差示扫描量热法测试PET聚酯Tg、Tc、Tm结果的不确定度评定研究OA

In accordance with the Chinese national standards GB/T 19466.1-2004,GB/T 19466.2-2004,and GB/T 19466.3-2004,differential scanning calorimetry(DSC)was employed to determine the glass transition temperature(Tg),crystallization temperature(Tc),and melting temperature(Tm)of polyethylene terephthalate(PET)-type polyes-ter.To ensure measurement reliability,a comprehensive uncertainty evaluation was conducted based on actual laborato-ry conditions and the full DSC testing procedure.A mathematical model was established to identify,quantify,and com-bine all significant sources of uncertainty.These include repeatability(random variation),balance weighing errors,DSC instrument calibration drift,deviations in the certified reference value of indium(used for temperature calibration),and rounding of reported results.The combined standard uncertainty for each thermal transition was calculated using the law of propagation of uncertainty.Based on measurements of two representative PET samples(A and B),the average ex-panded uncertainties were determined to be approximately±1.0℃for Tg,±3.2℃for Tc,and±2.0℃for Tm.This study not only enhances the metrological traceability and reliability of DSC measurements for PET but also identifies criti-cal control points,such as calibration accuracy and sample preparation,that significantly influence result quality.The methodology and findings provide a robust framework for uncertainty assessment in the thermal analysis of other semi-crystalline polymers.