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Effect of damp‐heat aging on the properties of ethylene‐vinyl acetate copolymer and ethylene‐ acrylic acid copolymer blends
Author(s) -
Chen Shuangjun,
Zhang Jun,
Su Jun
Publication year - 2009
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.30859
Subject(s) - materials science , crystallinity , ethylene vinyl acetate , copolymer , ultimate tensile strength , differential scanning calorimetry , vinyl acetate , composite material , fourier transform infrared spectroscopy , crystallization , acrylic acid , dynamic mechanical analysis , tensile testing , polymer chemistry , chemical engineering , polymer , thermodynamics , physics , engineering
The aim of this investigation is to evaluate the effect of damp‐heat aging on properties of ethylene‐vinyl acetate (EVA) copolymer (14 wt % vinyl acetate units), ethylene‐acrylic acid (EAA) copolymer (8 wt % acrylic acid units) and their blends. Attenuated total reflection Fourier transform infrared spectrum (ATR‐FTIR), differential scanning calorimeter (DSC), wide angle X‐ray diffraction (WAXD), and mechanical tests are employed to investigate the changes of copolymer blends' structures and properties. ATR‐FTIR tests show that increase of carbonyl index is owing to the incorporation of oxygen into the polymeric chain of EVA in the blends and has not much influence on the EAA. By DSC measurements, the low temperature endothermic peak ( T m2 ) of various EAA/EVA blends at about 43.7°C attributed to the secondary crystallization is increased with the aging time, which means the lamellar thickness of low temperature crystallite is increased. The increase of low temperature peaks probably derives from the interphase or even amorphous parts of both EVA and EAA components. The crystalline size detected by WAXD and degree of crystalline have both been improved by damp‐heat aging. By mechanical tests, the sample has more hardness, more modulus at 100% extension ratio, more tensile strength with less elongation at break as the proportion of EAA increase. Aging influence will induce deterioration of mechanical properties, and increase of degree of crystallinity can make the hardness, the modulus at 100% extension ratio and tensile strength increase. The two factors will both have effect on the mechanical properties of EAA/EVA blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009