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Correlation between morphology and radiation resistance of polypropylene materials

聚丙烯材料形貌与耐辐射性能的相关性

基本信息

批准号：
62550651
负责人：
NISHIMOTO Sei-ichi
金额：
$ 1.15万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

Polypropylene solid materials in medical use are subjected to radiation sterilization, which causes oxidative degradation of their mechanical properties. In this research, the influence of morphology on the radiation degradation of polypropylene materials was investigated. The results are summarized as follows:(1) The crystal structures, as verified by means of X-ray diffraction measurement, and the spherulitic size in the isotactic polypropylene films are strongly affected by the conditions of compression moulding on the hot press. Rapid cooling of the polypropylene melts produces smectic modification of crystallines and small sized spherulites, while slow cooling leads to well grown spherulites consisting of monoclinic crystallines.(2) Upon -irradiation, the elongation at break of polypropylene films decreases in a sigmoidal form as a function of radiation dose. The dose leading to 50 % residual elongation, which is defined as a critical dose, is a good measure of the radiation resis … More tance of polypropylene materials.(3) The radiation resistance of polypropylene films, as measured by the critical dose, increases as the content of smectic crystallines in the film increases.(4) The polypropylene films with smaller yield stress before irradiation show higher radiation resistance. The critical dose of homopolymer films is greater than that of copolymer films, when compared at the same size of spherulites contained.(5) For the films containing spherulites with 10 um mean diameter, the yield stress before irradiation decreases rapidly as the mean spherulitic diameter becomes smaller. The films containing spherulites with more than 10 um breaks down before reaching a yield point, and the corresponding tensile strength decreases with the increase in mean diameter of spherulites.(6) The weight swelling ratio of polypropylene films at room temperature, which is evaluated by immersion of the films in p-xylene at 25 C, increases rapidly with the decrease in mean diameter of spherulites.(7) For the films containing smaller sized spherulites, the yield stress before irradiation increases and thus the radiation resistance increases as the weight swelling ratio at room temperature becomes grater. Less

医用聚丙烯固体材料经辐射灭菌，导致其机械性能氧化降解。在本研究中，研究了形态对聚丙烯材料辐射降解的影响。结果表明：(1)热压成型条件对等规聚丙烯薄膜的晶体结构和球晶尺寸有较大影响。快速冷却聚丙烯熔体会产生晶型和小球晶的近晶改性，而缓慢冷却则会产生由单斜晶组成的成熟球晶。(2)辐照后，聚丙烯薄膜的断裂伸长率随辐照剂量呈s型曲线减小。残余伸长率达到50%的临界剂量是衡量聚丙烯材料抗辐射能力的一个很好的指标。(3)用临界剂量测定聚丙烯薄膜的耐辐射性能随薄膜中近晶含量的增加而增加。(4)辐照前屈服应力较小的聚丙烯膜具有较高的耐辐照性。当所含球晶尺寸相同时，均聚膜的临界剂量大于共聚物膜的临界剂量。(5)对于平均直径为10 um的球晶薄膜，辐照前屈服应力随平均球晶直径的减小而迅速减小。含有大于10um球晶的薄膜在达到屈服点之前就会破裂，相应的抗拉强度随着球晶平均直径的增加而降低。(6)室温下聚丙烯薄膜的重量膨胀率（用25℃对二甲苯浸渍法测定）随着球晶平均直径的减小而迅速增大。(7)对于含有较小球晶的薄膜，随着室温下重量膨胀比的增大，辐照前的屈服应力增大，因而辐照阻力增大。少