Masters Theses

Pankaj Gupta

Date of Award

12-2000

Degree Type

Thesis

Degree Name

Master of Science

Major

Polymer Engineering

Major Professor

J. E. Spruiell

Committee Members

Gajannan Bhat, K. Kit

Abstract

Aliphatic polyketones are a class of perfectly alternating co- and ter- polymers that have ethylene and carbon monoxide as the main repeat units. In the terpolymer, a small amount of propylene is added to improve the chain flexibility and to reduce the melting point.

Melt spinning followed by drawing of polyketones yields filaments that have high tensile strength that could be used for industrial applications such as tire cords. Polyketones as resins have extremely good chemical, hydrolytic, barrier and mechanical properties. In this study an attempt is made to investigate whether these polymers could be formed into a high-tenacity industrial grade fiber Spinning and post spinning operations like drawing and heat setting have been optimized so that the resulting fibers have good mechanical properties Characterization of the filaments was done using a number of techniques to study the structure development of the fibers with drawing The purpose of this study was, therefore, to optimize the processing conditions and thereafter investigate the structure-property relationship of both the copolymer and the terpolymer fibers The effects of molecular weight, propylene content, draw ratio and draw temperatures on the structure were also investigated

Four different grades of aliphatic polyketones were investigated in this study. The melt spun as-spun copolymer fibers have both α and β phases at room temperature. The high draw ratio copolymer fibers have predominantly α phase. The terpolymer fibers have β phase at all temperatures and preparation conditions The lattice parameters were measured for one of the terpolymer grades and they are in agreement with those obtained by other authors. The melting behavior of the as spun samples of both the co and terpolymer samples show a bi-modal peak distribution.

Birefringence and WAXS analysis indicate an increase in the orientation with draw ratio for all the sample grades. Microfibrillar structure develops with increasing draw ratio. This was also corroborated by the two-point small angle x-ray scattering contour plots. However, at high draw ratios the meridian peaks in the SAXS contour plots weaken indicating an increase in the order of the non-crystalline regions. A strong correlation was found between the orientation and tensile strength and modulus of the fibers. Fibers having tenacity in the range of 9-11 gpd were obtained. Another notable feature is the retention of their strength at elevated temperatures. It was observed that these fibers retain 85-90% of their original strength till a temperature of 125 °C The terpolymer fibers were comparatively stronger than the copolymer fibers both in terms of strength and modulus.

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