Assessment of kinetic release of thymol from LDPE nanocomposites obtained by supercritical impregnation: Effect of depressurization rate and nanoclay content
Assessment of kinetic release of thymol from LDPE nanocomposites obtained by supercritical impregnation: Effect of depressurization rate and nanoclay content
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DOI：
10.1016/j.eurpolymj.2017.05.049
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发表时间：
2017-08-01
影响因子：
6
通讯作者：
Romero, Julio
中科院分区：
文献类型：
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作者：
Rojas, Adrian;Torres, Alejandra;Romero, Julio
用不同浓度的有机改性蒙脱土（OM-MMT）（2.5和5.0%（w/w））制备的LDPE纳米复合材料用百里酚使用超临界二氧化碳浸渍，目的是获得抗微生物包装。浸渍实验在12 MPa，1 h，313 K和两种降压速率（10.0和1.0 MPa min（-1））下进行，浸渍产率在0.36-1.19%（w/w）范围内。此外，百里酚掺入有利于纳米粘土的存在。XRD结果表明，浸渍百里酚的插层纳米复合材料的改善。同时，一个唯象的传质模型已被用来描述释放百里酚从纳米复合材料在乙醇95%（v/v）的溶液。从该模型中，百里酚通过纳米复合材料的有效扩散系数似乎是独立的降压速率。这些值的范围为2.7至3.5 × 10（-13）m（2）s（-1），并且显著低于游离纳米粘土LDPE膜获得的值，游离纳米粘土LDPE膜显示的值范围为1.0至1.3 × 10（-12）m（2）s（-1）。这一结果可以解释为形成的聚合物-纳米粘土插层结构，减缓百里酚转移。
LDPE nanocomposites prepared with different concentrations of an organo-modified montmorillonite (OM-MMT) (2.5 and 5.0% (w/w)) were impregnated with thymol using supercritical carbon dioxide, with the aim of obtaining an antimicrobial packaging. Impregnation assays were carried out at 12 MPa, 1 h, 313 K and two depressurization rates, 10.0 and 1.0 MPa min(-1), with impregnation yields in the range of 0.36-1.19% (w/w).The highest incorporation percentages of thymol were obtained employing the lowest depressurization rate. Moreover, thymol incorporation was favored with the presence of nanoclays. XRD results indicated the improvement of nanocomposites intercalation impregnated with thymol. Simultaneously, a phenomenological mass transfer model has been used to describe the release of thymol from the nanocomposite in ethanol 95% (v/v) solution. From the model, the effective diffusion coefficient of thymol through the nanocomposite seem to be independent of the depressurization rate employed. These values were ranged from 2.7 to 3.5 x 10(-13) m(2) s(-1) and are significantly lower than the values obtained for free nanoclay LDPE films, which shows values ranged from 1.0 to 1.3 x 10(-12) m(2) s(-1). This result could be explained by the formation of a polymer-nanoclay intercalated structure that slows down the thymol transfer.