The influence of plasma gas species on the adhesion of thermoplastic to organic fibers

Abstract

SYNOPSISAdhesion between organic fibers and thermoplastics in a composite material is usually weak because of the lack of chemical and mechanical bonding. This study investigated the influence of plasma gas species in a novel technique to improve interfacial adhesion of Kevlar 49 fibers to polycarbonate. Single Kevlar fibers were exposed to radio-frequency plasma discharge in atmospheres of argon, oxygen, and ammonia. Plasma treatment has been shown to generate reactive free radicals on polymer surfaces. The fibers that were coated immediately with a polycarbonate melt while still in the vacuum environment of a plasma reactor showed an increase in interfacial shear strength that was maximum a t 4.1 s exposure and decreased at longer exposure times. At 4.1 s exposure, Ar and 0, plasma treatment increased shear strength by 20 and 18%, respectively. NH3 plasma treatment produced only a statistically insignificant increase at 4.1 s of exposure and a significant decrease in adhesion at 8.3 s of exposure. Fibers that were exposed to air for 1 h before coating showed no statistically significant increase or decrease in adhesion. The increase in adhesion of the directly coated fibers was attributed to free radical-initiated formation of covalent bonds between the Kevlar and the polycarbonate.

Effects of Twaron fiber surface treatment by air dielectric barrier discharge plasma on the interfacial adhesion in fiber reinforced composites

“…However, interfacial adhesion of thermoplastic composites reinforced by organic fiber is usually weak, weakening the transfer behavior of the loads from matrix to fiber. As for aramid fiber, to a great extent, the chemical inertness and smooth surface may account for the lack of chemical and mechanical bonding between fiber and matrix, which makes the fiber surface modification a necessary technology, like non-thermal plasma treatments [3][4][5].…”

Contact angle determination on plasma‐treated poly(ethylene terephthalate) fabrics and foils

“…The plasma treatment of fabrics has gained in importance over the past years as a textile finishing process for technical and medical textiles as well as for composite materials to improve their surface properties like wettability and adhesion 1–8. Compared to conventional wet‐chemical textile finishing, plasma technology is also of increasing interest because of its environmental sustainability 3, 9…”

Improving adhesion in interleaf composites using plasma processing

“…Other plasma processes have been shown to produce maximum strengths at intermediate process times. 17 Data from the ENF testing within each phase was examined by ANOVA to determine which processing parameters produced significant changes in the ENF values. In phase one processes, the parameters of RF power and processing time produced a significant GIIc response ( p < 0.01).…”