摘要
动态热机械分析仪(DMA)是一种用于检测材料模量变化及玻璃化转变温度(T_(g))等性能的仪器,而DMA在加热过程中普遍存在热效应的表观滞后,即数显温度高于样品实际温度,这是由于炉体加热样品到达目标温度的差异引起的,取决于样品本征的热扩散特性,热扩散系数越高,表观温度滞后误差越小.以材料的储能模量和T_(g)作为参考值,从样品的热扩散系数、尺寸、温度程序等因素入手,研究高分子材料的表观温度滞后现象.研究结果表明,低热扩散系数的高分子材料产生的表观热信号滞后随着材料本身的热扩散系数增大而减小.当热扩散系数较小时,特征温度(如T_(g))的实测值与真实值差距较大,其温度差值可以通过对照恒温下的储能模重与升温下同一诸能模里下的温度差值估算.在测试时,应在兼顾测试效率的前提下,采用较低的升温速率可缩小差距.另外,在一定的厚度范围内,厚度的增加对T_(g)测试结果基本无影响.
Dynamic thermomechanical analyzer(DMA)is an instrument used to detect changes in material modulus and glass transition temperature(T_(g)).However,DMA commonly exhibits thermal hysteresis during heating,where the displayed temperature is higher than the actual temperature of the sample.This is because the rate at which the furnace heats the sample to the target temperature is determined by the intrinsic thermal diffusion of the sample.The higher the thermal diffusivity coefficient,the smaller the apparent temperature hysteresis error.Using the storage modulus and T_(g) of the material as reference values,the apparent temperature hysteresis phenomenon of polymer materials was investigated with respect to factors such as the thermal diffusivity,size,and temperature program of the sample.The result showed that the hysteresis of the apparent thermal signal generated by polymer materials with low thermal diffusivity decreases as the material thermal diffusivity increases.When the thermal diffusivity is low,there is a significant difference between the measured values of characteristic temperatures(such as T_(g))and the true values.The temperature difference can be estimated by comparing the storage modulus at a constant temperature with the temperature difference corresponding to the same storage modulus.
作者
刘嘉成
水晓雪
刘蔓
李亚飞
LIU Jiacheng;SHUI Xiaoxue;LIU Man;LI Yafei(Ningbo Institute of Materials Technology&Engineering,Chinese Academy of Sciences,Ningbo 315000,Zhejiang China)
出处
《分析测试技术与仪器》
2025年第4期228-234,共7页
Analysis and Testing Technology and Instruments
关键词
动态热机械分析
温度滞后
储能模量
玻璃化转变温度
dynamic thermomechanical analysis
temperature hysteresis
storage modulus
glass transition temperature
