Preparation and kinetic analysis of room‐temperature vulcanized methylethylsilicone rubbers

Abstract

Random copolymer poly(dimethylsiloxane-co-diethylsiloxane) is synthesized through anionic ring-opening polymerization. Two-component room-temperature vulcanization (RTV-2) silicone rubbers with excellent low-temperature resistance are prepared using the poly(dimethylsiloxane-co-diethylsiloxane) and hydrosilicone. The mechanical properties of RTV-2 rubbers with different formulas are investigated, and the optimized formula is obtained. Moreover, the curing kinetic analysis of RTV-2 silicone rubber with optimized formula is conducted using in situ Fourier transform infrared spectroscopy. The obtained kinetic equations are used to forecast the tack-free time at different temperatures. The results converge with the actually measured tack-free time.

Stepwise cure and properties of silicone resin for high‐ultraviolet‐transmission optical elements

“…27 Therefore, an initial curing temperature as low as 258C (i.e., room temperature) was applied for a prolonged time-period of 10 h that was apparently prior to the gelation of the system, follow by 408C 3 3 h and finally by 1208C 3 1 h, which constituted a stepwise heating method to control the curing rate within a reasonable level that minimized bubbling, implosion, and spontaneous combustion. The corresponding FTIR spectra of the reactive mixture over four characteristic stages (Figure 3) show that: (1) across the entire process, the SiAOASi absorption bands appeared in the range of 1300-950 cm 21 ; 29 (2) the two peaks at 2963 and 2906 cm 21 , respectively, corresponded to the asymmetric and symmetric CAH stretching vibrations from the ACH 3 groups; (3) the peak at 2167 cm 21 was the characteristic absorption band of the SiAH bonds; (4) the peaks at 1598 and 3056 cm 21 were attributed to the respective stretching vibrations of the C@C and CAH bonds from the vinyl groups. Compared with Spectrum a (unreacted low-viscosity state), a new peak in Spectrum b (reacted viscous-flow state) appeared at 1140 cm 21 , which was assigned to the CAC stretching vibration 30 resulting from the hydrosilylation of BSiACH@CH 2 with BSiAH.…”

“…The corresponding FTIR spectra of the reactive mixture over four characteristic stages (Figure 3) show that: (1) across the entire process, the SiAOASi absorption bands appeared in the range of 1300-950 cm 21 ; 29 (2) the two peaks at 2963 and 2906 cm 21 , respectively, corresponded to the asymmetric and symmetric CAH stretching vibrations from the ACH 3 groups; (3) the peak at 2167 cm 21 was the characteristic absorption band of the SiAH bonds; (4) the peaks at 1598 and 3056 cm 21 were attributed to the respective stretching vibrations of the C@C and CAH bonds from the vinyl groups. Compared with Spectrum a (unreacted low-viscosity state), a new peak in Spectrum b (reacted viscous-flow state) appeared at 1140 cm 21 , which was assigned to the CAC stretching vibration 30 resulting from the hydrosilylation of BSiACH@CH 2 with BSiAH. The intensities of the peaks at 2167 and 1598 cm bonds of the vinyl groups, was found to disappear, indicating that the curing reaction proceeded almost to completion.…”

“…[20][21][22] In the process of curing, combustion and implosion was found to easily be triggered with violent exotherm, if the reaction mixture was cured directly at 1208C without using the stepwise heating method; the reaction mixture burst into ashes within seconds even in the absence of ignition. To accommodate the time-temperature superposition theory in terms of the curing effect, behaviors of complex-viscosity magnitude versus time were studied at 95, 100, and 1058C, respectively.…”

Synthesis of High Molecular Weight Vinylphenyl-Con Taining MQ Silicone Resin via Hydrosilylation Reaction

“…The FT-IR spectra of VMQ, PDPS and VPMQ are shown in Figure 2a. In the curve of the VMQ, the strong absorption peak at 3450 cm −1 is assigned to the H-bonded silanol (Si-OH) group [24]. The peaks at 2960 and 2910 cm −1 are attributed to the stretching vibration absorption of C-H in -CH 3 , and the peak at 1260 cm −1 is ascribed to the scissoring vibration absorption of Si-CH 3 .…”

Effects of Copper Oxide and Carbon Nanotubes on Thermal Stability of Silicone Rubber Nanocomposites

“…is Flynn-Wall-Ozawa (FWO) method. 29,30 The degree of decomposition (α) can be defined as the following equation:…”