PSI - Issue 17

Michał Kwietniewski et al. / Procedia Structural Integrity 17 (2019) 154 – 161 Michał Kwietniewski / Structural Integrity Procedia 00 (2019) 000 – 000

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al. (2012), where was stated that the elastomeric matrix of the composite should have such elastic and, at the same time, durable properties. Long polymer chains contained in elastomer ensure reaching several hundred percent strain during stretching. For this purpose, elastomers based on isocyanates and polyols were used. The review of knowledge presented in this article will be the base to describe the interaction of the composite matrix with auxetic fabrics reinforcement and the rule to be followed during the selection of the matrix material. 2. Polymers – overview Polymers are macromolecular compounds of following elements: C, H, Cl, O, N, F and others, composed of chains or lattices of repetitive molecules. Plastics are polymer-based According to the technological and application classification, one can divide polymers (plastics) into: • structural ones - used to build utility objects and construction elements, • coating ones - to protect the substrate from destruction and for decorative purposes - in the form of suspensions (e.g. acrylic paints - polymer suspension in water), solutions in a solvent (isophthalic), two component chemosetting resins (e.g. epoxy gelcoat), • adhesive ones (adhesives and binders), e.g. epoxy, polyester (based on epoxy resin, polyester), acrylic (methacrylic resins), • impregnation ones - e.g. impregnation for wood (type of paints), • elastoplastic (rubber) ones - in the form of hoses, thin plates, e.g. garden hoses, • fiber-forming ones - polymers capable of spinning (producing fibers), e.g. polyethylene (PE), polyamides (PA). Advantages of elastomers are as follows: low price of raw materials and finished products, low weight, high environmental resistance in contact with aggressive liquids, availability of raw materials (main obtained from coal, crude oil and natural gas), ease of forming (e.g. thermoplastics through waste-free plastic processing or injection), which gives the possibility of obtaining elements with complex shapes in one operation, the ability to obtain high strength construction materials by combining with fibers (e.g. glass). It is most often combined with duroplastic fibers, e.g. polyester (UP), epoxy (EP) resins. Disadvantages are: low durability and low Young's modulus (this feature is an advantage in the solution of the auxetic composite as it allows the occurrence of the auxetic effect in the applied HAY proposed by Sloan(2011)); low heat resistance, high creep resistance (e.g. extension under constant weight) already at ambient or slightly elevated temperature, susceptibility to degradation under the influence of UV radiation (reduction in strength and aesthetic values). Due to the behavior under load, polymers are divided into plastomers and elastomers. Plastomers are materials which elongation at room temperature does not exceed 100%. In the case of elastomers, the elongation may exceed 100% (Table 1). Table 1. Polymers division due to behavior under load proposed by Wirpsza (1991). Polymers Plastomers Elastomers Thermoplastics Duroplastics Polyethylene (PE) Unsaturated polyester (UP) Polyisoprene, Polybutadiene (BU) (rubber) Polyamide (PA) (nylon) Epoxy resin (EP) Polychloroprene (pc-rubber) Polycarbonate (PC) Phenol-formaldehyde resin (PF) (bakelite) Polysilioxane (Silicone) Polypropylene (PP) Polystyrene (PS) Polyvinyl chloride (PVC) Polytetrafluoroethylene (PTFE) (Teflon) Poly(methyl methacrylate) (PMMA)