Basalt fibers are efficient reinforcing fillers for polypropylene because they increase both the mechanical and the tribotechnical properties of composites. Basalt fibers can compete with traditional fillers (glass and asbestos fibers) of polypropylene with respect to technological, economic, and toxic properties. The level of mechanical properties of reinforced thermoplastics depends on numerous factors. Two of them a~re the most important, namely the adhesive strength of a polymer-fiber system and the residual length of a reinforcing filler in the composite after processing [i, 2]. It is obvious that these factors depend on the technological features of introducing the fibers into the polymeric matrix. The method of combined (screw-disk) extrusion seems to be the most efficient for combining a polymeric binder with a reinforcing t

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A study is made of the dependence of the mechanical and friction-engineering properties of polypropylene reinforced with basalt fibers on the viscosity of the polymer matrix. It is established that the main factors that determine the mechanical properties of the plastics are the quality of impregnation of the fibers by the binder and the residual length of the reinforcing filler in the composite after extrusion and injection molding. The material that was developed has a low friction coefficient and low rate of wear within a relatively broad range of friction conditions. The basalt-plastics can be used in the rubbing parts of machines and mechanisms subjected to dry friction.Glass and asbestos fibers are currently the materials most commonly used as reinforcing f'dlers for polypropylene [1, 2]. The introduction of these fibers into the polymer increases the strength properties and heat resistance of the plastic while reducing its shrinkage. However, fdling polypropylene with glass fibers appreciably diminishes the resistance of the material to shock loads, while asbestos is carcinogenic. It is thus important to f'md a replacement for glass and asbestos fibers. One possible substitute might be basalt fibers, which make it possible to create a composite with good service properties that is low in cost and less toxic.We used polypropylene with a melt index (MI) of 6 and.. 20 g/10 min as the polymer matrix. Basalt fibers based on ZhBTR 0-330 roving (TU U 00292729.001-96), chopped into segments with a length from 5 to 30 rnm, were used as the reinforcing fdler. The polymer matrix and fibrous Idler were mixed with a worm-disk extruder [3]. The content of basalt fibers in the polypropylene was 20% by weight. The high Idler content adversely affects the impregnation of the f'dler by the thermoplastic binder. The defect content of the composite increases and its strength characteristics decrease. We prepared standard specimens by injection molding to determine the mechanical properties of composites of the resulting granular material. The service characteristics of the specimens were determined in accordance with the GOST (All-Union State Standard) for plastics. A thermogravimetric analysis of the properties of the plastics was performed with a Paulik-Paulik-Erdei derivatograph made by the Hungarian f'nan MOM. The friction-engineering properties of the composites without lubrication were studied on friction testing machine 2070 SMT-1 by the disk-chock method. Steel 40Kh, heattreated to a hardness HRC 38-48 and having the roughness parameter R a = 0.63 ttm, was used to make the counterweight. The area of contact of the specimen and the counterweight was 2.10 -4 m 2.When thermoplastics are f'dled with individual fibers, the size of the particles of f'dler --especially their length --is of paramount importance [2]. It follows from the data shown in Fig. 1 that the dependence of the tensile strength of polypropylene-based basalt-plastics on the length of the reinforcing fibers is of an extreme nature. This is a manifestation...

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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