poliesteru

Poliesteru is a family of polymers characterized by ester linkages in their main chain. They are typically thermoplastics or fibers produced by condensation reactions between diols and dicarboxylic acids, or by transesterification of esters. The most widely used polyester is polyethylene terephthalate (PET), made from ethylene glycol and terephthalic acid; PET is common in beverage bottles and textile fibers. Other important polyesters include polybutylene terephthalate (PBT) and polyethylene naphthalate (PEN).

Key properties of poliesteru include high strength and stiffness, good abrasion resistance, chemical resistance, and dimensional stability. They can be crystalline or semi-crystalline, which influences barrier properties and transparency. PET, for example, is transparent when in an amorphous state and gains strength upon crystallization. Glass transition temperatures and melting points vary by type, with PET having a glass transition around 70°C and a melting point around 250–260°C. Poliesteru are typically processable by extrusion, injection molding, blow molding, film casting, and fiber spinning.

Applications are wide: textile fibers for clothing and upholstery, beverage and food packaging, films and sheets for packaging, engineering plastics for automotive and electrical components, and composite matrices in combination with fibers.

Environmental considerations include non-biodegradability and potential for microplastic release. Recycling options include mechanical recycling to produce recycled PET pellets and chemical recycling that depolymerizes the material back to monomers for re-use. Challenges include contamination, color, and energy use in processing. Poliesteru have a long-standing role in modern materials due to their balance of performance, processing versatility, and relatively low cost.