polyolefins


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polyolefins

(pŏl'ēōl`əfən), group of plasticsplastic,
any organic material with the ability to flow into a desired shape when heat and pressure are applied to it and to retain the shape when they are withdrawn. Composition and Types of Plastic
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 that are polymerspolymer
, chemical compound with high molecular weight consisting of a number of structural units linked together by covalent bonds (see chemical bond). The simple molecules that may become structural units are themselves called monomers; two monomers combine to form a dimer,
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 of various alkenesalkene
, any of a group of aliphatic hydrocarbons whose molecules contain one or more carbon-carbon double bonds (see chemical bond). Alkenes with only one double bond have the general formula CnH2n.
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, or olefins. The most important are polyethylenepolyethylene
, widely used plastic. It is a polymer of ethylene, CH2=CH2, having the formula (-CH2-CH2-)n, and is produced at high pressures and temperatures in the presence of any one of several catalysts, depending
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 and polypropylenepolypropylene
, plastic noted for its light weight, being less dense than water; it is a polymer of propylene. It resists moisture, oils, and solvents. Since its melting point is 121°C; (250°F;), it is used in the manufacture of objects that are sterilized in the course of
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.
References in periodicals archive ?
Flame-retardant concentrates in PS, ABS, and polyolefin bases supplied for varying letdown ratios.
Special sessions will focus on polyolefin characterization, surfaces and interfaces, miniaturization and high-throughput analysis, on-line process control, as well as other areas of polymer analysis.
Silicone and non-silicone products offered for polyolefins, styrenics and nylon parts.
* The impact of metallocene-catalyst technology on the polyolefins industry, including EP elastomers; and
Total demand for polyolefin foams in the three main markets grew by 4.8% in 1997, according to a new study by Chemical Market Resources of Houston, TX.
Hostavin N30 FDA-approved oligomerle HALS provides enhanced long-term thermo-oxidative stability to polyolefins allowing for a reduction in primary antioxidant needs, which can translate into better overall initial in PE applications.
Aimed at polyolefins, its lower volatility gave it an edge over Tinuvin 770 where higher processing temperatures were required, and it had better moisture resistance for use in humid environments.
As mentioned above, metallocene catalysts were initially developed, explored and commercialized for the production of semicrystalline polyolefins materials (ref.
The proposed company will be owned by Montell and Japan Polyolefins (the new polyolefins company created by the merger of the polyolefins businesses of SDK and Nippon Petrochemicals).
"The goal is to take polyolefins and make them softer or stiffer as alternatives to rigid and plasticized PVC and cellulose acetate." But he cautions that thick MDO film still isn't a large market.
Balaji Singh, president of CMR, says, "Three characteristics of the SB copolymers make them a top priority for replacement by the new generation elastomeric polyolefins: