Effects Of Screw Structure To Maleic Anhydride Grafted Polypropylene And Its Composites

With the modified polymer processing applied more widely, screw structuremodification process for machining has increasingly importance. This paper studiedthe impacts of screw structure to maleic anhydride grafted polypropylene and itscomposites. We all know different twin-screw extrude has different screw structure,in this research, three materials including maleic anhydride grafted polypropyleneand its composites glass fiber reinforced polypropylene (PPGF30) and nylon66/polypropylene alloy(PA66/PP alloy)were respectively prepared by co-rotatingtwin-screw extrude HT-30and KS-75. Comparative study was did to finddifferences and similarities of these three materials above which were prepared bydifferent screw structure.The characterizations of PP-g-MAH prepared by co-rotating twin-screwextruder HT-30and KS-75, were analyzed by Infrared Spectroscopy (IR),Differential Scanning Calorimetry (DSC). Besides, we also determined the graftingrate by titration method. We studied how screw structure effect grafting rate. Theresults indicate that the grafting rate of PP-g-MAH prepared by twin-screw extrudeHT-30is higher than that of KS-75.Comapred with PP-g-MAH prepared by HT-30,the other one had higher crystallization temperature, lower melting point, largermelting enthalpy and higher crystallinity.We prepared PPGF30by co-rotating twin-screw extruder HT-30and KS-75,and studied their performance of tensile strength, flexural strength and notched Izodimpact strength. The thermal properties of PPGF30were analyzed by DifferentialScanning Calorimeter (DSC) and Thermogravimetry (TG), and the length of glassfiber was observed by Scanning Electron Microscopic (SEM). The comparison ofmechanical and thermal performance between PPGF30prepared by two differentscrew structure led to conclusions. It showed that PPGF30prepared by HT-30havebetter mechanical performance than that of the material prepared by KS-75ontensile strength, flexural strength and notched Izod impact strength. Different screwstructure having different shearing action to glass fiber, the length of glass fiber isnot the same in PPGF30. Compared to PPGF30prepared by KS-75, the glass fiber islonger in PPGF30prepared by HT-30. Therefore, a great enhancement led to a bettermechanical performance. The screw structure has little influence on crystallization and melting properties. However, it had certain effect on thermal stability.In thisstudy, the PPGF30prepared by KS-75had a better thermal stability.Finally, PA66/PP alloys were prepared by different screw structure. Theirmechanical, thermal performances and impact fracture morphology were alsoanalyzed. The results showed that the tensile strength, flexural strength and notchedIzod impact strength of PA66/PP alloy prepared by HT-30were higher than that ofPA66/PP alloy prepared by KS-75. The degradation of polypropylene was affectedby screw structure. Because of more serious degradation, PA66/PP alloy prepared byKS-75showed poorer mechanical performance. Similarly, screw structures had littereffect on crystallization and melting properties. But the addition of PP-g-MAH madeboth PP and PA66reactive and generated a new graft polymer, thus a new meltingpeak appeared. The thermal stability of PA66/PP alloy prepared by KS-75was betterthan that of PA66/PP alloy prepared by HT-30.