Study of the effect of the dressing of carbon fibers on the properties of carbon-fiber-reinforced plastics based on polyacetals

Abstract

Studies are made of the mechanical and friction engineering properties of a copolymer of trioxane-l,3,5 Carbon fibers are being increasingly used as a reinforcing filler in thermoplastics. Due to their high thermal stability, strength, and elastic modulus and low density,'they are indispensable in aviation, rocketry, and automobile construction [l]. However, the strength of carbon fibers is not fully realized when they are in~oduced into thermoplastics. This ch~nse is related to the adhesional interaction of the polymer matrix with the surface of the reinforcing filler.The properties of polymer composites depend to a significant extent on the condition of the phase boundary [2]. The fibers must be given a surface treatment in order to obtain a greater reinforcing effect. There are several methods of modifying the surface of carbon fibers: gas-phase and liqnid-phase oxidation [3, 4], conversion of the fiber to whisker form [5], grafting of macromolecules of polymers to the surface of the fibers [5], suedin~ [6], and dressing ]7]. However, gas-phase oxidation lowers the strength of the fibers, while liquid-phase oxidation requires the additional steps of w'aqhin~ and neutralization of the reinforcing filler --as well as protection of the equipment from corrosion. Sneding, whisker formation, and graftin__g of macromolecules to reinforcing fibers all require that special conditions be present for performing the given operation. We thus chose dressing as the simplest, most accessible, and most efficient method of modigying the surface of carbon fibers. Dressing strengthens the phase boundary in the fiber-thermoplastic system by modifying the properties of the boundary layer in the fiber-matrix contact region.The use of block copolymers is very promising as a means of forming boundary layers in composites with a polyacetal matrix. Here, blocks sorbed by the surface of the filler combine with blocks that are congruent with the binder [8]. Occupying a special place among such block copolymers are organosilicon derivatives: siloxanpolyoxyalkylenes [9] and oligoorganosilanes containin~ alkylene groups with cross-linking oxygen atoms [10].We used a copolymer of trioxane-l,3,5 with dioxolan-l,3 (TDC) as the thermoplastic matrix in our investigation, since the volume of this material being used in machine construction is increasing. The polymer was reinforced with carbon fibers of "Ural LO-24" hydrated cellulose having moderate values of elastic modulns. We studied the effect of treatment of the fibers with organosilicon finishes (polyalkyloxysilanes) having the general formula [Si(CH3)2-O-CH2-R-CH2-O-]n. The

Polyoxymethylene Additives

“…-Bashtanik et al [103] illustrated the effect of organosilicon finishes on POM + cellulose fibers properties, showing an optimal mass fraction of finishes ca 1% (for a fiber mass fraction of 20 %).…”