摘要:

AbstractThe photodegradation of poly(ethylene 2,6‐naphthalate) is examined by absorption and emission spectroscopy and by flash photolysis techniques. A comparison of the emission spectra with that of a model compound 2,6‐dimethynaphthalate (DMN) shows that the chromophoric species responsible for light absorption in the near ultraviolet is the unit structure of the polymer itself. A flash photolysis study of DMN indicates that the major primary process in photodeterioration of the polymer involves scission by decarboxylation at the naphthyl‐carbon

ISSN:0021-8995    

DOI:10.1002/app.1978.070220801

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

年代:1978

数据来源: WILEY

摘要:

AbstractSynthesis of novel metal‐containing cured resins based on divalent metal salts of mono(hydroxyethyl) phthalate were investigated by the metal salt–anhydride–bisepoxide reactions. As the anhydrides, maleic anhydride (MA) and hexahydrophthalic anhydride (HPA) were used, and hexahydrophthalic acid diglycidyl ester (HPDG), bisphenol A diglycidyl ether (BADG), and ethylene glycol bis(glycidyl phthalate) (EBGP) were the bisepoxides used. The reactions were further studied in model reactions using the Ca salt of monoethyl phthalate. The metal carboxylate groups of the metal salts catalyzed the reactions. The reactivity of the bisepoxides decreased in the order HPDG ≫ BADG>EBGP, and MA was more reactive than HPA. Some of the metal‐containing cured resins obtained showed excellent physical properties. Resistance to chemical attack and boiling water, thermal behavior, and electrical resistance are also

ISSN:0021-8995    

DOI:10.1002/app.1978.070220802

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

年代:1978

数据来源: WILEY

摘要:

AbstractPolyacrylamide (MW 350,000) was ozonized at pH 2 and pH 10 buffer solution. There was little ozonization at pH 2, but at pH 10 the COD and the viscosity of the solution decreased upon ozonization, and a linear relationship existed between the ozone consumed and the number of breaks calculated from the viscosity. This relationship apparently indicated that 45 molecules ozone were consumed for one cleavage of the polymer chain. Such random cleavage was confirmed also by the observation of molecular weight distribution by means of gel filtration chromatography. The amide group decreased scarcely by the ozonization, while a small amount of aldehyde was observed in the ozonized solution. No remarkable change was observed in the IR spectra of the ozonized sample, except for a weak absorption band at 1725 cm−1which arose from the carbonyl of aldehyde or ketone. Although no variation was observed in the13C NMR spectra either, a strong absorption peak at 266 nm appeared in the UV spectra of the ozonized solution and increased with the ozonization time. This phenomenon was presumed to be due to the formation of a certain ring structure between the amide group and the small amount of ketone produced in the main chain. However, the details of the ozonization mechanism could not be ascertaine

ISSN:0021-8995    

DOI:10.1002/app.1978.070220803

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe correlation between number‐average molecular weight and intrinsic viscosity in 60:40 phenol‐sym‐tetrachloroethane at 30°C for poly(1,4‐butylene terephthalate) was established from endgroup determinations as well as by gel permeation chromatography, eqs. (1) and (10a). The GPC data also yielded relationships between weight‐ andz‐average molecular weight and intrinsic viscosity, eqs. (10b) and (10c). Melt viscosities, corrected for the thermal history of the melt, were measured at shear stresses in the range of 0.02–0.55 MPa. Linear PBT melts were found to become non‐Newtonian at a shear stress of approximately 0.11 MPa, independent of molecular weight within the range studied. Correlations between melt viscosity at low shear stress versus intrinsic viscosity are presented, as well as the dependence of melt viscosity in the non‐Newtonian region on shear stress and low‐stress (Newto

ISSN:0021-8995    

DOI:10.1002/app.1978.070220804

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

年代:1978

数据来源: WILEY

摘要:

AbstractDiscrepancies between the level of the viscosity at 200°C of the Dow series of polystyrenes and another narrow molecular weight distribution polystyrenes have been pointed out by Toosi, Porter, and Johnson in 1969. Penwell and Graessley have shown in 1974 that over a wide range in temperature one member of this series, S109, has a significantly lower viscosity than samples of similar molecular weight from other sources. Fetters has established the presence of high molecular weight tails in several of the much studied series. The investigation being reported here reveals the effect of the high molecular weight tail in the viscoelastic behavior of the S109 in the terminal zone of response. In addition, it is shown by an enhanced rate of creep in the glass to rubber‐like dispersion that the glass temperature of the S109 is depressed by about 4

ISSN:0021-8995    

DOI:10.1002/app.1978.070220805

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

年代:1978

数据来源: WILEY

ISSN:0021-8995    

DOI:10.1002/app.1978.070220806

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe dielectric loss tangent for polyethylene with low dielectric loss was approximated by tan δ =CfΣ(nμ2), wherenand μ are the number and dipole moment of polar groups, respectively, andCfis a parameter. The type and number of polar groups in the polyethylenes were mainly determined from infrared spectra obtained with a Fourier transform spectrometer. It was found that the contribution of hydroxyl and carbonyl groups to tan δ was significantly large, but the contribution of double bond groups was less significant. The tan δ was observed to decrease with a decrease of methyl group density although the overall contribution of methyl groups to tan δ was small. This suggests that tan δ is closely related to the secondary structure of polyethylenes, thus indicating the methyl groups seem to play an important role in the secondary st

ISSN:0021-8995    

DOI:10.1002/app.1978.070220807

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

年代:1978

数据来源: WILEY

摘要:

AbstractMelt blends of bisphenol A polycarbonate with poly(butylene terephthalate) were studied by DTA and dynamic mechanical behavior to determine their state of miscibility. Both techniques showed multiple glass transitions indicative of incomplete miscibility in the amorphous phase. However, these transitions in some cases did not correspond to those in the pure components and varied with overall blend composition in some instances. This indicates that there are amorphous phases containing both components, i.e., partial miscibility. This view was supported by the crystallization behavior of the polyester. Two crystallization exotherms were observed for quenched samples, which is interpreted as polyester crystallization from two separate phases, one richer in this component than the other. Other interpretations of these results are discussed.

ISSN:0021-8995    

DOI:10.1002/app.1978.070220808

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

年代:1978

数据来源: WILEY

摘要:

AbstractUV‐curable formulations do not UV cure when hydroxybenzophenone or hydroxyphenylbenzotriazole UV screens are added to them. Reaction of these UV screens with alkyl or aryl isocyanates gives urethane derivatives in high yields. These derivatives do not impede UV cures when they are incorporated in UV‐curable formulations at relatively high levels (3%–5%). After completion of the UV cure, the urethane derivatives are catalytically decomposed by heating to regenerate the corresponding UV screen within the cured co

ISSN:0021-8995    

DOI:10.1002/app.1978.070220809

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

年代:1978

数据来源: WILEY

摘要:

AbstractA series of quinazolone pre‐polymers have been prepared from 4,4′‐diaminodiphenyl‐3,3′‐dicarboxylic acid and aromatic diacetamido compounds by melt polycondensation. The pre‐polymers have been characterized by combustion analysis, viscometry, vapor pressure osmometry, and thermal analytical methods (TG, DTA, and DSC). Structures have been elucidated by spectroscopic methods (IR and NMR). The thermal cyclization of these pre‐polymers to the partial ladder polyquinazolone has been studied and optimized using IR, DSC/DTA, TG, and evolved gas analysis. The cyclization behavior of these systems has been resolved in terms of concurrent dehydration and

ISSN:0021-8995    

DOI:10.1002/app.1978.070220810

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

年代:1978

数据来源: WILEY