摘要:

AbstractPermeation measurements for CO2, CH4, O2, N2, and He were made with three polymers based on bisphenol‐A, namely a polyhydroxyether, a polyetherimide, and a polyarylate. Measurements were also made for CO2and CH4in polysulfone. The data for CO2, CH4, and N2plus previous data for these gases in polycarbonate and polysulfone were combined with equilibrium gas sorption data and analyzed with the dual mode/partial immobilization model and the more recent gas‐polymer‐matrix model. A comparison of the two models was done on the basis of physical interpretations of the resulting parameters. The diffusion coefficient for the Henry's law population was related to the kinetic diameter of the gas. The infinite dilution, Henry's law, and Langmuir diffusion coefficients were related to the free volume of the polymer. The work suggests a means for order‐of‐magnitude estimation of diffusion coefficients from polymer density and molecular

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260401

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractEquilibrium gas sorption measurements for CO2, CH4, and N2were made with three polymers based on bisphenol‐A, namely a polyhydroxyether, a polyetherimide, and a polyarylate. These data plus previous results for two other bisphenol‐A polymers, polycarhonate and polysulfone, were analyzed using the dual‐mode sorption model and the more recent gas‐polymer‐matrix model. The models were compared on the basis of physical interpretations of the resulting parameters. The Langmuir capacity from the dual‐model model was related to the unrelaxed volume of the glassy polymer. The Henry's law sorption parameter from the dual‐mode model was related to the internal pressure of the polymer and to its tensile stress at yield. The work suggests a means for estimation of gas sorption levels from thermal and mechanical properties o

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260402

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA dynamic small‐angle x‐ray scattering system (DSAXS) for the study of materials deformation and relaxation has been developed in the National Center for Small‐Angle Scattering Research, Oak Ridge National Laboratory (NCSASR‐ORNL), in collaboration with Polymer Research Institute of the University of Massachusetts. The principles of DSAXS are outlined, including experimental procedures such as π‐sector and Fourier expansion techniques. A few important functions required for studies of crystalline polymers, namely, static and dynamic lamellar orientation, dynamic lamellar separation, dynamic invariant function, etc., are defined. The hardware and software of the DSAXS system are described. Some preliminary results obtained for a spherulitic high‐density polyethylene by π‐sector technique and for a row‐nucleated polybutene‐1 by Fourier expansion techniques are demonstrated to evaluate the perfor

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260403

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe static and dynamic structures of butanediol diglycidal ether (BDGE) cured with phthalic anhydride are determined using high resolution solid state13C‐NMR. Crosslink and junction point resonances are identified by varying the cure state and confirmed using chemical shift calculations. As crosslinking increases, the variety of structures creates a broad distribution of chemical shifts and thus a single broad resonance for the crosslink region. The crosslinking also influences the dynamic structures of the network as indiated by the changes in the various relaxation times of the system. Motions in both the megahertz and kilohertz regimes decrease with cure due to the increasing motional restrictions imposed by the crosslink

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260404

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe solubility behavior of poly(vinylidene fluoride) (PVDF) in about 50 liquids was investigated. The results were input to a computer program to obtain a three‐dimensional representation of the polymer solubility region in the Hansen space; the values of dispersion, hydrogen bonding, and polar components of the total solubility parameter δt,Pwere evaluated. The latter was also estimated from limiting viscosity number data in the eight solvents found. Both experimental methods gave δt,Pvalues in very good agreement. Comparisons among our findings, the literature, and calculated results are discus

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260405

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractPoly(aryl‐ether‐ether‐ketone) (PEEK) films and rods have been solid‐state extruded at 154 and 310°C, respectively. The crystal orientation functions, melting behavior, density, and tensile properties of the drawn PEEK films (EDR ≤ 3.7) and rods (EDR ≤ 5.5) have been measured. As extrusion draw ratio (EDR) was increased, thec‐axis orientation function, melting temperature, and tensile modulus and strength increased. Moduli up to 6.5 GPa and the strengths up to 600 MPa, 3 and 6 times the values of undrawn films, respectively, were obtained for the drawn films. The thermal expansivities along (α‖) and perpendicular (α⟂) to the draw direction of PEEK rods were measured from −40 to +10°C. As EDR was increased, α⟂increased, but α‖decreased. At EDRs of 3.8 and 5.5, α‖even exhibited negative values (about −5 × 10−6°C−1), probably due to reversibl

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260406

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractBlending brittle polymer particles in a ductile polymer matrix is a new way to obtain toughened plastics. Although the nylon‐6/poly(acrylonitrile‐co‐styrene) (SAN) system is a ductile/brittle combination, the blend does not result in a toughened plastic. We have investigated the effect of adding a small amount of a third component, poly(styrene‐co‐maleic anhydride) (SMA), to the nylon/SAN system. SMA significantly improves the tensile and impact strength of the blend. Morphological observations indicate a finer dispersion of the SAN particles when SMA is present in the blend. The improved dispersion is attributed to the formation of nylon‐SMA graft copolymer, and infrared analysis supports this supposition. That is, a “compatibilizer” seems to be produced during melt mixing of the ternary system. The role that the compatibilizer plays in improving the stress transfer in the two‐phase system and its potential to induce a brittle‐ductile transition of the glassy SAN particles are considered to explain the t

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260407

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractX‐ray diffraction and differential scanning calorimetry studies of die‐drawn polypropylene have indicated the presence of a crystalline structure which does not identify with any of the usual crystallographic forms and has a melting point slightly below that of the monoclinic a form. The melting of this structure is stress sensitive and shows the superheating effect expected from the melting of an extended chain structure, whose chain ends are physically constrained. It is postulated that this structure bridges the gaps between adjacent monoclinic crystal blocks and provides the framework necessary to maintain mechanical stability at temperatures well above that of the glass transition. Moreover, together with taut tie molecules, this structure is considered to be the main source of the high material stiffn

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260408

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractDifference spectra of blends ofcis‐1,4‐polyisoprene and atactic poly(vinylethylene), obtained from the measured FTIR spectra of the pure components and the blends, indicate that mixing of these polymers is not accompanied by any specific chemical interactions. Miscibility in this system arises solely due to the small combinatorial entropy of mixing. The conformation and configuration of the polymer chains in the blends are, therefore, identical to those in the pure melts. As a consequence it was found that the entanglement density of the blends varied monotonically with composition. This variation, however, was not in accordance with predictions based simply on the mechanical interaction density. The principle rheological effect of miscible blending was a large change in the monomeric friction coefficient, which arises from the strong dependence of free volume on composition. The zero shear viscosity and the terminal relaxation time of the blends reflected this change in local chain mobility. Empirical relations, which have previously been proposed for the properties of miscible polymer mixtures, were found to be without merit in describing the obtained experimental resu

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260409

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractComputer‐sided design of plastic moldings requires knowledge of their thermal properties, e.g., thermal conductivity λ, under specific conditions. For this purpose, we constructed an apparatus that measures λ and functions within the 80–350°C temperature range and up to a pressure of 500 bar. It was used to carry out experiments on three types of polymers (polyamide, polystyrene, and polypropylene). This paper includes a description of the experimental setup and a presentation of the numerical modeling required for simulating the thermal behavior of tested samples whose measurements have been reported

ISSN:0887-6266    

DOI:10.1002/polb.1988.090260410

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY