Semester

Fall

Date of Graduation

2002

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Chemical and Biomedical Engineering

Committee Chair

Rakesh K. Gupta.

Abstract

Glass fibers are commonly added to thermoplastics by the process of extrusion compounding for a variety of reasons, mainly to enhance their strength and make them dimensionally stable. Since the extruder has to be flushed out each time product composition is changed, a large amount of incompatible polymeric waste is generated. This waste material is usually landfilled even though the polymers contained in it are valuable and worth being recycled. It is the drastic reduction in mechanical properties resulting from polymer incompatibility which restricts their recycling. A good strategy of recycling thermoplastics calls for separating materials from each other before utilizing them. This research deals with characterizing and rubber toughening of a post industrial glass-fiber-reinforced nylon 66 which was separated from other polymers. A virgin glass-fiber-reinforced nylon 66 was also used in order to compare its properties with those of the recycled ones.;Rubbers used in this study were Styrene-Ethylene-Butylene-Styrene and Ethylene-Propylene grafted with maleic anhydride; SEBS-g-MA and EP-g-MA. Composites of glass-fiber-reinforced nylon 66 with various rubber contents were prepared by extrusion. The pelletized extrudates were injection molded to different standard specimens for mechanical testing such as impact, tensile, and flexural. Flow properties of the composites were examined by the melt flow index and rotational viscometry. Morphology of the fractured surface of the composites was examined by scanning electron microscopy.;Elongation and impact strength of the composites were found to increase with increasing rubber content while tensile and flexural strength decrease with increasing rubber content. Elongation of the recycled material was slightly less than that of the virgin material. This is probably due to the presence of contaminants within the recycled material. The variation of rubber content with both tensile and flexural strengths was found to obey the rule of mixtures. The morphology of the fractured surfaces showed significant signs of plastic deformation such as shear bands and cavitations as rubber content increased, and this correlates well with mechanical properties which resulted in an increase in toughness of the composites when rubber content was increased. The results of this investigation clearly show the possibility of balancing strength and toughness of the material when adding rubber to a glass-fiber-reinforced nylon 66.

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