Sökning: "Glassy polymer"

Visar resultat 1 - 5 av 20 avhandlingar innehållade orden Glassy polymer.

  1. 1. Evaluating Cathode Catalysts in the Polymer Electrolyte Fuel Cell

    Författare :Henrik Ekström; Göran Lindbergh; Anders Lundblad; Anthony Kucernak; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; fuel cell; humidity; model electrodes; Nafion; oxygen reduction; PEMFC; platinum; polymer electrolyte; thin film evaporation; titanium oxide; bränslecell; fuktighet; modellelektroder; Nafion; PEMFC; platina; polymerelektrolyt; syrereduktion; tunnfilmsförångning; titanoxid; Electrochemistry; Elektrokemi;

    Sammanfattning : The polymer electrolyte membrane fuel cell (PEMFC) converts the chemical energy of hydrogen and oxygen (air) into usable electrical energy. At the cathode (the positive electrode), a considerable amount of platinum is generally required to catalyse the sluggish oxygen reduction reaction (ORR). LÄS MER

  3. 2. Glass Transition Dynamics in Soft Condensed Matter

    Författare :Johan Mattsson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; polymer films; beta relaxation; hydrogen bond; glass transition; polymer dynamics; cooperativity; confinement; IXS; Brillouin light scattering; excess wing;

    Sammanfattning : Materials of very different character, ranging from polymers to metals can be made into glasses. The structural and dynamical properties of glass-forming materials are fundamentally different from those found in crystals. Hence, glassy materials exhibit unique characteristics, which make them suitable for a wide range of applications. LÄS MER

  4. 3. 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

  5. 4. Transverse failure initiation in polymer composites

    Författare :Leif Asp; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Polymeric Composite Materials; Polymera konstruktionsmaterial;

    Sammanfattning : Transverse failure is one of the most important failure modes in polymer composites. The phenomenon often causes the first deviations from nonlinear laminate behavior. Also, in pressure vessels and pipes, fluid leakage through a path of transverse cracks is often the limiting design criterion. LÄS MER

  7. 5. Mechanical Properties and Deformation Behaviour of Polymer Materials during Nanosectioning : Characterisation and Modelling

    Författare :Fengzhen Sun; Kristofer Gamstedt; Kai Cheng; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Nanosectioning; Fracture toughness; Adiabatic shearing; Shear band; Nanosectioning; Glassy polymer; Nanocomposite;

    Sammanfattning : Research in local fracture processes and micro-machining of polymers and polymer-based composites has attracted increasing attention, in development of composite materials and miniaturisation of polymer components. In this thesis, sectioning (machining) of a glassy polymer and a carbon nanotube based composite at the nanoscale was performed by an instrumented ultramicrotome. LÄS MER