摘要:

AbstractThe following experiment was performed based on the assumption that the characteristic structural features of high molecular weight poly(vinyl chloride) (PVC) should be present to the same extent in its low molecular weight fractions. Two PVC fractions of molecular weight, 1500 and 800, respectively, (0.14% of total polymer) were isolated from bulk PVC (Mn32,000) by extraction with methanol. This extract was transformed into paraffins by a new hydrogenation method using an excess of Raney nickel in order to facilitate identification.13C‐NMR spectral data of the paraffins showed that almost 2 out of 1000 carbon atoms were linked to a side chain with more than five carbon atoms, and 5 out of 1000 carbon atoms were methyl branched. Gas chromatography‐mass spectrometry (GC–MS) analyses confirmed that the low molecular weight paraffins consisted of a sequence of even‐numbered homologs. These findings suggest indirectly that the surprisingly low degradation temperature of PVC is due to the arrangement of the chlorine atoms rather than to the branching of the alky

ISSN:0021-8995    

DOI:10.1002/app.1979.070230601

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

年代:1979

数据来源: WILEY

摘要:

AbstractBy treatment with alkali in 2‐methoxyethanol, poly(vinyl chloride) is converted to an insoluble network structure. On subsequent oxidation with 65% HNO3, a water‐soluble mixture of acids is obtained. Per 1000 carbon atoms of the original polymer chain, approximately 4 moles succinic acid, 2 moles glutaric acid, and 1 mole adipic acid are found. In spite of the fact that the occurrence of succinic acid is in the same order as tail‐to‐tail polymerization in PVC, it must be assumed that unexpected aggregation of more than two CH2groups is due to rearrangement during the alkali treatment or the oxidation pr

ISSN:0021-8995    

DOI:10.1002/app.1979.070230602

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

年代:1979

数据来源: WILEY

摘要:

AbstractFour monomers were synthesized and four copolymers prepared. The polymers were dark‐colored, poorly soluble, crystalline products. The x‐ray photographs were typical of triclinic crystals. The polymers degraded at temperatures lower than those characteristic of the analogous homopolymers. The recovered polymers were ferromagne

ISSN:0021-8995    

DOI:10.1002/app.1979.070230603

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe influence of both ethylene content and the degree of crystallinity on the thermal and dynamic mechanical properties of certain commercial EPDM rubbers were investigated using the TMA, DSC, and Rheovibron techniques. The six materials chosen for this study were Nordel 1560, Intolan 260, Royalene 1812, Vistolan 3708, Intolan 255, and Keltan 778.

ISSN:0021-8995    

DOI:10.1002/app.1979.070230604

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe morphology associated with the liquid‐induced crystallization of poly(ethylene terephthalate) (PET) blended either with poly(tetramethylene terephthalate) (PTMT), atactic polystyrene (APS), or polycarbonate of bisphenol A (PC) was studied, along with the effects of nucleating agents and polymer molecular weight on this type of crystallization in PET. It was found that melt‐mixed blends of PET and either PTMT or PC led to an apparent well‐mixed, two‐component material in which some copolymer formation may be in evidence judging from the material superstructure. Blending PET with APS appeared to produce distinctly phase‐separated materials in which PET could be crystallized and APS dissolved out of the structure as a result of treatment of the blend with certain types of liquid. The incorporation of nucleating agents into PET was shown to measurably influence the spherulitic character of the subsequently liquid‐induced crystallized polymer. Finally, it was determined that liquid‐induced crystallized PET samples with number‐average molecular weights of 18,000 and 30,000 had identical characteristic morphology and apparent crystalli

ISSN:0021-8995    

DOI:10.1002/app.1979.070230605

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

年代:1979

数据来源: WILEY

摘要:

AbstractA three‐parameter equation is put forward to evaluate the [η] of polymer solution from a wide range of concentrations, up to a relative viscosity of 100. The equation is tested by viscometric data of polystyrene, poly(vinyl chloride), poly(1‐vinylnaphthalene), poly(2‐vinylnaphthalene), and poly(4‐vinylbiphenyl) at different temperatures and in a variety of solvents including mixed solvents. A statistical method is employed to analyze the experimental data. It is found that the values of [η]obtained by the new equation are consistently lower than those derived from the Huggins equation. However, the discrepancy is not more than 3% on average, and it does not affect the values of Mark‐Houwink constants significantly. Other parameters of the equation are al

ISSN:0021-8995    

DOI:10.1002/app.1979.070230606

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

年代:1979

数据来源: WILEY

摘要:

AbstractA new method for measurement of dynamic flexile mechanical properties was developed by a modification of the Rheovibron viscoelastometer. The Rheovibron instrument is useful for obtaining dynamic tensile mechanical properties of films and fibers over a wide temperature range. A new flexile grip and procedure were used for measuring dynamic mechanical properties of material in the flexile mode using the Rheovibron instrument. The dynamic flexile properties on polyester, nylon 66, and acrylic fiber are presented.

ISSN:0021-8995    

DOI:10.1002/app.1979.070230607

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

年代:1979

数据来源: WILEY

摘要:

AbstractExtrusion die swell of natural rubber compounded with a wide variety of carbon blacks has been determined in a capillary rheometer using a long circular die. The range of variation of carbon black loading, surface area, and structure are, respectively, 10 to 60 phr, 44 to 124 m2/g, and 78 to 120 cc/100 g. The effective carbon black volume fraction φenot participating in the strain recovery leading to die swell is assumed to be the sum of the actual filler volume fraction and the fraction of unextractable rubber determined experimentally for each compound. Bagley and Duffey's analysis of extrusion die swell of unfilled polymers as unconstrained elastic recovery was adopted for a filled elastomeric system whose relative shear modulus (G/G0) is assumed to vary as (1 − φe)−N. The matrix shear modulusG0, originally introduced by Nakazima and Shida on the basis of a linearized approximation, will depend on the shear stress level because of nonlinear deformation. The powerNwill vary with shear stress which changes the orientation of carbon black aggregates. Except for these features, die swell data for a wide range of carbon black compounds fall on a single curve when plotted in the manner of the predicted relation between the wall shear stress, die swell, and φe. Replacing φeby Medalia's φ′ based on an equivalent sphere concept introduces a larger scatter around the

ISSN:0021-8995    

DOI:10.1002/app.1979.070230608

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

年代:1979

数据来源: WILEY

摘要:

AbstractSmall‐angle x‐ray methods were used to evaluate macromolecular parameters such as specific inner surface of the dispersed phase; transversal lengths such as length of inhomogeneity and length of coherence; and the air fraction of the scattering particles inSansevieria roxburghi;these parameters were found to be 12.76 × 10−6Å−1, 549.9 Å, 15.21 Å, and 0.17%, respectively. A small‐angle Kratky camera was used for the experimental measurements, and the theories of Kratky and Kratky and Porod were utilized to evaluate these parameters. The sample under investigation is treated as a densely packed colloidal system belonging to general mi

ISSN:0021-8995    

DOI:10.1002/app.1979.070230609

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe temperature dependence of the impact fracture energies of composites reinforced with random‐planar orientation of short fibers was studied theoretically and experimentally. The theoretical values of the impact fracture energy of these composites is described by the sum of the fracture energy of the matrix and the fibers and the energy necessary to pull out the fibers on the crack surface, taking into consideration the temperature dependence of the critical fiber length and the breaking probability of fibers. The impact fracture energies were studied experimentally for epoxy and unsaturated polyester resins reinforced with random‐planar orientation of short glass fibers. The theoretical values of the impact fracture energy were in good agreement with the experimental values. It was found that in any composite, the impact fracture energy of the fibers in a composite mainly contributes to the impact fracture energy of the composite at room temperature. At higher temperatures, fiber pull‐out energy is more signif

ISSN:0021-8995    

DOI:10.1002/app.1979.070230610

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

年代:1979

数据来源: WILEY