General Copolymers

This complicated triple sum can be simplified by applying the rooted tree treatment. Here the outline is confined to a binary copolymer the results may easily be generalized to copolymers with r components. 

In the binary copolymer the two molecular weights of the monomeric units are MoA and MoB, the corresponding refractive index increments vA and vB, and the overall composition (mole fractions) nA and nB. This overall composition will in general differ from the composition of individual molecules. Thus, the molecular weight MXI of the i-th isomer with polymerization degree x is given by 

Differentiation with respect to s = (sA, sB) at sA = 1 and sB = 1 yields after some rearrangements 

In a similar manner - outlined in the derivation of Eq. (C.78) for the average population of units in the n-th generation of a homopolymer - it can be shown that the number of A-monomers in the n-th generation is given by 

For Gaussian chains, the expression for the scattering function can be simplified further since then 

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A number of solid acrylic resins, all known under the commercial name of Paraloid, are used in art conservation, dissolved in organic solvents, as consolidants, coatings, or in varnish formulations these resins are generally copolymers formed by two acrylic/ methacrylic monomers [82], Paraloid B-72 is the most widely used acrylic resin in conservation, and is formed by a methyl acrylate/ethyl methacrylate (MA/EMA) copolymer with molar composition 70/30. 

In general, copolymers cross-link more readily than polyamide PA 66. Mechanical properties of polyamides are modified by irradiation, as seen by reduced tensile strength (50% loss when irradiated in air, 16% under vacuum). Aromatic polyamides retain strength better than aliphatic polyamides. ... 

Using the data in Table III, the general copolymer composition equations, and the Fineman-Ross procedure (16), the reactivity ratios were estimated at rx — 0.40 and 0.42 and r2 = 0.78 and 0.75 with mean values of 0.41 and 0.77 respectively. Values of rx = 0.406 and r2 = 0.773 were calculated by a computer program based on least squares. 

A few acrylate rubbers (such as Hycar 2121X38) are based on butyl acrylate. These materials are generally copolymers of butyl acrylate and acrylonitrile ( 10%) and may be vulcanized with amines. They have improved low-temperature flexibility compared to ethyl acrylate copolymers but swell more in aromatic oils. 

Polyacrylonitrile. A sub-group of acrylic plastics. The blow moulding, injection moulding, and fibre grade polyacrylonitriles are generally copolymers of acrylonitrile. Trade names Barex (USA), Soltan (B). Trade names of polyacrylonitrile fibres Acrilan (USA), Crumeron (H), Dralon (FRG), Orion (USA). 

Barton et al [17] have derived a general copolymer equation for the cyclocopolymerization of 1,4-dienes (Mi) and monoolefins (M2). The kinetic scheme considered is shown in Equations (l)-(9). 

Regarding the structure of compatibilisers, they are generally copolymers which are formed by the bonding of at least two different monomers. The properties of... 

Polymerization of fluorocarbon monomers proceeds by a free radical mechanism. Two types of polymerization are possible homopolymerization and heteropolymerization or copolymerization. Homopolymerization only involves one monomer while copolymerization requires more than one monomer. An example of the free radical reaction and the corresponding reaction rate is illustrated by homopolymerization in Sec. 5.2.1. Copolymerization involves two or more monomers with a significantly more complex expression of the reaction rate. Section 5.2.2 illustrates the derivation of the general copolymer equation. 

PFA polymers are fully fluorinated and melt processible. They have chemical resistance and thermal stability comparable to polytetrafluoroethylene (PTFE). Melt viscosity of PFA is over one million times lower than PTFE. Perfluoroalkoxy resins are in general copolymers of tetrafiuoroethylene with one or more of perfluoroalkyl vinyl ether comonomers. Commercial examples of the latter include perfluoromethyl vinyl ether (PMVE), perfluoroethyl vinyl ether (PEVE), and perfluoropropyl vinyl ether (PPVE). PFA resins are specified by ASTM Method D3307, which also provides procedures or references to other ASTM methods for the measurement of resin properties. Commercial PFA resins offered by major manufacturers have been listed in Tables 6.1 through 6.7. 

Most emulsion polymers used in coating appHcations are based on the general copolymer compositions outlined above. However, commercial polymers usually utilize small amounts of specialty monomers to provide added performance features desirable for specific appHcations. 

On more general copolymer models and the Brownian scaling... 

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