استفاده از روش طراحي آزمايشات رويه پاسخ (RMS) در مطالعه و پيش بيني تاثيرات توام دماي اكستروژن و شرايط انجماد در فرايند ذوب ريسي بر خواص فيزيكي و مكانيكي نخ نوريس پلي پروپيلن

As-spun filament yarn properties have high effects on final properties of drawn filament yarns. These properties are influenced significantly by spinning process parameters and freezing conditions. In this study, the simultaneous effects of extrusion temperature and cooling conditions (cooling air temperature and pressure) on the physical and mechanical properties of as-spun filament yarn samples produced in a melt spinning Pilot Plant under condition of 2200m/min take-up speed,235-260°C spinning temperature, 18-24 °C cooling air temperature and90-1302 N/m2 cooling air pressure, were investigated. In order to use an experimental design method and to obtain the optimum condition the Response Surface Methodology were used and according to this method, 15 samples under different extrusion temperatures and cooling conditions were produced. Then structural properties (birefringence, crystalinity), physical properties (tenacity, breaking elongation and shrinkage) and their thermal behavior were evaluated. Experimental results show that extrusion temperature has significant effects on structural and physical properties of all as-spun fiber samples .Birefringence, tenacity, modulus and shrinkage tests showed decreased trends with increasing extrusion temperature, while density showed an increased trend. Physical and structural properties (except for density) decreased with increasing cooling air temperature and pressure, while the density showed an increased trend. According to applied experimental design (RSM) the optimum processing conditions were determined in which extrusion temperature of 240 °C, cooling air temperature of 18 °C and cooling air pressure of 118 N/m2 were obtained.