Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 92 for “"polyurethanes"”.
-
Biodegradation and Properties of Phosphated Polyurethanes
… of biodegradable polymers. Three standard polyurethanes with varying soft:hard segment ratios were synthesised and characterized via FTIR, 1H NMR and GPC. Phosphate-functionalised polyurethanes (GP-PU) with equivalent soft:hard segment ratios were also synthesised and characterised. The …
-
Cure studies of network-forming polyurethanes
… make them good candidates for the manufacture of polyurethanes. The cure characteristics of hydroxypropyl-cellulose and hydroxypropyl lignin (HPC and HPL, respectively) with polymeric methylene diphenyl diisocyanate (MDI) was studied via dynamic mechanical thermal analysis (DMTA). HPC/MDI and …
-
Structure-property relationships in polyurethanes from lignin
… in the synthesis of the thermosetting polyurethanes. The investigation primarily addresses the effect of synthesis variables and soft segment incorporation on the thermal and mechanical properties. The first part of the study examined the effect of lignin type, of diisocyanate type and …
-
Self-amplifying degradable polyurethanes and their upcycling application
Polyurethanes are a type of polymeric material that have found use in applications, including in paints, coatings, elastomers, and insulating foams. Polyurethanes can demonstrate thermoplastic, thermoset, or elastomeric properties depending on their formulation. Because polyurethanes are used in …
-
Polydimethylsiloxane Modification of Segmented Thermoplastic Polyurethanes and Polyureas
… the polyurethane control and the PDMS modified polyurethanes, but the later displayed increased char yield in air with increased PDMS concentration. Quantitative measurements of the fire resistance of the modified polyurethanes by cone calorimetry showed that the peak heat release rate of the …
-
Characterization of graphite polyurethanes composite from renewable based oils
This thesis aims to evaluate the characterization of graphite polyurethane composite from renewable based oils. Virgin cooking oil (VCO) as a renewable resource is the main substance in fabricating the renewable polyurethane (PU) and its graphite as called polyurethane graphite (PG). The …
-
Multiblock Thermoplastic Polyurethanes For Biomedical and Shape Memory Applications
<p>Polyurethanes are a class of polymers that are capable of tailoring the overall polymer structure and thus final properties by many factors. The great potential in tailoring polymer structures imparts PUs unique mechanical properties and good cytocompatibility, which make them good candidates …
-
Isocyanate-derived organic aerogels: polyurethanes, polyureas, polyamides and polyimides
… isocyanates through reaction with (a) alcohols (polyurethanes); (b) water (polyureas); (c) carboxylic acids (polyamides); and, (d) acid anhydrides (polyimides). All processes are invariably single-step, one-pot and take place at room temperature or slightly elevated temperatures. The resulting …
-
Investigations of catalyst behaviour in the formation of polyurethanes
The mechanism of urethane formation using organotin carboxylate and titanium acetylacetonate chelate catalysts is investigated using computational and experimental methods. In this work, computational chemistry and statistical experimental design were selected as the computational modelling …
-
Segmented polyurethanes containing diacetylene units in multiple molecular environments
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996.
-
Application-oriented development of thermoplastic polyurethanes with shape memory properties
… a high degree of functionality. Thermoplastic polyurethanes (TPUs) can exhibit such shape memory properties. This is due to their copolymer structure and phase-segregated morphology, which impart shape memory characteristics to the TPUs. TPUs consist of a soft segment (SS) and a hard segment …
-
Design, synthesis and characterization of side chain liquid crystal segmented polyurethanes
Side chain liquid crystal polyurethanes are liquid crystal elastomers with the potential to couple mechanical stress fields with optical changes brought on by liquid crystal alignment. These materials excite interest because they are the first thermoplastic liquid crystal elastomers (LCTPEs) that …
-
Rheology of Filled and Unfilled Polyurethanes for Reactive Extrusion-Based Applications
Additive manufacturing (AM) is a form of production that directly processes raw materials into their final form by building the product in a layer-by-layer fashion. Numerous types of AM exist, including selective laser sintering (SLS) of polymeric powders, vat polymerization (VP) of low viscosity …
-
Advancing Step-Growth Polymers: Novel Macromolecular Design and Electrostatic Interactions in Polyesters and Polyurethanes
… of poly(ethylene glycol)-based, cationic polyurethanes with pendant phosphoniums in the hard segments (HS). Aqueous size exclusion chromatography (SEC) confirmed the charged polyurethanes, which varied the phosphonium alkyl substituent length (ethyl and butyl) and cationic HS content (25, …
-
Effects of Polybenzoxazine on Properties of Shape-Memory Polyurethanes with Glassy and Crystalline Soft Segments
… by the glassy or crystalline soft domain of polyurethanes (PU) with respectively glass transition temperature (Tg) or melting temperature (Tm). The study exploited the miscibility of the benzoxazine monomer with the PU prepolymer. The benzoxazine monomer was polymerized into PB after PU …
Page 1 of 5