Plastic (plastics) or plasticity — organic materials which basis are synthetic or prirodnyevysokomolekulyarny connections (polymers). Only plastic on the basis of synthetic polymers were widely used.
The name "plastic" means that these materials under the influence of heating and pressure are capable to be formed and keep the set form after cooling or hardening. Process of formation is followed by transition of plastically deformable (plastic) state a vstekloobrazny (firm) state.
The first plastic was received by the English metallurgist and the inventor Alexander Parks in 1855 [1]. Parks called it parkezin (other name — celluloid gained distribution later). Parkezin was for the first time presented at the Big International exhibition in London in 1862. Development of plastic began with use of natural plastic materials (chewing gum, shellac), then continued with use of chemically modified natural materials (rubber, nitrocellulose, collagen, galalit) and, at last, came to completely synthetic molecules (bakelit, epoxy, polyvinylchloride, polyethylene and others).
Parkezin was a trademark of the first artificial plastic and was made of the cellulose processed by nitric acid and solvent. Parkezin often called an iskusstvennoyslonovy bone. In 1866 Parks created Parkesine Company firm for mass production of material. However, in 1868 the company was ruined because of bad quality of production as Parks tried to cut down expenses on production. The successor of a parkezin became ksilonit (other name of the same material), the former employee Parks, and the celluloid made by John Vesli Hiatt made by Daniel Spill's company.
The main mechanical characteristics of plastic the same, as for metals.
Plastic are characterized by small density (0,85 — 1,8 g/cm ³), extremely low an electric and thermal provodimostyama, not really big mechanical durability. When heating (it is frequent with a preliminary softening) they decay. Are not sensitive to humidity, are steady against effect of strong acids and the bases, the relation to organicheskimrastvoritel various (depending on the chemical nature of polymer). Are physiologically almost harmless. Properties of plastic can be modified by methods of a sopolimerizatsiiila of stereospecific polymerization, by a combination of various plastic with each other or with other materials, such as glass fiber, textile fabric, introduction of fillers and dyes, softeners, warm and light stabilizers, radiation, etc., and also a raw materials variation, for example use of the corresponding polyols of idiizotsianat when receiving polyurethane.
Hardness of plastic is determined by Brinell at loads of 50 — 250 kgfs on a ball with a diameter of 5 mm.
To Teplostoykostpo Martens — temperature at which the plastic whetstone with sizes of 120 × 15 × 10 mm bent at the constant moment creating the largest tension of a bend on sides 120 × 15 mm, equal 50 kgfs/cm ² will collapse or will be bent so that the lever 210 mm long strengthened on the end of a sample will move to 6 mm.
Heat resistance on Vick — temperature at which the cylindrical core with a diameter of 1,13 mm under the influence of freight weighing 5 kg (for soft plastic of 1 kg) will go deep into plastic on 1 mm.
Fragility temperature (frost resistance) — temperature at which plastic or elastic material at blow can collapse it is fragile.
For giving of special characteristics to plastic add softeners (silicone, dibutylphthalate, PEG, etc.), fire-retarding agents (difenilbutansulfokislot), antioxidants to it (trifenilfosfit, unsaturated hydrocarbons).
