Nechifor Cristina-Delia, Aflori Magdalena, Dorohoi Dana-Ortansa
Department of Physics, Machine Manufacturing and Industrial Management Faculty, "Gheorghe Asachi" Technical University of Iasi, 67 Dimitrie Mangeron Bvd, RO-700050 Iasi, Romania.
Petru Poni Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania.
Polymers (Basel). 2019 Jun 21;11(6):1072. doi: 10.3390/polym11061072.
In this paper, poly(vinyl alcohol) (PVA) foils of comparable thickness were obtained by using 10 wt % PVA aqueous solutions exposed to microwave (MW) radiations for different times. The main goal of this paper is to identify the effects of MW irradiation on the induced optical birefringence of PVA stretched foils, since it is known that the changes in the chemical and physical properties of polymers induced by radiations can influence the asymmetry of their molecular structures from which the birefringence of polymers derives. The efficiency of the MW oven was estimated, and the contribution of sensible and latent heat and heat loss to the absorbed energy was discussed. The effects of MW irradiation, in terms of absorbed energy, were evidenced by using FTIR spectra analysis, contact angle measurements, scanning electron microscopy (SEM) images, and induced optical birefringence. The dehydration (cross-linking) of PVA in aqueous solution and the dependence of the anisotropy on the absorbed MW energy, stretching ratio, and the type of hydrogen bonds formed are discussed in this study.
在本文中，通过使用10 wt%的聚乙烯醇（PVA）水溶液在微波（MW）辐射下暴露不同时间，获得了厚度相当的PVA箔。本文的主要目标是确定MW辐射对PVA拉伸箔诱导光学双折射的影响，因为众所周知，辐射引起的聚合物化学和物理性质的变化会影响其分子结构的不对称性，而聚合物的双折射正是源于这种不对称性。评估了微波炉的效率，并讨论了显热、潜热和热损失对吸收能量的贡献。通过傅里叶变换红外光谱（FTIR）分析、接触角测量、扫描电子显微镜（SEM）图像和诱导光学双折射，证明了MW辐射在吸收能量方面的影响。本研究讨论了PVA在水溶液中的脱水（交联）以及各向异性对吸收的MW能量、拉伸比和形成的氢键类型的依赖性。
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