INFLUENCE OF EXTRUSION PARAMETERS AND ORIENTATION-AL STRETCHING ON FORMATION OF SUPRAMOLECULAR STRUCTURE AND PROPERTIES OF POLYPROPYLENE MULTIFILAMENT YARN

MUQYBS

Abstract

The paper presents a comprehensive study of the production process of fully oriented polypropylene multifilament yarn. It declares the relationship between process parameters, the resulting supramolecular structure, and the final performance properties of the material. Three key stages of the technological process are considered in detail: melt extrusion, orientation stretching, and pneumatic entangling. It is shown that already during the extrusion and spinning stages, the primary orientation of macromolecules and the formation of long-range order elements occurs under the influence of shear stress, which is fixed in the cooling well. Subsequent orientation stretching at elevated temperatures leads to further structural ordering, recrystallization, and a significant increase in the strength of the elementary filaments. The choice of PP H270 GP/1 injection-molded polypropylene grade with a high melt flow index is justified, driven by the requirements of the extrusion process and the influence of molecular weight characteristics on structure formation. A multi-level structural model of the final product is presented, explaining its high specific strength, abrasion resistance, chemical inertness, and hydrophobicity. It is concluded that targeted control of the parameters of each technological stage allows to obtain the production of a material with a specified set of properties.