Bravo-Osuna I, Ferrero C, Jiménez-Castellanos M R
Dpto. Farmacia y Tecnología Farmacéutica, Universidad de Sevilla, Sevilla, Spain.
Eur J Pharm Biopharm. 2007 Apr;66(1):63-72. doi: 10.1016/j.ejpb.2006.08.003. Epub 2006 Aug 18.
The water vapour sorption-desorption behaviour of graft copolymers (hydroxypropylstarch-methyl methacrylate -HSMMA- and carboxymethylstarch-methyl methacrylate -CSMMA-) synthetised by free-radical polymerisation and alternatively dried by oven (OD) or freeze-drying (FD) techniques was investigated in a previous paper. The aim of the present study was to analyse the influence of the amount and distribution of water molecules on the flow and compaction characteristics of this family of methyl methacrylate-starch copolymers. Products were stored at constant temperature (25 degrees C) and different relative humidity conditions (RH). Flow properties of the powdered materials were evaluated using glass and stainless-steel funnels and the densification behaviour was studied in detail by means of Heckel treatment and compression parameters. Results revealed that the storage at 25-50% RH was the optimum condition relating flowability for HSMMA and OD-CSMMA copolymers. At higher RH values, the flow characteristics worsened, due to an increment in cohesive forces. Compaction experiments showed that the 25-50% RH range improved also the compression performance of the copolymers, due to increasing powder compressibility and reduced compact relaxation. Under these circumstances, absorbed water might act as plasticiser and adsorbed water as lubricant.
在之前的一篇论文中，研究了通过自由基聚合合成、并分别采用烘箱干燥（OD）或冷冻干燥（FD）技术干燥的接枝共聚物（羟丙基淀粉-甲基丙烯酸甲酯-HSMMA-和羧甲基淀粉-甲基丙烯酸甲酯-CSMMA-）的水蒸气吸附-解吸行为。本研究的目的是分析水分子的数量和分布对该系列甲基丙烯酸甲酯-淀粉共聚物的流动性和压实特性的影响。产品在恒温（25℃）和不同相对湿度条件（RH）下储存。使用玻璃漏斗和不锈钢漏斗评估粉末材料的流动性能，并通过Heckel处理和压缩参数详细研究致密化行为。结果表明，对于HSMMA和OD-CSMMA共聚物，在25-50%RH下储存是与流动性相关的最佳条件。在较高的RH值下，由于内聚力增加，流动特性变差。压实实验表明，25-50%RH范围也改善了共聚物的压缩性能，这是由于粉末压缩性增加和压坯松弛减少。在这些情况下，吸收的水可能充当增塑剂，吸附的水充当润滑剂。
