温度和应变率对模内嵌膜片材力学性能的影响
|
摘要
通过单向拉伸试验研究了模内嵌膜工艺中常用的聚碳酸酯(PC)和聚甲基丙烯酸甲酯(PMMA)薄膜在不同温度和应变率下的力学性能。结果表明:随着温度的升高和应变率的降低,两种材料的屈服强度下降、断裂伸长率提高。当温度低于120℃时,PC薄膜的应变硬化系数(h)和图案变形度(r')对温度具有较弱的敏感性,而对应变率具有较强的敏感性,h和r'值随着应变率的增加而增大;当温度高于120℃时,PC薄膜的h和r'值则具有较弱的应变率敏感性和较强的温度敏感性,二者随着温度的升高而减小。由于PC薄膜的r'值远大于1而PMMA薄膜的r'值小于1,因此PMMA薄膜成型时的图案变形程度较PC薄膜轻。厚度对两款薄膜材料的屈服强度和h值无明显影响;但薄膜厚度会影响PC薄膜的r'值,薄膜越薄,r'值越小,但成型性能会变差。
The mechanical properties of polycarbonate(PC) and poly(methyl methacrylate)(PMMA) films commonly used in in-mold film processes at different temperatures and strain rates were investigated by uniaxial tensile tests. It is found that as the temperature increases and the strain rate decreases, the yield strength of the two materials decreases, and the elongation at break increases. When the temperature is lower than 120℃, the strain hardening coeffi cient(h) and the pattern deformation degree(r') of the PC film have weak sensitivity to temperature, and have strong sensitivity to the strain rate, which increase as the strain rate increases. When the temperature is higher than 120℃, the h and r' of the PC fi lm have weak sensitivity to strain rate and strong sensitivity to temperature, which decrease as the temperature increases. Since the r' value of the PC fi lm is much larger than 1, and the r' value of the PMMA fi lm is less than 1, the pattern of the PMMA film is deformed to a lower degree than that of the PC film. The fi lm thickness of the two materials has no signifi cant effect on the yield strength and h value of the two fi lm materials. The fi lm thickness affects the r' value of the PC fi lm. The thinner the thickness, the smaller the r' value, but the molding property is deteriorated.
The mechanical properties of polycarbonate(PC) and poly(methyl methacrylate)(PMMA) films commonly used in in-mold film processes at different temperatures and strain rates were investigated by uniaxial tensile tests. It is found that as the temperature increases and the strain rate decreases, the yield strength of the two materials decreases, and the elongation at break increases. When the temperature is lower than 120℃, the strain hardening coeffi cient(h) and the pattern deformation degree(r') of the PC film have weak sensitivity to temperature, and have strong sensitivity to the strain rate, which increase as the strain rate increases. When the temperature is higher than 120℃, the h and r' of the PC fi lm have weak sensitivity to strain rate and strong sensitivity to temperature, which decrease as the temperature increases. Since the r' value of the PC fi lm is much larger than 1, and the r' value of the PMMA fi lm is less than 1, the pattern of the PMMA film is deformed to a lower degree than that of the PC film. The fi lm thickness of the two materials has no signifi cant effect on the yield strength and h value of the two fi lm materials. The fi lm thickness affects the r' value of the PC fi lm. The thinner the thickness, the smaller the r' value, but the molding property is deteriorated.
引文
[1]苏占伟,孟正华,高成,等.模内装饰印刷涂层对薄膜导热系数的影响[J].塑料工业,2017,45(12):137-142.
[2]吴松琪,刘斌.塑件表面模内装饰技术应用现状分析[J].塑料工业,2015,43(1):10-14.
[3]A Dharia,D Hylton.Novel method for rapid determination of thermoformability of thermoplastics[C].ANTEC,2005.
[4]Li Z,Lambros J.Strain rate effects on the thermomechanical behavior of polymers[J].International Journal of Solids&Structures,2001,38(20):3 549-3 562.
[5]Phillips C O,Bould D C,Claypole T C,et al.Finite element modelling of low temperature forming of polymer films with application in in-mould decoration[J].Materials&Design,2009,30(3):537-550.
[6]Kim S Y,Lee S H,Youn J R.Warpage of film insert molded parts and optimum processing conditions[J].International Polymer Processing Journal of the Polymer Processing Society,2013,25(2):109-117.
[7]Chen J,Sherwood J A,Buso P,et al.Stamping of continuous fiber thermoplastic composites[J].Polymer Composites,2010,21(4):539-547.
[8]Chen S M,Zhang S J.Mechanical Behaviors and thermoforming features of PMMA used in-mold decoration[J].Applied Mechanics&Materials,2014,496-500:440-443.
[9]Phillips C O,Claypole T C,Gethin D T.Mechanical properties of polymer films used in in-mould decoration[J].Journal of Materials Processing Technology,2008,200(1):221-231.
[10]郑超.塑料片材真空阴模吸塑成型模拟及实验研究[D].武汉:华中科技大学,2011.
[11]沈忠良,郑子军,欧长劲,等.基于双向拉伸的温度对高聚物薄膜热成型性能的影响研究[J].塑料工业,2018,46(5):81-84.
[12]吴跃坚,边彬辉.模内镶件注射薄膜拉深成型工艺影响因素[J].模具工业,2010,36(8):42-45.
[13]危学兵,李伟,王辉,等.汽车仪表板右装饰面板IMD成型模具设计[J].塑料科技,2017,45(6):85-89.
[2]吴松琪,刘斌.塑件表面模内装饰技术应用现状分析[J].塑料工业,2015,43(1):10-14.
[3]A Dharia,D Hylton.Novel method for rapid determination of thermoformability of thermoplastics[C].ANTEC,2005.
[4]Li Z,Lambros J.Strain rate effects on the thermomechanical behavior of polymers[J].International Journal of Solids&Structures,2001,38(20):3 549-3 562.
[5]Phillips C O,Bould D C,Claypole T C,et al.Finite element modelling of low temperature forming of polymer films with application in in-mould decoration[J].Materials&Design,2009,30(3):537-550.
[6]Kim S Y,Lee S H,Youn J R.Warpage of film insert molded parts and optimum processing conditions[J].International Polymer Processing Journal of the Polymer Processing Society,2013,25(2):109-117.
[7]Chen J,Sherwood J A,Buso P,et al.Stamping of continuous fiber thermoplastic composites[J].Polymer Composites,2010,21(4):539-547.
[8]Chen S M,Zhang S J.Mechanical Behaviors and thermoforming features of PMMA used in-mold decoration[J].Applied Mechanics&Materials,2014,496-500:440-443.
[9]Phillips C O,Claypole T C,Gethin D T.Mechanical properties of polymer films used in in-mould decoration[J].Journal of Materials Processing Technology,2008,200(1):221-231.
[10]郑超.塑料片材真空阴模吸塑成型模拟及实验研究[D].武汉:华中科技大学,2011.
[11]沈忠良,郑子军,欧长劲,等.基于双向拉伸的温度对高聚物薄膜热成型性能的影响研究[J].塑料工业,2018,46(5):81-84.
[12]吴跃坚,边彬辉.模内镶件注射薄膜拉深成型工艺影响因素[J].模具工业,2010,36(8):42-45.
[13]危学兵,李伟,王辉,等.汽车仪表板右装饰面板IMD成型模具设计[J].塑料科技,2017,45(6):85-89.