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Rubber Particles (rubber + particle)
Selected AbstractsPhotoreactive nanomatrix structure formed by graft-copolymerization of 1,9-nonandiol dimethacrylate onto natural rubberJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2010Yoshimasa Yamamoto Abstract Formation of photoreactive nanomatrix structure was investigated by graft-copolymerization of an inclusion complex of 1,9-nonandiol dimethacrylate (NDMA) with ,-cyclodextrin (,-CD) onto natural rubber particle using potassium persulfate (KPS), tert -butyl hydroperoxide/tetraethylenepentamine (TBHPO/TEPA), cumene hydroperoxide/tetraethylenepentamine (CHPO/TEPA), and benzoyl peroxide (BPO) as an initiator. The graft copolymer was characterized by 1H NMR and FTIR after coagulation. The conversion of NDMA and the amount of residual methacryloyl group were found to be 58.5 w/w % and 1.81 w/w %, respectively, under the suitable condition of the graft-copolymerization. The morphology of the film specimen, prepared from the graft copolymer, was observed by transmission electron microscopy (TEM) after staining the film with OsO4. Natural rubber particle of about 1.0 ,m in diameter was dispersed in poly(NDMA) matrix of about 10 nm in thickness. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2418,2424, 2010 [source] A novel approach to the analysis of distributed shear banding in polymer blendsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2003K. G. W. Pijnenburg Abstract The toughness of glassy polymers can be enhanced by blending with rubber particles. The consensus is that this toughening is due to massive plastic deformation of the matrix that takes place once the particles have cavitated. Micromechanical studies of regular stackings of particles in a polymer matrix have provided much insight into the localized plastic flow in blends at the microscale of individual particles (or voids, once cavitated). Even some steps towards macroscopic constitutive models have been made. However, at intermediate length scales (i.e. larger than several particles, but smaller than the scale at which the material may be regarded as homogeneous) the situation is unclear. It is this length scale that becomes important around crack tips, for example, where a thorough understanding of the toughening effect has to be derived from. In this paper, we therefore present a novel approach to the analysis of distributed shear banding in polymer,rubber blends. A coarse-grain description, in which much of the morphology is retained but the local shear banding is idealized into ,shear surfaces', will enable us to analyse ensembles with large numbers of particles. The parameters of this model will be validated with results from detailed cell analyses. Copyright © 2003 John Wiley Sons, Ltd. [source] Effect of interfacial strengthening in blends of reclaimed rubber and polypropyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2010S.-H. Zhu Abstract Thermoplastic vulcanizates (TPVs) were prepared from polypropylene (PP) and reclaimed ground tire rubber crumbs. Three types of interfacial strengthening agents,degraded PP, hydrosilylated PP, and hydrosilylated PP grafted onto styrene,butadiene rubber,were prepared in melt via a stepwise series of reactions and employed to generate various degrees of interfacial adhesion in the aforementioned blends. The incorporation of the interfacial agents resulted in improvements in the mechanical properties of these TPVs, and the rubber particle size remained constant. The PP chain length and the functional groups present in the interfacial agents affected the magnitude of the improvement in the mechanical properties. The interfacial agents were primarily present on the surface of the rubber particles in the blends, as shown by energy-dispersive X-ray spectra. These interfacial agents in the PP/rubber crumb blends led to a unique preyield kink in their stress,strain curves, a plateau, or a sharp turning point in the region of approximately 3% elongation and approximately 4-MPa stress. These kinks were interpreted similarly to the cold flow of semicrystalline polymers in tension. The addition of the interfacial modifiers decreased the shear viscosity and increased the entrance pressure drop in flow through capillary dies, and this was attributed to changes in the elongational viscosity of the blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effect of acrylic core,shell rubber particles on the particulate flow and toughening of PVCJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2009M. R. Moghbeli Abstract Different types of acrylic core,shell rubber particles with a poly(butyl acrylate) (PBA) core and a grafted poly(methyl methacrylate) (PMMA) shell were synthesized. The average size of acrylic core,shell latex particles ranged from 100 to 170 nm in diameter, having the core gel content in the range of 35,80%. The melt blending behavior of the poly(vinyl chloride) (PVC) and the acrylic core,shell rubber materials having different average particle sizes and gel contents was investigated in a batch mixing process. Although the torque curves showed that the particulate flow of the PVC in the blends was dominant, some differences were observed when the size and gel content of the particles varied. This behavior can be attributed to differences in the plasticizing effect and dispersion state of various types of core,shell rubber particles, which can vary the gelatin process of the PVC in the mixing tool. On the other hand, the highest toughening efficiency was obtained using core,shell rubber particles with the smallest particle size (i.e., 100 nm). The results showed that increasing the gel content of the core,shell impact modifiers with the same particle size improved the particle dispersion state in the PVC matrix. The toughening efficiency decreased for the blends containing 100 and 170 nm rubber particles as the gel content increased. Nevertheless, unexpected behavior was observed for the blends containing 140 nm rubber particles. It was found that a high level of toughness could be achieved if the acrylic core,shell rubber particles as small as 100 nm had a lower gel content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Effects of SiO2 nanoparticles on the performance of carboxyl-randomized liquid butadiene,acrylonitrile rubber modified epoxy nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007Minfeng Zeng Abstract The effects of SiO2 nanoparticles on the performance of carboxyl-randomized liquid butadiene,acrylonitrile rubber (CRBN) modified epoxy resin (EP) nanocomposites were studied. With the addition of an appropriate amount of SiO2 (2%) to EP/CRBN (95/5), the nanocomposites could achieve the desired impact strength and modulus. The morphology of the nanocomposites was studied with scanning electron microscopy and transmission electron microscopy. The nanocomposites showed a three-phase system; both the rubber particles and SiO2 nanoparticles showed uniform dispersions in the EP matrix, with their phases all nanosized. A good correlation between the free-volume hole radius and mechanical properties was found. The introduction of a small amount of nanoparticles (both rubber and SiO2) into EP led to the formation of interactions between the EP and nanoparticles. The interactions restricted the segment motion and the mobilization of the EP chains and then reduced the free-volume concentration in the amorphous region of EP. The fact that the average free-volume hole radius of EP/CRBN was larger than that of pure EP was mainly attributed to the contribution of the larger size of the free-volume holes within the rubber phase. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] In vitro Transient Expression System of Latex C-serum was used for Analysis of Hevein Promoter in Response to Abscisic Acid in Hevea brasiliensisJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2008Xiao-Wen Fei Abstract Hevein has been found to be an essential element in coagulation of rubber particles in latex of rubber trees. In a previous study, we cloned a 1 241-bp fragment of a 5, upstream region of the hevein gene by genome walking. This fragment was analyzed by a 5, end nested deletion method in the present study, fused with a uidA (gus) gene to produce a series of tested constructs, which were transferred into C-serum of latex and the Gus activities were detected. Results showed that the fragment from ,749 to ,292 was sufficient for expression of gus gene in latex, and the fragment from ,292 to ,168 was crucial in response to abscisic acid inducement. In a transient transgenic test of rubber leaf with particle bombardment, construct Hev749 conferred gus -specific expression in veins, in which the latex tubes mainly distributed. This implies that the fragment from ,749 to ,292 was laticiferous-specific. [source] Co-continuous Polyamide 6 (PA6)/Acrylonitrile-Butadiene-Styrene (ABS) NanocompositesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 9 2005Yongjin Li Abstract Summary: Polyamide 6 (PA6)/acrylonitrile-butadiene-styrene (ABS) (40/60 w/w) nanocomposites with a novel morphology were prepared by the melt mixing of PA6, ABS and organoclay. The blend nanocomposites had a co-continuous structure, in which both PA6 and styrene-acrylonitrile (SAN) were continuous phases. It was found that the toughening rubber particles were only located in the SAN phase and the strengthening clay platelets were selectively dispersed in the PA6 phase. The co-continuous nanocomposites showed greatly improved mechanical properties over the whole temperature range when compared with the same blend sample without clay. Schematic diagram for the co-continuous ABS/PA6 blend nanocomposite. [source] Synthesis of HIPS using an A2B2 Star-Type Graft Copolymer (PB -g- PS)MACROMOLECULAR REACTION ENGINEERING, Issue 6-7 2010Carlos de Anda Abstract The properties of HIPS are largely related to the morphology of the disperse rubber particles developed during polymerization. Since the graft copolymer PB -g- PS formed in situ has the role of a compatibilizer between the disperse rubber particles and the continuous PS phase, through the control of the molecular characteristics of the grafting species, the rubber particles' morphology and distribution can be controlled. Several HIPS were synthesized by radical polymerization using a mixture of polybutadiene and model graft copolymers, PB -g- PS, and the final materials were characterized physicochemically and morphologically. Different ratios of PB/graft copolymer were used in order to study the effects on the molecular characteristics and morphology of the HIPS obtained. [source] Enhanced solvent extraction of polar lipids associated with rubber particles from hevea brasiliensisPHYTOCHEMICAL ANALYSIS, Issue 2 2007Frederic Bonfils Abstract Biochemical studies of lipids bound to rubber particles have been complicated due to the solubility of polyisoprene chains in most extracting solvents and the rather delicate nature of polar lipids that are often denatured when traditional solvent extraction techniques are employed. In this paper, we describe a traditional technique and accompanying solvents that permit optimal extraction of rubber particle bound lipids. The technique, which is validated after characterizing the lipid extracts by elemental analysis, silica column adsorption and thin layer chromatography, appeared more suitable for extracting total lipids with optimal glycolipid and phospholipid contents. This technique is proposed as an alternative to traditional extraction methods used for solid natural rubber as it offers advantages with respect to ease of application, extract quality, extraction yields and reproducibility. Copyright © 2007 John Wiley & Sons, Ltd. [source] Microstructure-properties correlations in dynamically vulcanized nanocomposite thermoplastic elastomers based on PP/EPDMPOLYMER ENGINEERING & SCIENCE, Issue 3 2007Ghasem Naderi Thermoplastic vulcanized (TPV) nanocomposites were prepared in a laboratory mixer using EPDM, polypropylene of different viscosities, maleic anhydride modified polypropylene, an organo-clay, and a sulfur-based curing system. Based on the obtained results from X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimeter, and mechanical properties, the microstructure of the prepared nanocomposites was found to be sensitive to the viscosity difference between the two phases and the clay content. X-ray diffraction and TEM images of the TPV nanocomposites showed that clay was nearly exfoliated and randomly distributed into the polypropylene phase. The SEM photomicrographs of the dynamically vulcanized thermoplastic elastomer samples showed that the rubber particles were dispersed through the polypropylene in form of aggregates and their size increased with the introduction of clay. The nanoscale dimensions of the dispersed clay resulted in a significant improvement of the tensile modulus of the TPV nanocomposite samples, from 20 to 90% depending on clay content and the viscosity ratio of PP/EPDM. In the PP nanocomposites, the clay layers act as nucleating agents, resulting in higher crystallization temperature and reduced degree of crystallinity. Moreover, the oxygen permeability in the TPV nanocomposites was found to be lower than in unfilled but otherwise similar materials. POLYM. ENG. SCI., 47:207,217, 2007. © 2007 Society of Plastics Engineers. [source] Synthesis of sub-micrometer core,shell rubber particles with 1,2-azobisisobutyronitrile as initiator and deformation mechanisms of modified polystyrene under various conditionsPOLYMER INTERNATIONAL, Issue 10 2009Rujun Dai Abstract BACKGROUND: Sub-micrometer core-shell polybutadiene- graft -polystyrene (PB- g -PS) copolymers with various ratios of polybutadiene (PB) core to polystyrene (PS) shell were synthesized by emulsion grafting polymerization with 1,2-azobisisobutyronitrile (AIBN) as initiator. These graft copolymers were blended with PS to prepare PS/PB- g -PS with a rubber content of 20 wt%. The mechanical properties, morphologies of the core-shell rubber particles and deformation mechanisms under various conditions were investigated. RESULTS: Infrared spectroscopic analysis confirmed that PS could be grafted onto the PB rubber particles. The experimental results showed that a specimen with a ,cluster' dispersion state of rubber particles in the PS matrix displayed better mechanical properties. Transmission electron micrographs suggested that crazing only occurred from rubber particles and extended in a bridge-like manner to neighboring rubber particles parallel to the equatorial plane at a high speed for failure specimens, while the interaction between crazing and shear yielding stabilized the growing crazes at a low speed in tensile tests. CONCLUSION: AIBN can be used as an initiator in the graft polymerization of styrene onto PB. The dispersion of rubber particles in a ,cluster' state leads to better impact resistance. The deformation mechanism in impact tests was multi-crazing, and crazing and shear yielding absorbed the energy in tensile experiments. Copyright © 2009 Society of Chemical Industry [source] Deformation mechanism of polystyrene toughened with sub-micrometer monodisperse rubber particlesPOLYMER INTERNATIONAL, Issue 11 2006Guanghui Gao Abstract Core,shell polybutadiene- graft -polystyrene (PB- g -PS) rubber particles with different ratios of polybutadiene to polystyrene were prepared by emulsion polymerization through grafting styrene onto polybutadiene latex. The weight ratio of polybutadiene to polystyrene ranged from 50/50 to 90/10. These core-shell rubber particles were then blended with polystyrene to prepare PS/PB- g -PS blends with a constant rubber content of 20 wt%. PB- g -PS particles with a lower PB/PS ratio (,70/30) form a homogeneous dispersion in the polystyrene matrix, and the Izod notched impact strength of these blends is higher than that of commercial high-impact polystyrene (HIPS). It is generally accepted that polystyrene can only be toughened effectively by 1,3 µm rubber particles through a toughening mechanism of multiple crazings. However, the experimental results show that polystyrene can actually be toughened by monodisperse sub-micrometer rubber particles. Scanning electron micrographs of the fracture surface and stress-whitening zone of blends with a PB/PS ratio of 70/30 in PB- g -PS copolymer reveal a novel toughening mechanism of modified polystyrene, which may be shear yielding of the matrix, promoted by cavitation. Subsequently, a compression-induced activation method was explored to compare the PS/PB- g -PS blends with commercial HIPS, and the result show that the toughening mechanisms of the two samples are different. Copyright © 2006 Society of Chemical Industry [source] Influence of the degree of grafting on the morphology and mechanical properties of blends of poly(butylene terephthalate) and glycidyl methacrylate grafted poly(ethylene- co -propylene) (EPR)POLYMER INTERNATIONAL, Issue 8 2006SL Sun Abstract Poly(ethylene- co -propylene) (EPR) was functionalized to varying degrees with glycidyl methacrylate (GMA) by melt grafting processes. The EPR- graft -GMA elastomers were used to toughen poly(butylene terephthalate) (PBT). Results showed that the grafting degree strongly influenced the morphology and mechanical properties of PBT/EPR- graft -GMA blends. Compatibilization reactions between the carboxyl and/or hydroxyl of PBT and epoxy groups of EPR- graft -GMA induced smaller dispersed phase sizes and uniform dispersed phase distributions. However, higher degrees of grafting (>1.3) and dispersed phase contents (>10 wt%) led to higher viscosities and severe crosslinking reactions in PBT/EPR- graft -GMA blends, resulting in larger dispersed domains of PBT blends. Consistent with the change in morphology, the impact strength of the PBT blends increased with the increase in EPR- graft -GMA degrees of grafting for the same dispersion phase content when the degree of grafting was below 1.8. However, PBT/EPR- graft -GMA1.8 displayed much lower impact strength in the ductile region than a comparable PBT/EPR- graft -GMA1.3 blend (1.3 indicates degree of grafting). Morphology and mechanical results showed that EPR- graft -GMA 1.3 was more suitable in improving the toughness of PBT. SEM results showed that the shear yielding properties of the PBT matrix and cavitation of rubber particles were major toughening mechanisms. Copyright © 2006 Society of Chemical Industry [source] Dynamically cured natural rubber/EVA blends: influence of NR- g -poly(dimethyl (methacryloyloxymethyl)phosphonate) compatibilizerPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 5 2010Punyanich Intharapat Abstract Graft copolymer of natural rubber and poly(dimethyl(methacryloyloxymethyl)phosphonate) (NR- g -PDMMMP) was prepared in latex medium via photopolymerization. It was then used to promote the blend compatibility of dynamically cured 40/60 natural rubber (NR)/ethylene vinylacetate copolymer (EVA) blends using various loading levels at 1, 3, 5, 7, 9, 12, and 15,wt%. It was found that the increasing loading levels of NR- g -PDMMMP in the blends caused the increasing elastic modulus and complex viscosity until reaching the maximum values at a loading level of 9,wt%. The properties thereafter decreased with the increasing loading levels of NR- g -PDMMMP higher than 9,wt%. The smallest vulcanized rubber particles dispersed in the EVA matrix with the lowest tan , value was also observed at a loading level of 9,wt%. Furthermore, the highest tensile strength and elongation at break (i.e., 17.06 MPa and 660%) as well as the lowest tension set value (i.e., 27%) were also observed in the blend using this loading level of the compatibilizer. Addition of NR- g -PDMMMP in the dynamically cured NR/EVA blends also improved the thermal stability of the blend. That is, the decomposition temperature increased with the addition of the graft copolymer. However, the addition of NR- g -PDMMMP in the blends caused the decreasing degree of crystallinity of the EVA phase in the blend. However, the strength properties of the blend are still high because of the compatibilizing effect. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||