Preparation And Performance Of Polymethyl (Ketoxime) Siloxane

Polysiloxane with dense pendant active groups is a new kind of multifunctional liquid resin that can be cured. In the presence of catalyst, pendant active groups crosslinked to a network of high density, which made curing produce exhibited excellent thermal stability besides conventional properties. Therefore they can replace inorganic materials in many areas and have extensive application prospects.In this thesis, Polymethyl(ketoxime)siloxane(PMKS) with dense pendant ketoxime groups was synthesized. Also, the synthetic conditions, crosslinking reactions, performances and usages were studied.1. PMKS with dense pendant silicone-ketoxime groups was synthesized by dehydrocoupling reaction. Synthesis reaction was characterized by FTIR and 1H NMR spectroscopy.2. PMKS was crosslinked at room temperature via hydrolytic condensation to prepare high crosslinking density polysiloxane, and the apparent activation energy for crosslinking reaction was 72.2kJ/mol. The residual mass of crosslinked PMKS at 680℃was 10 wt%, and the residual mass of crosslinked PMKS at 850℃was 15 wt%. 3. PMKS/mullite composite displayed good thermal stability and impact strength. As the addition of mullite, impact strength trended from increasement to reduction. While the weight of mullite was 60% of PMKS/mullite composite, the maximum impact strength was 1.50kJ/m2, and as temperature increased, the impact strength reached to a minimum of 0.55kJ/m2.4. PMKS was used as crosslinking reagent for room temperature vulcanized polydimethylsiloxane (PDMS), and the apparent activation energy for crosslinking reaction was about 103.4 kJ/mol. TG analysis demonstrated that thermostability raised as PMKS increased. Compared to methyltris(diacetylketoxime)silane as crosslinking reagent, both elastic module and elongation at break were improved because of the crosslinking. Meanwhile, as the addition of PMKS increased, tensile strength and elongation at break were increased at first and then decreased.5.Polymethyl(diacetylmonoxime)siloxane (PMDS) with dense pendant silicone-diacetylmonoxime groups was synthesized and characterized by IR spectroscopy analyse. PMDS was crosslinked at room temperature via hydrolytic condensation to prepare high crosslink density polysiloxane, and the apparent activation energy for crosslink reaction was 85.2kJ/mol. While PMKS was used as crosslinking reagent for room temperature vulcanized PDMS, both tensile strength and elongation at break are improved. However, the corresponding performances were insignificant for PMKS as crosslinking reagent.