Sökning: "free volume"

Visar resultat 1 - 5 av 315 avhandlingar innehållade orden free volume.

  1. 1. Macroscopic Volume and Free Volume of Polymer Blends and Pressure-densified Polymers

    Författare :Marcus Schmidt; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; free-volume theories; refractive index; Lorentz-Lorenz equation; loss tangent; Avrami equation; freezing fractions; copolymers; polymer blends; pressure dilatometry; Tait equation of state; free-volume distributions; pressure-densified polymers; entropy of melting; dynamic-mechanical analysis; positronium; positron annihilation; free volume; cavity size; polymers; bulk modulus; PVT; phase separation; compressibility; thermal expansivity;

    Sammanfattning : The macroscopic volume V as a function of pressure P and temperature T is obtained from PVT measurements. PVT data is sensitive to the state of polymers and changes therein. Moreover, PVT data gives access to the free-volume fraction. LÄS MER

  3. 2. Free Volume and Mesopores in Polymer Nanocomposites

    Författare :Petra Winberg; Centrum för analys och syntes; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemical technology and engineering; Kompositmaterial; Composite materials; Macromolecular chemistry; permeability ; membrane ; positron annihilation ; fumed silica ; clay ; mesopores ; polymer nanocomposites ; free volume ; Kemiteknik och kemisk teknologi; Makromolekylär kemi;

    Sammanfattning : The free volume in polymers is coupled to several important physical properties, such as density, viscosity and gas diffusivity. The physical properties of polymers close to a solid surface have been shown to be significantly perturbed as compared to their bulk state. LÄS MER

  4. 3. Free Volume Determination in Polymers and Polymer Blends

    Författare :Camilla Wästlund; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; positronium formation; crystallinity; polymer blends; inhibition; polymers; free volume; positron annihilation; phase separation; distribution;

    Sammanfattning : The free volume of a polymer, which corresponds to the unoccupied regions accessible to segmental motions, is an important parameter for understanding and predicting many of its characteristic properties. The concept of free volume is the basis for understanding the molecular mobility in polymers. LÄS MER

  5. 4. Water diffusion and free volume in hydrophilic polymers

    Författare :Charlotte Trotzig; Centrum för analys och syntes; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physical chemistry; free volume; self-diffusion; degree of crystallinity; glass transition temperature; tensile storage modulus; surface tension; isotherm; HPMC; PEO; water; triacetin; clay; Macromolecular chemistry; dynamic mechanical analysis; Fysikalisk kemi; differential scanning calorimetry; nuclear magnetic resonance; positron annihilation; Makromolekylär kemi;

    Sammanfattning : During moisture uptake in polymers, the diffusion of the water molecules is believed to occur via unoccupied voids. These voids are called free volume cavities and their sizes are continuously altered when the moisture content in the polymer is enhanced. LÄS MER

  7. 5. Free Volume Depth Profiling at Polymer Surfaces and Interfaces

    Författare :John Algers; Centrum för analys och syntes; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biopolymers; Polymerteknik; Polymer technology; polymer interfaces; polymer surfaces; positron lifetime; free volume;

    Sammanfattning : Pulsed low energy positron beams provide a unique and non-destructive tool to depth probe the free volume of polymers at surfaces and interfaces. Since the employment of low energy positron beams in polymer research is an emerging technique, some focus in this thesis has been on extracting methods and equations needed to interpret the experimental data. LÄS MER