{"title":"Understanding enzymes, 2nd edition. By T. Palmer, Ellis Horwood, Chichester, 1985. pp. 411, price £33.00, $42.90 (hardback), ISBN 0-85312-873-1; £13.75, (softback), ISBN 0-85312-874-X","authors":"J. Kennedy, C. White","doi":"10.1002/PI.4980180523","DOIUrl":"https://doi.org/10.1002/PI.4980180523","url":null,"abstract":"","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84133292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Developments in Epoxies","authors":"W. W. Wright","doi":"10.1002/PI.4980180502","DOIUrl":"https://doi.org/10.1002/PI.4980180502","url":null,"abstract":"","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79878578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of relatively severe hygrothermal aging on the sorption and also the diffusion of water at 40°C has been studied for a number of epoxy networks comprising tetraglycidyl 4,4′-diaminodiphenyl methane, and the curing agent 4,4′-diaminodiphenyl sulphone, 4,4′-diaminodiphenyl methane and 2,2′-dichloro-4,4′-diaminodiphenyl methane. Aging at high temperatures is accompanied by a pronounced increase in sorptive capacity at 40°C consistent with a significant expansion of the network. Dry annealing of the aged network at sub- Tg temperatures collapses the expanded structure to recover the sorptive capacity of the unaged network. Preliminary studies of the sorption-desorption kinetics for aged networks indicate that the effective diffusion coefficient is not markedly affected.
{"title":"Hygrothermal Aging Effects in Cured Epoxies","authors":"J. A. Barrie, H. Rudd, P. Sagoo, P. Johncock","doi":"10.1002/PI.4980180505","DOIUrl":"https://doi.org/10.1002/PI.4980180505","url":null,"abstract":"The effect of relatively severe hygrothermal aging on the sorption and also the diffusion of water at 40°C has been studied for a number of epoxy networks comprising tetraglycidyl 4,4′-diaminodiphenyl methane, and the curing agent 4,4′-diaminodiphenyl sulphone, 4,4′-diaminodiphenyl methane and 2,2′-dichloro-4,4′-diaminodiphenyl methane. Aging at high temperatures is accompanied by a pronounced increase in sorptive capacity at 40°C consistent with a significant expansion of the network. Dry annealing of the aged network at sub- Tg temperatures collapses the expanded structure to recover the sorptive capacity of the unaged network. Preliminary studies of the sorption-desorption kinetics for aged networks indicate that the effective diffusion coefficient is not markedly affected.","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73558132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carefully designed resin precursors of high purity, viz. N,N-bis-(2,3-epoxypropyl)-N',N-dimethyl-4,4′-diaminodiphenylenemethane (G2A) and N,N-bis-(2,3-epoxypropyl)-N,N-dimethyl-4,4′-diamino-diphenylenemethane (G2S) were used in combination with N,N,N',N-tetrakis-(2,3-epoxypropyl)-4,4′-diaminodiphenylene methane, TGDDM, and cured with stoichiometric amounts of 4,4′-diamino-diphenylene methane (DDM) to produce networks with a range of controlled crosslink density. The tensile moduli E of the networks in the rubbery state, at Tg+30°C, Tg+45°C and Tg+60°C, were measured using a thermal mechanical analyser. Using the statistical theory of rubber elasticity and the observed values of E, the number average molecular weights between crosslink points Mc for the cured resins were deduced. The experimental Mc values were then compared with those derived by calculations based on a probabilistic model of the network proposed by Chu and Seferis.1 The experimental Mc values were 2.5 to 5.5 times larger than the calculated ones. The differences were attributable to a consumption of only 40% of the available secondary amino hydrogen via epoxy-amine reaction. A direct relationship was established between the glass transition temperature and the crosslink density 1/Mc for the resins, and the dynamic mechanical properties were studied. The thermal stability of cured resins studied by thermo-gravimetric analysis indicated an enhancement of stability as 1/Mc was reduced. The amount of water absorbed by cured resin was directly proportional to 1/Mc.
{"title":"Structure and Properties Relationships of Epoxy Resins Part 1: Crosslink Density of Cured Resin: (II) Model Networks Properties","authors":"C. H. Lau, K. Hodd, W. W. Wright","doi":"10.1002/PI.4980180508","DOIUrl":"https://doi.org/10.1002/PI.4980180508","url":null,"abstract":"Carefully designed resin precursors of high purity, viz. N,N-bis-(2,3-epoxypropyl)-N',N-dimethyl-4,4′-diaminodiphenylenemethane (G2A) and N,N-bis-(2,3-epoxypropyl)-N,N-dimethyl-4,4′-diamino-diphenylenemethane (G2S) were used in combination with N,N,N',N-tetrakis-(2,3-epoxypropyl)-4,4′-diaminodiphenylene methane, TGDDM, and cured with stoichiometric amounts of 4,4′-diamino-diphenylene methane (DDM) to produce networks with a range of controlled crosslink density. The tensile moduli E of the networks in the rubbery state, at Tg+30°C, Tg+45°C and Tg+60°C, were measured using a thermal mechanical analyser. Using the statistical theory of rubber elasticity and the observed values of E, the number average molecular weights between crosslink points Mc for the cured resins were deduced. The experimental Mc values were then compared with those derived by calculations based on a probabilistic model of the network proposed by Chu and Seferis.1 The experimental Mc values were 2.5 to 5.5 times larger than the calculated ones. The differences were attributable to a consumption of only 40% of the available secondary amino hydrogen via epoxy-amine reaction. A direct relationship was established between the glass transition temperature and the crosslink density 1/Mc for the resins, and the dynamic mechanical properties were studied. The thermal stability of cured resins studied by thermo-gravimetric analysis indicated an enhancement of stability as 1/Mc was reduced. The amount of water absorbed by cured resin was directly proportional to 1/Mc.","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90181795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Epoxy resins and composites II (Advances in polymer science, Volume 75). Edited by K. Dusek, Springer‐Verlag, Berlin, Heidelberg, 1986. pp. xiii+l80, price DM 118.00. ISBN 3‐540‐15825‐1","authors":"W. Wright","doi":"10.1002/PI.4980180514","DOIUrl":"https://doi.org/10.1002/PI.4980180514","url":null,"abstract":"","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81333995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mike Hajimichael, A. Lewis, Dave Scholey, C. Simmonds
The development of low toxicity rigid epoxy foams as an alternative to polyurethane foams for electronics encapsulation is described. The basic foam components - epoxy resin, hardener, accelerator, blowing agent and surfactant - are blended to form a two part system which is mixed and foamed when required. Each foam component is selected for its contribution to the foaming reaction and the final foam properties. The balance of component miscibility, viscosity, reaction rate and exotherm determine foam quality. Foam properties are affected by (1) density (2) cell structure and (3) the molecular structure of the reactants. Initial foam development utilised epoxy/amine chemistry and produced two foams, Feldex F3 and F4. Subsequently, use of a more reactive polymercaptan hardener improved foam strength and process times, resulting in Feldex F5 and F6 which have been used successfully to prepare quality mouldings and encapsulated electronics. Recently, development has been extended to new areas of application, e.g. high temperature foams. The mechanical, electrical, thermal and chemical properties of the best epoxy foams have been evaluated; selected results are reported. The epoxy foams developed offer low density, high strength, low dielectric constant and loss tangent, high volume resistivity, good thermal insulation, low corrosivity and low toxicity. In addition, epoxy foams soften in acetone, an advantage over their polyurethane counterparts since encapsulated electronics may be retrieved without employing corrosive solvents. (Feldex is a registered trade mark of THORN EMI Electronics.)
{"title":"Investigation and Development of Epoxy Foams","authors":"Mike Hajimichael, A. Lewis, Dave Scholey, C. Simmonds","doi":"10.1002/PI.4980180506","DOIUrl":"https://doi.org/10.1002/PI.4980180506","url":null,"abstract":"The development of low toxicity rigid epoxy foams as an alternative to polyurethane foams for electronics encapsulation is described. The basic foam components - epoxy resin, hardener, accelerator, blowing agent and surfactant - are blended to form a two part system which is mixed and foamed when required. Each foam component is selected for its contribution to the foaming reaction and the final foam properties. The balance of component miscibility, viscosity, reaction rate and exotherm determine foam quality. Foam properties are affected by (1) density (2) cell structure and (3) the molecular structure of the reactants. Initial foam development utilised epoxy/amine chemistry and produced two foams, Feldex F3 and F4. Subsequently, use of a more reactive polymercaptan hardener improved foam strength and process times, resulting in Feldex F5 and F6 which have been used successfully to prepare quality mouldings and encapsulated electronics. Recently, development has been extended to new areas of application, e.g. high temperature foams. The mechanical, electrical, thermal and chemical properties of the best epoxy foams have been evaluated; selected results are reported. The epoxy foams developed offer low density, high strength, low dielectric constant and loss tangent, high volume resistivity, good thermal insulation, low corrosivity and low toxicity. In addition, epoxy foams soften in acetone, an advantage over their polyurethane counterparts since encapsulated electronics may be retrieved without employing corrosive solvents. (Feldex is a registered trade mark of THORN EMI Electronics.)","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88444311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new procedure for the glycidylation of aromatic amines has been developed recently, which leads to resins of lower viscosity, longer shelf-life and higher purity than methods used previously. Resins made by the new process show considerable processing and applications advantages over those made by earlier methods. The new process has also made accessible high purity glycidyl derivatives of amines which have hitherto proved difficult to glycidylate effectively.
{"title":"Recent Advances with Glycidylamine Resins","authors":"M. R. Thoseby, B. Dobinson, Christopher H. Bull","doi":"10.1002/PI.4980180503","DOIUrl":"https://doi.org/10.1002/PI.4980180503","url":null,"abstract":"A new procedure for the glycidylation of aromatic amines has been developed recently, which leads to resins of lower viscosity, longer shelf-life and higher purity than methods used previously. Resins made by the new process show considerable processing and applications advantages over those made by earlier methods. The new process has also made accessible high purity glycidyl derivatives of amines which have hitherto proved difficult to glycidylate effectively.","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82468733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of structure, composition, and cure on the water absorption and Tg of amine-cured epoxies was investigated. Water absorption is considered to depend on the polar group concentration and type, and on the amount of free volume in the polymer network. The contribution of polar groups in terms of their hydrogen bonding capabilities is reflected by the effect of meta (with respect to the diglycidylamino group) chloro, bromo, and methyl substituents on the water absorption of bis[N,N-bis(2,3-epoxypropyl)-4-aminophenyl]methane cured with 4,4′-diaminodiphenylsulphone. The observed water absorptions are in line with the expected electronic effects of the substituents on the basicity of the amine group. Substituents in the ortho position adversely affect the hydrogen bonding capability of the amine group and limit the extent of reaction by steric interference. Examination of four O-glycidyl systems (Epon 825, Epon 1153/114, Epon 1031, and Dow XD-7342) cured with 4,4′-diaminodiphenylsulphone has revealed quite a good linear relationship between the equilibrium water absorption and Tg for a particular hardener concentration irrespective of the epoxy compound employed. Networks ranged from those of low Tg (110°C) and water absorption (1.3%) to those of high values (300°C and 6.1%) for these parameters. Differences in slope for low (50-65%) and high (100%) stoichiometric amounts of hardener are attributed to differences in the relative importance of OH/epoxy and NH2 or NH/epoxy reactions. The theoretical polar group concentrations and polar group type are much the same for these different systems and thus, free volume is considered to be a function of Tg and to play an important part in determining the level of water absorption.
{"title":"Some effects of structure, composition and cure on the water absorption and glass transition temperature of amine-cured epoxies","authors":"P. Johncock, G. Tudgey","doi":"10.1002/PI.4980180504","DOIUrl":"https://doi.org/10.1002/PI.4980180504","url":null,"abstract":"The effect of structure, composition, and cure on the water absorption and Tg of amine-cured epoxies was investigated. Water absorption is considered to depend on the polar group concentration and type, and on the amount of free volume in the polymer network. The contribution of polar groups in terms of their hydrogen bonding capabilities is reflected by the effect of meta (with respect to the diglycidylamino group) chloro, bromo, and methyl substituents on the water absorption of bis[N,N-bis(2,3-epoxypropyl)-4-aminophenyl]methane cured with 4,4′-diaminodiphenylsulphone. The observed water absorptions are in line with the expected electronic effects of the substituents on the basicity of the amine group. Substituents in the ortho position adversely affect the hydrogen bonding capability of the amine group and limit the extent of reaction by steric interference. Examination of four O-glycidyl systems (Epon 825, Epon 1153/114, Epon 1031, and Dow XD-7342) cured with 4,4′-diaminodiphenylsulphone has revealed quite a good linear relationship between the equilibrium water absorption and Tg for a particular hardener concentration irrespective of the epoxy compound employed. Networks ranged from those of low Tg (110°C) and water absorption (1.3%) to those of high values (300°C and 6.1%) for these parameters. Differences in slope for low (50-65%) and high (100%) stoichiometric amounts of hardener are attributed to differences in the relative importance of OH/epoxy and NH2 or NH/epoxy reactions. The theoretical polar group concentrations and polar group type are much the same for these different systems and thus, free volume is considered to be a function of Tg and to play an important part in determining the level of water absorption.","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80967312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Adhesives, sealants, and coatings for the electronics industry. By E. W. Flick, Noyes Publications, New Jersey, 1986. pp. xviii+197, price $39.00. ISBN 0-8155-1055-1","authors":"W. Wake","doi":"10.1002/PI.4980180518","DOIUrl":"https://doi.org/10.1002/PI.4980180518","url":null,"abstract":"","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78723967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Rubber-modified thermoset resins. Edited by C. K. Riew and J. K. Gillham, ACS, Advances Chemistry Series No. 208, American Chemical Society, Washington, D.C., 1984. pp. xi + 372, price $89.95 (USA Canada), $107.95 (rest of world). ISBN 0-8412-0828-X","authors":"W. Wright","doi":"10.1002/PI.4980180425","DOIUrl":"https://doi.org/10.1002/PI.4980180425","url":null,"abstract":"","PeriodicalId":9298,"journal":{"name":"British Polymer Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1986-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72621335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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