微交联聚乙烯应力-光氧老化开裂行为的研究

为了提高桥梁缆索护套耐老化性能，通过制备微交联的聚乙烯材料研究不同交联度聚乙烯材料的应力-光氧老化开裂行为.采用剥离一段缆索护套并测定收缩率来计算聚乙烯护套在实际中的内应力，利用表面形貌观察、形变量测定、红外光谱分析、差式量热扫描法、凝胶含量测定等表征手段研究样品老化过程中的老化开裂行为.研究表明：随着交联度的增加，聚乙烯材料发生断裂的时间先增加后减少，表面裂纹发展的速度先增加后减小，裂纹发展速度及抗老化开裂性能最佳的交联度约为10%；聚乙烯材料的氧化速率与断裂时间呈正相关；表面裂纹出现后，材料被完全氧化；老化过程中，聚乙烯凝胶含量和结晶度均不断上升.
To improve anti-aging performance of bridge cable sheath, the stress light oxygen aging cracking behavior of different cross-linking polyethylene materials was studied by preparing micro crosslinked polyethylene material. The actual internal stress was calculated by measuring the shrinkage of cable sheath; and the cracking and aging behaviors of micro-crosslinked polyethylene under stress were studied by using various tools such as microscopic observation, strain measurement, Fourier Transform Infrared Spectroscopy, differential scanning calorimetry analysis, determination of gel content and so on. It can be found that the breaking time of samples was increased firstly and then decreased as the degree of crosslinking increased, and samples showed the slowest crack growing rate, best aging and cracking resistance at a crosslinking degree of~10%. The results showed that there was a positive correlation between oxidation rate and breaking time; and samples were fully oxidized when the cracks appeared on the surface. The gel content and the crystallinity of samples were increased with aging time.