Properties of copolymers

Copolymers are synthesized in order to hopefiiUy combine the properties of the components. In the case of a statistical mixture of the monomers one can expect the properties to vary in a continuous manner by changing the ratio between the two components. 

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There are a number of physical properties of copolymers that are directly related to the multicomponent character of these materials and which an... 

The dilute solution properties of copolymers are similar to those of the homopolymer. The intrinsic viscosity—molecular weight relationship for a VDC—AN copolymer (9 wt % AN) is [77] = 1.06 x 10 (83). The characteristic ratio is 8.8 for this copolymer. 

The presence of three oxyethylene units in the spacer of PTEB slows down the crystallization from the meso-phase, which is a very rapid process in the analogous polybibenzoate with an all-methylene spacer, P8MB [13]. Other effects of the presence of ether groups in the spacer are the change from a monotropic behavior in P8MB to an enantiotropic one in PTEB, as well as the reduction in the glass transition temperature. This rather interesting behavior led us to perform a detailed study of the dynamic mechanical properties of copolymers of these two poly bibenzoates [41]. 

Firstly, some of the important characteristics of the performance properties of copolymers can be expressed through the fractions of these sequences. So, for example, dealing with copolymers they normally make extensive use of semiempiri-cal relationships relating the glass transition temperature, T , with the fractions of dyads in macromolecules [7]. The simplest of such relationships reads ... 

Effects of Variation of Composition and Block Sequence on Properties of Copolymers Containing Semicrystalline Block(s)... 

An early study of the influence of composition heterogeneity on the physical properties of copolymers was undertaken by Nielson (4), but to the knowledge of the authors, there have been no similar Investigations involving tin-based polymers. In this work a range of different acrylic co- and terpolymers has been prepared and the effects of composition and composition distribution on the physical and performance-related properties of the polymers in their native state and In paints have been examined. 

Tphis paper is concerned with the effect of ionizing radiation on the physical and mechanical properties of copolymers of ethylene with alkyl acrylates, such as ethyl acrylate, butyl acrylate, and 2-ethvlhexyl acrylate (J, 2, 3). These polymers are made by the free radical copolymerization of ethylene under high pressure with alkyl esters of acrylic acid (9). They are more flexible than polyethylene and because of the polar nature of the comonomer, they are more compatible with fillers and with other polymers than is polyethylene. 

N 034 Helix-Coil Stability Constants for the Naturally Occurring Amino Acids In Water. I. Properties of Copolymers and Approximate Theories ... 

In summary, our studies have show n that graft copolymers of PVN with PEO form homogeneous, rubbery materials. The properties of copolymers having low PEO content remain to be investigated to evaluate the use of PEO as an internal plasticizer. Also, the effect of the size of side chains will have to be considered. 

Copolymerization of two mesogenic monomers is, at the present time, the only pathway to obtain polymers with cholesteric mesophase (see Part 4.4). On the other hand, only by copolymerizing smectogenic and nematogenic monomers and investigating the properties of copolymers in a broad interval of compositions, is it possible to establish the principles of formation of each type of mesophase. We demonstrate... 

Free-Radical Initiation. The effects of the method of free-radical initiation of the copolymerization reaction of acrylonitrile with fibrous cellulose on the properties of copolymer fabrics are shown in Table IV (31). At the same level of polymer add-on (25-27%), the molecular weight of... 

The effects of type of vinyl monomer on the properties of copolymer fabrics are shown in Table VII. Two different fabric constructions, print cloth and twill, were used. After the copolymer fabrics were prepared, they were given the usual treatment with dimethyloldihydroxyethylene urea to crosslink the cellulose. The wash-wear appearance ratings, flat abrasion resistances, and, in most cases, wrinkle-recovery angles of copolymer twill fabrics were improved over fabric controls. For copolymer... 

Table II. The measured electro-optic coefficients and physical properties of copolymers of MAI and MMA...

The properties of copolymers primarily depend upon their chemical composition but also on the microstructure of the polymer chains. However, the chemical composition of copolymers can often depend on their molecular weight fractions [1,8-10],... 

Copolymers have been studied extensively for several decades, partly because of their industrial and biological importance, and partly because of their interesting and sometimes perplexing properties. Many physical and mechanical properties of copolymers, which comprise two or more covalently bonded sequences of chemically distinct monomer species, depend on both the comonomer composition and the arrangement of these comonomers in the polymer chain. There may be significant differences, for example, between two polymer systems with the same chemical composition, but one of which has the comonomers randomly distributed in the chain while the other has long blocks of each monomer type. 

Following this line, Zheligovskaya et al. [55] compared the adsorption properties of copolymers with special adsorption-tuned primary structures (adsorption-tuned copolymers, ATCs) with those of truly random copoly-... 

Finally, nothing at all can be stated or predicted at present concerning the stereochemical configuration of the monomer units in copolymers of any type, even the random or alternating types to which the copolymerization equations apply and whose structure might therefore be thought to be well understood in other respects. It is true that from the practical viewpoint such information is of less interest than for homopolymers, because it appears less likely that the properties of copolymers will be profoundly affected by variations in the stereochemistry of the monomer units. Nevertheless, some effect on both physical and chemical properties is certainly to be expected, and in any case the question is of theoretical interest. 

Heal resistance is regarded to be one of the well-studied properties of copolymers. Many different empirical correlations are known [314-316] between glass transition temperature Tg and fractions P(U2) = P(MjMj) of the diads (M Mj) in macromolecules. We have chosen the simplest form of such a dependence ... 

The properties of copolymers are different from those of the corresponding monomers. 

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