Influence of molecular weight distribution on the structure and properties of melt‐spun polypropylene filaments

Abstract

SYNOPSISThe role of molecular weight distribution on the spinnability, structure, and properties of melt-spun isotactic polypropylene filaments was studied with the aim of clearly distinguishing the effect of the breadth of the distribution from the effect of the average molecular weight and resin melt flow rate (MFR). Nine resins were chosen for this purpose, ranging in MFR from 16 to 78 and in polydispersity from 2.6 to 5.4. It was observed that the spinnability, structure, and properties of the spun filaments were all strong functions of the breadth of the distribution. Spinnability decreased with increasing breadth. At given spinning conditions and polydispersity, an increase in the weight-average molecular weight (decrease in MFR) produces an increase in crystallinity, birefringence, tensile strength, and tensile modulus. But at given spinning conditions and resin MFR, broadening the molecular weight distribution (increasing the polydispersity) produces an increase in crystallinity, tensile modulus, and elongation-to-break while birefringence and tensile strength decrease. The major influence of the polydispersity on the structure and properties developed was attributed to its effect on both the elongational viscosity of the resin and the ability of high molecular weight tails in the distribution to influence the stress-induced crystallization that occurs in the spinline. 0 1995 John Wiley & Sons, Inc.

Spun bonding Technology and Fabric Properties: a Review

“…Broad molecular weight distribution polymers show more elongation, thinning and higher tendency to undergo stressinduced crystallization, resulting in fibers with higher density and lower birefringence than the filaments produced from narrow molecular weight distribution. Fibers spun from narrow molecular weight distribution have higher tensile strength and lower elongation to break [34].…”

Quiescent crystallization kinetics and morphology of isotactic polypropylene resins for injection molding. I. Isothermal crystallization

“…Fi-G of iPP decreases with the increase in the number nally, in the third part, we will formulate the conaverage molecular weight (M n ). However, in a more stitutive equation for crystallization, and we will recent and comprehensive study made by Misra and use it in the simulation of the postfilling stages coworkers 14 on this subject, the authors found that of the injection molding of these polymers into a increasing the weight average molecular weight rectangular mold. (M w ) for a given polydispersity increased the overall crystallization rates.…”

Structure and property characterization of spunbonded filaments and webs using thermal analysis

“…Thermomechanical Analysis Although the effect of processing variables on the properties of the webs has been studied, there Thermomechanical analysis responses were reis no information available on the structure and corded using the Mettler TMA 40 with a heating properties development of the filaments. 4 This rerate of 10ЊC/min at tension, compression, and dysearch was done to elucidate the filament mornamic mode. The samples were scanned in the phology and property development using thermal nitrogen environment with different levels of preanalysis.…”