Development Of Standard Materials For Glass Transition Temperature And Thermal Expansion Coefficient Of Polymer

Polymer materials have been widely used in communication products,medical devices,aerospace and other fields.The accurate measurement of glass transition temperature and thermal expansion coefficient is very important to evaluate and guide the functional and technological properties of materials,as well as the study of polymer physics.At present,the mainly used method of glass transition temperature and thermal expansion coefficient mainly is thermal analysis.These relative measurement methods all need the corresponding standard materials for instrument calibration or method verification.It is difficult to realize the traceability due to the lack of standard material in China up to now.This paper aims to develop the standard materials of glass transition temperature and thermal expansion coefficient,and systematically studies the measuring factors affecting the glass transition temperature and thermal expansion coefficient of polymer.The main research contents are as follows:The accurate measurement method of glass transition temperature is studied.The dynamic mechanical analysis(DMA)is adopted to calibrate the temperature of the instrument through the metal certified standard material,which to ensure the accuracy of the instrument's temperature value transfer.Through the selection and optimization of the experimental measurement conditions,such as the experimental fixture,frequency,heating rate,amplitude and torque force value,the method of dynamic mechanical analysis is established to accurately measure the glass transition temperature.The accurate measurement method of the coefficient of thermal expansion is studied.Using the standard measuring block and certified thermal analysis standard material to calibrate size and temperature,the influence parameters of measuring the thermal expansion coefficient such as heating rate,eliminating heat history time,the force applied on the sample and heating rate in the process of experimental are systematically researched.Based on the above measurement methods,the three standard materials of glass transition temperature of PVC,PC and PEI,and one standard material of thermal expansion coefficient of PEEK,are developed.The uncertainty of the measurement results is evaluated by the method of class A and class B.The results show that the standard uncertainty of PVC,PC and PEI are 0.35?,0.33?and 0.36?,and the expanded uncertainty are 0.70?,0.66? and 0.72?(k=2),respectively.The standard uncertainty of PEEK is 0.51 ?m/(m??),and the expanded uncertainty is 1.02 ?m/(m??)(k=2).The above standard materials fill in the gap of domestic and foreign related standard materials.