Styrene copolymer dispersions

The inisurfs can be used in emulsion polymerization without addition of surfactants to obtain, for example, butyl acrylate-styrene-copolymer dispersions with a solid content of about 35%. 

Styrene Copolymer Dispersions. The and hardness of polystyrene can be adjusted over a wide temperature range by copolymerization of styrene with soft monomers such as butadiene and acrylate esters. Styrene-butadiene (SB) dispersions are quantitatively the most important. With a styrene-butadiene weight ratio of 85 15 the is ca. 80 C, at a ratio of 45 55 the T, is ca. — 25 C. On account of the cross-linking capability of butadiene, SB copolymers are not thermoplastics, but elastomers. Elasticity can be modified by controlling the molecular mass and degree of cross-linking. 

Table 13.1 Properties of hardened Portland cement pastes modified with a butadiene-styrene copolymer dispersion.

PAINTS BASED ON ACRYLIC DISPERSIONS. I. COMPARATIVE STUDIES OF PURE ACRYLATE/STYRENE COPOLYMER DISPERSIONS... 

A waterborne system for container coatings was developed based on a graft copolymerization of an advanced epoxy resin and an acryHc (52). The acryhc-vinyl monomers are grafted onto preformed epoxy resins in the presence of a free-radical initiator grafting occurs mainly at the methylene group of the aHphatic backbone on the epoxy resin. The polymeric product is a mixture of methacrylic acid—styrene copolymer, soHd epoxy resin, and graft copolymer of the unsaturated monomers onto the epoxy resin backbone. It is dispersible in water upon neutralization with an amine before cure with an amino—formaldehyde resin. 

Co-continuous polymer blends of 50/50 polyamide6/acrylonitrile-butadiene-styrene copolymer (PA6/ABS) involving multiwall carbon nanotubes (MWNTs) were prepared by melt mixing technique in order to develop conducting composites utilizing the concept of double-percolation. To control the dispersion and to selectively restrict MWNTs in the PA6 phase of the blends, MWNTs were pre-treated with two modifiers which differ in their molecular length scales and... 

Figure 7. Charge levels of polymer-carbon black blends of varying dispersion levels as a function of applied electrode potential. Key O, styrene copolymer , poor dispersion and A, good dispersion.

In a similar way, Wood and Cooper [268] used isopropoxyethanol as a transfer agent and the telomers were then functionalized with methacry-loyl chloride however, only 28% of the telomers were functionalized with methacryloyl chloride. Macromonomers were then copolymerized with styrene in dispersion copolymerization, in the presence of 1,1,2,2-tetrafluoroethylene. Such copolymers have been used as dispersing agents for the styrene polymerization in supercritical CO2. 

Revacryl. [Harlow Chem. Co. Ltd.] Acrylic, styrene/acrylic and ester copolymer dispersions. 

Several blends comprising PC and diverse styrenics, viz., ABS, SAN, SB, SBS, MBS, etc., are known (see Table 1.15). Similarly as for PVC blends (see Table 1.16) the strong interactions between AN and carbonyl groups of PC (in PVC it is the tertiary carbon) are responsible for the good performance. An interesting variation of the compatibilization procedure involved dispersing PC in water with vinyl monomer(s) that subsequently were polymerized. The in situ formed graft copolymer acted as a compatibilizer [Kanai et al., 1978 Kakizaki et al., 1979]. In 1974, polyphenylenesulfide, PPS, was blended with either PS or a styrene-copolymer [Miyanishi, 1976]. 

Studies have been made of PEST/PO/styrene copolymer blend compatibilization in which a copolymer may be formed between polyester alcohol end-groups and pendent anhydride functionality on a styrene copolymer (Table 5.27). Because the alcohol-anhydride reaction is reversible (with the equilibrium lying on the side of unreacted anhydride), only a relatively small amount of copolymer may be formed. In consequence, the dispersed phase polymer may not be well stabilized against coalescence upon further thermal treatment [Sun et al., 1996]. Alternatively, at least some copolymer may be formed by a degradative mechanism through transesterification between PEST main-chain linkages and a low concentration of pendent acid groups in anhydride-functionalized styrene copolymer (see Section 5.7.12.5). 

The crosslinking of finear polystyrene as well as styrene—DVB copolymers dispersed in excess aqueous solutions of Lewis acids is accompanied by a certain loss, due to a noticeable solubifity of both EDC and the cross-linking agents MCDE or DMM, in the catalytic mixture. The unspecified change in the concentration of the main reaction partners, particularly at an elevated temperature, makes it more difficult to correctly evaluate the relationships between the conditions of synthesis and the properties of the resulting hypercrosslinked products. Still, the use of very inexpensive aqueous catalytic solutions for the preparation of beaded hypercrossfinked materials from industrially available linear polystyrene may be of practical significance. 

Block and graft copolymers (incompatible copolymers) — For block or graft copolymers in which the component monomers are incompatible, phase separation will occur. Depending on a number of factors — for example, the method of preparation — one phase will be dispersed in a continuous matrix of the other. In this case, two separate glass transition values will be observed, each corresponding to the Tg of the homopolymer. Figure 4.6 shows this behavior for polyblends of polystyrene (100) and 30/70 butadiene-styrene copolymer (0). 

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