The Study On Polypropylene Modified By Thermo-cross-linked Rubber

Polypropylene is one of the general plastics,which has excellent properties such as light weight,high temperature resistance and corrosion resistance,which makes it have broad application prospects in the packaging,automotive and other industries,especially as a biomaterial in medical industry.However,polypropylene is a semi-crystalline polymer,and has poor impact resistance because of large spherulites,which limits its use greatly.It's necessary to tough the PP by rubber.Meanwhile,PP modified by rubber also reduces the tensile strength and elastic modulus.So,we want to find out a method for modifying PP,which increases the toughness as well as decreases the reduction of tensile strength and elastic modulus.In this study,thermos-reversible cross-linked rubber is used for modifying PP.While toughing,the rubber of cross-linked plays a important role on decreasing the reduction of tensile strength and elastic modulus,and maintain thermos-plasticity.Esterification cross-linking of unsaturated rubber with DCPDCA is studied to obtain cross-linked rubber cross-linked with dicyclopentadienyl(-DCPD-),which can be dimerize at high temperature and polymerize at low temperature.So thermo-reversible cross-linked rubber is prepared successfully.The thermo-reversible cross-linked rubber,consisting of EPDM and PB,was used to modify PP to study on the influence of thermo-reversible cross-linked rubber on mechanical and crystallizing behavior of modified PP.The main research work includes:1.Study on esterified cross-linking catalysts and suitable process conditions for unsaturated rubber with DCPDCA.The thermo-reversible cross-linked rubber was successfully prepared by the in situ esterification of DCPDCA and double bond in rubber,characterized by FT-IR,solubility in toluene and repeatability.The suitable condition for esterification is 175?,60 min.2.The obtained thermo-reversible cross-linked rubber was filled with ultra-fine kaolin and carbon black respectively,and the mechanical test of the samples cross-linked under suitable condition were tested.The results showed that the tensile strength of thermo-reversible cross-linked rubber filled with carbon black was higher than cross-linked rubber not filled.We can get conclusion that carbon black has reinforcing effect while ultra-fine kaolin don't.3.The thermo-reversible cross-linked rubber was used to modify PP to study on the influence of esterification cross-linking timing(pre-cross-linking or in-situ cross-linking),rubber content,mixing conditions on the mechanical properties of modified PP.The results of mechanical test showed that the optimal condition for the thermo-reversible cross-linked rubber modified polypropylene was 40 parts of pre-crosslinked rubber esterificated cross-linking at 175?×60 min,with 100 parts of polypropylene blened at 170?×10 min.4.The DSC and PLM were used to study on the influence of processing technology on the crystallizing behavior of PP modified by thermo-reversible cross-linked rubber.The results of DSC and PLM analysis showed that the crystalline temperature and degree of crystallization are both decreased,while spherulites is more dispersed in PP modified by thermo-reversible cross-linked rubber.5.Biological sterilization experiments show that the sterilization process has no obvious effect on the tensile strength of modified polypropylene,indicating that the modified polypropylene could be used in biomedical materials.The thermo-reversible cross-linked rubber prepared in this study has repeatability to protect the environment and save resources.The PP modified by thermo-reversible cross-linked is expected to have higher strength while increasing toughness,expanding the application of polypropylene...