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Polyethylene absorbs almost no water; the gas and water vapour permeability (only polar gases) is lower than for most plastics. Oxygen, carbon dioxide and flavorings, on the other hand, can pass it easily. Polyethylene burns slowly with a blue flame having a yellow tip and gives off an odour of paraffin (similar to candle flame). The material ...
A monomer is dispersed or emulsified in a solution of surfactant and water, forming relatively large droplets in water. Excess surfactant creates micelles in the water. Small amounts of monomer diffuse through the water to the micelle. A water-soluble initiator is introduced into the water phase where it reacts with monomer in the micelles.
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula C 2 H 4 or H 2 C=CH 2.It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. [7] It is the simplest alkene (a hydrocarbon with carbon–carbon double bonds).
Examples include group transfer polymerization (GTP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation chain transfer (RAFT). [1] Graft copolymers are a popular type to synthesize because their structure is a backbone with branches. The composition of the branches can be changed to achieve different properties. [2]
The degradation of polyethylene occurs by random scission—a random breakage of the bonds that hold the atoms of the polymer together. When heated above 450 °C, polyethylene degrades to form a mixture of hydrocarbons. In the case of chain-end scission, monomers are released and this process is referred to as unzipping or depolymerization ...
Epoxide monomers may be cross linked with themselves, or with the addition of a co-reactant, to form epoxy; BPA is the monomer precursor for polycarbonate; Terephthalic acid is a comonomer that, with ethylene glycol, forms polyethylene terephthalate. Dimethylsilicon dichloride is a monomer that, upon hydrolysis, gives polydimethylsiloxane.
For example, polyester chains grow by reaction of alcohol and carboxylic acid groups to form ester links with loss of water. However, there are exceptions; for example polyurethanes are step-growth polymers formed from isocyanate and alcohol bifunctional monomers) without loss of water or other volatile molecules, and are classified as addition ...
The newly formed nucleophile will then attack the atom X in another monomer molecule, and the sequence would repeat until the polymer is formed. [20] Anionic ring-opening polymerizations (AROP) involve nucleophilic reagents as initiators. Monomers with a three-member ring structure - such as epoxides, aziridines, and episulfides - undergo ...