Phenyl Silicone Rubber Research Articles

Synthesis of phenolic resin modified silicone rubber utilizing for ablation thermal protection materials

Phenolic resin modified silicone rubber (PMS) was synthesized via hydrosilation reaction between novolak with allyl group and silicone rubber containing Si-H groups. The chemical structure of PMS was characterized by FT-IR, 1H NMR and GPC. The thermal stability of PMS was characterized through TGA and compared with traditional single phenyl silicone rubber (PSR). Ablation properties was measured through muffle furnace ablation test. Compared with PSR, the PMS has better thermal stability and wider pyrolysis temperature range. The carbon yield after ablation was promoted greatly and stable ablation layer was obtained.

Thermal stability of CeO2/graphene/phenyl silicone rubber composites

Thermal stability mechanism of CeO2/graphene/phenyl silicone rubber composites (PMVQ) are investigated by means of SEM, TGA, swelling and mechanical testing. First, the degradation mean activation energy E of rubber composites with Td (the temperature of 50% weight loss, TGA) are used to analyze the action mechanism of CeO2 and graphene in thermal oxidative aging process. The results rev eal that CeO2 and graphene have joint effects on improving thermal stability of phenyl silicone rubber composites. Second, swelling test indicates that aging of rubber composites is dominated by oxidation crosslinking at 300°Cfor 48 h. Finally, mechanical analysis shows tensile strength of PMVQ-3 (PMVQ containing graphene: 0.8phr and CeO2: 2phr) can reach 4.67 MPa increasing by 82.4% compared with PMVQ-1 (PMVQ without graphene and CeO2) after aging, and elongation at break of PMVQ-3 can remain at 180%, and even at 213% in PMVQ-4 (PMVQ containing graphene: 1.5phr and CeO2: 2phr).

How the Crosslinking Agent Influences the Thermal Stability of RTV Phenyl Silicone Rubber.

In this work, a thermal degradation mechanism of room temperature vulcanized (RTV) phenyl silicone rubber that was vulcanized by different crosslinking agents was discussed. Firstly, RTV phenyl silicone rubber samples were prepared by curing hydroxyl-terminated polymethyldiphenylsiloxane via three crosslinking agents, namely, tetraethoxysilane (TEOS), tetrapropoxysilane (TPOS), and polysilazane. Secondly, the ablation properties of RTV phenyl silicone rubber were studied by the muffle roaster test and FT-IR. Thirdly, thermal stability of the three samples was studied by thermogravimetric (TG) analysis. Finally, to explore the thermal degradation mechanism, the RTV phenyl silicone rubber vulcanized by different crosslinking agents were characterized by TG analysis-mass spectrum (TG-MS) and pyrolysis gas chromatogram-mass spectrum (pyGC-MS). Results showed that the thermal stability of RTV phenyl silicone rubber is related to the amount of residual Si–OH groups. The residual Si–OH groups initiated the polysiloxane chain degradation via an ‘unzipping’ mechanism.

Synthesis and Properties of Phenyl Silicone Resin Reinforced Addition Type Liquid Phenyl Silicone Rubber

Phenyl silicone resin reinforced addition type liquid phenyl silicone rubber was prepared by vulcanization of vinyl end-capped polymethylphenylsiloxane (PVPS), phenyl MT resins and hydrogen end-capped polydiphenylsiloxane (PHPS) under Pt catalysis at 150°C for 4h. The effects of the proportion and the vinyl content of phenyl MT resins on the mechanical properties of cured products were investigated. The thermal stability was explored by thermogravimetric analysis. The changes of mechanical properties were also studied before and after irradiation. Phenyl silicone rubber with good performance was obtained when the phenyl MT resin content was 50~60 wt% and the vinyl content was at 5.5~6.6 wt%. The onset temperature of thermal degradation and the center temperature of thermal degradation were 443.7°C and 502°C, respectively. When the radiation dose increased from 0 to 300 KGy, the tensile strength decreased from 4.1MPa to 2.3MPa and the tearing strength decreased from 8.9MPa to 5.1MPa. When the radiation dose continues to increased from 300 to 900 KGy, the tensile strength increased from 2.3MPa to 6.4MPa and the tearing strength increased from 5.1MPa to 6.5MPa. During the process of radiation, the elongation at break had been kept down from 96% to 52%, and the hardness increased from 80A to 90A.

Study on the preparation and performance of low gas permeability trifluoropropyl phenyl silicone rubber

Low gas permeability coating can prevent oxygen and sulphur vapour from permeating into silicone rubber and protect electronic components, chips, electrodes, medicines, etc. from oxidation and sulfuration.

Effects of functional graphene oxide on the properties of phenyl silicone rubber composites

Graphene oxide (GO) was treated with two types of surfactants, i.e., silane coupling agent (KH550) and 4,4’-diphenylmethane diisocyanate (MDI), incorporated into phenyl silicone rubber at a low concentration (≤0.2 wt%), and cured by the room temperature vulcanized method. The effects of functional graphene oxide on the dielectric behaviour, thermal conductivity, optical transmittance and mechanical properties of the composites were investigated. The results showed that the particle size changed after modification and that the modified GO dispersed well in the phenyl silicone rubber. The composites with MDI modified GO exhibited better electrical insulation and lower light loss in the ultraviolet–visible region than the composites with KH550 modified GO. However, composites filled with KH550 modified GO present better thermal conductivity.

Effect of Electron Beam Irradiation Cross-Linking on Polyolefin/Phenyl Silicon Rubber Composite

The effect of polyolefin/phenyl silicon rubber composite with different proportion were investigated before and after irradiation cross-linking treatment, The changes in the properties such as tensile strength and elongation at break were monitored. A correlation between the mechanical properties and irradiation doses has been explained on the basis of INSTRON strength tester and XN-1 spandex elastic tester studies. The optimum radiation dose was found to be dependent on blend composition and morphology, however, an absorbed dose of 150KGy to 200 KGy were found to be effective enough to ensure good mechanical properties of the polyolefin/ phenyl silicone rubber composite.

Effect of SiO2 and TiO2 nanoparticle on the properties of phenyl silicone rubber

ABSTRACTTwo types of nanoparticles TiO2 and SiO2 treated with silane coupling agents were incorporated into phenyl silicone rubber at a low concentration (≤1.0%) and cured by the room temperature vulcanized method. The results showed that treated TiO2 or SiO2 nanoparticles improved the ultraviolet (UV)‐shielding ability and enhanced the visible transmittance of the phenyl silicone rubber, compared with their respective untreated particles. Moreover, when comparing treated nanoparticles, TiO2 was more responsible for augmenting the UV‐shielding ability of the phenyl silicone rubber, while SiO2 played a more important role in increasing the transmittance of visible light. Low levels of nanoparticles reduced the dielectric constant of the nanocomposite; however, on reaching a critical concentration, increasing the nanoparticle content had the opposite effect. The thermal conductivity of nanocomposites increased linearly with the amount of treated nanoparticles, while SiO2 nanocomposites exhibited better thermal conductivity than those of TiO2. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42806.

The Mobility and Rheological Properties of Phenyl Silicone Rubber

In this paper the mobility and factots affecting mobility of phenyl silicone rubber is studied. The results showed that the crystallinity of phenyl silicone rubber was declined because of the presence of phenyl and the higher the phenyl content, the lower the crystallinity when the phenyl content was low. The viscosity of the phenyl silicone rubber was rised as molar mass and phenyl content of the rubber was increased but the changes was not uniform. The viscosity of the phenyl silicone rubber was declined as temperature was increased and viscosity-temperature dependence of the high molar mass phenyl silicone rubber was larger. The influence of shearing on the viscosity and mobility of the phenyl silicone rubber were evident.