An In situ Experimental Study on Solidification Kinetics of Polyolefins: Effect of Cooling Conditions |
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| Authors: | Bin Yang Yan-Dong Guo Ru Xia Ji-Bin Miao Li-Feng Su Jia-Sheng Qian |
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| Affiliation: | 1. College of Chemistry &2. Chemical Engineering, Key Laboratory of High-Performance Rubber &3. Products of Anhui Province, and Key Laboratory of Environment-Friendly Polymeric Materials of Anhui Province, Anhui University, Hefei, Anhui, China |
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| Abstract: | The solidification kinetics of polyolefins (PO) under three cooling conditions were investigated using an in situ measurement of the temperature decay within the PO resins. The phase-change temperature range of high-density polyethylene (HDPE) was located between 110 and 120°C, and those of low-density polyethylene (LDPE) and polypropylene (PP) were 90–110°C and 100–120°C, respectively. The cooling rate of the liquid-state stage is larger than that of the crystallization stage, primarily owing to the release of the latent heat of crystallization as well as the reduced temperature difference between the sample and cooling medium; they jointly slow down the cooling rate to an extent. The time with respect to phase transformation and its lasting period have close relations to the materials' molecular characteristics (e.g., Mw, MWD, LCB, etc.). Three empirical equations were proposed, and found to be applicable for the cooling analysis of the PO molten materials at relatively low cooling rates prior to crystallization. |
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| Keywords: | cooling rate in situ measurement phase-change polyolefin solidification kinetics |
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