We report on the preparation, characterization, and foaming behavior of cellular polymers based on 1-vinyl-2-pyrrolidone (VP) and methyl methacrylate (MMA). Samples with different feed ratios proportions of VP and MMA were prepared following the bulk radical copolymerization procedure, using commercially available monomers and testing two different initiators (photochemical and thermal), obtaining solid samples of around 1.5 mm thick. To evaluate the polymerization process, the chemical structure of VP/MMA copolymers was determined by proton nuclear magnetic resonance measurements. In a second step, single-batch supercritical carbon dioxide (CO2) foaming tests were carried out at different temperatures to evaluate the influence of the VP to MMA feed ratios and the foaming temperature in the density, the presence of solid outer skin, the CO2 sorption–desorption process, and the cellular morphology of the foamed polymers.

中文翻译：

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1-乙烯基-2-吡咯烷酮-甲基丙烯酸甲酯共​​聚物在ScCO2下的发泡行为

我们报告了基于 1-乙烯基-2-吡咯烷酮 (VP) 和甲基丙烯酸甲酯 (MMA) 的多孔聚合物的制备、表征和发泡行为。按照本体自由基共聚程序制备具有不同进料比例的 VP 和 MMA 的样品，使用市售单体并测试两种不同的引发剂（光化学和热），获得约 1.5 毫米厚的固体样品。为了评估聚合过程，通过质子核磁共振测量确定了 VP/MMA 共聚物的化学结构。第二步，在不同温度下进行单批次超临界二氧化碳 (CO2) 发泡试验，以评估 VP 与 MMA 进料比和发泡温度对密度、固体外皮的存在、