Research Institute for Man Made Fibres (Slovakia)

CHOVANEC, Jaroslav: Ústava

In this paper the structure and properties of fibres prepared from the polypropylene/polyamide (PP/PA6) blend have been studied as a function of the interfacial-agent (IFA) content. For this purpose the grafted polypropylene-maleic anhydride copolymer was used. Fibres containing 20% of PA6 and 80% of PP possess the phase matrix-fibril structure. The size and distribution of fibres in the dispersed PA6 phase in the PP matrix depend on the interfacial-agent amount. Due to the indirect nucleating effect the PA6 phase has been found to act, in the presence of the interfacial agent, on the PP crystallization during fibre formation. As a result, undrawn fibres have the more pre-oriented and crystalline PP matrix with the morphological rod-like structure. The pre-orientation of the dispersed fibrilar PA6 phase is minimum. Mechanical properties of the drawn blended fibres are favourably influenced provided that the interfacial-agent concentration is higher than 1%. The growing rate of the mutual interaction between the components was mostly reflected in the increased values of Young's modulus.

Abstract The influence of different preparation conditions upon formation of the morphological structure of polypropylene fibres was studied by X‐ray method, scanning electron microscopy, and small‐angle light scattering technique. It was found that the formation process and the deformation of the morphologic structure in polypropylene fibres changed when using the traditional and the high velocity technologies, respectively.

The polypropylene melt viscosity dependence upon temperature, shear and molecular weight, and the molecular weight dependence upon temperature and time were measured and mathematically described. For the dependence of the melt viscosity upon temperature, shear and molecular weight (melt index), a master curve has been found. The influence of the progressive degradation of polypropylene during the extrusion upon the temperature, pressure and dissipated energy down-channel profiles is given.

The method of calculation of the intrinsic viscosity [η] from one viscosity measurement according to the Solomon and Ciutǎ's equation has been analysed. The difference between [η] extrapolated from the measurement of viscosity at several concentrations and [η] calculated has been defined in dependence on the product [η]c and the value of Huggins' constant k'. It has been demonstrated that the proposed equation is often useful but not generally valid; the range of its applicability has been defined.