Properties of heat-humidity cured cellulose acetate phthalate free films.
Properties of heat-humidity cured cellulose acetate phthalate free films.
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DOI：
10.1016/s0928-0987(02)00131-8
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发表时间：
2002-10
期刊：
影响因子：
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通讯作者：
Jiping Liu;R. Williams
中科院分区：
文献类型：
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作者：
Jiping Liu;R. Williams
以邻苯二甲酸二乙酯（DEP）或柠檬酸三乙酯（TEC）为增塑剂，采用喷雾法制备了不含邻苯二甲酸醋酸纤维素（CAP）的薄膜。在仅加热（50°C持续24小时）和热-湿固化（50°C/75%RH持续24小时）条件下比较膜的化学和机械性质。与未固化和仅加热固化的膜相比，湿热固化的膜的表面粗糙度降低。与仅加热固化条件相比，热-湿固化条件抑制增塑剂的蒸发，导致膜中残留的增塑剂水平更高。湿热固化还显著提高了薄膜的机械强度，降低了薄膜的透湿率。当暴露于酸性介质时，尽管增塑剂快速浸出，但热-湿固化膜在暴露之前保留了膜的最大机械强度。湿热固化后的水分含量和邻苯二甲酸含量略有增加，但没有达到干扰肠溶性能的水平。TEC是较少挥发性和生产的薄膜与增加%伸长率，并降低拉伸强度和弹性模量与DEP增塑的薄膜相比。然而，DEP增塑的膜比TEC增塑的膜在热-湿固化后的渗透性差。结果表明，CAP膜在固化过程中短期暴露于热和湿度，大大提高了膜聚结的程度和机械强度，而不会引起聚合物的显著化学降解。
Cellulose acetate phthalate (CAP) free films containing diethyl phthalate (DEP) or triethyl citrate (TEC) as the plasticizer were prepared by the spray method. The chemical and mechanical properties of films were compared following heat-only (50°C for 24 h) and heat-humidity curing (50°C/75% RH for 24 h) conditions. The surface roughness of the heat-humidity cured films decreased compared to that of the uncured and heat-only cured films. The heat-humidity curing condition suppressed evaporation of the plasticizer, resulting in higher plasticizer levels remaining in the films, as compared to the heat-only curing condition. The heat-humidity curing also significantly increased the mechanical strength and decreased the water vapor permeability of the films. When exposed to the acidic media, despite rapid leaching of plasticizer, the heat-humidity cured films retained the most mechanical strength of the films prior to exposure. The moisture content and phthalic acid content after heat-humidity curing were increased slightly, but did not reach a level that would interfere with enteric performance. TEC was less volatile and produced films with increased % elongation, and decreased tensile strength and elastic modulus compared to the films plasticized with DEP. However, the DEP plasticized films were less permeable than TEC-plasticized films following heat-humidity curing. The results indicated that a short-term exposure of the CAP films to heat and humidity during the curing process greatly improved the degree of film coalescence and mechanical strength, without causing significant chemical degradation of the polymer.