软质PVC交联对增塑剂迁移行为的影响

研究了软质PVC交联前后,对苯二甲酸二辛酯(A)、乙酰柠檬酸三正丁酯(B)和邻苯二甲酸二辛酯(C)三类增塑剂在40℃橄榄油浸泡环境中的迁移行为.结果表明,不管PVC是否交联,A、B、C三类增塑剂的迁移率均随浸泡时间的延长,呈总体上升趋势;在浸泡的前24 h,迁移率迅速上升,当浸泡时间超过192 h后,迁移率上升逐渐趋于平缓.PVC交联对各类增塑剂的迁移均起到了明显的抑制作用,且随着凝胶含量的增加,其抑制作用越明显;当凝胶含量为最大值、增塑剂达到最终的迁移平衡时,均能降低约30%的增塑剂迁移率.几类增塑剂中,B 增塑剂迁移率>C增塑剂迁移率>A增塑剂迁移率;PVC交联对A、B、C三类增塑剂之间迁移抑制率的影响无明显规律.

Migration of Plasticizers in Flexible Crosslinked PVC

In this paper,the migration of three kinds of plasticizers(terephthalate,citrate,phthalate) in flexible crosslinked PVC was studied in 40℃ olive oil.The results show that the migration ratio increases with time,and increases quickly in initial 24 h,and then tends to be gently after 192 h,which can be attributed to two reasons.The first,concentration gradient of plasticizers between the samples and solution is high at beginning,it is propitious to migration.The second,crosslinked net which is formed by peroxide is located at the inner of PVC sample and can?t inhibit the migration of the plasticizers located at the edge of the sample,which consequently migrate quickly into solution in initial stage.As the soak time increasing,the concentration gradient of plasticizers between sample and solution is reduced.Moreover,crosslink structure of PVC could effectively inhibit the migration of plasticizers,and the higher gel content the sample has,the more effective inhibition it shows.The migration ratio can be reduced about 30% when the sample has the maximal gel content.In addition,the results reveal that the migration ratio of plasticizers is ranged in the order of citrate,phthalate,terephthalate from large to small,which can be attributed to the difference of molecular structure of plasticizers.The higher molecular polarity the plasticizer has,the smaller migration ratio is shown in 40℃ olive oil environment.It was found that the effect of PVC crosslink on inhibiting the migration ratio among the three plasticizers has no obvious rule.