- Country of manufactureRussia
Polyethylene of high pressure
Polyethylene of high pressure (interpretation of PVD or PEVD - an abbreviation) is the thermoplastic polymer received by method of polymerization of the hydrocarbonic ethylene connection (eten) under the influence of high temperatures (till 1800), pressure to 3000 atmospheres and with oxygen participation. PVD is the light, strong, elastic material applied in many spheres of activity of the modern person. Also can be called as polyethylene of the low density (PNP or PENP) as has rather weak intramolecular communications and, therefore, lower density, than polymers of other types. Also LDPE reduction - the English equivalent of PENP is applied to its designation.
Features of PVD (PNP)
Chemical and physical characteristics
The Polyethylene of High Pressure (PHP) is made in the form of PVD granules. Has density of 900-930 kg/m3, temperature of melting 100-115 0C and temperature of fragility to-120 0C, and also small water absorption (about 0,02% in a month) and high plasticity. These physical and chemical characteristics of PVD as substances explain the following properties of the objects and materials made of it:
- Softness and flexibility of products from polyethylene of low density,
- Possibility of creation from granules of PVD of especially smooth and brilliant surfaces,
- Stability of objects from PVD to mechanical destructions by a gap and blow, and also to deformations of stretching and compression,
- High durability of PVD (penp) at influence of low temperatures,
- Vlago-and air tightness of PENP - products,
- Resistance of PEVD to light influence, in particular to sunlight.
IMPORTANT! Use of the polyethylene of high pressure (PHP) is absolutely safe both for the person, and for state of environment as it does not emit any toxic substances. For this reason PEVD can be used even for contact with food and at production of children's goods.
Difference of PVD from other polymers
Polyethylene (PVD, PND, etc.) is materials which are made of one monomer, but can be various density depending on features of production. This indicator strongly influences properties of polyethylene: increase in density leads to increase in rigidity, hardness, durability of products and their chemical firmness. But at the same time other indicators fall: crash-worthiness, a possibility of stretching at a gap, permeability for liquids and gases. So, PVD has essential differences from other similar polymers:
- PVD and PND. Polyethylene of high pressure not for nothing is called also polyethylene of low density (Pnpili of PENP). In comparison with it such solid polymers as PLP (polyethylene of low pressure), give in to gaps under the influence of blow quicker, to a thicket break on a frost and crack at increase in loading, though have bigger resistance to influence of radiation, alkalis and acids. Granules of PVD and a product from them transfer ultra-violet radiation much better, and also have more beautiful glossy surface.
- PVD and LPNP. Other polymer - LPNP (linear polyethylene), as well as PND, has rigid structure, but on the technical characteristics is between PVD and PND. He is more firm to chemically hostile environment, than PENP, and has big resistance to a puncture and cracking, than PND.
Types of PENP polyethylene
Additional processing of polyethylene of high pressure gives qualitatively new materials differing on chemical and physical properties. In particular, there are modifications of PEVD with the improved adhesion to paints and other materials (e.g., to metal) and with the lowered combustibility. At the moment distinguish polyethylene:
- the made foam PVD,
- the sewed PVD,
- copolymers of the polyethylene of low density (PLD) with other monomers or with polyethylene of other look.
Polyethylene of the high pressure (PEVD) at the moment takes a leading place on the world outputs among a set of other polymers. Thanks to a successful set of chemical and physical properties, granules of PVD find application in production:
- films of PENP, opened and in the form of PVD sleeve for bags and packages,
- PENP plastic by casting under the influence of pressure (polymeric pipes, technical details, etc.),
- blown products (bottle, canister, etc.),
- heat-insulating materials from made foam penp,
- electroinsulating materials (cover of cables and so forth),
- PVD thermoglue in the form of the powder prepared by crushing of granules of PVD.
INTERESTINGLY! PVD was the first polymer which began to be used as insulating material in the electrotechnical industry for isolation of underwater cables later - for radars.