Blended polypropylene/polyethylene terephthalate fibres: Crystallisation behaviour of polypropylene and mechanical properties

Polyethylene terephthalate (PET) and the compatibilisers ethylenedistearamide (EDSA) and ethylenevinylacetate (EVAc) are used for the modification of PP fibres that are aimed at improving the dyeability by dyeing fibres in a bath. This causes changes in the melting and crystallisation process that affect the creation of the morphological structure in blended PP/PET fibres as well as the content of the crystalline phase of the PP matrix. The thermal properties of modified PP fibres were evaluated by the DSC method Some thermal characteristics (Avrami exponent n, crystallisation kinetic constant K and free enegy of crystal creation sigma(e)) of the blended PP/PET fibres at crystallisation were determined as well as their physical-mechanical properties. The various compatibilisers have a different influence on the crystallisation of PP in the PP/PET fibre blend EDSA behaves as a nucleating agent and increases the crystallisation of PP. The compatibiliser EVAc decreases the crystallisation of PP in the PP/PET fibre blend For the crystallisation of PP heterogeneous nucleation with a tridimensional spherulitic growth of crystallites is characterised. The aforementioned additives emphasise this heterogeneous nucleation of crystallites in the crystallisation of PP in the blended PP/PET fibres. The tensile strength and elongation of the blended PP/PET fibres were changed by the influence of PET and compatibilisers.