| Summary: | 博士 === 國立臺灣科技大學 === 高分子工程系 === 94 === ABSTRACT
Polyethylene terephthalate(PET) is the cheapest engineering plastic with excellent mechanical and physical properties at present; however, pool toughness is its weakness. In recent ten years, it is widely used in packaging and containers to replaces metals, and cellophane, and the other plastics(e.g PVC). Regarding the statistics from Environmental Protection Administration(see table 1-1).PET is the fastest growing and the greatest number of waste plastic containers in the last ten years. Polypropylene(PP) and Polyethylene(PE) are No. 2. In 2004, there are 80,358 tons recycled PET bottles in Taiwan. It is equal to 3.15 billion 600cc mineral water bottles.The quantity is alarming. Thus, the subjects of resource “reusing”, “recycling”and “recovering” are very important to us. In the process of recycling, to completely sieve and separate out PE/PP(the second largest quantities of waste plastic containers)is very difficult, so a few might be mixed up with PET. Because PET is polar polymer, but PE and PP are nonpolar polymer materials, they are not compatible. If we recycle them together, it will influence the quality and value added of recycling materials. So, how to improve the compatibility of PET, PET and PE, or PP is the major objective of this research.
Using polyethylene-octene elastomer(POE) to graft maleic anthydride(MA), then it will become POE-g-MA copolymer. It could be compatibilizer and impact modifier to do a blending processing modifying research on blends, like PET, PET/HDPE and PET/PP. Also, use mechanical properties testing analysis, Fourier transform infra-red spectroscopy(FITR), dynamic mechanical analysis(DMA), morphology observation analysis, rheological behavior and interfacial tension analysis to research their modification effects, such as compatibility and toughness
Regarding the analysis above, we got the following important results.
1. POE-g-MA is an elastomer with polar functional group. Because MA is interacting well with –OH of PET, it could improve the compatibility between POE-g-MA and PET. So, the impact strength modification is outstanding. Adding 20% POE-g-MA will increase PET’s notched Izod impact strength from 30 J/m to 1000 J/m. The toughening effect is over 33 times better than before. Even in low temperature(0℃,-20℃, and -40℃), the toughening effect is excellent as well. POE-g-MA also brings nice toughening modification to recycling materials of PET bottle.
2. Regarding the results of FTIR, scanning eclectron microscopy(SEM), and rheological behavior analysis, POE-g-MA could efficiently improve the compatibility between PET and HDPE, and we find interfacial adhesion between the faces of PET substrate and HDPE dispersed phase. The result of impact strength test show adding 30 phr POE-g-MA will increase 80PET/20PP blends’ room temperature impact strength 31 times (from 30 J/m to 930 J/m). Even in low temperature, toughness modification is still outstanding.
3. FTIR, SEM, DMA and rheological behavior analysis reveal better compatibility between PET and PP brings better modification effect. And interfacial adhesion is also found between the faces of PET substrate and PP dispersed phase. Impact strength test result shows adding 20 phr POE-g-MA will increase 80 PET/20PP blends’ room temperature impact strength 24 times(from 33 J/m to 789 J/m). Due to the material specialty that POE-g-MA is a soft elastomer, PET/PP/POE-g-MA blends’ mechanical properties, such as tensile strength, flexural strength and flexural modulus, are weaker than PET/PP blends’.
4. To compare the toughness modification effects that POE-g-MA acts on PET/HDPE and PET/PP blends, adding 20 phr POE-g-MA would increase 80PET/20HDPE blends’ impact strength from 30J/m to 930 J/m, but increase 80PET/20PP blends’ impact strength from 33J/m to 789J/m only. Obviously, POE-g-MA provides better toughening modification effect on PET/HDPE blends.
Keywords:PET, POE, HDPE, PP,elastomer,toughness, compatibilizer
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