低轮廓不饱和聚酯树脂的中低温固化形态

研究了加有低轮廓添加剂的不饱和聚酯树脂在中低温固化时的形态,结果表明:温度对加入聚醋酸乙烯酯类LPA试样的固化形态影响不大,而加入聚苯乙烯类LPA对试样的固化形态则有较大的影响.在固化过程中极性较大的LPA更有利于从UPR相中分离出来,形成有利于补偿收缩的两相交互连续的相态结构,而玻璃转化温度与UPR的差别大并且低于固化温度的LPA,使得固化试样形成微孔有更多的时间和更高的效率对于加入聚醋酸乙烯酯类LPA的试样,试样的固化形态随着LPA含量的增加发生两次明显的转变.对于具有较高分子量的LPA,只需要加入较低的含量就能使试样形成相互连续的两相结构,而加入聚苯乙烯类LPA的试样,固化的形态随着LPA含量的增加没有明显的改变.

Morphology of low profile unsaturated polyester resins cured at low--medium temperature

The morphology of low-profile unsaturated polyester resins cured at low-medium temperature was investigated. The experimental results show that the influence of temperature on morphology of cured sample is small for poly(vinyl acetate) based LPAs but large for polystyrene based LPA. Polar polymers tend to phase out from UPR and make system form co-continuous structure, which make for shrinkage compensation. Big difference of glass transition temperature Tg between UPR and LPA and a Tg below the cure temperature are preferred, which make microvoid formation of cured sample have more time and higher efficiency. For the sample with poly(vinyl acetate) based LPAs, the morphology exists two transitions with increasing the LPA concentration. LPA with higher molecular weights needs lower concentration to obtain co-continuous structure. However, for the sample with polystyrene based LPA, the morphology has little change with increasing the LPA concentration.