, and X-ray Scattering Characteristics for Vinyl Ester Resins". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/a2yyyd.
Abstract (sommario):
碩士國立臺灣科技大學
化學工程系
107
In this study, silica nanoparticles(SNP) with a diameter ranging from15 nm to 60 nm were synthesized by size-controllable hydrolysis of elemental silicon. The effects of six other additives, including (1) reactive microgel particles, (2)graphene oxide,(3)thermally reduced graphene oxide, (4) polymer-grafted thermally reduced graphene oxide, (5) silane-grafted graphene oxide, and (6) silane-grafted silica nanoparticles on the cure kinetics, glass transition temperature and X-ray scattering characteristics for the styrene(St)/vinyl ester resin(VER)/special additives ternary systems after the cure have also been investigated. The particle size distribution of silica nanoparticles was measured by dynamic light scattering (DLS) samples such as and identified (1) graphene oxide, (2) thermally reduced graphene oxide, (3) polymer-grafted thermally reduced graphene oxide, (4) silane-grafted graphene oxide, and (5) the VER in dilute St/VER binary system were also characterized by X-ray scattering methods (SAXS and WAXS). Moreover, the reaction kinetics for the St/VER/special additive ternary system during the cure was measured by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The viscosity of the St/VER/special additive ternary system was measured by using a falling ball viscometer. Finally, based on the Takayanagi mechanical models, the glass transition temperature in each region of the cured samples for St/VER/special additive ternary system has been measured by dynamic mechanical analysis (DMA).
12
Liao, Wan-Ju, e 廖婉儒. "Synthesis of nano-scale colloidal silica from elemental silicon by hydrolysis, and effects of silane-grafted silica nanoparticles, core-shell rubbers, reactive microgel particles, and silane-grafted and polymer-grafted graphene oxide and thermally reduced graphene oxide on the cure kinetics, glass transition temperatures, and X-ray scattering characteristics for epoxy resins". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/54w685.
Abstract (sommario):
碩士國立臺灣科技大學
化學工程系
106
In this study, silica nanoparticles(SNP) with a diameter ranging from 15 nm to 60 nm were synthesized by size-controllable hydrolysis of elemental silicon. The effects of six other additives, including (1) nano-scale and submicron-scale core-shell rubber additive, (2) reactive microgel, (3) graphene oxide, (4) thermally reduced graphene oxide, (5) polymer-grafted thermally reduced graphene oxide (6) silane-grafted graphene oxide and thermally reduced graphene oxide, on the cure kinetics, glass transition temperature and X-ray scattering characteristics for the styrene(St)/vinyl ester resin(VER)/special additives and epoxy resin(EPR)/ DDM/special additives ternary systems after the cure have also been investigated. In addition, the chemical structures of functionalized graphene oxide (GO) and functionalized thermally reduced graphene (TRGO) and polymer-grafted thermally reduced graphene oxide and silane-grafted graphene oxide and silane-grafted thermally reduced graphene oxide were also characterized by Raman Spectroscopy (RS). Moreover, the reaction kinetics for the St/VER/special additive and Epoxy/DDM/ special additive ternary system during the cure was measured by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Finally, based on the Takayanagi mechanical models, the glass transition temperature in each region of the cured samples for Epoxy/DDM/special additive ternary system has been measured by dynamic mechanical analysis (DMA).
13
Huang, Pei-Yu, e 黃姵瑜. "Synthesis of nano-scale colloidal silica from elemental silicon by hydrolysis, and effects of core-shell rubber, inorganic silica nanoparticles, silane-grafted and polymer-grafted graphene oxide and thermally reduced graphene oxide on the cure kinetics and glass transition temperatures for vinyl ester resins". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3q7swx.
Abstract (sommario):
碩士國立臺灣科技大學
化學工程系
105
In this study, silica nanoparticles(SNP) with a diameter ranging from15 nm to 60 nm were synthesized by size-controllable hydrolysis of elemental silicon. The effects of five other additives, including (1) nano-scale and submicron-scale core-shell rubber additive , (2) graphene oxide, and (3) thermally reduced graphene oxide, (4) polymer-grafted graphene oxide (5) silane-grafted graphene oxide, on the cure kinetics, glass transition temperature and X-ray scattering characteristics for the styrene(St)/vinyl ester resin(VER)/special additives ternary systems after the cure have also been investigated. In addition, the chemical structures of functionalized graphene oxide (GO) and functionalized thermally reduced graphene (TRGO) and polymer-grafted graphene oxide and silane-grafted graphene oxide were also characterized by Raman Spectroscopy (RS). Moreover, the reaction kinetics for the St/VER/special additive ternary or tetra system during the cure was measured by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Finally, based on the Takayanagi mechanical models, the glass transition temperature in each region of the cured samples for St/VER/special additive ternary system has been measured by dynamic mechanical analysis (DMA).
14
Wu, Chen-Yu, e 吳晨瑜. "Synthesis of nano-scale colloidal silica from elemental silicon by hydrolysis, and effects of nano-scale and submicron-scale core-shell rubber additives, inorganic silica nanoparticles, silane-grafted and polymer-grafted graphene oxide and thermally reduced graphene oxide, and reactive microgel particle on the cure kinetics, glass transition temperatures, and X-ray scattering characteristics for vinyl ester resins". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/92054015694380640503.
Abstract (sommario):
碩士國立臺灣科技大學
化學工程系
104
In this study,silica nanoparticles(SNP) with a diameter ranging from15 nm to 60 nm were synthesized by size-controllable hydrolysis of elemental silicon, which can be used as a special additive for vinyl ester resins(VER) in the volume shrinkage control and mechanical property improvements . The effects of three other additives, including (1) nano-scale and submicron-scale core-shell rubber additive , (2) graphene oxide, and (3) thermally reduced graphene oxide . On the cure kinetics, glass transition temperature and X-ray scattering characteristics for the Styrene(St)/Vinyl ester resin(VER)/special additives ternary systems after the cure have also been investigated. The 15 nm silica nanoparticles was then given the surface treatment by the silane coupling agent, 3-methacryloxypropyltrimethoxysilane (γ-MPS),to obtain the MPS SiO2. In this work, the effects of MPS-SiO2 on the cured sample morphologies, and mechanical properties of the styrene(St)/ vinyl ester(VER)/MPS-SiO2 ternary systems during the cure have also been explored. The scattering intensity of vinyl ester resin (VER) with different chemical structure in dilute styrene solution was measured by the method of small angle X-ray scattering (SAXS), and the radius of gyration of VER can then be calculated by using the Guinier law. The phase separation of the cured St/VER/CSR ternary system can be studied by measuring the X-ray scattered intensity profile of the cured specimens for St/VER/CSR ternary system by using small angle X-ray scattering (SAXS). In addition, the chemical structures of functionalized graphene oxide (GO) and functionalized thermally reduced graphene (TRGO) were also characterized by Raman Spectroscopy (RS). Moreover, the reaction kinetics for the St/VER/special additive ternary or tetra system during the cure was measured by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Finally, based on the Takayanagi mechanical models, the glass transition temperature in each region of the cured samples for St/VER/special additive ternary system has been measured by dynamic mechanical analysis (DMA).
15
Tassia, Yuliana, e 許麗琪. "Effects of silane-grafted silica nanoparticles and montmorillonite clay on the volume shrinkage, internal pigmentability, mechanical properties and cured sample morphology for unsaturated polyester, vinyl ester, and epoxy resins". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75680818314138415635.
Abstract (sommario):
碩士國立臺灣科技大學
化學工程系
101
The synthesis of silane-grafted silica nanoparticles with different size (d = 15 and 30 nm) and montmorillonite clay (MMT) with the subsequent characterization of the grafting efficiency, grafting density, as well as the surface silanol groups conversion have been carried out. The silane coupling agents used for the treatment are γ-methacryloxy propyl trimethoxy silane (MPS) and γ-glycidyloxy propyl trimethoxy silane (GPS). The effects of those silane-modified silica nanoparticles and MMT on the volume shrinkage characteristics, internal pigmentability, mechanical properties, and cured sample morphology for styrene (St)/unsaturated polyester (or vinyl ester)/additive ternary systems have been carried out. The number of silane coupling agents grafted on the MMT or silica surface and their silanol groups conversion were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The cured sample morphology was observed by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The volume shrinkage of the cured sample was measured by density method. Mechanical properties of the St/VER(n=2)/MPS-grafted silica (d = 30 nm) was investigated by using the universal testing machine and impact tester. The addition of silane-grafted MMT or silica nanoparticles reveals different results in the reduction of volume shrinkage for different UP or VER, each with different molecular weight, which is due to the incompatibility of the ternary system. Higher viscosity of the resin matrix, the characteristics of the silane-grafted MMT or silica nanoparticles, and the interfacial adhesion determine the sufficient incompatibility between the additive and the resin matrices. Therefore, an acceptable volume shrinkage and even a volume expansion could be achieved.
16
Wang, Yu-Jhen, e 王妤榛. "Synthesis of silane-grafted graphene oxide (sg-GO) and silane-grafted thermally reduced graphene oxide (sg-TRGO), and effects of nano-scale and submicron-scale core-shell rubber additives, inorganic silica nanoparticles, GO, TRGO, and reactive microgel particle on the volume shrinkage, mechanical properties, cured sample morphology, and X-ray scattering characteristics for vinyl ester resins". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/49464116337646099748.
Abstract (sommario):
碩士國立臺灣科技大學
化學工程系
104
The effects of graphene oxide (GO), low grafting density silane-grafted graphene oxide (LD-sg-GO), high grafting density silane-grafted graphene oxide (HD-sg-GO), thermally reduced graphene oxide (TRGO), and silane-grafted thermally reduced graphene oxide (sg-TRGO) as special addities on the cured sample morphologies, volume shrinkage characteristics and mechanical properties for low-shrink vinyl ester resins (VER) cured at 120 oC were investigated. The TRGO was produced by placing the GO in a high-temperature furnace kept at 1050 oC for 30 s, which was synthesized from natural graphites with average particle size of 2 to 15 μm by a modified Hummers method. The sg-GO was synthesized by using the silane coupling agent bearing acrylic C=C bonds, namely, γ-methacryloxy propyl trimethoxy silane (MPS), as a surface modifier for the surface treatment of GO at varied reaction temperatures (60 oC-100 oC) and reaction times (1.5 hr-48 hr), with different times of reaction for surface treatment between GO and MPS (n=1 or 3), using different reagents, such as toluene, ethanol and dimethyl formamide, as the solvent and with a fixed weight ratio of GO/MPS/solvent at 1:5:94, where the grafting density was 112 mmole MPS/100 g GO and 492 mmole MPS/100 g GO for low grafting density of silane-grafted GO (LD-sg-GO) and high grafting density of silane-grafted GO (HD-sg-GO), respectively, as measured by FTIR. As for the silane-grafted TRGO (sg-TRGO), the grafting density was 83 mmole MPS/100 g TRGO, as measured by FTIR. Depending on the type of GO and their contents (0.5 wt% to 5.0 wt% for GO and sg-GO, and 0.5 wt% to 1.0 wt% for TRGO and sg-TRGO) added, the GO could lead to a reduction of volume shrinkage after the cure to differing degrees. In general, a higher content of GO may result in a lower volume shrinkage after cured. Among the four additives studied in this work, namely, GO, sg-GO, TRGO, and sg-TRGO at a fixed content of additive, sg-TRGO and TRGO would result in the best volume shrinkage control, followed by sg-GO and GO. The performance of volume shrinkage control was quite close to each other for the 5.0 wt% GO and the 0.5 wt% sg-GO systems, whereas the 0.5 wt% sg-TRGO system and 0.5 wt% TRGO system could lead to a better volume shrinkage control than the 0.5 wt% sg-GO system. In this work, it has been found that adding 0.5 wt% of TRGO, 0.5 wt% of sg-TRGO or 1.0 wt% sg-TRGO as the LPA for the St/VER(n=2)/additive ternary system during the cure at 120 oC is the best recipe for a good volume shrinkage control, which exhibited a fractional volume shrinkage of 2.6%, about one half of that for the neat VER cured system. However, the 1.0 wt% sg-TRGO ternary system would possess the best mechanical properties, exhibiting a slight increase of 10% in Young’s modulus, and a slight decrease of 5% in tensile strength, and a 100% increase in impact strength, when compared with that of neat VER(n=2) cured system.