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Blends of Poly(vinyl alcohol) and Poly(vinyl pyrrolidone): Interrelation between the Degree of Hydration and Thermal and Mechanical Properties
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2021-09-29 , DOI: 10.1021/acs.iecr.1c02650
Petros Oikonomou 1 , Merope Sanopoulou 1 , Kyriaki G. Papadokostaki 1
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2021-09-29 , DOI: 10.1021/acs.iecr.1c02650
Petros Oikonomou 1 , Merope Sanopoulou 1 , Kyriaki G. Papadokostaki 1
Affiliation
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Blends of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) readily absorb water when exposed to external humidity. The plasticizing action of water affects several properties of the blends that are critical for the performance of the materials in various applications. Blend films of PVA and PVP, with the compositions 0, 20, 30, 40, 50, 60, 80, and 100% PVP, were thermally annealed, equilibrated at four different humidities, and the effect of increasing humidity levels on the degree of hydration and the thermal and tensile mechanical properties was studied. A linear relation between the weight fraction of absorbed water at a specific external humidity, and the composition of the blend was observed. Both the compositional dependence of the glass transition temperature (Tg) of dry blend films and the depression of the Tg of each blend with increasing amounts of absorbed water, as studied by differential scanning calorimetry, were equally described well by the Couchman–Karasz and Gordon–Taylor equations. The physical meaning of the respective fitting parameters was evaluated in terms of measured or literature values of PVA and PVP properties. The satisfactory fitting of the Tg depression data allowed us to establish a linear relation between the composition of the blend and the minimum amount of absorbed water needed to transform the initially glassy material to a rubber. For all blend compositions, the Young modulus of hydrated samples suffers a sharp drop of approximately 1 order of magnitude when the degree of hydration was sufficient to transform the initially dry, glassy films to rubbery materials.
中文翻译：
聚（乙烯醇）和聚（乙烯基吡咯烷酮）的混合物：水合度与热和机械性能之间的相互关系
聚乙烯醇 (PVA) 和聚乙烯吡咯烷酮 (PVP) 的混合物暴露在外部湿气中时很容易吸水。水的增塑作用会影响混合物的多种特性，这些特性对于材料在各种应用中的性能至关重要。PVA 和 PVP 的共混膜，其组成为 0、20、30、40、50、60、80 和 100% PVP，经过热退火，在四种不同的湿度下平衡，以及增加湿度水平对水化和热力学和拉伸力学性能进行了研究。观察到在特定外部湿度下吸收的水的重量分数与共混物的组成之间存在线性关系。玻璃化转变温度 ( T g通过差示扫描量热法研究，干混薄膜的 ) 和每种混合物的T g随着吸收水量的增加而降低，这同样可以通过 Couchman-Karasz 和 Gordon-Taylor 方程得到很好的描述。各个拟合参数的物理意义是根据 PVA 和 PVP 特性的测量值或文献值来评估的。T g的满意拟合凹陷数据使我们能够在共混物的组成与将最初的玻璃状材料转变为橡胶所需的最小吸收水量之间建立线性关系。对于所有共混组合物，当水合程度足以将最初干燥的玻璃状薄膜转变为橡胶状材料时，水合样品的杨氏模量急剧下降约 1 个数量级。
更新日期：2021-10-06
中文翻译：
聚（乙烯醇）和聚（乙烯基吡咯烷酮）的混合物：水合度与热和机械性能之间的相互关系
聚乙烯醇 (PVA) 和聚乙烯吡咯烷酮 (PVP) 的混合物暴露在外部湿气中时很容易吸水。水的增塑作用会影响混合物的多种特性，这些特性对于材料在各种应用中的性能至关重要。PVA 和 PVP 的共混膜，其组成为 0、20、30、40、50、60、80 和 100% PVP，经过热退火，在四种不同的湿度下平衡，以及增加湿度水平对水化和热力学和拉伸力学性能进行了研究。观察到在特定外部湿度下吸收的水的重量分数与共混物的组成之间存在线性关系。玻璃化转变温度 ( T g通过差示扫描量热法研究，干混薄膜的 ) 和每种混合物的T g随着吸收水量的增加而降低，这同样可以通过 Couchman-Karasz 和 Gordon-Taylor 方程得到很好的描述。各个拟合参数的物理意义是根据 PVA 和 PVP 特性的测量值或文献值来评估的。T g的满意拟合凹陷数据使我们能够在共混物的组成与将最初的玻璃状材料转变为橡胶所需的最小吸收水量之间建立线性关系。对于所有共混组合物，当水合程度足以将最初干燥的玻璃状薄膜转变为橡胶状材料时，水合样品的杨氏模量急剧下降约 1 个数量级。
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