Comparative Study of Silicone Resin Cured with a Linear and a Branched Cross-Linking Agent
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- 作者：Xibing Zhan ; Huijuan Liu ; Junying Zhang ; Jue Cheng ; Xin Lin
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2014
- 出版时间：March 19, 2014
- 年：2014
- 卷：53
- 期：11
- 页码：4254-4262
- 全文大小：542K
- 年卷期：v.53,no.11(March 19, 2014)
- ISSN：1520-5045
文摘
The molecular structure of hydropolysiloxane curing agents is expected to greatly affect the curing reaction and properties of the cured species, but the exact influence still remains somewhat misunderstood. Herein, we choose two representative cross-linking agents: a linear polysiloxane with the Si鈥揌 group (LPHS for short) and a branched polysiloxane with the Si鈥揌 group (TPHS for short) and a kind of high refractive index of polysiloxane resin with the vinyl-end group (short for MPSR) which was successfully synthesized in laboratories. The curing behaviors, dynamic mechanical properties, optical and electrical properties, and thermal stability of two kinds of curing systems (MPSR/TPHS and MPSR/LPHS) were systematically investigated and compared. The effect of molecular architecture of two different cross-linking agents on the curing activation energy, reactivity, and reaction rate has been studied by DSC and online FT-IR spectroscopy. The results confirm that the MPSR/TPHS system shows lower effective activation energy, higher reaction rate, and higher the degree of cure (伪) than MPSR/LPHS under the same cure conditions. Furthermore, the MPSR/TPHS system shows excellent optical transparency in the UV鈥搗isible region, low dielectric constant, and stable dielectric loss over the whole frequency compared to MPSR/LPHS. At last, DMA exhibits cured MPSR/TPHS which has much higher glass transition temperature, storage modulus, and cross-link density than MPSR/LPHS, and thermogravimetric analysis (TGA) reveals the LPHS-cured silicone resin has excellent thermal stability with high char yield.