Backbone polymers polyolefins

Polymers with saturated carbon chain backbone include polyolefins, polystyrenes, halogenated polyolefins, halogenated polystyrenes, polyvinyls substituted with various groups such as -OH, -OR, -0(0)C-R, -C(0)0-R, -C(0)-R, -C5H4N, etc. In this class also are included polyacrylates, polymethacrylates, polymers with ketone groups in the backbone, as well as other polymers with saturated carbon chain backbone. The polymers with a saturated carbon chain backbone form the most important and common class of polymers. 

With respect to the other backbone polymers in UV grafting, PVC Is as expected whereas the results for the polyolefins, especially polyethylene, are surprising when compared with cellulose. The relatively high copolymerization yields with polyethylene may be attributed to the presence of trace impurities in the backbone polymer which are present during synthesis. These impurities sensitize the grafting process. 

In the present work, the application of novel additives for accelerating the radiation copolymerization of monomers to polymers will be discussed. All work will involve the simultaneous irradiation procedure with the polyolefins and styrene as model system. Extension of the process to other backbone polymers and monomers will also be considered. 

The use of n-alkane properties (with suitable equations) to estimate amorphous polyethylene properties has the advantage the ra-alkanes (unlike the polyolefins) ean be prepared pure, and accurate properties can be determined. The use of n-alkane data has the limitations, however, that some properties (e.g., boiling points) are irrelevant for polymers and some polymer properties (e.g., tensile strength) are lacking in the lower alkanes. This method treats the main backbone polymer chain as the functional group and the pendant alkyl groups or repeat units as the homolog chain for correlation purposes. 

Degradation of polyolefins such as polyethylene, polypropylene, polybutylene, and polybutadiene promoted by metals and other oxidants occurs via an oxidation and a photo-oxidative mechanism, the two being difficult to separate in environmental degradation. The general mechanism common to all these reactions is that shown in equation 9. The reactant radical may be produced by any suitable mechanism from the interaction of air or oxygen with polyolefins (42) to form peroxides, which are subsequentiy decomposed by ultraviolet radiation. These reaction intermediates abstract more hydrogen atoms from the polymer backbone, which is ultimately converted into a polymer with ketone functionahties and degraded by the Norrish mechanisms (eq. 

Most commercial polymers are substantially linear. They have a single chain of mers that forms the backbone of the molecule. Side-chains can occur and can have a major affect on physical properties. An elemental analysis of any polyolefin, (e.g., polyethylene, polypropylene, poly(l-butene), etc.) gives the same empirical formula, CH2, and it is only the nature of the side-chains that distinguishes between the polyolefins. Polypropylene has methyl side-chains on every other carbon atom along the backbone. Side-chains at random locations are called branches. Branching and other polymer structures can be deduced using analytical techniques such as NMR. 

Polymers with mesogenic groups directly attached to backbone, properties, 97,98/ Polyolefin hydroperoxides and alcohols, IR bands of nitrates and nitrites, 384/ Polyolefins... 

And finally, irrespective of the types of elements in the backbone, the properties of a linear polymer will depend on the side groups attached to that backbone. This principle underlies all polyolefin and polyvinyl macromolecular science and technology. It applies equally well to inorganic polymer systems. 

After five decades of catalyst research there is slowly emerging a family of discrete late transition metal catalysts that are capable of generating high molecular weight, linear, random copolymers of ethylene and polar comonomers such as acrylates. Further advances in the efficiency of these catalysts will likely give rise to new families of commercial polyolefins with a wealth of new performance properties imparted by the polar groups attached to the polymer backbone. 

In polysilane polymers, the polymer backbone is made up entirely of silicon atoms. Therefore these materials differ from other important inorganic polymers, the siloxanes and phosphazenes, in which the polymer chain is heteroatomic. Structurally, they are more closely related to homoatomic organic polymers such as the polyolefins. However, because the units in the main chain are all silicon atoms, the polysilanes exhibit quite unusual properties. The cumulated silicon-silicon bonds in the polymer chain allow extensive electron delocalization to take place, and this delocalization of the sigma electrons in the Si-Si bonds gives the polysilanes unique optical and electronic properties. Many of the potential technical uses, as well as the remarkable properties, of polysilanes result from this unusual mobility of the sigma electrons. 

Random ethylene copolymers with small amounts (4-10 wt-%) of 7-olefins, e.g. 1-butene, 1-hexene, 1-octene and 4-methyl- 1-pentene, are referred to as linear low-density polyethylene, which is a commercially relevant class of polyolefins. Such copolymers are prepared by essentially the same catalysts used for the synthesis of high-density polyethylene [241]. Small amounts of a-olefin units incorporated in an ethylene copolymer have the effect of producing side chains at points where the 7-olefin is inserted into the linear polyethylene backbone. Thus, the copolymerisation produces short alkyl branches, which disrupt the crystallinity of high-density polyethylene and lower the density of the polymer so that it simulates many of the properties of low-density polyethylene manufactured by high-pressure radical polymerisation of ethylene [448] (Figure 2.3). 

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