摘要:

AbstractThe thermal reaction of equimolar quantities of isophthalonitrile ando‐carborane has been shown to produce an adduct oligomer of isophthalonitrile. The structure was determined to involve condensation of three to five isophthalonitrile molecules to form a triazine‐type system. This type of bonding gave rise to a trimer and pentamer. Further, the reaction was a homogeneous liquid phase reaction in whicho‐carborane is involved in a catalytic manner in the oligomerization. The overall reaction has first‐order kinetics with an activation energy of 32.2 kc

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170301

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractSample charging phenomena arising in the ESCA experiment have been investigated for gold and polymer films of known thickness ranging from 5 Å to 20 μ deposited on gold either insulated from or in electrical contact with the spectrometer. Charging induced by a monochromatic x‐ray source is typically an order of magnitude greater than that induced by a nonmonochromatized source and exhibits a marked time dependence. A novel source of secondary electrons which employs a low‐power, low‐pressure mercury lamp external to the spectrometer source chamber as an alternative to an electron flood gun is described, and the charging and biasing characteristics of polymer films as a function of film thickness are discussed and demonstrated to provide an extra informational dimension for the study of polymeric ma

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170302

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractSAXS measurements on dilute solutions of polyisobutene inn‐hexane (Mν= 25,600−3.55 × 106,c<53 g/liter) were carried out by combining conventional slit collimation with the new cone collimation technique. With a fractionated sample (Mν= 25,600;U<0.2) the radius of gyration (R= 48 Å), the cross‐sectional radius of gyration (Rq= 3.9 Å), the molecular weight per unit length (M/L= 22.8 Å−1), and the Porod persistence length (a*= 8.1 Å) are found. The persistence length appears to be dependent on the molecular weight. The partial specific volumeνof polyisobutene inn‐hexane also depends on the molecular weight according toν= 1.0

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170303

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe electric properties of polymer composites with highly conductive 7,7,8,8‐tetracyanoquinodimethan (TCNQ) salts such as quinolinium–TCNQ complex salt (), acridinium–TCNQ complex salt (), andN‐methylacridinium–TCNQ complex salt () were studied. Polyacrylonitrile (PAN), poly(N‐vinylcarbazole) (PVK), and poly(4‐vinylpyridine), (P4VP), etc., were chosen as matrix polymers. The resistivity (ρ) of the was 0.37 Ω cm at the content of 20 wt % in the film. When the content of was increased up to 40 wt%, a phase separation of the needle crystals was observed and the ρ value increased. When was dispersed into PAN or PVK, the separation was also observed and the samples showed low conductivity. The uniform films were obtained in the and systems, but the values of ρ were high because of the degradation of the TCNQ salts. Uniform films with the naked eye were obtained in the and systems, and the values of Ω were 0.37, 1.05, and 3.40 Ω cm, respectively. was stable even when dispersed into P4VP. The properties of the composites were influenced by the combination of the TCNQ salts and the polymers. The uniformity and the stability of the composites were necessary to obtain the high co

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170304

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe effect of ionization (α) and added salts (NaCl, CaCl2, MgCl2) on the dimensions of commercially available high‐molecular‐weight polyacrylamides (Mw≃ 4 × 106), hydrolyzed at various extents (0.04<τ0.45) in media containing large amounts of salts that lead to precipitation of polymers, especially in the presence of

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170305

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe rate ofn‐butyl vinyl ether polymerization by chromyl chloride is first order in [catalyst] and second order in [monomer]. Added H2O (after a certain concentration) and HCl increase the rate, thiophene retards the rate, while pyridine inhibits the rate.DPis independent of [chromyl chloride] and increases with increasing [monomer]up to 1M, thereafter becoming independent of it. Both rate andDPincrease over the range 10−32°C and decrease at higher temperat

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170306

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe crosslinking mechanism and kinetics of low‐molecular‐weight polybutadiene, its mixtures with maleic anhydride, and the products of its grafting with maleic anhydride and styrene, using dicumyl peroxide (DCP) as an initiator, were studied. It was shown that for all systems crosslinking is a radical polymerization of the double bonds. Modification of polybutadiene changes only the kinetic parameters of the crosslinking reaction and causes mainly a decrease of the termination step velocity. From DSC data the crosslinking reaction order, activation energy, and reaction heats were calcula

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170307

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThermoelastic (stress–temperature) measurements in elongation have been carried out on polyurethane elastomers obtained from poly(ethylene adipate), poly(ethylene maleate), poly(ethylene glycol), and 4,4′‐diphenylmethane diisocyanate. The elastomers were crosslinked by an excess of diisocynate and some of them were additionally crosslinked by dicumyl peroxide. Values of the temperature coefficientdlnr 02/dTof the unperturbed dimensions of the network chains and the fractionfe/fof the stress, which is due to energetic effects, were calculated from measurements of unswollen samples and samples swollen in benzene to a constant volume fraction ν2of about 0.6. The coefficientdlnr 02/dTand the ratiofe/ffor unswollen samples were positive but dependent on the extension ratio α and crosslinking density. Thefe/fratio displayed a tendency to decrease with increasing α and this decrease was smaller for elastomers of higher crosslinking density. Additional crosslinking due to dicumyl peroxide reduced the dependence offe/fon α. Swollen samples had lower positive values offe/f; which were somewhat independent of α and crosslinking density. Departures from the molecular theories of rubberlike elasticity are explained by intermolecular effects, which, in general, are influenced b

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170308

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractPolyimides with different proportions ofm‐phenylene andp‐phenylene (orp,p′‐biphenylene) were prepared by polymerizing different molar ratios ofm‐phenylene diamine andp‐phenylene diamine (orp,p′‐diaminobiphenyl) with pyromellitic dianhydride in dimethylformamide at 0°C. Chemical cyclodehydration of polyamic acids resulted in the corresponding polyimides. Polymers were characterized by infrared (IR), viscosity, and density measurements. Viscosity and density of polymers decreased with an increase onm‐phenylene groups in the backbone. The thermal and thermooxidative stabilities were investigated by dynamic thermogravimetry. Stability decreased whenm‐phenylene groups were introd

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170309

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractWe have studied the rose bengal‐sensitized photooxygenation ofcis‐ andtrans‐polyisoprene model compounds that contain one unit in methanolic solution, characterized the resulting monohydroperoxides, and determined their yield. We have also demonstrated the possibility of a second addition of singlet oxygen on the same unit and have undertaken a kinetic study to determine the rate constants of all the reactions of 4‐methyl

ISSN:0360-6376    

DOI:10.1002/pol.1979.170170310

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY