Effects of preparation temperature on swelling and mechanical properties of PVA cast gels

Abstract

Poly(vinyl alcohol) cast gels (PVA cast gels) were prepared at different gelation temperatures, T gel , and the swelling ratio and mechanical properties were characterized by the equilibrium weight measurement, a uniaxial loading test, a tearing force measurement, and a cyclic compression test at room temperature. The results showed that the swelling ratio decreased and both the breaking stress and the tearing energy increased with an increase in T gel . The compression deformation energy of 50% reduction of its original size increased monotonically, while the hysteresis loss was not affected by T gel . To understand these macroscopic properties, the network structures of the samples were examined by X-ray diffraction and Fourier transform infrared measurements. As a result, the size of the microcrystallites increased with an increase in T gel and the average distance between the microcrystallites also increased. These results suggested that the structures of PVA networks, crosslinked by the microcrystallites, have essential roles in determining the mechanical properties of PVA cast gels. The macroscopic mechanical properties are discussed on the basis of the size, number, and distribution of microcrystallites as crosslinkers and the homogeneity of amorphous PVA networks, which were determined at gelation. Experimental procedure Sample preparationPVA powder was kindly supplied by Kuraray Co., Ltd. (cat. no. PVA117), and was used without further purification. The

PVA/Carbon Dot Nanocomposite Hydrogels for Simple Introduction of Ag Nanoparticles with Enhanced Antibacterial Activity

“…However, different from NTs and GO, C‐dots did not possess extremely high tensile modulus and strength, which meant the main factor for the enhancement of the mechanical properties in PVA/C‐dot hydrogel was not load transfer. As we mentioned above, in PVA hydrogel, the PVA chains were cross‐linked by PVA crystal nuclei and finally formed intact 3D network . Therefore, the degree of crystallinity and the distribution of PVA crystal nuclei had a significant impact on the mechanical properties of PVA hydrogels .…”

“…[10][11][12][13]21,22] Therefore, the number and distribution of PVA crystal nuclei have great influence on the mechanical properties of PVA hydrogel. [23,24] As we know, proper nucleating agent can help form much more crystal nuclei with uniform dispersion. Therefore, the addition of appropriate nucleating agent into PVA hydrogel could help form a denser and more uniform cross-linked network in PVA hydrogel, which could also enhance the mechanical properties of PVA hydrogel.…”

A Novel Method to Control the Elution Behavior of PVA Cast Gels

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