摘要:

Atactic poly(vinyl alcohol) (PVA), which has some branches or acetyl groups, was crystallized by shearing force under turbulent flow from its aqueous solution in order to clarify the effects of branches or acetyl groups on the shearing stress-induced crystallization. The crystallization became more difficult with an increase in their number. In partially acetylated PVA, the acetyl groups of randomly acetylated PVA markedly influenced the shearing stress-induced crystallization in comparison with that of nonrandomly acetylated PVA. In addition, this paper describes the shearing: stress-induced crystallization under laminar flow of syndiotactic-rich PVA partially acetalized with glyoxylic acid.

ISSN:0022-2348    

DOI:10.1080/00222347408204537

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Ionomers are a recently developed class of copolymers consisting of a hydrocarbon repeat unit such as ethylene or butadiene and an ionized carboxylic acid group such as ionized acrylic or methacrylic acid. In this paper measurements of crystallinity in poly(ethylene-methacrylic acid) ionomers from DSC endotherms and polymer densities are shown to be in good agreement.

ISSN:0022-2348    

DOI:10.1080/00222347408204538

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The influence of the mosaic block structure of bulk-crystallized high-density polyethylene upon deformation within the elastic limit and upon fatigue phenomenon has been extensively studied in the temperature range of the α relaxation mechanism. The magnitude of elastic limit, estimated from two models involving a tilt sliding mechanism and a simple tension mechanism, was compared with experimental results obtained using a tensile tester and a dynamic viscoelastometer at various temperatures of measurement. The two models for onset of deformation are applied on the assumption that the intermosaic block region is selectively affected by strain without any structural change occurring in the mosaic block crystalline core. Also, dynamic mechanical properties were obtained on specimens subject to an increasing number of fatigue cycles. The variation of E'1, max, attributed to deformation processes of the intermosaic block region, is strongly affected by slight elongation and by fatigue cycling of the sample. A direct observation of the mosaic block structure is made with the electron microscope using a detachment replica of the surface of the bulk crystallized material, that has been elongated by 15% at 55°C in biaxial directions.

ISSN:0022-2348    

DOI:10.1080/00222347408204539

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The deformation of drawn and annealed polyethylene film was examined by electron microscopy and small-and wide-angle x-ray diffraction, and is compared with that of oriented, annealed thin films redrawn on Mylar film. Although the detailed results obtained with redrawn thin film can not be directly compared with the thick films, in both cases the observed kabob structure first undergoes separation and tilting of the lamellae followed by breakage of the lamellae into blocks and probable unfolding of the molecules in the blocks to form extended-chain fibrils. The results are similar to those that have been reported for the deformation of solution grown polyethylene shish-kabobs.

ISSN:0022-2348    

DOI:10.1080/00222347408204540

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The feasibility of certain modes of intra-and intermolecular motion in polymeric solids are examined in terms of interaction energetics and geometrical constraints. Energy methods for determining equilibrium chain structures and stable deformation structures are reviewed. A systematic approach to the specification of explicit geometrical constraints in condensed phase polymeric systems is developed by matrix techniques. Combination rules are derived which provide straightforward means of constructing deformation structures for oriented polymers.

ISSN:0022-2348    

DOI:10.1080/00222347408204541

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The longitudinal acoustical (LA) mode has been studied in solution and bulk-crystallized polyethylene by Raman spectroscopy. In bulk-crystallized polyethylene the crystalline repeat, estimated from the LA frequency, corresponds to the larger of the two small angle repeat distances. Observations of the LA linewidth indicate that upon annealing the distribution of lamellar thicknesses broadens for single crystal mats and narrows for quenched bulk material. In successive annealing experiments on preannealed polyethylene where the spectra were recorded at the annealing temperature, the crystalline core maintains a constant thickness and does not melt-inward from the fold surfaces. The intensity of the LA mode decreases during such annealing. These results are interpreted in terms of the α-relaxation process which increases the number of defect chains in the crystalline core upon annealing.

ISSN:0022-2348    

DOI:10.1080/00222347408204542

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

An important industrial property of a polymer is its impact strength, the ability to dissipate the energy of an impact, through some mechanical loss process, without breaking. This property may be enhanced through the judicious use of fillers and grafts, yet the reason why oneunmodifiedpolymer has a higher impact strength than another is not understood. It is anticipated that an understanding of this phenomenon will provide a firm foundation for the modification of polymers in order to improve their impact properties.

ISSN:0022-2348    

DOI:10.1080/00222347408204543

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The Research Group of Polymer Physics in Japan, in cooperation with the Research Group of Polymer Solutions, publishes an annual summary of the work done on high polymer physics in Japan. The publication consists of short reports (2 to 4 pages) describing current or recently completed research. This journal, in cooperation with Professor S. Oka, Chief Editor of the Report, publishes the table of contents of each issue as soon as it is available. Papers on biophysical matters are also included, since Annual Reports of the Research Group on Biophysics in Japan has been discontinued. Copies of the complete report (and back issues) can be obtained from the publisher:

ISSN:0022-2348    

DOI:10.1080/00222347408204544

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor