Polyolefine polyethylene

Polyolefins (Polyethylene, Polypropylene) Powder, pellets Tough and chemical resistant. Weak in creep and thermal resistance. Polyethylene maximum use temperature 210 F, polypropylene 260 F. May be injection and extrusion molded, vacuum formed. Low cost. Antistatic sheet and tiles, heat-shrinkable tubing, deicer boots. 

Experiments carried out on laboratory and pilot plants, both with viscoplastic systems13 -l5) and with thermoplastics, polyolefins (polyethylene, polypropylene, and filled materials based thereon) 7,9,28) and various PVC-compositions36) corro-... 

Polyolefins. Polyethylene (conventional and linear) and polypropylene have excellent chemical resistance and are readily molded and machined, although they are rather soft. Conventional polyethylene adheres well to metals, and polyethylene tubing can be readily sealed around metal rods and wires to make simple electrodes suitable for use at temperatures below 60°C. The material is resistant to mineral acids and bases (except concentrated sulfuric and perchloric acids) and most organic solvents except halogenated or aromatic hydrocarbons. 

The decorative laminates described in the previous chapter are made with selected thermosetting resins while resins of this type can be moulded and extruded by methods similar to those outlined in the present and the next chapter the materials employed for these processes predominantly are thermoplastic. Many such plastics can be moulded and extruded under suitable conditions, the most important in terms of quantities used being those that combine properties satisfactory for the purpose with convenience in pro-cessing-especially the polyolefins (polyethylene and polypropylene), poly(vinyl chloride), and styrene polymers and blends. Other plastics with special qualities, such as better resistance to chemical attack, heat, impact, and wear, also are used—including acetals (polyformaldehyde or polyoxymethylene), polyamides, polycarbonates, thermoplastic polyesters like poly(ethylene terephtha-late) and poly(butylene terephthalate), and modified poly(phenylene oxide),... 

A large-volume intraocular solution (for irrigation) may be packaged in a polyolefin (polyethylene and/or polypropylene) container. 

Polyolefins. Polyethylene and polypropylene—some use as a separate disc or wad, but are now widely used in the form of wadless closures where the closure acts as its own wad. 

The original, simplest polyolefins, polyethylene and polypropylene, continue to dominate the scene, even after two decades, to such an extent that no other polyolefin even appears on the production charts. Nevertheless, a great many (we may assume all) available olefins have been tested, and many have been found capable of being converted to stereoregular polymers. As was mentioned above, poly(l-butene) and poly(4-methy1-1-pentene) are being offered commercially and may be expected to achieve significant volume in the future. Isotactic and syndiotactic polystyrene are of much theoretical interest (26) but are not yet commercial products. 

Though there are metals other than copper (such as iron, manganese and cobalt) that can accelerate thermal oxidation of polyolefins and related polymers such as EPDM, in practice, however, the inhibition of copper-catalyzed degradation of polyolefins is of paramount importance because of the steadily increasing use of polyolefin insulation over copper conductors. Among polyolefins, polyethylene is still the most common primary insulation material for wire and cable. In the United States, high-density polyethylene and ethylenepropylene copolymers are used in substantial amounts for communications wire insulation. 

As all polyolefins, polyethylene is sensitive to UV radiation, although less than polypropylene. For outdoor use polyethylene needs special stabilization against UV light. The light stabilizers for polyethylene are in principle the same as for polypropylene. On accelerated weathering, HALS show much better performance in HDPE tapes than UV absorbers, despite the latter being used in much higher concentrations. The comparison between HALS is, however, in favor of the polymeric HALS-III, which has the same performance when added at a concentration of 0.05% as HALS-I and HALS-II at 0.1%. 

Since the density of plastics highly depends on the presence of fillers or other additives, this property is far from being a characteristic feature. Unfilled polyolefines (polyethylene and polypropylene), a number of elastomers (natural rubber and silicone rubber), and foamed plastics come within the rare category of polymers which float on water. Some fluoropolymers exhibit a density around or greater than 2 g/cvo (see also Table 3.3). 

Basic stoichiometry teaches that for every 100 kg of polyolefin (polyethylene, PE polypropylene, PP) manufactured, a net 314 kg of CO2 is released into the environment at its end of life (100 kg of PE contains 85.7 kg carbon and upon combustion will yield (44/12) x 85.7 = 314 kg of CO2). Similarly, PET contains 62.5% carbon, which results in 229 kg of CO2 released into the environment at end of life. However, if the carbon in the polyester or polyolefin comes from biomass feedstock, the net release of CO2 into the environment is zero, because the CO2 released is sequestered in a short time period by the next crop or biomass plantation (Eigure 14.2). Thus, the fundamental value proposition for bio-based plastics arises from this intrinsic zero material carbon footprint and not necessarily from the process carbon footprint, which may be equal to or slightly better than current processes. 

Sodium etch Sodium hydroxide Sanitizing melamine or urea polymer, polyolefin, polyethylene oxide, polystyrene, polysulfone, and styrene-acrylonitrile (SAN) Fluoroplastics and some polyesters Polystyrene, polyesters, polyamide, and polysulfone Homopolymer polyacetal Developed by... 

Reactive grafting of polyolefins, polyethylenes (PE), or polypropylenes (PP) was disclosed. The extruder was modified, allowing to feed polymer, grafting monomer and peroxide. As an example, PP was grafted with acrylic acid... 

A significant recent innovation in the formulation of toughened acrylics is the ability to bond polyolefins (polyethylene and polypropylene) without any substrate pre-treattnents. This beneficial aspect of the toughened acrylic adhesives performance is attributed mainly to newly developed and patented cure technologies and provides an unique performance feature that cannot currently be matched with any other adhesive type." ... 

Polyvinylidenechloride (Saran ) Polyolefins Polyethylene Good Good Resistant Resistant except NH4OH Resistant Resistant Unstable Resistant... 

Plastics. Plastics denotes the matrix thermoplastic or thermoset materials in which additives are used to improve the performance of the total system. There are many different types of plastics that use large volumes of chemical additives including (in order of total additive consumption) polyvinyl chloride (PVC), the polyolefins [polyethylene (PE) and polypropylene (PP)], the styrenics —[polystyrene (PS) and acrylonitrile butadiene styrene (ABS)], and engineering resins such as polycarbonate and nylon. 

PVC, fluorocarbon, pol5fpropylene, pol5fphenylene ether, phenolic, TP polyester, nylon (glass), polyolefin, polyethylene... 

Kiran, E. and Gillham, J. (1976) Pyrolysis-molecular weight chromatography A new on-line system for analysis of polymers. II. Thermal decomposition of polyolefins Polyethylene, polypropylene, polyisoprene J. Appl. Polym. Sci. 20, 2045-2068. 

Other insulation foams (water/frost) PU, PS, polyolefins [polyethylene (PE), polypropylene (PP)], PVC... 

Polyolefins, Polyethylenes, Polyisobutylenes, Poly(Methyl Methacrylates), and Poly(Styrene Sulfonates), In addition to polyurethane foams, polyethylene and polypropylene fibers can be manufactured as alternative polymeric sorbents. However, based on sorbent capacity, cost, and availability, these materials would be considered inferior to polyurethane. 

---