1,6-己二醇二丙烯酸酯和苯乙烯多单体熔融接枝制备长支链聚丙烯研究

PREPARATION OF LONG CHAIN BRANCHED PP VIA MULTI-MONOMER MELT GRAFTING IN THE PRESENCE OF BI-FUNCTIONAL MONOMER 1,6-HEXANEDIOL DIACRYLATE

采用哈克转矩流变仪制备了1,6-己二醇二丙烯酸酯(HDDA)和苯乙烯(St)多单体熔融接枝聚丙烯(PP)体系.红外测试结果表明St的加入能够促进HDDA接枝到PP主链,提高接枝率.动态流变行为研究结果也表明采用多单体熔融接枝PP更有利于体系在熔融接枝中生成长支链(LCB).随着St单体添加量的增加,HDDA的接枝率增大,体系的MFR降低,分子量和分子量分布宽度增加,LCB的含量也随之增加.热重分析(TGA)研究发现采用多单体熔融接枝制备的接枝物的热稳定性得到了显著的提高,分解温度提升幅度达到了几十度之高.X射线衍射(XRD)实验结果表明多单体熔融接枝可以促进PP中β晶的形成.结晶和熔融行为测试表明接枝PP可以促进结晶异相成核导致结晶温度升高.

In this work,long chain branched（LCB） polypropylene（PP） was prepared by multi-monomer melt grafting with the presence of 1,6-hexanediol diacrylate（HDDA） and styrene（St） in a Haake Rheomix batch mixer.FTIR spectra showed the addition of St to the melt grafting system could significantly promote the graft degree of HDDA onto PP backbones.For fixed initiator and HDDA monomer content,the more the addition of St monomer,the higher the graft degree of HDDA monomer was.Investigations on the rheological properties of grafted PP indicated the existence of LCB structures.During melt grafting,the graft degree of HDDA monomer increased,melt flow rate（MFR） of the grafted PP decreased and more LCB PP was generated with increasing the St monomer concentration.Derivative thermogravimetry（DTG） measurements showed that the thermal stabilities of the grafted PP were greatly enhanced,which was much better than iPP.The decomposition temperatures,known as T5% and Tmax,were more than 46 K higher than iPP,and more than 30 K higher than grafted PP without St,implying the thermal stabilities of the grafted PP were greatly enhanced by multi-monomer melt grafting with St and HDDA monomers.X-ray diffraction（XRD） results demonstrated the graft processing by multi-monomer melt grafting could well induce the crystallization of PP β form crystals.Differential scanning calorimetry（DSC） characterization showed that grafted PP had higher crystallization temperature and wider melting and crystallization peaks,due to the heterogeneous nucleation effect and restriction of the existence of grafted PP chains,respectively.