Other comonomers

Because of the capacity to tailor select polymer properties by varying the ratio of two or more components, copolymers have found significant commercial appHcation in several product areas. In fiber-spinning, ie, with copolymers such as nylon-6 in nylon-6,6 or the reverse, where the second component is present in low (<10%) concentration, as well as in other comonomers with nylon-6,6 or nylon-6, the copolymers are often used to control the effect of sphemUtes by decreasing their number and probably their size and the rate of crystallization (190). At higher ratios, the semicrystalline polyamides become optically clear, amorphous polymers which find appHcations in packaging and barrier resins markets (191). 

A variety of trichloroethylene copolymers have been reported, none with apparent commercial significance. The alternating copolymer with vinyl acetate has been patented as an adhesive (11) and as a flame retardant (12,13). Copolymerization with 1,3-butadiene and its homologues has been reported (14—16). Other comonomers include acrylonitrile (17), isobutyl vinyl ether (18), maleic anhydride (19), and styrene (20). 

Copolymers. Copolymers have also been studied (16-18). While one comonomer contains 1-2 quaternary nitrogen in a flexible pendant chain, the other comonomer was nonionic. Copolymers of the methyl chloride salt of dimethylaminoethyl methacrylate (one quaternary nitrogen atom) and dimethylaminoethyl methacrylate (DMAEMA) and of MDTHD (2 quaternary nitrogen atoms) and DMAEMA, N,N-dimethylacryl-amide (NNDMAm) or dimethylaminopropyl methacrylate (DMAPMA) have been studied and the results summarized in Table VI. 

Fig. 15 Cooling curves of crystallinity (solid line) and demixing parameter of comonomers (dashed line). The latter is defined as the mean fraction of neighboring sites occupied by other comonomers around each comonomer. The cooling program is a stepwise increase of Ep/(k T) from zero with a step length of 0.002 and a step period of 300 Monte Carlo cycles, a The slightly alternating copolymer with a comonomer mole fraction 0.36 b the heterogeneous copolymer with a comonomer mole fraction of 0.36 [52]...

Addition of a core molecule, or any other comonomers (chain extending AB, terminating A or B). 

Although the scope of this review mainly covers CHDM-based polyesters modified with isophthalic acid or ethylene glycol (i.e. PCTA or PCTG, and PETG, respectively), many other copolyesters with interesting properties have been prepared with a variety of other comonomers. 

The modification of PET with naphthalene-2,6-dicarboxylic acid and other additional comonomers is a common measure in bottle manufacturing. Copolyesters based on this compound show excellent barrier properties. Such materials can be produced by addition of the desired amount of comonomer during polymer processing or by blending PET with poly(ethylene naphthalate) (PEN). Additionally, PEN can also be modified by other comonomers such as isophthalic acid (IPA) to improve the flow properties and reduce the melting point. The high price of naphthalene dicarboxylic acid is the reason for its limited application. The overall cost may be reduced by using TPA or IPA as comonomers. 

Figure 4.8 ((a), (b), (c), and (d)) displays, in a simplified manner, the alteration of the basic properties of homopolymer (H-PP) when modified with other comonomers (co-PP), with elastomer (impact) or with an inorganic filler mineral, talc, short or long glass fibres (SGF or LGF). 

Phenolic resins are based on phenol and some other comonomer like formaldehyde. Phenolics are widely used in areas of tough duty, and where they don t have to look pretty, such as switchgear, handles, and plywood glue. 

Penultimate effects have been observed for many comonomer pairs. Among these are the radical copolymerizations of styrene-fumaronitrile, styrene-diethyl fumarate, ethyl methacrylate-styrene, methyl methacrylate l-vinylpyridine, methyl acrylate-1,3-butadiene, methyl methacrylate-methyl acrylate, styrene-dimethyl itaconate, hexafluoroisobutylene-vinyl acetate, 2,4-dicyano-l-butene-isoprene, and other comonomer pairs [Barb, 1953 Brown and Fujimori, 1987 Buback et al., 2001 Burke et al., 1994a,b, 1995 Cowie et al., 1990 Davis et al., 1990 Fordyce and Ham, 1951 Fukuda et al., 2002 Guyot and Guillot, 1967 Hecht and Ojha, 1969 Hill et al., 1982, 1985 Ma et al., 2001 Motoc et al., 1978 Natansohn et al., 1978 Prementine and Tirrell, 1987 Rounsefell and Pittman, 1979 Van Der Meer et al., 1979 Wu et al., 1990 Yee et al., 2001 Zetterlund et al., 2002]. Although ionic copolymerizations have not been as extensively studied, penultimate effects have been found in some cases. Thus in the anionic polymerization of styrene t-vinylpyri-dine, 4-vinylpyridine adds faster to chains ending in 4-vinylpyridine if the penultimate unit is styrene [Lee et al., 1963]. 

Fluorocarbon elastomers represent the largest group of fluoroelastomers. They have carbon-to-carbon linkages in the polymer backbone and a varied amount of fluorine in the molecule. In general, they may consist of several types of monomers poly-vinylidene fluoride (VDF), hexafluoropropylene (HFP), trifluorochloroethylene (CTFE), polytetrafluoroethylene (TFE), perfluoromethylvinyl ether (PMVE), ethylene or propylene.212 Other types may contain other comonomers, e.g., 1,2,3,3,3-pentafluropropylene instead of HFP.213 Fluorocarbon elastomers exhibit good chemical and thermal stability and good resistance to oxidation. 

The essential and only monomer for UHMWPE per definition is ethene, also addressed as ethylene. However, this should not taken too seriously. In special cases, some other comonomers are used. 

Many combinations of diacids—diamines and amino acids are recognized as isomorphic pairs (184), for example, adipic acid and terephthalic acid or 6-aminohexanoic acid and 4-aminocyclohexylacetic acid. In the type AABB copolymers the effect is dependent on the structure of the other comonomer forming the polyamide that is, adipic and terephthalic acids form an isomorphic pair with any of the linear, aliphatic C-6—C-12 diamines but not with -xylylenediamine (185). It is also possible to form nonrandom combinations of two polymers, eg, physical mixtures or blends (Fig. 10), block copolymers, and strictly alternating (187—188) or sequentially ordered copolymers (189), which show a variation in properties with composition differing from those of the random copolymer. Such combinations require care in their preparation and processing to maintain their nonrandom structure, because transamidation introduces significant randomization in a short time above the melting point. 

The other approach [27] was to interrupt the length of a comonomer block by inserting one unit of the other comonomer. The results for the series B T and BTy are shown in Figs. 30 and 31, respectively. 

A variety of copolymers have been synthesized by the direct copolymerization of S8 with other comonomers.56 For example, S8 undergoes an equilibrium copolymerization with Se8, as shown in reaction (8) ... 

A method for calculating apparent reactivity ratios based on run number theory has been applied to "starved-feed" styrene/ ethyl acrylate systems. The reactivity ratios found are in agreement with those determined from solution polymerization data. The further confirmation of the observed agreement between reactivity ratios determined at low conversions and those determined by run number theory in "starved-feed" high conversion copolymerization requires the analysis of other comonomer pairs. 

Copolymers are ubiquitous and important because they allow monomers to be combined in such a way so as to provide useful and sometimes unique properties. For example, linear polyethylene (PE) and isotactic polypropylene (i-PP) are both semi-crystalline plastics, but copolymers of ethylene and propylene (EPR) (usually with other comonomers) are rubbers at room temperature (depending on composition). The homopolymers are shown in the top two figures in Figure 6-2, and if you don t know which one s which by now you should collapse in deepest humiliation. A section of an EPR copolymer chain is shown at the bottom. 

Scheme 2, The modification of acrylated epoxidized soybean oil (AESO) shown using cyclohexane dicarboxylic anhydrade or maleic anhydride. These AESOs were cured with styrene or other comonomers (20).

They also rednce monomer recovery as well as recovery of other comonomers during pyrolysis becanse of the distnrbance of the step-by-step radical degradation process [29]. 

The other comonomers for PTS given in Table 5 form mixed crystals only in a limited concentration range. In contrast to PBS the chloro and bromo derivatives PCS and PBS form completely unreactive triclinic structures (cf. Table 1). However, by crystallization of these monomers at very high supersaturations crystals of metastable reactive modifications are obtained which have been shown to be isomorphous to PTS Owing to the crystallization conditions these crystals are unfortunately not suited for detailed structural investigations. The metastable phases melt up to 50 degrees below the stable modifications which spontaneously recrystallize from the melt. 

A weak bond, comparable to that in VBr, could in principle be introduced by other comonomers, such as styrene or a-methylstyrene (270 and 253 kJ/mol respectively, cf Table 2). However, these weak bonds are located within the main chain. Moreover, these monomers have a large molar volume, hence a large negative effect on the molecular orientation. Thus, also from this point of view, VBr appears unique. 

Substituted styrenes are also included in a number of copolymers. Frequently, these copolymers use styrene or divinylbenzene as the other comonomer. Some copolymers of substituted styrenes were already discussed in Section 6.2 (see Figures 6.2.5 through... 

The pyrolysate of polyacrylic-/nfer-nef-polysiloxane copolymer contains as main fragment molecules pyrolysis products similar to those of poly(butyl acrylate) and of poly(dimethylsiloxane (see Figure 6.7.8. and Section 16.1). The identification of fragments that would indicate sequences of other comonomers or any molecular connections between the two types of comonomer units was not possible. Other copolymers with acrylic acid as comonomer were studied using analytical pyrolysis. Among these are copolymers with special properties such as the copolymer with the formula shown below ... 

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