SMA resin

Smallpox vaccine Smalt Smaltite SMA resins SMART Smart catalysts Smart gels Smart hydrogels Smart material Smart materials... 

Koppers produced SMA moulding powders under the tradename Dylark . Arco has since acquired this business and continues to produce these SMA resins today under the Dylark tradename. Another styrene copolymer with better heat resistance than regular polystyrene is the copolymer of styrene and fumaronitrile which was reported in 1948 [27]. Both of these styrene copolymers are based on nonpolymerizable monomers - that is, fumaronitrile, like its corresponding anhydride (maleic anhydride), does not form homopolymers but readily copolymerizes with styrene at levels of up to 40%. Monsanto attempted to commercialize the styrene-fumaronitrile copolymer under the tradename Cerex , but residual fumaronitrile was a powerful vesicant (an irritant which causes blisters) and the project was shelved [28]. 

Dow and Monsanto, among others, have investigated the manufacture of SMA resins both with and without rubber modification. Moore at Dow Chemical Company described a method of producing SMA copolymers via a recirculated coil reactor [74]. 

A commercial blend of SMA and polycarbonate (Arloy , ARCO) was offered for some time, but recently it was discontinued. The polarity of SMA copolymer may account for the good degree of compatibility between the two resins. The blend contained the polybutadiene rubber normally used in SMA resins for impact strength. It exhibited good low temperamre impact strength (Table 15.8) and in many properties was similar to ABS/PC blend. 

Some imidized derivatives of SMA resins, containing N-phenyl maleimide units in place of maleic anhydride comonomer units have been offered commercially (Denki Kagaku, Japan) as blend components to modify the heat distortion temperature of styrenics (HIPS and ABS). Blends of such resins with ABS have been commercialized in Japan (Malecca , Denki Kagaku). 

Figure 2,92 Tensile stress vs. strain for SABIC Innovative Plastics Prevex IP-16 SMA resin.

Figure 2.94 Flexural modulus vs. temperature for Nova Chemicals Dylark SMA resins.

Figure 2.96 Tensile strength vs. temperature for Bayer Cadon SMA resin.

Figure 2.97 Tensile strength at yield vs. temperature for INEOS Lustran 2316 16% glass fiber reinforced SMA resin.

Commercial SMA resins (Xiran , Polyscope Polymers) are amorphous, random copolymers of styrene and maleic anhydride (8-30 %) that exhibit higher glass transition temperatures (20-60 °C higher) and higher heat distortion temperatures than polystyrene. The SMA resins were originally commercialized under the trade name of Dylark by ARCO and by Nova chemicals but later on discontinued. 

Table 19.11 Properties of commercial SMA/elastomer blends (impact modified SMA resins) ...

The composition and quantity of styrene-maleic anhydride (SMA) copolymer resins were varied in emulsion copolymerisation of methyl methacrylate and n-butyl acrylate conducted by both batch and semicontinuous processes. The resulting particle sizes and levels of coagulum were measured to determine the optimum conditions for incorporation of the SMA resins into the resulting latexes. A semicontinuous process, in which no buffer was included and the SMA was added in a second stage comonomer emulsion, was found to produce coagulum-free latexes. 13 refs. 

Styrene-co-MA resins were first introduced in the 1960s by Sinclair Petrochemicals and called SMA resins. There are two commercial producers of SMA-type copolymers, Monsanto and ARCO Chemical. ARCO s SMA resin series have styrene to MA ratios of 1 1, 2 1, and 3 1, with molecular... 

Monsanto also markets a product called Stymer S , which is the sodium salt of a styrene-MA resin. The free-flowing, fine powder picks up moisture readily and is very soluble in water, exhibiting a pH of 7.5-8.5. This product has also been called at various places Sodium Stymer, Vinylite SYHM, Polyco 328, Styromol, and Polvimal resins. SMA resins are easily converted to Stymer... 

The molecular weight of SMA resins is reported the following Mark-Houwink relationship ... 

A dual-calibration method for the determination of molecular weights and molecular weight distribution of SMA resins, using gel permeation chromatography (GPC), was recently disclosed.A linear relationship of intrinsic viscosity [r/] and weight average molecular weight (Mw) for unfractionated copolymer in tetrahydrofuran at 25°C can be expressed as follows ... 

SMA resins swell and eliminate carbon dioxide when heated at 200 C. The resultant soft, brown-colored resins are soluble in acetone, as well as hydrocarbons, to which it imparts a brilliant white fluorescence under ultraviolet light. Pyrolyzed polymer also dissolves in aqueous potassium hydroxide to produce a fluorescent solution.Sequence analysis and microstructure of SMA-type resins can be studied by pyrolysis/gas chromatography (PGC). Styrene yields are generally extremely low by the PGC technique. In a truly alternating copolymer it might be expected to be zero. For a copolymer showing 51.5 wt. % styrene, the styrene yield was 3.6%. 

SMA resins may be chemically modified by a host of other reactions, such as nitration, reduction, chloromethylation, " sulfon-ation, " " grafting with intermediates such as E-caprolactam, " and treatment with alkyl tin compounds. The latter organometallic copolymers exhibit... 

In the same manner as the SMA resins, ethylene-co-MA polymers may be dissolved and heated in refluxing alcohols to form clear solutions of the... 

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