Hannover, Tierärztl. Hochsch., Diss., 2002. / Computerdatei im Fernzugriff.

No description available.

Potsdam, Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Potsdam, Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Potsdam, University, Diss., 2003.

Mainz, Univ, Diss., 2001.

Tierärztl. Hochsch., Diss., 2004--Hannover.

Please read the abstract (summary) in the section 00front of this document. / Thesis (PhD)--University of Pretoria, 2011. / Food Science / unrestricted

A liquid foaming technology was developed to produce bio-foams for packaging applications. Liquid foaming consists in the transformation of a liquid foamed solution into a porous solid polymer through liquid removal. Five bio-based liquid foaming formulations systems were explored in this research: starch-PVA-calcium sulfate, starch-gelatine, gelatine hydrogel, gelatinecomposites and hydrogel alternatives to gelatine. Gelatine hydrogel-composite foams secondary materials included bio-mass powders from agriculture waste, expanded vermiculite particles, silica aero-gel powders and honeycomb sandwich panels. The hydrogel foams alternative to gelatine were based on agar and gellan gum as main biopolymers. The feasibility of each formulation system was explored, and the key parameters of formulation and process conditions were identified. The role of different formulation (e.g. biopolymer content, gelatine strength, surfactant type and content, among others) and processing (e.g. expansion ratio, processing temperature and drying process, among others) factors on foaming and drying behaviour of the liquid foam, and the impact on foam structure and properties (density, drying shrinkage and mechanical, thermal and acoustic properties) of the solid foams were investigated. Hydrogel-foams with comparable densities and thermal conductivity to conventional polymeric foams were produced. Gelatine foams made with both surfactants "A" and C2 exhibited desirable properties for being a strong alternative to conventional plastic foams. Low densities (< 20 kg/m3), thermal conductivity (≈0.039 W/k·m), and relatively low shrinkage level were achieved. Production upscale research would need to consider drying process optimization for drying time reduction and drying shrinkage minimization.

In Tissue Engineering, scaffolds composed of natural polymers often show a distinct lack in stability. The natural polymer gelatin is highly fragile under physiological conditions, nevertheless displaying a broad variety of favorable properties. The aim of this study was to fabricate electrospun gelatin nanofibers, in situ functionalized and stabilized during the spinning process with highly reactive star polymer NCO-sP(EO-stat-PO) (“sPEG”). A spinning protocol for homogenous, non-beaded, 500 to 1000 nm thick nanofibers from different ratios of gelatin and sPEG was successfully established. Fibers were subsequently characterized and tested with SEM imaging, tensile tests, water incubation, FTIR, EDX, and cell culture. It was shown that adding sPEG during the spinning process leads to an increase in visible fiber crosslinking, mechanical stability, and stability in water. The nanofibers were further shown to be biocompatible in cell culture with RAW 264.7 macrophages. / Tissue Engineering Scaffolds aus natürlichen Polymeren zeigen häufig mangelnde Stabilität, insbesondere unter physiologischen Bedingungen. Das natürliche Polymer Gelatine besitzt einige sehr vorteilhafte Eigenschaften für die Anwendung bei der Produktion künstlicher Körpergewebe. Beim Einsatz im menschlichen Organismus ist die Gelatine durch ihre Wasserlöslichkeit höchst fragil. Das Ziel dieser Arbeit war die Herstellung von Nanofaser-Scaffolds aus Gelatine mittels Elektrospinning und deren in situ Stabilisierung durch das Sternpolymer NCO-sP(EO-stat-PO) („sPEG“). Zunächst wurde ein Spinningprotokoll zur Fabrikation homogener, glatter, 500 bis 1000 nm dicker Nanofasern in verschiedenen Verhältnissen von Gelatine und sPEG erarbeitet. Mittels REM Bildgebung, Zugversuchen, Wasserinkubationsversuchen, FTIR, EDX und Zellkultur wurden die Fasern untersucht und charakterisiert. Es konnte gezeigt werden, dass die Zugabe von sPEG während des Spinningprozesses zu einer sichtbaren Quervernetzung der Fasern, sowie zu einem Anstieg der mechanischen Festigkeit und der Wasserstabilität führt. Des Weiteren wurde die Biokompatibilität der Nanofasern in der Zellkultur mit RAW 264.7 Makrophagen belegt.