Copolymers and terpolymers

A number of commercial vinyl chloride copolymers are predominantly made up of VCM units with comonomer units randomly distributed in minor proportions. The suspension polymerisation process is normally used. 

Grafted copolymers obtained by VCM polymerisation and polyacrylic elastomer grafting, give high bulk density resins for products with high impact strength suitable for outdoor applications. The separate addition of acrylate impact modifiers to the PVC formulation is covered in Section 4.5.2. 

A vinyl chloride-ethylene-vinyl acetate terpolymer system gives products with superior impact strength suitable for an outdoor environment. The modifier component is a 45% vinyl acetate (EVA) copolymer with PVC grafted on it. EVA modification depends on a network structure. 

Vinyl chloride-vinyl acetate copolymers are produced containing 5-15% of vinyl acetate. These materials, having a lower glass transition temperature, can be processed at considerably lower temperatures and are particularly suited for thermoforming. Finished products are highly transparent. 

A block copolymer system of PVC and polyethylene -co-propylene) (EPM) resulting from ultrasonic irradiation, has been investigated (248). 

Since the synthesis of the first chiral smectic C side chain LCP by Shibaev et al. [6], chemists over the last ten years have considerably extended that field. Now, the SmC mesophase can be exhibited by a variety of polymeric materials including homopolymers, copolymers and terpolymers, oligomers, combined polymers, and cross-linked polymers. 

This synthesis work was not only aimed at obtaining a better knowledge of the structure-properties relationships, but also at designing either polymers with reduced viscosity and improved response time, suitable for display applications, or polymers bearing in their side chains an electron donor-IT system-electron acceptor moiety for second order nonlinear optics. 

The general structure of a homopolymer is shown in Fig. 1. Most of the SmC LCPs synthesized so far are derived from polyacrylate, polymethacrylate, or polymethylsi-loxane backbones. Some polyoxyethylenes [7] as well as some poly vinylethers [8] have also been prepared. The mesogenic core structures, the tails, and the spacers generally used to obtain SmC LCPs are respectively summarized in Figs. 2-4. 

The optically active center essential for obtaining the SmC phase is generally placed at the tail of the side chain, but it can also be part of the flexible spacer. An SmC LCP, having the chiral centers located both in the spacer and in the tail, has been reported [21, 52, 53]. Another way of introducing chirality into LCPs is their mixing with chiral dopants [54]. This approach has been used by Ido et al. for getting more suitable materials (mainly in terms of response times) for display applications compared with pure SmC LCPs [24]. Finally, an example of an SmC LCP where the chirality is located in the polymer backbone instead of the side chain has been found [55, 56]. It is a polytartrate derivative, as shown in Fig. 5. 

SmC LCPs can retain their mesomorphic properties when their side chains are diluted by functional groups like dyes [57], crosslinkable moieties [20], or NLO chro- 

---

Organic peroxides are used in the polymer industry as thermal sources of free radicals. They are used primarily to initiate the polymerisation and copolymerisation of vinyl and diene monomers, eg, ethylene, vinyl chloride, styrene, acryUc acid and esters, methacrylic acid and esters, vinyl acetate, acrylonitrile, and butadiene (see Initiators). They ate also used to cute or cross-link resins, eg, unsaturated polyester—styrene blends, thermoplastics such as polyethylene, elastomers such as ethylene—propylene copolymers and terpolymers and ethylene—vinyl acetate copolymer, and mbbets such as siUcone mbbet and styrene-butadiene mbbet. 

The most effective and widely used dispersants are low molecular weight anionic polymers. Dispersion technology has advanced to the point at which polymers are designed for specific classes of foulants or for a broad spectmm of materials. Acrylate-based polymers are widely used as dispersants. They have advanced from simple homopolymers of acryflc acid to more advanced copolymers and terpolymers. The performance characteristics of the acrylate polymers are a function of their molecular weight and stmcture, along with the types of monomeric units incorporated into the polymer backbone. 

The anomalous effect of the last two rubbers in the table with their low solubility parameters is possibly explained by specific interaction of PVC with carbonyl and carboxyl groups present respectively in the ketone- and fumarate-containing rubbers to give a more than expected measure of compatibility. It is important to note that variation of the monomer ratios in the copolymers and terpolymers by causing changes in the solubility parameter and eompatibility will result in variation in their effect on impact strength. 

A number of thermosetting acrylic resins for use as surface coatings have appeared during recent years. These are generally complex copolymers and terpolymers such as a styrene-ethyl acrylate-alkoxy methyl acrylamide... 

The simultaneous polymerization and sol-gel reaction often brings complexity to the overall reaction. Moreover, it is difficult to control the molecular weight of the sample. Recently, Patel et al. [51] have synthesized the rubber grade acrylic copolymers and terpolymers-/n situ silica hybrid nanocomposites using this technique. 

Finer dispersion of silica improves the mechanical and dynamic mechanical properties of the resultant composites. Figure 3.11a and b compares the tensile properties of the acrylic copolymer and terpolymers in the uncross-hnked and cross-linked states, respectively. 

Adsorption of rubber over the nanosilica particles alters the viscoelastic responses. Analysis of dynamic mechanical properties therefore provides a direct clue of the mbber-silica interaction. Figure 3.22 shows the variation in storage modulus (log scale) and tan 8 against temperature for ACM-silica, ENR-silica, and in situ acrylic copolymer and terpolymer-silica hybrid nanocomposites. 

Fluid loss additives such as solid particles and water-thickening polymers may be added to the drilling mud to reduce fluid loss from the well bore to the formation. Insoluble and partially soluble fluid loss additives include bentonite and other clays, starch from various sources, crushed walnut hulls, lignite treated with caustic or amines, resins of various types, gilsonite, benzoic acid flakes, and carefully sized particles of calcium borate, sodium borate, and mica. Soluble fluid loss additives include carboxymethyl cellulose (CMC), low molecular weight hydroxyethyl cellulose (HEC), carboxy-methYlhydroxyethyl cellulose (CMHEC), and sodium acrylate. A large number of water-soluble vinyl copolymers and terpolymers have been described as fluid loss additives for drilling and completion fluids in the patent literature. However, relatively few appear to be used in field operations. 

Controlling fluid loss loss is particularly important in the case of the expensive high density brine completion fluids. While copolymers and terpolymers of vinyl monomers such as sodium poly(2-acrylamido-2-methylpropanesulfonate-co-N,N-dimethylacrylamide-coacrylic acid) has been used (H)), hydroxyethyl cellulose is the most commonly used fluid loss additive (11). It is difficult to get most polymers to hydrate in these brines (which may contain less than 50% wt. water). The treatment of HEC particle surfaces with aldehydes such as glyoxal can delay hydration until the HEC particles are well dispersed (12). Slurries in low viscosity oils (13) and alcohols have been used to disperse HEC particles prior to their addition to high density brines. This and the use of hot brines has been found to aid HEC dissolution. Wetting agents such as sulfosuccinate diesters have been found to result in increased permeability in cores invaded by high density brines (14). 

The isoprene units in the copolymer impart the ability to crosslink the product. Polystyrene is far too rigid to be used as an elastomer but styrene copolymers with 1,3-butadiene (SBR rubber) are quite flexible and rubbery. Polyethylene is a crystalline plastic while ethylene-propylene copolymers and terpolymers of ethylene, propylene and diene (e.g., dicyclopentadiene, hexa-1,4-diene, 2-ethylidenenorborn-5-ene) are elastomers (EPR and EPDM rubbers). Nitrile or NBR rubber is a copolymer of acrylonitrile and 1,3-butadiene. Vinylidene fluoride-chlorotrifluoroethylene and olefin-acrylic ester copolymers and 1,3-butadiene-styrene-vinyl pyridine terpolymer are examples of specialty elastomers. 

The dicyclopentadiene terpolymer can give higher states of cure with peroxides than the copolymer, although in peroxide curing of both the copolymer and terpolymer it is common practice to add a coagent, to increase the state of cure. Triaryl isocyanurate or sulphur are the most common coagents. 

Glass transition data for copolymers and terpolymers of controlled and uncontrolled composition are shown in Figures 6 and 7. The Tg s calculated using the equations 7 and 8 of Fox (12) and Woods (13) have been used with the following hompolymer Tg s methyl methacrylate, 108°C tributyltin methacrylate, 0°C 2-ethylhexyl acrylate, -50"C (14-16) are also shown. 

Polyepichlorohydrin and copolymers and terpolymers of epichlorohydrin with ethylene oxide and allyl glycidyl ether are useful elastomers [Body and Kyllinstad, 1986]. 

Copolymers and terpolymers of ethylene and propene, commonly known as EPM and EPDM polymers, respectively, are useful elastomers [Ver Strate, 1986], EPM and EPDM are acronyms for ethylene-propene monomers and ethylene-propene-diene monomers, respectively. The terpolymers contain up to about 4 mol% of a diene such as 5-ethylidene-2-norbomene, dicyclopentadiene, or 1,4-hexadiene. A wide range of products are available, containing 40-90 mol% ethylene. The diene, reacting through one of its double bonds, imparts a pendant double bond to the terpolymer for purposes of subsequent crosslinking (Sec. 9-2b). 

An appropriate formalism for Mark-Houwink-Sakurada (M-H-S) equations for copolymers and higher multispecies polymers has been developed, with specific equations for copolymers and terpolymers created by addition across single double bonds in the respective monomers. These relate intrinsic viscosity to both polymer MW and composition. Experimentally determined intrinsic viscosities were obtained for poly(styrene-acrylonitrile) in three solvents, DMF, THF, and MEK, and for poly(styrene-maleic anhydride-methyl methacrylate) in MEK as a function of MW and composition, where SEC/LALLS was used for MW characterization. Results demonstrate both the validity of the generalized equations for these systems and the limitations of the specific (numerical) expressions in particular solvents. 

In this paper a generalized approach is presented to the derivation of H-H-S equations for multispecies polymers created by addition polymerization across single double bonds in the monomers. The special cases of copolymers and terpolymers are derived. This development is combined with experimental results to evaluate the numerical parameters in the equations for poly(styrene-acrylonitrile ) (SAN) in three separate solvents and for poly(styrene-maleic anhydride-methyl methacrylate) (S/HA/MM) in a single solvent. The three solvents in the case of SAN are dimethyl formamide (DMF), tetrahydrofuran (THF), and methyl ethyl ketone (MEK) and the solvent for S/HA/HH is HER. 

We attempt here to develop a mathematical expression for the dependence of the dilute solution intrinsic viscosity of multispecies polymers on both molecular weight and polymer composition with some broad degree of generality and to particularize the result for the specific cases of copolymers and terpolymers such as SAN and S/MA/MM. The details of the derivation are specific to polymers resulting from addition polymerization across a single double bond in each monomer unit. In principle the approach may be expanded to other schemes of polymerization so long as... 

PVC, another widely used polymer for wire and cable insulation, crosslinks under irradiation in an inert atmosphere. When irradiated in air, scission predominates.To make cross-linking dominant, multifunctional monomers, such as trifunctional acrylates and methacrylates, must be added. Fluoropolymers, such as copol5miers of ethylene and tetrafluoroethylene (ETFE), or polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), are widely used in wire and cable insulations. They are relatively easy to process and have excellent chemical and thermal resistance, but tend to creep, crack, and possess low mechanical stress at temperatures near their melting points. Radiation has been found to improve their mechanical properties and crack resistance. Ethylene propylene rubber (EPR) has also been used for wire and cable insulation. When blended with thermoplastic polyefins, such as low density polyethylene (LDPE), its processibility improves significantly. The typical addition of LDPE is 10%. Ethylene propylene copolymers and terpolymers with high PE content can be cross-linked by irradiation. ... 

Natural Rubber and Synthetic Polyisoprene Polybutadiene and Its Copolymers Polyisobutylene and Its Copolymers Ethylene-Propylene Copolymers and Terpolymers Polychloroprene Silicone Elastomers Fluorocarbon Elastomers Fluorosilicone Elastomers Electron Beam Processing of Liquid Systems Grafting and Other Polymer Modifications... 

Ethylene propylene rubber (EPR) has been also used for wire and cable insulation. When blended with thermoplastic polyefins such as LDPE its processibility improves significantly. The typical addition of LDPE is 10%. Ethylene propylene copolymers and terpolymers with high PE content can be cross-linked by irradiation.34... 

The mechanism for improvement in mechanical properties of the hybrids has been explained. The effect of acrylic copolymer and terpolymer composition on the properties of in situ polymer/silica hybrid nanocomposites has been further studied by Patel et al. [145]. They have observed that terpolymer-silica hybrids demonstrate superior mechanical properties compared to the copolymer-silica hybrids. 

Polyacrylates have remained vitally important ever since and are used by virtually every service company around the world as primary components in most cooling water treatment program formulations. However, the diversity of these acrylic acid-based materials, plus the various copolymer and terpolymer derivatives they have spawned, has grown beyond all recognition during the last 40 years. 

The same authors report the formation of copolymers and terpolymers of tetramethylene urea, 7-butyrolactone, and ethylene carbonate or 1,2-propylene carbonate <2004MM6755>. 

Monomers for commercially important large-volume fluoropolymers and their basic properties are shown in Table 1.1. These can be combined to yield homopolymers, copolymers, and terpolymers. The resulting resins range from rigid resins to elastomers with unique properties not achievable by any other polymeric materials. Details about the basic chemistry and polymerization methods are included in Chapter 2, fundamental properties of the resulting products are discussed in Chapter 3, and processing and applications in Chapter 4. 

Hexafluoropropylene does not polymerize into a homopolymer easily therefore, it can be stored as a liquid. Flowever, it forms industrially useful copolymers and terpolymers with other fluorinated monomers. Oxidation of F1FP yields an intermediate for a number of perfluoroalkyl perfluorovinyl ethers.30... 

Explain why tetrahydrofuran can be concatenated into the polymer chain in copolymerisation systems with coordination catalysts. Give examples of copolymers and terpolymers, obtained by coordination polymerisation, that contain oxytetramethylene units in the main chain. 

Applications of ethylene-propylene copolymers and terpolymers include automotive (the major use area), thermoplastic olefin elastomers, single-ply roofing, viscosity index improvers for lube oils, wire and cable insulation, hose, appliance parts, and polymer modification. 

Products The process can produce a broad range of propylene-based polymers, including homopolymer PP, various families of random copolymers and terpolymers, heterophasic impact and speciality impact copolymers (up to 25% bonded ethylene), as well as high-stiffness, high-clarity copolymers. 

---