Surface and dynamic viscoelastic properties of cork from Quercus variabilis

Abstract

Surface and dynamic viscoelastic properties of the reproduction cork from Quercus variabilis were studied in detail. There were 16 chemical elements in the Q. variabilis cork determined by the energy dispersive spectrometric (EDS) spectrum, and the contents of C and O were the highest. The mean colorimetric parameters L*, a*, and b* were 60.8, 14.0, and 30.6, respectively. The surface contact angles of Quercus variabilis cork were measured using an automatic contact angle meter. Three different types of liquid media (distilled water, formamide, and diiodomethane) were respectively dropped on the surface of corks using a microsyringe. The initial contact angles of water, formamide, and diiodomethane on the cork surface were 112.0°, 85.1°, and 75.2°, and the corresponding values decreased to 102.1°, 30.7°, and 72.1° when the liquids permeated the cork surface for 10 s. The moisture content values were 4.3%, 6.0%, and 9.0% when the dry cork samples were placed in the relative humidity conditions of 45%, 65%, and 85%, respectively, for 30 days. FT-IR spectra indicated the content of suberin in the sclereids and lenticels was much less than the content found in the pure corks. In the dynamic mechanical analysis (DMA) spectrum, three obvious relaxation processes could be observed in the tan δ curve.

Qualitative anatomical characteristics of the virgin cork in Quercus variabilis grown in Korea

“…Zhao et al (2013) and Bai et al (2014) reported that the cork of Q. variabilis contained impurities in the tissue of cork, such as lenticels tissue, dark-brown zone, and sclereids. Li et al (2019) reported that the virgin cork and reproduction cork of Q. variabilis showed lenticular channels, sclereids surrounded by dark and hard layers, and a smaller lenticular channel in the reproduction cork than in the virgin cork. Additionally, lenticular channels and sclereids in the dark and hard layers of the reproduction cork were less frequent compared to the virgin cork.…”