Blends of polypropylene with poly(vinyl butyral)

Abstract

ABSTRACT:The thermal stability, crystallization behavior, and morphology of poly-(vinyl butyral) (PVB) with differing compositions of vinyl alcohol and butyral units were investigated. It was found that the glass-transition temperature of PVB decreases with increasing concentration of butyral units, mainly because of the reduced number of hydrogen bonds between hydroxyl groups of the chains. PVB samples with high vinyl alcohol content (Ն63.3% by weight) are crystallizable and present an endothermic melting peak in the range 170 -220°C. The thermal stability of PVB is also influenced by composition and increases with the number of butyral units. The thermal and crystallization characteristics of PVB were compared with those of neat polyvinyl alcohol (PVA), and the differences explained in terms of molecular structure. Two amorphous PVB samples, containing 31 and 14 wt % of vinyl alcohol units, respectively, were blended with isotactic polypropylene grafted with maleic anhydride (PP-MA), the latter of which was present to favor compatibilization of the components through chemical reaction or dipolar interactions involving the anhydride groups of the PP-MA and the hydroxyl groups of PVB. Properties of PP-MA/PVB 90/10 blends, prepared by melt extrusion, were compared to those of neat PP-MA. Both the PVBs used were immiscible with PP-MA, as indicated by the invariance of glass-transition temperatures with the composition of the blends. However, a high level of compatibility between the components was achieved because the blends showed good mechanical properties that were comparable to, or even superior to, those of neat PP-MA. The analysis of the crystallization kinetics, performed both in isothermal and nonisothermal modes, showed that crystallization of polypropylene is only slightly influenced by the presence of the PVB phase.

Water Clustering in Polyvinyl Butyral (PVB): Evidenced by Diffusion and Sorption Experiments

“…To strengthen the case for hydrogen bonding, Figure presents a comparison between our sorption isotherm for the PVB sheet and that of Hauser and McLaren for unplasticized PVB (25 °C, conditioning under acidic mixtures). Despite the differences in method and PVB composition, the isotherms elegantly overlapa remarkable finding considering that unplasticized PVB is in the glassy sate ( T g ≈ 75 °C) . Hence, the polymer matrix, even in this highly constrained and complex state, appears to play a minimal role on water sorption.…”

“…Despite the differences in method and PVB composition, the isotherms elegantly overlap�a remarkable finding considering that unplasticized PVB is in the glassy sate (T g ≈ 75 °C). 21 Hence, the polymer matrix, even in this highly constrained and complex state, appears to play a minimal role on water sorption. In this regard, the one similarity that stands out is the amount of −OH when accounting for the plasticizer in our case.…”

Properties of Polyvinylbutyral/Vermiculite nanocomposites prepared byin-situreaction method

“…The crystallinity of the nanocomposites was also determined by DSC measurements. The fusion enthalpy values of nanocomposites were obtained from the area of the melting peak, divided by the theoretical fusion enthalpy taken as 143 J g −1 [1, 23, 24]. The crystallinity for PVB values was observed higher than aggregated clay additions.…”

“…As well, polyvinyl alcohol is a derivative of polyvinyl acetate so, PVB contains a small fraction of vinyl acetate units that remain after hydrolysis. However, depending on the degree of butyralisation, PVB is hydrophobic, insoluble in water, more adhesive and tough comparing to polyvinyl alcohol [1][2][3][4]. These properties make PVB a desirable polymer especially for food packing, adhesion and glass films industries.…”

Flexible thermoplastic composite of Polyvinyl Butyral (PVB) and waste of rigid Polyurethane foam

“…PUr residues are not adequately reprocessed to obtain new product, as they are thermoset polymers with low density [3][4][5] . Polyvinyl butyral (PVB) is an amorphous random copolymer of vinyl butyral, vinyl alcohol, and vinyl acetate, mainly used in laminated safety glass in automotive, aerospace and architectural glass sections [6,7] . The chemical structure of PVB is very important because it deeply influences the properties of the polymer.…”