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The effect of processing parameters of injection molding on the mechanical and tribotechnical properties of carbon plastics based on polyacetals is investigated. The copolymer of 1,3,5-trioxane with 1,3- Thermoplastic carbon fiber-reinforced plastics (CFRPs) are increasingly being used in mechanical, radio, and instrument engineering since they have high physicomechanical properties, low friction coefficient, and can be easily processed into products. To manufacture parts of plain bearings for the friction joints of machines and mechanisms, randomly reinforced CFRPs based on polyamides are often used [1]. However, these composites cannot be utilized when producing parts that will be operated in humid environment. CFRP based on copolymers of formaldehyde have high resistance to moisture and chemical reagents, low friction coefficient and wear intensity, and relatively low processing temperature, and their mechanical properties do not degrade up to a temperature of 120"C. The mechanical properties of products made of CFRP based on copolymers of formaldehyde (polyacetals) are~considerably affected by the technological parameters of processing by . injection molding. The effect of these parameters on the properties of unfilled copolymers of formaldehyde has been described earlier [2]. The aim of the present study is to examine this effect for CFRP based on copolyrners of formaldehyde.As the thermoplastic matrix, the copolymer of 1,3,5-trioxane with 1,3-dioxolane (CTD) was utilized. As a reinforcing filler, we used medium-modulus hydrated cellulose Ural LO-24 carbon fibers (filling degree 20 wt.% ). The polymer was mixed with the carbon fibers in an ED-2,2 screw-disk extruder. Standard test specimens were obtained by injection molding. The physicomechanical properties of the CFRP were determined

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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

At present, the interest in polymer composites is still growing. Thermoplastic carbon fiber-reinforced plastics attract particular attention because of their high strength, high elastic modulus, electrical conductivity, low friction coefficient, and recyclability. In making products from CFRPs with high physical-mechanical properties, all stages of the process of their production and processing are important, which include preparation of the components, method of introducing a reinforcing filler in the polymer matrix, and molding technology of the final product. The introduction of fibers into CFRPs ivcreeses their physical-mechanical characteristics, the higher the length of the fibers and the degree of filling, the higher the increase. We should note that the attainment of high physical-mechanical properties of fibrous composites is hindered by processes taking place in the prodessing equipment (extruder, casting machine) itself [1]. To process filled thermoplastic composites, it is necessary to maintain technological conditions where the fibrous filler would suffer minimum failure in the working units of the processing equipment.