Experimental evidence is presented that during the conditions of aqueous heterophase polymerization radical generation and subsequent polymerization are induced by the interfacial energy. A comprehensive study of the emulsion polymerization of styrene at 25 °C with various types of emulsifiers and with different nonredox initiators such as potassium peroxodisulfate, 2,2′-azoisobutyronitrile, dibenzoyl peroxide, and poly(ethylene glycol)-azo-initiator reveals that the particular initiator-stabilizer combination has a strong influence on the achievable final conversion and the latex properties. The deceleration of the polymerization due to the low temperature allowed the recognition of basic differences in the behavior of monomer-and water-soluble initiators, especially at low conversions during the prenucleation period.
Soluble and processable conductive copolymers of silicone tegomers and pyrrole were developed. This was easily accomplished by the oxidative polymerization of pyrrole monomer by Ce(IV) salt in the presence of silicone tegomers with hydroxyl chain ends. The resulting copolymers were soluble in dimethylformamide. The products were characterized by Fourier transform infrared, 1 H-NMR, and four-point probe conductivity, and their surface properties were investigated with contact-angle measurements.
In this study, a small amount of vinylphosphonic acid was used to produce fire‐retardant copolymers and terpolymers from acrylonitrile and methyl acrylate. The structures of copolymer and terpolymers were elucidated by 1H‐NMR and phosphorous analysis. Thermal decomposition of vinylphosphonic acid‐containing copolymers and terpolymers started at lower temperatures than of poly(acrylonitrile‐co‐methyl acrylate). Methyl acrylate contributes to the thermal resistance of the terpolymers. Poly(acrylonitrile‐co‐methyl acrylate‐co‐vinylphosphonic acid) with a phosphorous content about 0.25% burned at a slower rate and emitted less smoke compared to poly(acrylonitrile‐co‐methyl acrylate). The burning tests showed that both copolymer and terpolymers containing vinylphosphonic acid behaved as a fire‐retardant polymer. The phosphonate and phosphonic acid groups in the copolymer and terpolymers accelerate the cyclization of nitrile groups and inhibit the fire in the gas phase. Nanofibers were successfully produced by the electrospinning method from the copolymers and terpolymers containing vinylphosphonic acid moiety.
Poly(acrylic acid) with molecular weight of 5000 was produced by using 2‐aminoethanethiol hydrochloride as chain transfer agent. Amine chain end groups of the resulting polyacrylic acid were transformed into nitrilodi(methylenephosphonic acid) by reacting formaldehyde‐phosphorous acid in the presence of hydrogen chloride. 1H NMR, 31P NMR and microanalysis were used for structural analysis.The modified polyacrylic acid had much better calcium carbonate scale inhibition effect than commercial poly(acrylic acid).
A mixture of Ce ϩ3 salt and an aminomethylene phosphonic acid, such as amino tri(methylene phosphonic acid) (ATMP), diethylene triamine penta(methylene phosphonic acid), N,N-di(methylene phosphonic acid) ethanol amine, N,N-di(methylene phosphonic acid)-N-methylamine, N-oxo-N,N,N-tri(methylene phosphonic acid), or 1-hydroxy-ethylidene-1,1-diphosphonic acid, was used for the photopolymerization of acrylonitrile, vinyl acetate, acrylic acid, and styrene in water. Molecular weights of the polymers decreased with increasing concentration of both Ce ϩ3 salt and ATMP. The effect of oxygen, light, pH, and the addition order on polymerization were also studied.
Purpose
The purpose of this paper is the production of fire retardant and smoke suppressant rigid polyurethane foam (RPUF) with lower toxicity by using several fire-retardant combinations.
Design/methodology/approach
Fire-retardant additives with cooling effect, barrier ash formation effect, gas-phase inhibition effect and smoke suppressant effect combined to produce an optimum outcome on RPUF. The additive amount and burning time correlation were studied to find out the minimum amount of fire-retardant to obtain fire-retardant polyurethane foam.
Findings
Zinc borate powder was coated with 1.5 wt % of stearic acid and hydroxy stearic acid. Polyammonium diborates (PABs) were synthesized and used as a fire-retardant and smoke suppressant for rigid PU foam. Fire-retardant rigid polyurethane foams (FR-RPUF) composites formed by using several combinations of zinc borate, aluminum trihydroxide, trischloroisopropyl phosphate (TCPP), PABs, zinc borate coated with stearic acid and hydroxy stearic acid. Produced FR-RPUF were horizontal burning grade, and burning time was in the range of 1–10 s.
Research limitations/implications
There were limitations during the mixing of fire-retardant powders with polyol due to the high viscosity of the mixture.
Practical implications
FR-RPUF foam with lower toxicity can be produced industrially with these fire-retardant combinations.
Social implications
FR-RPUF could be produced by using non-toxic additives. During a fire, these additives do not evolve toxic gases. The TCPP content of RPUF foam was reduced, and fire-retardant PU with lower toxicity was produced.
Originality/value
Coated zinc borate and the combinations of the fire-retardants were successful in producing non-toxic fire-retardant and smoke suppressant PU foam.
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