界面粘结对聚氯乙烯/丁腈橡胶共混物脆韧转变的影响

应用丙烯腈（ＡＮ）含量不同的丁腈橡胶（ＮＢＲ）与聚氯乙烯（ＰＶＣ）共混，研究了界面粘结对ＰＶＣ／ＮＢＲ共混物脆韧转变的影响．结果表明：当基体层度Ｔ相等时，过强的界面粘结，使ＰＶＣ／ＮＢＲ共混物的冲击强度降低，并且其产生脆韧转变的临界基体层厚度Ｔｃ减小．界面粘结对于聚合物共混物的增韧行为具有直接的影响．损伤区分析给出：随着界面粘结强度增大，空洞化过程受阻，减弱能量的耗散，并且不利于诱导剪切屈服损伤的产生，因而不利于增韧；但是界面粘强度过小，意味着共混物的相容性太差，致使分散相粒径过大，也不利于增韧．所以对增韧来讲，共混物的界面粘结强度存在一个最佳范围．

EFFECT OF INTERFACIAL ADHESION ON THE IMPACT TOUGHNESS AND TOUGHENING MECHANISMS OF PVC/NBR BLENDS

The present work studies the effect of interfacial adhesion on the brittle ductile transition (BDT) in PVC/NBR by strengthening the interfacial adhesion through an increase of the acrylonitrile (AN) content in NBR The rubbers,NBR18 and NBR26,consist of 18 and 26 wt % of AN,respectively There are two BDT master curves for PVC/NBR blends,when impact strength ( S I ) is plotted against matrix ligament thickness ( T=T(d,σ, ),where d is the NBR particle diameter, σ the dispersity of particle diameter,and  the volume fraction of dispersed phase,respectively) Below the critical value T c of T ,the blend becomes extremely tought At any given T the S I of PVC/NBR26 is lower than that of PVC/NBR18,and the transition in PVC/NBR26 occurs at a lower T value,indicating that strong interfacial adhesion is not favorable for achieving high toughness The stress whitening zone and SEM photograph of fracture surface of the samples shows that,as interfacial adhesion is too strong,interfacial debonding and hence cavitation is hindered,thereby delaying the occurrence of shear yield deformations