Papers by Author: Yan Hua Zhang

Abstract: The differential scanning calorimetry(DSC) was used to study the curing reaction of low toxic UF resin with poplar, birch, larch powder in different pH value. The results showed that the effect of different wood flour and its pH value on the curing reaction of UF resin was not the same. Along with the increase of the pH, the peak temperature and the onset temperature was raised; the peak temperature and the onset temperature of poplar was higher than that of the birch. The tempera- ture of the curing reaction of UF resin modified by melamine was higher than the UF resin without modification.

Abstract: This paper is concerned about the synthesis of shape memory styrene copolymer and the investigation of the influence of cross-linking degree on its shape memory effect. The influence of cross-linking degree on shape memory effect of styrene copolymer was investigated through altering the dosage of cross-linking agent. The Tg increased from 65 to 80.7 with the gel content increase from 35% to 80% which is achieved by increasing the dosage of cross-linking agent from 1% to 4%. Moreover, the SMP experienced good SME and the largest reversible strain of the SMP reached as high as 150%. When the copolymer was heated above Tg+30 (different copolymers performed different Tg), the shape recovery speed of the copolymers increased with the gel content increase.