Influence of pigments on super-molecular structure of polypropylene fibres

WAXS and DSC investigations of the structure of uncoloured and coloured pol ypropylene fibres were carried out. Two organic pigments: a phthalocyanine and a quinacridone with different nucleating abilities were used for the co louring of fibres. The fibres were formed at various take-up velocities, an d heat stabilized at temperature in the range 120-160 degrees C. It was sta ted, that two polymorphic forms alpha and beta occur in uncoloured fibres s pun at extrusion velocity. Fibres spun at small and medium take-up velocity contain the mesophase, whereas fibres spun at high take-up velocity contai n the crystalline alpha-form. In the fibres coloured with a phthalocyanine the alpha-form occurs independently of the take-up velocity. Fibres coloure d with a quinacridone contain both forms alpha and beta. A great content of beta-form occurs in fibres spun at the lowest take-up velocity. The observ ed changes of the structure of fibres are connected with the change of nucl eation mechanism. During heat stabilization perfecting of alpha-form occurs . The mesophase and a hexagonal beta-form transform into a monoclinic alpha -form. The degree of transformation depends on the stabilization temperatur e. For coloured fibres the structure of unstabilized fibres is mon perfect and undergoes smaller changes during stabilization than the structure of un coloured fibres. (C) 2000 Elsevier Science Ltd. All rights reserved.