Effect of the morphology of two phase polymer blends on glass transition temperature

Abstract

Blends of poly(cyclohexylmethacrylate), PChMA, with poly(vinylacetate), PVAc, were prepared by casting THF and chloroform solutions. A calorimetric and morphologic study was performed. Differential scanning calorimetry investigations of the blends show two glass transition temperature that give evidence of inmiscibility. For polymer less flexible (PChMA) was observed an enhancement of T g by 20 8C approximately in blends of PVAc-rich composition. Epifluorescence microscopy, using PChMA labelled by copolymerization pirenyl-methylmethacrylate, Py, shows also phase separation providing imaging of the distribution of PChMA in the different domains and in the matrix. Blends containing 80% w/w PChMA show a bicontinuous primary morphology suggesting a spinodal phase separation mechanism. The 50 and 20% PChMA samples show morphologies composed of PChMA-rich domains in a matrix composed by PVAc mainly. Blends with domain-matrix morphology present a higher T g than pure homopolymer more rigid (PChMA) due to packing in microphases in matrix of more flexible polymer (PVAc).

Cross-Linked Polymer Hydrogel Electrolytes for Electrochemical Capacitors

“…It was found that with an increase in the proportion of PAA in the PVA/PAA blend, from PVA: PAA ratio of 5:0 to 1:1, the glass transition temperature ͑T g ͒ decreased from ϳ358 to ϳ 344 K. This decrease in T g of the PVA/PAA blend hydrogel in comparison to pristine PVA hydrogel might be due to the increased flexibility of the blend. 44 The increased flexibility suggested by a decrease in T g resulted in an increase in the amorphicity that, in turn, enhanced the segmental motion of the polymers in the PVA/PAA blend hydrogel as compared to the pristine PVA hydrogel.…”

Insights into PU/EVA Blends Produced Using Industrial Residues Towards Eco-efficient Materials

“…Usually, the presence of void affects the mechanical performance of materials, since voids are initiation sites for shear bands and crazes [27]. In turn, the two-phase morphology is associated with the fact that two immiscible polymers can originate phase segregation [28]. As mentioned earlier, EVA presents high polarity (hydrophilic character) due to the polar nature of the acetoxy side group [15].…”