论文部分内容阅读
一前言聚丙烯是在六十年代发展起来的新颖的热塑性塑料。它具有比重小、突出的刚性和抗弯曲疲劳强度、良好的耐热性(可在100℃以上使用,在没有外力作用下,于150℃亦不变形)以及价格便宜等特点。它的原料来源于石油或天然气,在我国资源极为丰富,即将大规模生产。但是,聚丙烯由于它的结构特征,其分子链易取向、易结晶和适宜结晶的温度较低,决定了它具有成型收缩率大(1.0～2.5％)、易变形和尺寸稳定性差等缺点。因此,用它制造
A preface Polypropylene is a novel thermoplastic developed in the sixties. It has the proportion of small, outstanding rigidity and bending fatigue strength, good heat resistance (which can be used in more than 100 ℃, without external force, at 150 ℃ nor deformation) and the characteristics of low prices. Its raw materials come from oil or natural gas, which is extremely rich in resources in our country and is about to be mass-produced. However, due to its structural characteristics, polypropylene has the disadvantages of easy molecular orientation, easy crystallization and suitable crystallization temperature, which has the advantages of high shrinkage (1.0-2.5%), easy deformation and poor dimensional stability. So use it to make