部分水解聚甲基丙烯酸甲酯/氢氧化钙复合物对硬质聚氯乙烯热稳定性与透明性及塑化行为的影响

INFLUENCE OF PARTIALLY HYDROLYZED POLY(METHYL METHACRYLATE)/Ca(OH)_2 COMPOSITES ON THERMAL STABILITY,TRANSPARENCY AND FUSION BEHAVIORS OF RIGID POLY(VINYL CHLORIDE) COMPOUNDS

采用溶液沉淀法制备了部分水解的聚甲基丙烯酸甲酯(h-PMMA)/氢氧化钙(Ca(OH)2)复合物.采用X-射线衍射(XRD)、红外光谱(FTIR)、等离子体发射光谱和差示扫描量热表征了h-PMMA/Ca(OH)2复合物的组成与结构;采用刚果红测试、动态热稳定测试和热失重分析(TGA)研究了复合物对聚氯乙烯(PVC)的热稳定效果;通过紫外-可见(UV-Vis)光谱、扫描电镜(SEM)照片和熔融塑化曲线研究了复合物对PVC透明性和塑化行为的影响.结果表明,在Ca(OH)2晶体生长过程中,h-PMMA通过—COO-/Ca2+离子配位作用吸附于Ca(OH)2表面,不仅限制了Ca(OH)2粒子尺寸,且有助于Ca(OH)2在PVC中均匀分散.所得h-PMMA/Ca(OH)2复合物在显著提高PVC热稳定性和塑化能力的同时,还使PVC保持透明性.

Partially hydrolyzed poly （methyl methacrylate ） （h-PMMA）/Ca （OH）2 composites were synthesized by partially hydrolyzing PMMA in alkaline isopropanol solution followed by precipitating Ca（OH） 2 in the solution. Composition and structure of h-PMMA/Ca （OH） 2 composites were characterized using X-ray diffraction （XRD）, Fourier-transform infrared （FTIR）, inductively coupled plasma atomic emission spectrometry （ICP） and differential scanning calorimetry （DSC）, and influence of the composites on thermal stability of PVC was studied through Congo red tests, dynamic thermal stability tests and thermogravimetry analysis （TGA）. UV-Vis spectra, scanning electron microscopy （SEM） and fusion curves were analyzed to study influence of h-PMMA/Ca （OH）2 composites on transparency and fusion behaviors of rigid PVC compounds. The experimental results showed that h-PMMA chains adsorbed on the surface of growing Ca（OH） 2 particles through--COO-/Ca2＋ bonds decreased the size of the final particles and make a better distribution of Ca （ OH）2 in the melt-blended PVC compounds. Compared with traditional stabilizers, the prepared h-PMMA/Ca （OH）2 composites were able to quickly capture catalytic, highly mobile HC1 so as to improve thermal stability of PVC compounds during the melt-blending significantly. Furthermore, PVC compounds stabilized with h-PMMA/Ca （OH）2 composites displayed an excellent long-time stability with increasing Ca（ II ） content in h-PMMA/Ca （ OH）2 composites. At the same time, the h-PMMA/Ca （ OH）2 composites could obviously promote fusion of melt-blended PVC compounds while maintaining their transparency.