No abstract available

[en] A method was developed for calculating the molecular weight distribution of a polymer melt from its rheology, specifically dynamic or relaxation moduli data. The molecular weight range covered by the solution is specified by the source data or the entanglement molecular weight, and the blending rule consistent with double reptation was used. The solutions for both the discrete relaxation spectrum and final molecular weight distribution were obtained by Tikhonov regularization with the molecular weight distribution solution being particularly sensitive to the value of the regularization parameter λ_R used in the calculations. Here, λ_R was varied and patterns developed between the most appropriate values for an acceptable solution and the polydispersity of the corresponding samples. For relatively low λ_R values, the algorithm was precise enough to resolve individual components in nearly monodisperse, binary blend, and multimodal systems with as many as 13 components. Results for commercial materials of varying polydispersity generally agreed with the molecular weight distributions from chromatography with slightly higher λ_R values, particularly the location of peak molecular weights. Commercial polyolefins, which required still higher λ_R values, gave consistently poorer results due to restricted molecular weight ranges allowed by the source data

No abstract available

No abstract available

[en] The design thermoplastic-film recording camera and its performance for holography of extended objects are reported. Special corona geometry and accurate control of development heat by constant current heating and high resolution measurement of the develop temperature make easy recording of reproducible, large aperture holograms possible. The experimental results give the transfer characteristics, the diffraction efficiency characteristics and the spatial frequency response. (orig.)

[en] Conductive membranes show many benefits including fouling reduction for feeds containing ionic species. These membranes may be prepared either by conductive polymers or coating of the surfaces of non-conductive membranes with conductive polymer. In this research, the commercial micro filtration GVHP membrane manufactured from PVDF was coated with poly pyrrole using two different techniques. The conductivity of the prepared membranes was measured. In this paper, effects of various factors including concentration of the solutions, oxidizing agents, time for leaving the support in the solutions, support type and temperature on membrane conductivity were investigated

[en] Tests were performed on small-size elastomer specimens and scale-size laminated elastomeric bearings to correlate the material properties in shear between the two types of tests. An objective of the tests was to see how well the material properties that were determined from specimen tests could predict the response of scale-size laminated elastomeric bearings. Another objective was to compare the results of specimen test and scale-size bearing test conducted by different testing organizations. A comparison between the test results from different organizations on small specimens showed very good agreement. In contrast, the correlation of scale-size bearing tests showed differences in bearing stiffness

[en] This study was performed to localize the high frequency ultrasonic transducers using polyvinylidene fluoride (PVDF) and polyvinylidene fluoride trifluorethylene (copolymer). The characteristics of fabricated high frequency transducers such as beam diameter, frequency spectrum and pressure level of the first echo signal from the specimen in the water were analyzed and compared. As test specimens, the steel balls with 0.5 mm and 1.5 mm diameter and steel block with 30 mm thick were used. The high frequency detection field of a transducer was affected by increasing the length of cable between high frequency transducer and ultrasonic pulser/receiver. As the size of a specimen increased, the high frequency detection field decreased and the amplitude of a reflection signal increased. The pressure level of copolymer tranduser was found to be higher than that of PVDF transducer but the high frequency detection field of PVDF was wider than that of copolymer.

No abstract available

[en] We study the conformational behavior in a plane of a comb copolymer molecule, consisting of a semiflexible backbone and rigid side chains interacting via a van der Waals potential. Using a mean-field approach, two different regimes are distinguished depending on the strength of the attraction between the side chains. In the weak attraction limit the side chains are oriented preferably perpendicular to the backbone. The persistence length λ of the comb copolymer molecule scales as the second power of the length of the side chain L: λ∝L². In the strong attraction limit all side chains become strongly tilted and the persistence length scales as λ∝L⁴. The nonlinear bending regime is also studied and characterized by a change in structure and a decreasing moment of bending force as a function of curvature, i.e., bending becomes easier