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Plastics based on thermosetting phenol-formaldehyde binders, modified by polyamide, and discrete organic fibred fillers
Authors: M.V. Burmistr, O.O. Lipko, O.I. Mikhaylova, Yu.M. Kobelchuk, L.I. Sula
Number of views: 328
We developed new polymeric composite materials based on phenol-formaldehyde matrix modified by alcohol-soluble polyamide P-548 and such discrete organic polyamide fibers as home-produced polyhexamethylenadipamide fibers of aliphatic type "Anid" and polybenzimidazole ones of aromatic type "Rusar®" (their analogues being "Kevlar", "SVM" etc.). The physical-mechanical properties of the synthesized composites exceed those typical of common phenol-formaldehyde matrix. The introduction of thermoplastic linear polyamide fragments into the structure of hard phenolic matrix allowed increasing the physical-mechanical properties of composites as follows: impact strength by Sharp increases by 20%, the ultimate bending strength increases by 23 to 38%, the ultimate compression strength increases by 32%, and the water absorption reduces by 12 to 17%. The process of the reinforcement of phenol-formaldehyde matrix by polyamide discrete fibers was studied. The adhesion interaction between polymer-fibers surfaces was examined. The effects of the reinforcement degree and the length of discrete fibers on the rheological properties of prepregs as well as on the physical-mechanical properties of composite materials have been investigated. The optimum compositions and technological parameters of the fabrication and processing of the developed composite materials were considered. Due to modification of the phenol-formaldehyde matrix by polyamide, new polymeric composite materials have been obtained with the enhanced properties. When polyhexamethylenadipamide reinforcing filler is used, the impact strength by Sharp is 98-154 кJ m-2, the tensile strength at a static bend is 118-148 MPa, the compression strength is 111-132 MPa, the heat resistance by Martens is 98-103 С, and the water absorption is 0.16%. When polybenzimidazole filler is used, the impact strength by Sharp is 235-431 кJ m-2, the tensile strengths at a static bend is 320-437 MPa, the compression strength is 150-245 MPa, the heat resistance by Martens is 240-245С, and the water absorption is 0.23-0.27%. The developed polymeric composite materials meet the requirements for structural materials that can be operated in friction units and corrosive environments to substitute textolite and other composite materials with inferior properties.