Meisterprüfung Kunststoffverarbeitung Practice Questions - Österreichische Meisterprüfung Für Das Handwerk Der Kunststoffverarbeiter Exam

Semi-crystalline thermoplastics exhibit significantly higher volumetric shrinkage (typically 1.0% to 3.5%) due to the dense, ordered folding of polymer chains into crystallites below Tm, whereas amorphous thermoplastics exhibit lower shrinkage (typically 0.4% to 0.8%) Amorphous thermoplastics exhibit higher volumetric shrinkage because random chain tangles contract more sharply upon passing the glass transition temperature Tg Both morphologies exhibit identical volumetric shrinkage, but semi-crystalline plastics experience shrinkage exclusively in the transverse direction relative to the melt flow Semi-crystalline thermoplastics expand upon cooling due to exothermic crystal lattice formation, requiring negative shrinkage allowances in mold design