三层共挤聚乙烯流延膜的热封强度与组成关系
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摘要
通过差示扫描量热法(DSC)和升温淋洗分级研究了3种三层共挤聚乙烯流延膜的热封强度与组成的关系。结果表明:不同热封层组成的薄膜起封温度主要与热封层的非晶比例有关,可用热封层树脂的DSC熔融行为来推测薄膜起封温度大致范围;当热封温度高时,薄膜在热封后的冷却结晶过程中形成高的结晶度和晶体熔点,有利于形成高的热封强度;热封层相同但芯层不同的薄膜其高温热封性能也有差异,说明在高温时芯层也部分参与到热封层的形成;3种薄膜在高温时的热封强度大,足以抗衡薄膜的拉伸屈服和一定程度的应变硬化。
The effect of compositions on the seal strengths of three different three-layer co-extruded polyethylene(PE) cast films were observed by differential scanning calorimeter(DSC) and temperature rising elution fractionation(TREF). The results indicate that the initial sealing temperature depends on the ratio of the non-crystalline phase in the sealing layer,which can be estimated from the melt behaviors of the sealing layer resins by DSC. The crystallinity and crystal melting point of the films are high at a high sealing temperature during cooling and crystallization process after heat sealing,which is in favor of higher seal strength. The films with same sealing layer and different compositions in the middle layer show different sealing properties,indicating the involvement of the middle layer resins in the sealing processes. The heat sealing strengths of the three-layer films at high sealing temperature are strong enough to resist the yielding and strain hardening to some extent.
The effect of compositions on the seal strengths of three different three-layer co-extruded polyethylene(PE) cast films were observed by differential scanning calorimeter(DSC) and temperature rising elution fractionation(TREF). The results indicate that the initial sealing temperature depends on the ratio of the non-crystalline phase in the sealing layer,which can be estimated from the melt behaviors of the sealing layer resins by DSC. The crystallinity and crystal melting point of the films are high at a high sealing temperature during cooling and crystallization process after heat sealing,which is in favor of higher seal strength. The films with same sealing layer and different compositions in the middle layer show different sealing properties,indicating the involvement of the middle layer resins in the sealing processes. The heat sealing strengths of the three-layer films at high sealing temperature are strong enough to resist the yielding and strain hardening to some extent.
引文
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[11]Zhang Mingzong,Yuen F,Choi P.Differences in the solidstate structures of single-site and Ziegler-Natta linear lowdensity polyethylenes as revealed by molecular dynamics simulation[J].Macromolecules,2006,39(24):8517-8525.
[12]Wang Shujun,Wu Changjiang,Ren Minqiao,et al.Liquidliquid phase separation in a polyethylene blend monitored by crystallization kinetics and crystal-decorated phase morphologies[J].Polymer,2009,50(4):1025-1033.
[2]佚名.茂名石化成功试产出两种流延聚乙烯膜料[J].塑料科技,2018,46(3):106.
[3]Prasadarao M,Ferdinand C S.Heat sealing of semicrystalline polymer films.Ⅰ.Calculation and measurement of interfacial temperatures:effect of process variables on seal properties[J].J Appl Polym Sci,1994,51(1):89-103.
[4]Ferdinand C S,Prasadarao M.Heat sealing of semicrystalline polymer films.Ⅱ.Effect of melting distribution on heat-sealing behavior of polyolefins[J].J Appl Polym Sci,1994,51(1):105-119.
[5]Mueller C,Capaccio G,Hiltner A,et al.Heat sealing of LLDPE:relationships to melting and interdiffusion[J].J Appl Polym Sci,1998,70(10):2021-2030.
[6]Simanke A G,de Lemos C,Pires M.Linear low density polyethylene:microstructure and sealing properties correlation[J].Polym Test,2013,32(2):279-290.
[7]黄川华.聚乙烯薄膜热封性能研究[J].塑料包装,2008,18(4):46-49.
[8]罗欣,盛平厚,李鑫,等.mLLDPE熔融与热封性能的研究[J].塑料工业,2002,30(5):25-34.
[9]林渊智,苏羽航,卢莲卿.POE/mPE/PE-HD改性PE-LD热封薄膜性能研究[J].中国塑料,2016,30(2):28-31.
[10]Anantawaraskul S,Soares J B P,Wood-Adams P M.Fractionation of semicrystalline polymers by crystallization analysis fractionationand temperature rising elution fractionation[M].Berlin:Springer-Verlag,2005:1-54.
[11]Zhang Mingzong,Yuen F,Choi P.Differences in the solidstate structures of single-site and Ziegler-Natta linear lowdensity polyethylenes as revealed by molecular dynamics simulation[J].Macromolecules,2006,39(24):8517-8525.
[12]Wang Shujun,Wu Changjiang,Ren Minqiao,et al.Liquidliquid phase separation in a polyethylene blend monitored by crystallization kinetics and crystal-decorated phase morphologies[J].Polymer,2009,50(4):1025-1033.