Mechanical Properties Of Silicone Rubber Research Articles

The Effect of Filler on the Properties of Silicone Rubber

Fillers play important roles in the performances of silicone rubber, such as mechanical and physical properties. In this paper, the silicone rubber filled with silica in a wide volume range was measured in order to study the effects of filler loading on the mechanical properties of silicone rubber. The composites samples added with surface treated silica filler was characterized by Scanning Electron Microscopy (SEM) and fluorescent microscope with that reinforced by the unmodified filler as a comparison. The results showed that the surface treated filler are more easily diffused without agglomerate in the polymer network compared to the unmodifiedd filler. Incorporation of modified filler loading leads to the increase in both tensile strength and the elongation at break, but along with further increase in filler content, mechanical properties of silicone rubber decreased due to the filler particles aggregate state, which can be observed by SEM images. The tack-free time and the hardness of the silicone rubber decrease as the filler loading increases.

Effects of polymeric curing agent modified with silazanes on the mechanical properties of silicone rubber

AbstractPolymeric curing agent modified with hexamethyldisilazane (PCA‐D), or with hexamethylcyclotrisilazane (PCA‐T), was used to improve the mechanical properties of hydroxyl‐teminated polydimethylsiloxane (PDMS) rubber. The structure and the gel time of PCA were characterized by 29Si NMR and shear viscosity measurement, respectively. The PCA modified with silazanes was more stable in storage than that without treatment (PCA‐0). Chemical bonds were formed during the reaction of silazanes and PCA according to 29Si NMR results. The crosslink density (γe) and the mechanical properties of PCA/PDMS rubber were determined by swelling equilibrium and stress–strain tests. It was found that PCA treated with both silazanes could better enhance the mechanical properties of PCA/PDMS rubber compared with PCA‐0. PCA‐T/PDMS rubber, with additional crosslinks, was the best among the three types of PCA/PDMS rubber on the mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Effect of the particle size of Al2O3 on the properties of filled heat‐conductive silicone rubber

AbstractAn elastomeric thermal pad with a thermal conductivity of 1.45 W/m K, needed for the heat dissipation of microelectronics, was obtained with hybrid alumina of different particle sizes as a filler and silicone rubber (vinyl‐end‐blocked polymethylsiloxane) as the matrix. The effects of the amount, particle size, and mixing mass ratio of the filler particles on the thermal conductivity and mechanical properties of silicone rubber were investigated. The results indicated that the thermal conductivity of the rubber filled with larger particles was superior to that of the rubber filled with the smaller grain size, and the rubber incorporated with a mixture of hybrid particles at a preferable mass ratio exhibited higher thermal conductivity than the rubber for which a filler with only a single particle size was used. In addition, the surface treatment of the hybrid filler with 3‐methacryloyloxypropyltrimethoxysilane could increase the thermal conductivity of the composite rubber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1312–1318, 2007

Cure Characteristics, Mechanical and Thermal Properties of Al2O3 and ZnO Reinforced Silicone Rubber

ABSTRACT The effects of alumina (Al2O3) and zinc oxide (ZnO) fillers on the curing characteristics, thermal and mechanical properties of silicone rubber were studied. Rheometer results indicate that the incorporation of ZnO fillers retards the curing process, whereas an enhancement in cure rate was observed for Al2O3. Higher maximum torque (MH) and minimum torque (ML) values was also observed for ZnO silicone rubber compounds compared to Al2O3. Thermogravimetric analysis (TGA) showed that ZnO silicone rubber compounds are thermally more stable than Al2O3; however, the coefficient of thermal expansion of the Al2O3 silicone rubber compounds are lower than that of ZnO. Comparison in mechanical strength between the two silicone rubber hybrids indicates that ZnO is a better reinforcement filler, as evidenced in the tensile strength, elongation at break, and modulus at 300% elongation.

Investigation of allyl‐capped carbosilane dendrimers used as crosslinker for silicone rubber

AbstractHigh‐temperature vulcanized silicone rubber was prepared by using allyl‐capped carbosilane dendrimers, in which the core molecules were Si(CH2CHCH2)4 and Ph2Si(CH2CHCH2)2 as crosslinker and nanoscale reinforcing filler, respectively. Allyl‐capped carbosilane dendrimers improved the mechanical properties of silicone rubber. The optimum tensile strength and tear strength were 9.6 MPa and 31.0 kN/m, respectively, when using SiGn(allyl)m as the crosslinker and 10.1 MPa and 32.0 kN/m, respectively, when using Ph2SiGn(allyl)m as the crosslinker. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1772–1775, 2006

Reiterated tension testing of silicone elastomer

A peristaltically actuated device, PADeMIS, composed of silicone rubber (SR) is under development for use in minimally invasive surgery. During locomotion, the device will be subject to a few thousand load changes involving varying, sometimes high, strains. The design is being optimised by finite element analysis, for which a constitutive law for the mechanical behaviour of silicone rubber is required. Uniaxial and biaxial tension tests have been performed on specimens of used silicon rubber. Synchronous fitting of uniaxial and biaxial tensile data gives significantly better results than using uniaxial or biaxial results alone to derive constitutive laws. The mechanical properties of SR were found to change from loading to loading up to few thousand cycles. Hence, simulating the deformation of SR structures is problematic. Furthermore, variability was observed between batches of SR.

Assessment of the Mechanical Properties of Silicone Rubber before Vulcanisation

Assessment of the Mechanical Properties of Silicone Rubber before Vulcanisation

Design of silicone rubber according to requirements based on the multi-objective optimization of chemical reactions

The explicit expression between composition and mechanical properties of silicone rubber was derived from the physics of polymer elasticity, the implicit expression among material composition, reaction conditions and reaction efficiency was obtained from chemical thermodynamics and kinetics, and then an implicit multi-objective optimization model was constructed. Genetic algorithm was applied to optimize material composition and reaction conditions, and the finite element method of cross-linking reaction processes was used to solve multi-objective functions, on the basis of which a new optimization methodology of cross-linking reaction processes was established. Using this methodology, rubber materials can be designed according to pre-specified requirements.

Finite element simulation of mechanical property evolvement of silicone rubber in the hot vulcanizing process

AbstractThe technical outline of integrated research on the mechanical properties, the crosslinked structure and the hot vulcanizing technology of silicone rubber materials is formulated. From the statistics of rubber elasticity, the relationship of stored energy function and crosslinked structure parameters is constructed. Following the stress–strain theory of elastomers, related expressions for the mechanical properties and the crosslinked structure are deduced. On the basis of previous research findings, numerical expressions of the mechanical properties of silicone rubber in hot vulcanizing process are obtained. Consequently, the properties of silicone rubber can be predicted and the crosslinked structure can be controlled based on a forward simulation method, or the processing parameters and the initial polymeric material can be optimized on the basis of a backward simulation method Copyright © 2003 Society of Chemical Industry

Volume fraction and temperature dependence of mechanical properties of silicone rubber particulate/epoxy blends

At all temperatures, both the Young's modulus and tensile strength of silicone rubber particle/epoxy resin blends decreased as the volume fraction of the silicone rubber particles was increased, and this decrease became greater with falling temperature. A volume fraction-temperature superposition held for both the Young's modulus and tensile strength of the blends. The shifted volume fraction of silicone rubber particles needed to obtain master curves increased with increasing temperature and the shift was almost the same for both properties. An optimum suitable volume fraction of rubber particles existed in terms of improving impact fracture energy. A volume fraction of silicone rubber particles of 5–10% appears to be the most suitable for obtaining a blend in which the decrease in Young's modulus and the tensile strength is relatively low and the increase in impact fracture energy is relatively high.

Volume fraction and temperature dependence of mechanical properties of silicone rubber particulate/epoxy blends

At all temperatures, both the Young's modulus and tensile strength of silicone rubber particle/epoxy resin blends decreased as the volume fraction of the silicone rubber particles was increased, and this decrease became greater with falling temperature. A volume fraction-temperature superposition held for both the Young's modulus and tensile strength of the blends. The shifted volume fraction of silicone rubber particles needed to obtain master curves increased with increasing temperature and the shift was almost the same for both properties. An optimum suitable volume fraction of rubber particles existed in terms of improving impact fracture energy. A volume fraction of silicone rubber particles of 5–10% appears to be the most suitable for obtaining a blend in which the decrease in Young's modulus and the tensile strength is relatively low and the increase in impact fracture energy is relatively high.