Browsing by Author "Bechev C."

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    Characterization of polyester resins solidification process by the method of mechanical impedance
    (2000-01-01) Koleva M.; Bechev C.; Petkov S.
    Mechanical impedance measurements were carried out in order to characterize the curing process of unsaturated polyester resins. A dynamic model of experimental set-up composed of two elements: an inertial (mass of the probe) and viscous element (damper) was constructed. The influence of additive, such as high impact polystyrene, was also investigated. The experimental results obtained show that the method of mechanical impedance spectroscopy has very good resolution when viscosity (or inertial damping) is changed over a relatively wide range.
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    On the characterization by shrinkage forces of as-spun poly(ethylene terephthalate) filaments
    (1995-01-01) Bechev C.
    There are many difficulties in checking the structural pecularities of poly(ethylene terephthalate) (PET) as-spun filaments because of the very low degree of crystallinity of samples obtained under conventional spinning speeds. In the present paper, our attention is concentrated on the new possibilities of applying thermal shrinkage stress diagrams as a method for characterization of as-spun PET filaments. A method giving a new approach for characterization of orientation in as-spun PET filaments is proposed in this paper. © 1995.