摘要:

AbstractNew thioether glycidyl resins by condensation of bis(4‐mercaptophenyl)sulfide or bis(4‐mercaptophenyl)sulfone with epichlorohydrin were obtained by heterophase alkaline condensation in aqueous and isopropanol medium using sodium hydroxide. The detailed studies on their structures from elemental analysis and IR and1H‐NMR spectra, physical and chemical properties, and curing conditions are presented. Thioether glycidyl resins compositions were also prepared using curatives typical for epoxy resins and after curing they were characterized from derivatographic, thermomechanical, and mechanical st

ISSN:0021-8995    

DOI:10.1002/app.1990.070390801

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractDiglycidyl ether–bisphenol‐A‐based epoxies toughened with various levels (0–12%) of chemically reacted liquid rubber, hydroxyl‐terminated poly(butadiene‐co‐acrylonitrile) (HTBN) were studied for some of the mechanical and thermal properties. Although the ultimate tensile strength showed a continuous decrease with increasing rubber content, the toughness as measured by the area under the stress‐vs.‐strain curve and flexural strength reach a maximum around an optimum rubber concentration of 3% before decreasing. Tensile modulus was found to increase for concentrations below 6%. The glass transition temperatureTgas measured by DTA showed no variation for the toughened formulations. The TGA showed no variations in the pattern of decomposition. The weight losses for the toughened epoxies at elevated temperatures compare well with that of the neat epoxy. Scanning electron microscopy revealed the presence of a dual phase morphology with the spherical rubber particles precipitating out in the cured resin with diameter varying between 0.33 and 6.3 μm. In contrast, a physically blended rubber–epoxy showed much less effect towards toughening with the precipitated rubber particles of much bigger di

ISSN:0021-8995    

DOI:10.1002/app.1990.070390802

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractNew polythioesters by interfacial polycondensation of 1,4‐dimercaptomethyl–tetramethylbenzene with oxalyl, succinyl, adipoyl, suberoyl, sebacoyl, and isomeric phthaloyl dichlorides were obtained. To define the optimal conditions for interfacial polycondensation, the influence of the following factors on yield and value of reduced viscosity were studied: type of organic phase, concentration of hydrogen chloride acceptor, the quantitative ratio of aqueous to organic phase, molar ratio of reagents rate of acid chloride addition, contribution of benzyltriethylammonium chloride as a catalyst, and the temperature of the reaction. Thorough studies were carried out only for polycondensation of the dithiol with adipoyl, sebacoyl, and isophthaloyl chlorides. The structure of polythioesters obtained under the model conditions was determined by elementary analysis and infrared spectra. Initial decomposition temperature, mass loss in percentage at the same temperature, maximum rate of decomposition, and mass loss percentage at 100–400°C were defined from the curves of thermogravimetric analysis. Chemical resistance of the polythioesters was determined by treatment with some organic solvents, mineral acids (concentrated and 10%) and sodium hydroxide (10% and 50%). The molecular weight was not measured because of the low solubility of the polythio

ISSN:0021-8995    

DOI:10.1002/app.1990.070390803

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe polymerization of acrylonitrile in the presence of Ce(IV) salts and ketonic resin such as methyl ethyl ketone/formaldehyde and cyclohexanone/formaldehyde resin was investigated. Block copolymer of ketonic resin–polyacrylonitrile was produced. The effect of Ce(IV) concentration, temperature, time, and monomer concentration on the yield and molecular weight was studied. Maximum yield was obtained at 50°C and ceric ammonium nitrate concentration of 0.033 mol

ISSN:0021-8995    

DOI:10.1002/app.1990.070390804

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractPolymer‐supported phase transfer catalysts, which were prepared by immobilizing tributylamine on chloromethylpolystyrene, were characterized by optical microscope, SEM, EPMA, and ESCA. Both optical photograph and electron micrograph showed that the exterior surface of polymer support became wrinkly after immobilization in dry condition. The surface of the triphase catalyst may become smooth after being swelled by solvent. From the ESCA analysis in a depth of about 100 Å, it was found that 46.5% of covalent chloride in chloromethylpolystyrene had reacted with tributylamine and converted to quaternary ammonium chloride. However, the EPMA, which analyzed in a depth of about 1 μm, gave a value of only 31% and the titration method which was for the whole bead gave 14.3%. These results reveal that the catalyst has a higher content of quarternary ammonium chloride in the outer shell. It is concluded that the high activity of this catalyst is due to the fact that it contains both hydrophobic and hydrophilic groups on the exterior surface, and more active species in the outer sh

ISSN:0021-8995    

DOI:10.1002/app.1990.070390805

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe method of graft copolymerization of methyl methacrylate on halogen‐containing polymer has been utilized for grafting of methyl methacrylate–methacrylic acid monomer pair onto poly(vinyl chloride) and chlorinated rubber. Substantial grafting could be obtained by using the method reported earlier. However, the compositions of the grafted chains are found to deviate appreciably from the compositions calculated fromr1andr2values reported in literature. The reactivity ratios for this pair of monomers have been therefore evaluated using azobisisobutyronitrile andn‐butane thiol–dimethyl sulfoxide as initiators. The anomalies of the grafted chain compositions have been discussed and an explanation presented on preferential so

ISSN:0021-8995    

DOI:10.1002/app.1990.070390806

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe viscoelastic anomaly found at 208 K for as‐polymerized polytetrafluoroethylene (PTFE) is investigated on the basis of thermal treatment dependence of mechanical spectra. The loss intensity and relaxation strength of the anomaly tend to decrease at annealing temperatures much lower than the melting point. The structural region relevant to the anomaly can be rearranged in more ordered states on annealing; accordingly, the loss peak of the crystalline dispersion is intesified, although that of the amorphous γ‐relaxation remains nearly unchanged. The anomaly originates from the intermediate or paracrystalline regions, many of which are included in the virgin samples; segmental motions like local mode relaxation are consid

ISSN:0021-8995    

DOI:10.1002/app.1990.070390807

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractPolydimethylsiloxane (PDMS)–polyamide multiblock copolymers were synthesized by three different methods, i.e., two‐step low‐temperature solution polycondensation, one‐step solution polycondensation, and interfacial polycondensation. In the two‐step method, α,ω‐diacid chlorideterminated polyamide oligomers were prepared fromtrans‐2,5‐dimethylpiperazine (DMP) and terepthaloyl chloride (TPC) or isophthaloyl chloride (IPC) in chloroform in the presence of triethylamine, which in turn were subjected to reaction with α,ω‐bis (3‐aminopropyl) polydimethylsiloxane (PDMS–diamine) in the same solvent to from multiblock copolymers. In the one‐step method, the reaction components, DMP, TPC (or IPC), and PDMS–diamine, were reacted altogether in chloroform in the presence of triethylamine. In the interfacial method, the reaction components were also reacted altogether in an aqueous sodium hydroxide–chloroform two‐phase system. These polycondensations afforded the multiblock copolymers having inherent viscosities of 0.1–1.3 dL g−1inm‐cresol. The PDMS–polyamide multiblock copolymers dissolved in formic acid and 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP), and transparent, ductile, and elastomeric films were obtained by casting from the HFIP solutions. The films of the multiblock copolymers prepared by three different methods exhibited similar properties by means of thermal analysis and tensile measurements. In the multiblock copolymers, the tensile strength and modulus of the films decreased with increasing the PDMS con

ISSN:0021-8995    

DOI:10.1002/app.1990.070390808

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAn experimental study was conducted to investigate the rheological, morphological, and mechanical properties of a heterogeneous polymer blend system consisting of low density polyethylene (LDPE) and plasticized poly(vinyl chloride) (PVC). The components were mixed using a single‐screw extruder, which was equipped with a special measuring head for the determination of rheological quantities. The morphology of blends was examined by scanning electron microscopy. Die swell was determined by photography. The velocity of ultrasound through the polymer melt was also measured. The dependencies of viscosity, die swell, and ultrasonic velocity on blend composition were qualitatively similar, exhibiting a minimum at about 70 wt % PVC. The morphology of the blend system at this blending ratio was different from morphologies of the other blends. Tensile properties of blends, except elongation at break, were not significantly inferior to those of the LDPE componen

ISSN:0021-8995    

DOI:10.1002/app.1990.070390809

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractX‐ray diffraction halo of alkyd, amino, and epoxy resins were recorded. The effectivedobtained from them was used to estimate certain physical parameters like cross‐sectional area, number of carbon atoms per chain, and stiffness parameters from the empirical curves of Boyer and Miller. Amino resin was found to behave differently than the rest of the resins which have a benzene ring in their backbone. These ideas find a confirmation from the ultrasonic and dielectric measurements performed on these very samp

ISSN:0021-8995    

DOI:10.1002/app.1990.070390810

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY