Most common used materials for stiffness improvement, glass fibre is best, talc, wollastonite and mica are next with calcium carbonate being last.
Warpage is usually caused by differential shrinkage, irregular crystallisation, and polymer orientation. Talc will not stop warpage.
I am making a glass filled PET compound on a twin screw extruder. Properties are good except for an extremely low HDT value of approx 80 C instead of 215 which commercially available grades have. I still get this low number even when I use an alternative grade of PET. Strand length in the...