Influence of physical cross-links in amorphous PET on room temperature ageing

Physical cross-links arise in amorphous PET upon solidification from the melt, their size distribution depending on the cooling rate adopted during a CCT (Continuous Cooling Transformation). They form a fading network structure. Above the T_g, their stability decreases with temperature. Physical cross-links stable above the T_g can influence the nucleation rate. Ageing, below T_g, is also affected by cooling rate and therefore by physical cross-links. However upon ageing new physical cross-links arise although their size and stability continue to depend on cooling rate.