A dynamic mechanical and thermal analysis of unplasticized and plasticized poly(vinyl alcohol)/methylcellulose blends

Abstract

ABSTRACT:The miscibility of poly(vinyl alcohol) (PVA)/methylcellulose (MC) blends was investigated over the entire composition range using the dynamic mechanical analyzer (DMA) and the differential scanning calorimeter (DSC). On the basis of the glass transition temperature, determined by DMA, one could conclude that the blends exhibited some miscibility below 80 wt % of MC and a good miscibility above 80 wt % of MC. The highest depressions of the melting and crystallization temperatures of the blends compared to those of PVA, determined via DSC analysis, were observed for MC contents greater than 80 wt %. The miscibility between PVA and MC can be attributed to the hydrogen bonds formed between the two components. The DMA studies showed that water is a good plasticizer for PVA and poly(ethylene glycol) 400 (PEG 400), a good plasticizer for MC. The inclusion of both water and PEG 400 in the blends revealed a synergistic plasticizing effect, which resulted in an increased miscibility between PVA and MC over a greater range of MC compositions (Ͼ60 wt %). The elongations of PVA, MC, and their blends were found to increase with the addition of PEG 400, but the tensile strengths to decrease.

Investigation on the thermal properties of new thermo-reversible networks based on poly(vinyl furfural) and multifunctional maleimide compounds

“…The first one is attributed to the local relaxation of the crystalline phase, while the second one is caused by the melting of the crystalline domains [39][40][41]. In our case the first peak of PVA is shifted to higher temperatures (147.6°C), while the melting of the crystalline domains could not be observed.…”

“…The drop of E! and two peaks of E% and tan & centred at 42.4 and 54.4°C, respectively can be attributed to the glass transition of the amorphous phase [39][40][41]. Moreover, the small decrease of E!…”

Novel Film Modifiers to Alter the Physical Properties of Composite Ethylcellulose Films

“…DMA has been reported to be more sensitive to macroscopic as well as molecular relaxation processes compared to other thermal analysis techniques that depend solely on temperature probe (41). It is widely used to determine T g and miscibility between polymers (34,(43)(44). Generally, a dynamic thermal analysis profile may show three forms of transition relaxation.…”

Thermal properties in strong hydrogen bonding systems composed of poly(vinyl alcohol), polyethyleneimine, and graphene oxide

“…Hydrogen bonding in polymer blends has been of interest to polymer scientists for several decades [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. One major characteristic in such systems is the large positive deviation of glass transition temperature (T g ) from conventional mixing rules [22,23,26,35].…”