Лако-красочные материалы — производство

Plastics that can be repeatedly solidified from the melt state without significant crystallisation are described as amorphous thermoplastics. Amorphous thermoplastics

have long macromolecule chains which are highly entangled with large side chains (Figure 2.2).

Amorphous thermoplastics are frequently used in applications where clarity is important and in applications where they may be thermo-processed (e. g., ultrasonic welding). They can be moulded to a high-dimensional accuracy and stability, and have a good appearance and mechanical properties (depending on the grade). At elevated temperatures or at high stress levels, the polymer chains can uncoil and thus alter the properties of the polymer. Generally, amorphous thermoplastics are less chemically resistant than semi-crystalline thermoplastics and can be subject to stress cracking and can swell or dissolve in some solvents.

Some typical examples of amorphous thermoplastics are acrylonitrile-butadiene-styrene (ABS), polymethylmethacrylate (PMMA), polystyrene (PS) and polycarbonate (PC). Applications for amorphous thermoplastics vary from car bumpers to Lego® bricks, and from motorcycle helmets to ski boots.