中文摘要：

以硬质聚氯乙烯（PVC）为研究对象,通过色差实验、FTIR、UV等方法探究了PVC在湿热、辐射低的琼海和暖温、干旱且辐射高的若羌地区自然老化的变色行为与分子结构变化.结果表明,太阳辐射是影响PVC自然老化过程中变色行为和分子结构变化的主要环境因素,PVC在干旱、辐射高的若羌地区比在湿热、辐射低的琼海地区更易变黄和变红,而在两地变暗的程度相近;这是因为随着自然老化时间的延长,PVC逐渐发生脱除氯化氢反应和氧化反应,在干旱且辐射高的若羌,更易发生脱除氯化氢反应,而在湿热且辐射低的琼海,脱除氯化氢反应和氧化反应的速度相近,在若羌老化的PVC样品生成了更多的共轭长度（n）≥8的C=C长共轭序列所致.

英文摘要：

The effects of different natural environment on rigid PVC natural aging were studied in detail.Rigid PVC samples were placed in Sinkiang Ruoqiang country and Hainan Qionghai city of China,respectively,for natural aging.Then,color and corresponding molecular structure changes of the natural aged PVC were investigated by chromatic aberration,FTIR and UV methods.In particular,monthly solar radiation in Ruoqiang is508.25 MJ/m2,which is higher than that of Qionghai.But average temperature,medial humidity,monthly total precipitation and oxygen pressure in Ruoqiang are far lower than those in Qionghai.As a result,color change and molecular structure change of the rigid PVC samples aged in the two places were different.It was found that brightness（（35）L）of PVC surface decreased with increase of aging time.However,redness（（35）a）,yellowness（（35）b）and color difference（（35）E）increased with increase of aging time.In addition,redness（（35）a）,yellowness（（35）b）and color difference（（35）E）of the PVC aged in Ruoqiang were larger than those in Qionghai.Meanwhile,surface color change was accompanied by molecular structure change.Firstly,FTIR results showed that C=C and C=O were formed and they increased with the aging time,which indicated that dehydrochlorination and oxidation reactions took place.And when aged in Ruoqiang,the amount of C=C was larger than C=O,indicating that dehydrochlorination played a dominant role.When aged in Qionghai,the amount of C=C was similar to that of C=O,indicating that dehydrochlorination was at a similar reaction speed with oxidation.Secondly,UV results confirmed that C=C long conjugated sequence（conjugation length≥8）of PVC increased with aging time.In addition,the amounts of C=C,C=O and C=C long conjugated sequence（conjugation length≥8）of PVC aged in Ruoqiang were larger than those in Qionghai.Thirdly,it was also found that there was a good correlation between the color change and the C=C long conjugated sequence（conjugation length?