Molecular weight strength

After the free radical initiators are generated in the adhesive, by mixing the redox couple, ultraviolet light, heat, or other means, the adhesive remains liquid for some period of time until the gel point is reached. Then the molecular weight, strength, and toughness of the adhesive build rapidly. 

The polymeric products can be made to vary widely in physical properties through controlled variation in the ratios of monomers employed in thek preparation, cross-linking, and control of molecular weight. They share common quaHties of high resistance to chemical and environmental attack, excellent clarity, and attractive strength properties (see Acrylic ester polymers). In addition to acryHc acid itself, methyl, ethyl, butyl, isobutyl, and 2-ethylhexyl acrylates are manufactured on a large scale and are available in better than 98—99% purity (4). They usually contain 10—200 ppm of hydroquinone monomethyl ether as polymerization inhibitor. 

Engineering problems involved in the production of TEE seem simple compared with those associated with polymeriza tion and processing of PTEE resins. The monomer must be polymerized to an extremely high molecular weight in order to achieve the desired properties. The low molecular weight polymer does not have the strength needed in end use appHcations. 

Automotive and architectural laminates of PVB develop maximum impact strength near 20°C, as shown in Figure 2. This balance is obtained by the plasticizer-to-resin ratio and the molecular weight of the resins. It has been adjusted to this optimum temperature based on environmental conditions and automobile population at various ambient temperatures. The frequency and severity of vehicle occupant injuries vs temperature ranges at the accident location have been studied (5), and the results confirm the selection of the maximum performance temperature and decreasing penetration resistance at temperature extremes. 

Some substances are odorous, others are not. Humans can smell at a distance if one smells the roses in a garden, it is not ordinarUy considered that part of the rose is in contact with the nose. Substances of different chemical constitution may have similar odors. Substances of similar constitution usuaUy have similar odors, eg, in a homologous series nevertheless, even stereoisomers may have different odors. Substances of high molecular weight are usuaUy inodorous and often nonvolatile and insoluble. The quaUty as weU as the strength of odor may change on dUution. 

The tailoring of PE properties in commercial processes is achieved mostiy by controlling the density, molecular weight, MWD, or by cross-linking. Successful control of all reaction parameters enables the manufacture of a large family of PE products with considerable differences in physical properties, such as the softening temperatures, stiffness, hardness, clarity, impact, and tear strength. 

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