Masters Theses

Date of Award

12-2004

Degree Type

Thesis

Degree Name

Master of Science

Major

Polymer Engineering

Major Professor

Dong Zhang

Committee Members

Christine (Qin) Sun, Kermit Duckett

Abstract

Ever since the potential applications of superfine fibers were realized, bicomponent fibers have received considerable commercial interest. Webs containing microfine bicomponent fibers, such as bicomponent meltblown webs, have found great opportunities in production of finer fibers by subsequent fiber splitting, though technical problems still exist due to special features of the meltblown fibers, including low molecular orientation, low crystallinity and low strength.

In this research, the mechanics of polymeric interfacial adhesion in side-by-side bicomponent meltblown fibers was discussed and the method of enhancing the fiber splitting in bicomponent meltblown webs by additive application prior to the extrusion process was proposed and experiments conducted on Polypropylene (Exxon PP 3746G), Polyester (Eastman PET 14965) and Polyamide 6 or Nylon 6 (BASF PA6 B3).

Twenty-two additives from different chemistry families were applied first for the lab-screening test. The effect of these additives on the polymer surface energy was studied using contact angle measured on the single fibers of PP and PET. Based on the study, five silicone-containing copolymer additives were selected at the optimal weight ratio of 2% for future trial test on TANDEC 6’’ meltblown line to produce PP, PET, PA6 meltblown webs.

Meanwhile, additive migration in single fibers and mono-component meltblown webs produced from PP, PET and PA6 polymers was investigated by both contact angle on single fibers and surface energy on the webs. The effect on tensile strength was also studied by comparison of the webs before and after the additive application. The results showed that additive migration happened in about one week and the web strength was slighted influenced by the additives.

Finally, selected polymers and additives based on the above research were tested on Reicofil® 24’’ bicomponent Meltblown Line to produce side-by-side bicomponent fiber nonwoven webs. Twelve side-by-side bicomponent meltblown webs were produced at varied bicomponent ratios (67/34, 50/50, 34/67), where additives were applied to one component in each bicomponent web. The fiber splitting was induced using hot water without any mechanical agitation. The fiber structure was examined through Scanning Electronic Microscopy (SEM). The effect of the water treatment on web properties such as fiber diameter, basis weight, web thickness, air permeability, water resistance, tensile property and flexural rigidity were investigated according to corresponding ASTM standards. It was found that fiber splitting in PP/PA6 bicomponent web was improved by additive application and web characterization indicated that detection of fiber splitting from web properties, specifically air permeability, seemed possible.

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