摘要:

AbstractOxidation and ignition of flexible polyurethane foams have been investigated by observing the effects of internal and external heating. External temperatures of some 190°C are required to induce combustion. Internal temperatures of 250 −350°C initiate a self‐propagating internal reaction which results in foam ignition when the reaction reaches the foam surface. The stability of a polyurethane foam to such heating increases with the age of the

ISSN:0007-1641    

DOI:10.1002/pi.4980080202

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe flammability of flexible poly(vinyl chloride) sheet containing barium, calcium and zinc borates, alone and in combination with antimony oxide, was measured by BS2782‐508C and ASTM D2863. A statistical comparison of these tests was made. Barium and calcium borates, with or without antimony oxide, had little or no effect on flame retardancy, but zinc had a synergistic effect with antimony oxide.The value of these inorganic borates in reducing smoke is compared using the Stanton Redcroft F.T.B. Unit, an attachment of the manufacturer's Critical Oxygen Index (C.O.I.) test. This test consists of passing the smoke from the C.O.I, test directly into a chamber where the maximum smoke density is measured using a light source and photocell assembly. Formulations containing zinc borate and antimony oxide gave the least smoke.The advantages of zinc borate in flame retardant poly(vinyl chloride) were found to be offset by inferior mechanical and electrical properties and heat stability, unless small amounts of epoxidised oil were added. The degree of hydration of the zinc borate was not critica

ISSN:0007-1641    

DOI:10.1002/pi.4980080203

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractPolyurethanes exposed to fire conditions might generate decomposition products which would be responsible for a significant part of the toxicity of the fire gases.Polyurethanes have been prepared from a commercial mixture of tolylene‐2, 4‐ and 2,6‐di‐isocyanates, pure tolylene‐2,4‐di‐isocyanate, pure tolylene‐2,6‐di‐isocyanate and purem‐phenylene di‐isocyanate. All polymers except that prepared from tolylene‐2,6‐di‐isocyanate were obtained as flexible foams. When each polyurethane was heated at 300°C in a stream of nitrogen, a sublimate was obtained. The sublimates were all apparently polymers derived from the di‐isocyanate rather than from the diol constituents of the polyurethanes. Pyrolysis of these materials at high temperatures (800–1000°C) led to similar mixtures of volatile products: at 1000°C the most abundant nitrogenous product

ISSN:0007-1641    

DOI:10.1002/pi.4980080204

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe diffusion of both Direct Blue 76 and acid orange dyes in aqueous dilute polymer solutions was studied using the capillary method. The polymer systems studied included dilute solutions of carboxymethyl cellulose, polyethylene oxide and polyacrylamide. It was found that the diffusion coefficients of the two dyestuffs in carboxymethyl cellulose solutions are higher than that in pure water, while in polyacrylamide solutions the values of the coefficients are lower than that in pure water. In case of polyethylene oxide solutions, the diffusion coefficient of Direct Blue 76 was found to be lower than that in pure water, whereas that of acid orange was found to be higher than that in pure water.The diffusion coefficients of both dyes were found to decrease with increasing polymer concentration in the case of polyethylene oxide and polyacrylamide, whereas in the case of carboxymethyl cellulose the diffusion coefficients increased with polymer concentration.With change of temperature, the diffusion coefficients of both dyes in the three polymer solutions were found to obey the Arrhenius equation. The activation energy for diffusion of the two dyes was calculated in pure water, as well as in the different polymer solutions.

ISSN:0007-1641    

DOI:10.1002/pi.4980080205

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe self‐condensation of formaldehyde in heavy water (D2O) has been studied against the more general background of the urea—formaldehyde system. Proton magnetic resonance data are reported for monomethylol urea (MMU), dimethylol urea, methylolbisurea (MBU) and solutions of formaldehyde in D2O at various concentrations over a limited temperature range. The results for formaldehyde lead to disagreement with the statistical interpretation of previous workers. The more accurate n.m.r. data presented here fit the random difunctional polycondensation model with a single parameter, within experimental, error, in contrast to the two needed by other auth

ISSN:0007-1641    

DOI:10.1002/pi.4980080206

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe synthesis of dimethyl‐2, 5‐dicyanoterephthalate from 2,5‐dibromo‐p‐xylene and its conversion to 1,3′‐benzobis (iminopyrrolenone) are reported.1,3 ‐Benzobis (N‐phenyliminopyrrolenone) was prepared by reaction of 1,3′‐benzobis (iminopyrrolenone) with aniline. The product was a bright yellow crystalline solid which was also formed when dimethyl‐2,5‐dicyanoterephthalate was condensed with aniline under suitable conditions.Poly (1,3′‐benzobis (iminopyrrolenones)) were synthesised by the condensation of 1,3′ ‐benzobis (iminopyrrolenone) with aromatic diamines and with 1,6‐diaminohexane at high temperatures in dimethyl sulphoxide. The degrees of polymerisation of the polymers obtained were low, as judged by the completeness of the condensation reaction.Thermogravimetric analyses of these polymers in air showed that they have 10% weight‐loss temperatures in the range 420 to 520°C, for the polymers prepared from aromatic diamines, and of 350°C for the polymer derived from 1,6‐diaminohexane. The insoluble, intractable nature of these polymers prec

ISSN:0007-1641    

DOI:10.1002/pi.4980080207

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980080208

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980080201

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY