Heat Deflection Temperature vs.Dynamic Mechanical Analysis

摘要

Here's a real-world example of a part failure demonstrating why DMA curves have more value than single-point data generated by HDT.Several years ago,I was working with a client on a part being molded from an unfilled PBT polyester.The part was exhibiting excessive deformation at the operating temperature of 140 C(284 F).The engineers I was working with were baffled by the failures.They had a data sheet that showed that the material had a heat-deflection temperature(HDT)of 153 C(309 F).Consequently,in their minds,this was a guarantee of success at 140 C.This reflects a lack of understanding regarding the meaning of HDT.What is actually being measured?