Dynamic rheological properties of poly(methyl vinyl)siloxane(PMVS) filled with ultratra silica (SiO 2) were analyzed on an advanced rheometric expansion system(ARES) at 25 ℃ by varying the strain (γ) and the frequen...Dynamic rheological properties of poly(methyl vinyl)siloxane(PMVS) filled with ultratra silica (SiO 2) were analyzed on an advanced rheometric expansion system(ARES) at 25 ℃ by varying the strain (γ) and the frequency (ω). The results show that an incorporation of 5% SiO 2 into PMVS at 25 ℃ could be enough to impact a significant increase on the storage modulus (G′) of the uncured system, which is believed to be caused by the strong interactions among silica fillers. Meanwhile, γ dependence of G′ related to Payne effect was observed upon increasing γ amplitude, and no distinct “second plateau” was observed even the content of SiO 2 approached 20%. We owe this phenomenon partly to the surface esterification of silanols and partly to the unvulcanized PMVS.展开更多
The dynamic viscoelastic behavior of polysiloxanes filled with ultrafine SiO 2 has become ever-lasting important due to its unique properties. In present article, the influence of SiO 2 treated with silane coupling ag...The dynamic viscoelastic behavior of polysiloxanes filled with ultrafine SiO 2 has become ever-lasting important due to its unique properties. In present article, the influence of SiO 2 treated with silane coupling agent bis(3-triethoxysilyl)tetrasulfane(TESPT) on dynamic viscoelastic properties of uncured polymethylvinylsiloxane(PMVS)/ultra fine-silica(SiO 2) composites was investigated by using an advanced rheometric expansion system(ARES) under the conditions of temperature 25 ℃, strain(γ) from 0.01% to 100% and frequency(ω) from 0.01 to 100 rad/s. The results reveal that the treated SiO 2 particles leads to the frequency-dependent storage modulus(G′) which approaches linear viscoelastic behavior in the lower frequency region. Based on an examination of the dynamic viscoelastic behavior and TEM observation, we owe these characteristics to improved dispersion of SiO 2 particles in the polymer matrix due to their surface-treatment as compared with the untreated case. On the other hand, dynamic viscoelastic behavior sensitively reflects the dispersion of SiO 2 particles with diameters from 100 to 500 nm, which further evidence the promotion of filler dispersion induced by the incorporation of TESPT.展开更多
The effect of crosslinking degree on the piezoresistive behavior of carbon black(CB) filled poly(methyl vinyl siloxane)(PMVS) vulcanites under uniaxial compression was studied.The results reveal that increasing the am...The effect of crosslinking degree on the piezoresistive behavior of carbon black(CB) filled poly(methyl vinyl siloxane)(PMVS) vulcanites under uniaxial compression was studied.The results reveal that increasing the amount of crosslinking agent could weaken the negative pressure coefficient of resistance(NPCR) effect at the late stage of compression and enhance the piezoresistivity intensity at a high stresses.The recovery property of resistance was related to the content of CB,the stress level and the degree of crosslinking.It was proved that repeated compression with the same maximum stress level could improve piezoresistive stability considerably.展开更多
文摘Dynamic rheological properties of poly(methyl vinyl)siloxane(PMVS) filled with ultratra silica (SiO 2) were analyzed on an advanced rheometric expansion system(ARES) at 25 ℃ by varying the strain (γ) and the frequency (ω). The results show that an incorporation of 5% SiO 2 into PMVS at 25 ℃ could be enough to impact a significant increase on the storage modulus (G′) of the uncured system, which is believed to be caused by the strong interactions among silica fillers. Meanwhile, γ dependence of G′ related to Payne effect was observed upon increasing γ amplitude, and no distinct “second plateau” was observed even the content of SiO 2 approached 20%. We owe this phenomenon partly to the surface esterification of silanols and partly to the unvulcanized PMVS.
文摘The dynamic viscoelastic behavior of polysiloxanes filled with ultrafine SiO 2 has become ever-lasting important due to its unique properties. In present article, the influence of SiO 2 treated with silane coupling agent bis(3-triethoxysilyl)tetrasulfane(TESPT) on dynamic viscoelastic properties of uncured polymethylvinylsiloxane(PMVS)/ultra fine-silica(SiO 2) composites was investigated by using an advanced rheometric expansion system(ARES) under the conditions of temperature 25 ℃, strain(γ) from 0.01% to 100% and frequency(ω) from 0.01 to 100 rad/s. The results reveal that the treated SiO 2 particles leads to the frequency-dependent storage modulus(G′) which approaches linear viscoelastic behavior in the lower frequency region. Based on an examination of the dynamic viscoelastic behavior and TEM observation, we owe these characteristics to improved dispersion of SiO 2 particles in the polymer matrix due to their surface-treatment as compared with the untreated case. On the other hand, dynamic viscoelastic behavior sensitively reflects the dispersion of SiO 2 particles with diameters from 100 to 500 nm, which further evidence the promotion of filler dispersion induced by the incorporation of TESPT.
文摘The effect of crosslinking degree on the piezoresistive behavior of carbon black(CB) filled poly(methyl vinyl siloxane)(PMVS) vulcanites under uniaxial compression was studied.The results reveal that increasing the amount of crosslinking agent could weaken the negative pressure coefficient of resistance(NPCR) effect at the late stage of compression and enhance the piezoresistivity intensity at a high stresses.The recovery property of resistance was related to the content of CB,the stress level and the degree of crosslinking.It was proved that repeated compression with the same maximum stress level could improve piezoresistive stability considerably.
