成核剂含量对β晶相聚丙烯结晶与熔融行为的影响

EFFECT OF β-NUCLEATOR CONTENT ON THE CRYSTALLIZATION AND MELTING BEHAVIOR OF β-PHASE POLYPROPYLENE

用DSC研究了β成核剂含量对β聚丙烯在等温与非等温结晶条件下的结晶与熔融行为的影响,发现当成核剂含量为0.005％时,结晶焓△H_c、β晶的熔融焓△H_(mβ)及熔点T_(mβ)均为最大,而α晶的相对含量最小.广角X-衍射数据表明,成核剂含量高的试样的(301)衍射峰的相对强度下降,反映分子链排列的纵向有序性降低.根据聚丙烯分子在β成核剂上附生结晶的成核机理解释了上述结果.

Effect of β-nucleator content on the isothermal and nonisothermal crystallization of β-phase polypropylene was studied using differential scanning calorimetry. The melting curves of the foregoing samples at isothermal and non-isothermal crystallization condition were also measured in DSC-2. The results obtained indicated that the sample containing 0.005% β-nucleator have the highest β-form crystallinity as expressed by △Hmβ the highest melting temperature of β-form and lower α-form crystallinity. The WAXD measurement shows that the samples, crystallized in the presence of higher content of nucleator, have lower relative intensity of β(301) diffraction peak which signifies the lower order of packing of β-form crystals along the chain direction.