葡甘聚糖-壳聚糖-聚乙烯醇复合胶黏剂的流变特性
Rheological properties of konjac glucomannan chitosan PVA laminating adhesive
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摘要: 为开发环境友好型木材胶黏剂, 利用差示扫描量热法(DSC)和流变仪分析了葡甘聚糖、 壳聚糖、 聚乙烯醇共混胶黏剂的热固化过程和流变特性。结果表明: 三元共混胶黏剂的流变特性呈明显的非线性, 黏度与剪切速率的关系可用Cross模型拟合, 黏度与温度的关系可用Arrhenius方程拟合, 前置因子K为1.25×10-6Pa·s, 流动活化能为54.24kJ/mol, 频率曲线可用四阶多项式拟合, 同时可得到胶黏剂的平均分子量随温度升高逐渐降低, 分子量分布随着温度升高逐渐增大。温度和时间扫描得到凝胶化温度110.4℃, 凝胶时间20.1min, 玻璃化转变温度87.4℃, 加热温度130℃。Abstract: In order to develop environment-friendly wood adhesive, the thermosetting process and the rheological properties of the blending adhesive consisted of konjac glucomannan (KGM), chitosan (CA) and polyvinyl alcohol (PVA) were investigated by DSC and rheometer. The results show that the rheological behavior of adhesives is significantly nonlinear. The relationship between the viscosity and the shear rate fit the Cross model well, while the dependence of the viscosity on the temperature can meet the Arrhenius equation well in which the pre-exponential factor is 1.25×10-6Pa·s and the flow activation enthalpy is 54.24kJ/mol. The fourth order polynomials can be used to fit the frequency curves which show that average molecular mass of adhesive decreases gradually with the temperature increase while wider molecular mass distribution of adhesive reverse. The gelling temperature, gel time, glass transition temperature and heating temperature are 110.4℃, 20.1min, 87.4℃ and 130℃ respectively according to the temperature and time curves.