A study of verification on the mixing ratio of recycled and new polypropylene plastics.

Autor: Hsuan Yen, 嚴萱
Rok vydání: 2015
Druh dokumentu: 學位論文 ; thesis
Popis: 103
Petrochemical plastic products have been widely used in modern societies, but environmental impact resulted from waste plastics has become a vital issue regarding environmental protection. Currently there are green marks or regulations regarding recycled plastics, which request that specific products must be blending with certain ratios of postconsumer recycled plastics. To follow the rules, manufacturers can verify their renewable materials by self-declaration or commission the renewable materials to a third party for verification. However, there’s still no scientific methods of verification on plastics blended with various ratios. Furthermore, seldom studies have investigated scientific methods to examine the mixing ratio of postconsumer recycled plastics. Consequently, this study is aimed to establish a method of verification on polypropylene (PP) plastics blended with various ratios by investigated the thermal and mechanical properties of the blended plastics. In this study, the experimental parameters and analysis of PP, e.g., viscosity DSC, melt index, and melting point were conducted to determine the conditions for injection molding. Afterwards, the blended specimens were produced by injection molding with various of ratios. The blended specimens were analyzed and tested with their thermal properties (by melt index, melting point, and TGA), mechanical properties (by viscosity, tensile test, and impact test), and morphological observations (by SEM and TEM), to investigate the characteristics of the specimens with various of ratios. Finally, we estimated the activation energies for pyrolysis reactions (Ea) based on the results of TGA, and established equations with tested items and mixing ratios using regression analysis. The results revealed that the viscosity of new PP chips covered the range of 11,600 to 13,400 poise while that of postconsumer recycled PP covered the range of 7,120 to 8,320 poise. The melt index of new PP chips was 8.3 g/10 min while that of postconsumer recycled PP was 25.6 g/10 min. The melting peak temperature of new PP chips was 171.97℃ while that of postconsumer recycled PP was 170.24℃. The operational parameters to inject blended specimens were set based on their thermal properties and operating conditions on-site, and produced the specimens with various mixing ratios. The melt flow indexes were in between 7.59-18.36 g/10 min, and the values increased with increase of the ratio that recycled PP took account in the mixture. The melting peak temperatures of the specimens were in between 167-169℃. The activation energies (Ea) were in between 39.91~12.07 kcal/mol, and the values decreased with increase of the ratio that recycled PP took account in the mixture. The maximum decomposition temperature decreased with increase of the ratio that recycled PP took account in the mixture, and increased with increase of heating rates. The viscosities decreased with increase of the ratio that recycled PP took account in the mixture, and decreased with increase of rotational speed as well. The impact strength were in between 37.94~49.41 J/m and revealed no specific trends. The Young’s Modulus (E) were in between 112.11~191.02 Mpa, and the values increased with increase of the ratio that recycled PP took account in the mixture. TEM results showed good dispersions and indicated no difference in the distribution of the microstructure among the specimens. The results of SEM showed that brittle with ductile pulling of fibrils could be observed in S1-S3 as the tensile strain increased as well, which was corresponding to the results of the tensile tests. In the mean time, the results of impact tests indicated decent compatibilities among the specimens, and the distribution characteristics of the specimens did not differ with the mixing ratios. Statistical analysis indicated that mixing ratios had significantly and highly negative correlation with viscosity, and had significantly and highly positive correlation with MI, Ea, and E. According to the experimental and statistical analysis results, we established equations to estimate mixing ratios in three different ways, and those equations can serve as reference for verifying the mixing ratios of PP plastics.
Databáze: Networked Digital Library of Theses & Dissertations
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