Sökning: "spherulite"

Visar resultat 1 - 5 av 7 avhandlingar innehållade ordet spherulite.

  1. 1. Polypropylene : Morphology, defects and electrical breakdown

    Författare :Sari J. Laihonen; Ulf W. Gedde; Erling Ildsten; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Chemical engineering; polypropylene; poly propylene-stat-ethylene ; crystal structure; morphology; crystallinity; crystallization kinetics; lamellae; spherulite; defect; Kemiteknik; Chemical engineering; Kemiteknik;

    Sammanfattning : Crystal structure, morphology and crystallization kinetics of melt-crystallized polypropylene and poly(propylene-stat-ethylene) fractions with 2.7 to 11.0 mol% of ethylene were studied by differential scanning calorimeter, wide- and small-angle X-ray scattering, polarized light microscopy, transmission electron microscopy and infrared spectroscopy. LÄS MER

  3. 2. Small Molecule Diffusion in Spherulitic Polyethylene : Experimental Results and Simulations

    Författare :Alessandro Mattozzi; Ulf W. Gedde; Alan H. Windle; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diffusion; polyethylene; poly ethylene-co-octene ; free volume; morphology; intermediate phase; spherulite; Monte Carlo simulation; Polymer chemistry; Polymerkemi;

    Sammanfattning : The diffusion of small-molecule penetrants in polyethylene is hindered by impenetrable crystals and by the segmental constraints imposed by the crystals on the penetrable phase. Liquid and vapour n-hexane sorption/desorption measurements were performed on metallocene catalyzed homogenous poly(ethylene-co-octene)s. LÄS MER

  4. 3. Simulations of Semi-Crystalline Polymers and Polymer Composites in order to predict Electrical, Thermal, Mechanical and Diffusion Properties

    Författare :Fritjof Nilsson; Mikael Hedenqvist; Gerhard Goldbeck; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Several novel computer simulation models were developed for predicting electrical, mechanical, thermal and diffusion properties of materials with complex microstructures, such as composites, semi-crystalline polymers and foams. A Monte Carlo model for simulating solvent diffusion through spherulitic semicrystalline polyethylene was developed. LÄS MER

  5. 4. Crystallization in Constrained Polymer Structures : Approaching the Unsolved Problems in Polymer Crystallization

    Författare :Eugenia Núñez; Ulf W. Gedde; Bernard Lotz; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Crystallization; Constrained structures; poly ε–caprolactone ; poly ethylene oxybenzoate .; Polymer chemistry; Polymerkemi;

    Sammanfattning : The knowledge regarding certain issues in polymer crystallization e.g. the possible existence of short–lived mesophases remains inconclusive due to experimental limitations. Polymers undergo chain folding upon crystallization, which introduces some complications that are not found in crystallization of low molar mass materials. LÄS MER

  7. 5. Processing and Properties of Nanostructured Biocomposites

    Författare :Natalia Herrera Vargas; Maria Soledad Peresin; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Trä och bionanokompositer; Wood and Bionanocomposites;

    Sammanfattning : In this work, nanostructured biocomposite fibers and films with cellulose nanofibers (CNF), cellulose nanocrystals (CNC) and chitin nanocrystals (ChNC) were prepared using solutions mixing followed by electrospinning and melt compounding. The main processing challenges for these materials were to find parameters for: 1) fiber alignment in electrospinning, 2) feeding the nanomaterials into the extruder and 3) dispersion and distribution of the nanomaterials in the polymeric matrix. LÄS MER