聚碳酸亚丙酯/壳聚糖熔融共混改性研究

采用熔融共混法将聚碳酸亚丙酯(PPC)与壳聚糖(CS)共混改性,研究了CS含量对PPC/CS共混物相容性、玻璃化转变温度(Tg)、热失重温度和拉伸性能的影响,并探讨了CS改性PPC的作用机理。结果表明:PPC与CS的共混属于简单物理共混,CS对PPC的Tg影响不大,但可显著提高PPC基体的耐热性能,扩大复合材料的加工温度范围。同纯PPC相比,PPC/CS共混物的TGA曲线向高温区偏移,共混物的5%分解温度(T-5%)较PPC提高了51⁵9℃,其50%分解温度(T-50%)提高了1259℃,其50%分解温度(T-50%)提高了12²1℃;另外,共混物的TGA曲线只存在一个高温区的失重台阶,这是由于CS的引入抑制了PPC在低温区的解拉链式降解,因而只有高温区的无规降解发生。此外,随着CS含量的增加,PPC/CS共混物的拉伸强度不断增大,当CS含量增至20%时,材料的拉伸强度由纯PPC的4.7 MPa上升至12.5 MPa。

Study on Melt Blending Modification of PPC/CS

Poly(propylene carbonate)(PPC) and chitosan(CS) blends were prepared by melt-blending method.The effects of CS content on the properties of PPC/CS blends were researched,including compatibility,glass transition temperature(Tg),heat resistance,and tensile property.And the mechanism of the modification was also discussed.The results show that the PPC/CS blends belong to simple mechanical blending composites,the introduction of CS has little effect on Tg of PPC,but it is found that the heat resistance of the PPC blends increases obviously,which would expand the processing temperature range of the blends.With the addition of CS,the thermal degradation temperature shifts to a higher temperature range.The 5% weight loss temperatures(T-5%) of PPC/CS blends are in the range of 227~235℃,which are 51~59℃ higher than that of pure PPC.And the 50% weight loss temperatures(T-50%) of the blends are in the range of 271~280℃,which are 12~21℃ higher than that of pure PPC.Compared with two weight loss steps in the TGA curve for pure PPC,there are only one weight loss step for the PPC/CS blends on the high temperature zone.Obviously,the unzipping degradation of PPC is inhibited by CS at low temperature region,and only the random degradation happened at high temperature region.Moreover,the tensile strength of the blends increases with the increasing CS content.When the CS content reaches to 20%,the tensile strength increases to 12.5 MPa.