Change of Crystalline Properties of Poly(ethylene-co-vinyl acetate) according to the Microstructures

Abstract

Microstructure-dependent changes in the crystalline properties of poly(ethylene-co-vinyl acetate) (EVA) was investigated using various EVAs at different VA contents via X-ray diffraction (XRD). The parameters analyzed herein were percentage crystallinity (Xc), interplanar crystal spacing (dhkl), crystal stack size (Dhkl), and the number of crystal plane piles (Nhkl). The Xcs of [110] and [200] crystals were 21.0-4.1 and 6.7-1.4%, respectively, and they decreased by approximately 2.3 and 0.7% for every mol% of the VA content, respectively. The Xc ratios of the [110] and [200] crystals were approximately 3. The d110s and d200s values were 0.41-0.42 and 0.37-0.38 nm, respectively. The D110s and D200s values were 9.56 -21.92 and 7.00-16.42 nm, respectively. The dhkls increased with an increase in the VA content, whereas the Dhkls decreased. The N110s and N200s were 22.7-51.3 and 18.3-43.2, respectively, and they decreased by increasing the VA content. EVA with the same VA content showed different crystalline properties as per the suppliers, and some EVAs deviated from the average trends. This could be explained by the difference in their microstructures such as the sizes and distribution uniformity of the ethylene sequences in EVA chains.