"Plastic" - what is it, definition of the term
A polymeric, moldable material derived chiefly from petrochemical feedstocks, composed of long-chain macromolecules that may be thermoplastic—softening on heating and resolidifying on cooling—or thermosetting—hardening irreversibly through chemical cross‑linking; its hallmark traits include durability, low density, chemical resistance, and the ability to incorporate additives that adjust color, flexibility, strength, or flame retardancy.
Detailed information
Synthetic polymers are long‑chain molecules derived primarily from petrochemical feedstocks. They are produced through polymerization processes such as addition, condensation, and copolymerization, yielding materials with diverse molecular architectures. Common categories include thermoplastics, which soften upon heating and harden on cooling, and thermosets, which cure into irreversible networks.
Physical properties stem from molecular weight, crystallinity, and additives. High tensile strength, impact resistance, and chemical inertness enable use in packaging, automotive components, medical devices, and construction. Modifiers such as plasticizers, flame retardants, and fillers tailor performance for specific applications.
Manufacturing techniques encompass extrusion, injection molding, blow molding, and rotational molding. Each method shapes the polymer while controlling parameters like temperature, pressure, and cooling rate to achieve desired dimensions and surface quality.
Environmental considerations focus on persistence, degradation pathways, and waste management. Biodegradation occurs slowly under natural conditions; accelerated breakdown requires photolysis, thermal oxidation, or enzymatic action. Recycling streams separate polymers by resin type, then melt‑process or chemically depolymerize material for reuse. Contamination with residues from arthropod control products—such as insecticide‑impregnated traps for ticks, bugs, lice, or fleas—can affect recyclability and necessitate specialized handling.
Health and safety aspects address leaching of additives, especially in food‑contact containers. Regulatory frameworks set limits for migration of substances like bisphenol A, phthalates, and heavy metals. Proper formulation and testing reduce exposure risks.
Key advantages include lightweight construction, design flexibility, and barrier properties against moisture and gases. Limitations involve susceptibility to UV‑induced embrittlement, accumulation of micro‑particles in ecosystems, and challenges in achieving closed‑loop circularity without compromising material performance.