Properties of recycled polypropylene from extrusion processes
สมบัติของพอลิโพรไพลีนที่ผ่านการรีไซเคิลในกระบวนการเอกซ์ทรูด
Charoen Nakason, Asst. Prof., D. of Rubber Tech. and Polymer Sci., F. of Sci. and Tech., PSU.
Azizon Kaesaman, D. of Rubber Tech. and Polymer Sci., F. of Sci. and Tech., PSU.
Sakrapong Na Piboon, B.Sc. Student in Rubber Tech., PSU.
Corresponding e-mail : ncharoen@bunga.pn.psu.ac.th
Grant : Government Budget
Presented : The 1st Thailand Materials Science and Technology, 19-20 July 2000,
The Amari Watergate Hotel, Bangkok, p. 350-353
Key words : polypropylene, recycle, flow curve, viscosity curve, tensile strength,
impact strength
The effect of numerous reprocessing cycles on rheological, physical and thermal properties
for two grades of polypropylene were studies. It was found that flow curve (i.e., plot of shear stress versus shear rate) and viscosity curve (i.e., plot of shear viscosity versus shear rates decreased with increasing the number of reprocessing cycles. The results correspond to the increasing trend of melt flow index (MFI). Mechanical properties in terms of tensile strength at yield and impact strength also decreased with increasing the number of reprocessing cycles. This may be attributed to degradation
of polypropylene molecules under mechanical and thermal effect. Influence of the residence time was also studied. The results found that longer residence time provided the lower flow curve, viscosity curve, tensile strength and impact strength.
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