D. J. David

Bio: D. J. David is an academic researcher from University of Massachusetts Amherst. The author has contributed to research in topics: Vinyl alcohol & Miscibility. The author has an hindex of 7, co-authored 7 publications receiving 143 citations.

Blends of polypropylene with poly(vinyl butyral)

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 (≥63.3% 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. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2934–2946, 2001

Miscibility and Phase Behavior in Blends of Poly(vinyl butyral) and Poly(methyl methacrylate)

Abstract: The miscibility and phase behavior in blends of poly(vinyl butyral) (PVB) and atactic poly(methyl methacrylate) (PMMA) were studied by dynamical mechanical thermal analysis (DMTA) and optical microscopy (OM). PVB is regarded as a random copolymer containing vinyl butyral (VB) and vinyl alcohol (VA) units. In this study the copolymer composition was varied over a wide range, and PMMA was varied with respect to molecular weight. DMTA measurements show two distinct Tg's for the blends of all PVBs with PMMAs of high molecular weights (Mw = 1.2 × 105 and 1.5 × 104), indicating completely immiscibility. However, OM observations show that the size of phase-separated domains of PVB blends with PMMA (Mw = 1.2 × 105) depends on copolymer composition and displays a minimum in the range 22−33 wt % VA content. For low molecular weight PMMAs (Mw = 2 × 103 to 5 × 103), miscibility with UCST-type phase behavior was observed in certain blends, the miscibility range depending on the copolymer composition and the molecular ...

Handbook of Thermoplastics

Abstract: Conventional polyolefins new polyolefins stereoregular polar thermoplastics syndiotactic polystyrene unplasticized polyvinyl chloride (uPVC) - fracture and fatigue properties acrylonitrile-butadiene-styrene (ABS) polymers styrene copolymers polyacrylonitrile polyacrylates polyacrylamides vinyl acetate polymers vinyl alcohol polymers synthetic water-soluble polymers cellulose plastics thermoplastic elastomers thermplastic polyurethanes polyester-based thermplastic elastomers polybutylene terephthalate compatibilized thermoplastic blends toughening of thermoplastics polyacetal polyether polyarylates polycarbonates polyamides polyimides polybenzimidazoles aromatic polyhydrazides and their corresponding polyoxadiazoles polyphenylquinoxalines polyphenylene sulfide polyphenylene vinylene conducting thermoplastics conducting thermoplastics composites poly(aryl ether sulfone)s poly(aryl ether ketone)s poly(aryl ether ketones-co-sulfones) poly(aryl ether ketone amide)s polytetrafluoroethylene liquid crystalline polymers advanced thermoplastics composites.