摘要:

AbstractPolyamic acids with different proportions of benzidine (Bz) and 4,4′‐diamino‐diphenylmethane (DADPM) were prepared by polycondensating different molar ratios of Bz and DADPM with pyromellitic dianhydride (PMDA) in dimethyl formamide. Chemical cyclodehydration of copolyamic acids by acetic anhydride/pyridine resulted in corresponding copolyimides. Polymers were characterized by determination of intrinsic viscosity and nitrogen content. Thermal stability was investigated by thermogravimetric analysis. Some of the copolyamic acids were wet spun into fibres and subsequently converted to polyimides. Copolyimide fibres containing benzidine moiety had better mechanical properties than those containing

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130101

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractBlends of polyether‐based thermoplastic polyurethane (TPU) and poly(ethylene‐co‐methyl acrylate) (EMA, 21 wt.‐% MA) were prepared by melt mixing and subsequent compression moulding. Infrared spectroscopy studies and dynamic mechanical analysis reveal that the polymers are miscible in the entire compositio

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130102

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThree‐block copolymers polyamide‐block‐polyX‐block‐polyamide (where X is styrene, ethylene‐co‐1‐butene, and others) are able to improve substantially the toughness of poly(ϵ‐caprolactam). Outer blocks of these copolymers are able to take part in folding lamellae of semi‐crystalline polyamide, inner blocks are not. They operate as a spacer, meaning that the end blocks of copolymers capable of folding become parts of different lamellae, or that the unfoldable part of a block copolymer is pushed out of a folding lamella with a certain probability of the remaining outer block taking part in folding another lamella.This increases the num

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130103

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractVarious substituted phenyl acrylates (4‐nitro (NPA), 4‐benzoyl (BPA), 2‐carbomethoxy (CPA), 2‐formyl (FPA) and 2,4,6‐trichloro (TCPA) phenyl acrylate) were copolymerized with 4 mol‐% DVB in aqueous suspension at 80°C. The resulting copolymers were characterized by means of FT‐IR and high resolution solid state13C NMR spectroscopy. The particle size distribution and average particle size of the typical systems were determined. Scanning electron microscopy provided information about size, shape and morphological features of the resins. The thermal stabilities of the resins were determined by thermogravim

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130104

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this study, the effect of the particle size of solid protective agent, commercially obtained and in‐situ formed tricalcium phosphate (TCP), on the particle size of suspension polymerized polystyrene (PS) is investigated. It is concluded that when a solid protective agent like TCP is used, its particle size and distribution plays an important role in both suspension stability and particle size of the PS obtained. As the particle size of the TCP becomes smaller, the particle size of the PS obtained is reduced in line with it. In situ precipitation of TCP reduces its particle size considerably. Therefore, to produce PS with the same particle size, lesser amount of in‐situ precipitated TCP is required which gives way to production recipe savings and cleaner PS produ

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130105

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractGraft polymerization of acrylamide (Aam) onto maize starch using potassium persulfate as initiator was investigated under different conditions including concentration of initiator and monomer, polymerization time and temperature and liquor ratio. Based on the results obtained, appropriate conditions for grafting acrylamide onto starch were established. These conditions were also used for grafting other monomers onto maize starch. Results obtained indicate that acrylamide acquires the highest graft ability while acrylic acid acquires the least, while acrylonitrile and methacrylic acid in between. The water solubility of both nitrogen‐ and carboxy‐containing copolymers increases by increasing the monomer content up to a certain value, then it decrea

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130106

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractPolymerization of acrylamide initiated with ceric (IV) ion in the presence of methionine, phenylalanine, serine and aspartic acid was investigated in sulfuric acid solution. Maximum yield was obtained at 70°C and sulfuric acid concentration of 0.16 mol/1. Both conductometric titration and FT‐IR results showed that the resulting polymers contained carboxy end groups. According to these findings and previous studies in this field, a suitable polymerization mechanism was propos

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130107

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe free‐radical copolymerization of styrene with (2‐oxo‐1,3‐dioxolan‐4‐yl)methyl methacrylate (cyclic carbonate of glycidyl methacrylat; GMACC) was carried out in N,N‐dimethylformamide and toluene solution under batch conditions. In toluene, a precipitate was formed during polymerization. The composition of the copolymers was determined by1H‐NMR, IR spectroscopy and elemental analysis. The monomer reactivity ratios were calculated by different methods from the copolymer composition data. The values obtained for the different techniques were compared and showed a

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130108

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractTensile and dielectric relaxation properties of sulfobetaine polyurethane ionomers based on polyesters were studied comparatively to the non‐ionic polyurethane and derived compounds with Pb2+and Co2+, using stress‐strain and thermally stimulated depolarization currents (TSDC) methods. Introduction of ionic centers into polyurethane chain improves the tensile properties and modifies the TSDC spectra. These effects are assigned to an enhancement of the microphase segregation. Complexation with Pb2+and Co2+diminishes the tensile properties, suggesting that an increase of phase mixing occurs determined by a partial neutralization of ionic centers. Treatment with H2S slightly increases tensile properties and changes TSDC spectra owing to the presence of the semiconducting microphases formed by clustering of the metal sulfides PbS and CoS, respectiv

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130109

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe removal and recovery of indium ion (In3+) from solutions with water‐insoluble amphoteric starches containing the phosphate anionic group and the quaternary ammonium or tertiary amine cationic group was investigated. The adsorption capacity of tertiary amine phosphate starch (TAP) and quaternary ammonium phosphate starch (QAP) is 0.54 meq/g and 0.48 meq/g, respectively. The adsorption process has been found to be concentration‐dependent and exothermic, and follows the Langmuir isothermal adsorption. The heat of adsorption (ΔH) is equal to −5.86 kJ/mol for QAP, and equal to −90.44 kJ/mol for TAP. The amount of adsorbed In3+ion on the adsorbents decreases when inorganic acids (HCl or H2SO4) or sodium salts (NaCl or Na2SO4) are added to the solution. The adsorbed In3+ion can be desorbed by treating with a HCl solution (1 and 3 M); the maximum percentage of desorption reaches about 80% when 1 N HCl solution

ISSN:0003-3146    

DOI:10.1002/apmc.1993.052130110

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY