Mechanical and Thermal Properties of Waterborne Polyurethane Films Modified by CaCO3@TiO2 Particles with UV Absorption Activity

CaCO3@TiO2 particles were synthesized through a direct carbonation method, which can be used as the substitutes of TiO2 in pigments and coatings. To improve the dispersion in waterborne polyurethane（WPU） suspensions, CaCO3@TiO2 particles were modified by stearic acid. SEM tests of the fractured surfaces of the composites films showed that the CaCO3@TiO2 particles were well embedded in the WPU matrix. And the mechanical properties, thermal stability and water resistance of the composites films were improved by the introduction of CaCO3@TiO2 particles.

合成超细CaCO_3的非稳态碳化反应特征和颗粒形态

在合成超微细CaCO3 的非稳态体系中 ,跟踪测定了Ca(OH) 2 悬浮液在有添加剂Na5P3 O10 存在时的碳化过程。研究表明 ,在Ca(OH) 2 悬浮液中加入 (0 .380 4～ 1.5 2 2 )× 10 -4 mol/LNa5P3 O10 就足以抑制Ca(OH) 2 碳化反应的进行。随着溶液中Na5P3 O10 浓度的增加 ,碳化反应速度减小。Ca(OH) 2 的碳化过程可分为两个阶段 ,即反应初期的恒速反应阶段和反应末期的变速反应阶段。