When SBS modified bituminous sheet materials were used as the roof waterproof material without protective layer,it was going to undergo natural aging. This paper studied natural aging of SBS sheet materials by testing the parameters changes of tensile properties,heat resistance and low temperature flexibility of two kinds of polyester base materials SBS sheet materials. The results showed that the influence law of natural aging on the SBS sheet materials which had same type and different formula was basically the same,but the influence degree was different. During natural aging process,the upper surface of the bituminous cover layer would become hard and powder in the ultraviolet light condition,and the cracks caused by local shrinkage evolved into fractures gradually. In the early natural aging,SBS sheet materials had experienced three processes,namely,the internal moisture content increased,the internal moisture content decreased (dry after soaking) and the freezing-thawing cycle,these three processes directly affected performance of polyester base materials.%SBS改性沥青防水卷材作为无保护层的屋面防水材料使用时，要经受自然老化。论文通过检测自然老化过程中两种聚酯胎SBS防水卷材的拉伸性能、耐热性和低温柔性等参数的变化，对SBS防水卷材的自然老化进行研究。结果表明：自然老化对型号相同，配方不同的SBS防水卷材影响规律基本一致，但影响程度不同。自然老化过程中，上表面沥青涂盖层在紫外线辐射作用下会变硬、粉化，因局部收缩等原因产生裂纹，并逐渐演变为裂缝。在自然老化初期，SBS防水卷材主要经历了内部含水率增加、内部含水率减少（浸水再烘干）以及冻融循环3个过程，这3个过程直接影响聚酯胎基的性能。
展开▼
