Abstract
Two polyethylene (PE) resins (samples A and B) are synthesized as high-speed extrusion coatings with similar minimum coating thickness and neck-in performance but different maximum coating speeds. Both samples are separated into seven fractions using preparative temperature rising elution fractionation. The microstructures of the original samples and their fractions are studied by high-temperature gel permeation chromatography, Fourier transform infrared spectroscopy, 13C nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and successive self-nucleation/annealing thermal fractionation. Compared with sample B, sample A has a broader MWD, more LCB contents, and less SCB contents. Moreover, sample A contains slightly more 30 °C and 50 °C fractions with lower molecular weights, and more fractions at 75 °C and 85 °C with higher molecular weight. The chain structure and its distribution in the two PE resins are studied in detail, and the relationship between the chain structure and resin properties is also discussed.
Highlights
Coating polyethylene (PE) resin has high strength, good toughness, strong adhesiveness, good film formation, and excellent heat-sealing performance, as well as water- and moisture-proof properties[1 5]
Two PE resins are selected as high-speed extrusion coating resins with similar minimum coating thickness and neck-in performance but different maximum coating speeds. Both resins are fractionated by P-Temperature-rising elution fractionation (TREF) according to their crystallizability
Their 13C nuclear magnetic resonance spectroscopy (13C-NMR) assignments are based on previous studies[7, 35]
Summary
Coating polyethylene (PE) resin has high strength, good toughness, strong adhesiveness, good film formation, and excellent heat-sealing performance, as well as water- and moisture-proof properties[1 5]. Two PE resins are selected as high-speed extrusion coating resins with similar minimum coating thickness and neck-in performance but different maximum coating speeds Both resins are fractionated by P-TREF according to their crystallizability. Each sample (~6 mg) was first heated from 25 °C to 200 °C at a rate of 10 K/min, and the temperature was maintained at 200 °C for 5 min to erase its thermal history. The DSC cooling scan was set at 10 K/min from Ts to 0 °C, in which the thermal treatment effects would be reflected on the crystallization of the samples. The third to fifth steps were repeated with a lower Ts. the sample was heated from 0 °C to 200 °C at a rate of 10 K/min, and the multiple melting endotherm was obtained
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