Polymethacrylates unsaturation

In polystyrene, polymethacrylate, unsaturated polyester resins, or similar media, P.R.31 affords highly transparent colorations of medium red shades, which are used as automobile tail lights and for other signalling purposes. Its heat stability in... 

Isophorone [14.268], [14.269] is an unsaturated cyclic ketone. It consists of a-isophorone [78-59-1] (3,5,5-trimethyl-2-cyclohexen-l-one), which contains about 1-3% of the isomer P-isophorone [471-01-2] (3,5,5-trimethyl-3-cyclohexen-l-one). Isophorone is a stable, water-white liquid with a mild odor that is miscible in all proportions with organic solvents. It dissolves many natural and synthetic resins and polymers, such as poly(vinyl chloride) and vinyl chloride copolymers, poly(vinyI acetate), polyacrylates, polymethacrylates, polystyrene, chlorinated rubber, alkyd resins, saturated and unsaturated polyesters, epoxy resins, cellulose nitrate, cellulose ethers and esters, damar resin (dewaxed), kauri, waxes, fats, oils, phenol-, melamine-, and urea-formaldehyde resins, as well as plant protection agents. However, isophorone does not dissolve polyethylene, polypropylene, polyamides. 

Polymethacrylates degrade primarily by a free radical depolymerisation. When a free radical is produced in the backbone of PMMA, for example, the molecule undergoes scission to produce an unsaturated small molecule (ethyl methacrylate) and another terminal free radical. This radical will also cleave to form ethyl methacrylate and propagate the free radical. The net effect is often referred to as unzipping the polymer ... 

The synthesis and characterization of a photocrosslinkable liquid-crystal polymethacrylate with both biphenyl unit as a mesogen and styryl-2-pyridine unit as a photosensitive center in the same side-chain was described. Unsaturated polyamide-imides are light sensitive and can be crosslinked by UV radiation. The polymers consist of polyamide backbones and... 

By certain physical factors like thermal, ultraviolet irradiation, high pressure and other chemical parameters like organic solvents the helical pol5mers are easily denaturalized. A variety of helical polymers are synthesized, which include polyisocyanates, polyisocyanides, polychloral, polymethacrylates, polysilanes, polythiophenes, poly (p-phenylene)s, poly(l-methylpropargyl-ester)s, poly(phenylacetylene)s and poly (-unsaturated ketone) [18-24] (Fig. 1). Other polymers are whose optical activity is main chain or side chain chirality dependent e.g. amino-acid-based polymers are nontoxic, biocompatible and biodegradable. 

The early workers in the field of lubricants observed that small amoimts of rubber dissolved in a mineral oil raised the VI substantially. However, high unsaturation in the polymer led to oxidation and sludge formation. Otto et al. [3] discovered that this could be overcome through the use of a synthetic polymer prepared from the light ends of the gasoline. Similar observations were later made for polymethacrylates by Rohm and Haas Co. [4,5] and for polyisobutylenes by Farbenindustrie AG [6,7]. Because these materials were initially used mainly to increase the VI, they became known as the viscosity index improvers. 

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