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 383 for “"polyurethane"”.
-
Aging of polyurethane foams
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1986.
-
Microbial degradation of polyester polyurethane
During the course of these studies, polyester polyurethane foam has been found to be readily degraded in soil and marine environments. The incorporation of the formulation biocide Vinyzene E.P. reduced the rate and extent of degradation in test material exposed to soil conditions, but was found to …
-
Mechanical degradation of a polyurethane elastomer
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986.
-
Smoldering combustion of flexible polyurethane foam
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1980
-
Variable Frequency Microwave Curing of Polyurethane
… properties. Of these coating compositions, polyurethanes (PURs) were one of the most prevalent. Polyurethanes became possible in 1937 when Otto Bayer developed the diisocyanate polyaddition process [Randall et al, 2002]. Since that time, literally thousands of PUR compositions have been used …
-
Polyurethane nanocomposites as potential drug delivery systems
… of this research was to examine the potential of polyurethane nanocomposites (PUNCs) as controlled drug delivery systems. Specifically, the aims were to investigate the impact of adding a drug on the silicate dispersion and release behaviour of PUNCs, as well as to assess the impact of fabrication …
-
Mechanistic studies in carbene and polyurethane chemistry
<p>The chemistry of benzylchlorocarbene was investigated through both theory and experiment. Photolysis of a phenanthrene-based precursor in an NMR tube gave evidence for isomeric beta-chlorostyrenes but not the alpha-isomer. Computations showed that insertion into the aromatic ring should have a …
-
Polyurethane foams containing renewable castor oil replacement
Polyurethane foams have a wide variety of commercial applications in daily life due to their unique advantages. Traditionally, polyurethane foams are made from petroleum-based polyols and isocyanates. Due to the shortage of fossil resources, renewable biobased materials are studied as alternatives …
-
UV-curable organic-inorganic hybrid polyurethane coating
… explored a series of organic-inorganic hybrid polyurethane oligomers with varying molecular weights and functional groups (acrylate and/or silane) that were cured with a single ultraviolet (UV) trigger but two photo-initiators. Upon UV irradiation, the free-radical initiator initiated a …
-
The Rheology of Anionic Aqueous Polyurethane Dispersions
… being developed to satisfy this need is aqueous polyurethane. Aqueous polyurethane particles have a very unique structure, which lies somewhere between that of polymer chains and traditional colloidal particles. In this fundamental study, we attempt to characterize and understand the flow …
-
Structure-Property Relationships of Flexible Polyurethane Foams
This study examined several features of flexible polyurethane foams from a structure-property perspective. A major part of this dissertation addresses the issue of connectivity of the urea phase and its influence on mechanical and viscoelastic properties of flexible polyurethane foams and their …
-
Mercury Emissions from Polyurethane Flooring in Gymnasiums
… mercury which was used as a catalyst in the polyurethane formulation. Many of these floors now have been found to be releasing mercury vapors into the school gymnasiums, leading to a concern that these mercury concentrations might be elevated enough to cause harmful effects. This paper …
-
Incorporation of lignin copolymers into polyurethane materials
… CEHPL copolymers were incorporated into lignin polyurethane networks (LPUs). The LPUs contained 17 to 43% lignin and showed a single Tg. Both the Tg and the Youngs modulus (MOE) of the LPUs were strongly correlated to the lignin content and type of diisocyanate used to prepare the network. …
-
Structure-Property Relationships of Flexible Polyurethane Foams
… several structure-property features of flexible polyurethane foams that are important aspects of foam production. AFM and WAXS were used to demonstrate the existence, for the first time in typical polyurethane foam systems, of lamellae-like polyurea structures ca. 0.2 mm long and ca 5-10 nm …
-
Preliminary investigation into the cracking of polyurethane
… were determined for a commercially available polyurethane. Multiple specimen geometries were used to “benchmark” the optical methods. Tests have been run to determine the surface effect on a straight front crack. Results of these tests were compared with analytical results and related to LEFM …
-
Morphology of water-blown flexible polyurethane foams
A series of four water-blown flexible polyurethane foams was produced in which the water content was varied from 2 to 5 pph at a constant isocyanate index of 110. A portion of each foam was thermally compression molded into a plaque. The morphology of the foams and plaques was investigated using …
-
Polymeric Nanoparticles for the Modification of Polyurethane Coatings
… strategies and were used as impact modifiers in polyurethane (PU) automotive clearcoats to improve chip resistance. Various narrowly distributed polybutadiene-b-poly(methyl methacrylate) (B-M) block copolymers differing in composition and molecular weights were synthesized and studied with …
-
Size-dependent mechanical properties of single polyurethane nanofibres
… the mechanical properties of single electrospun polyurethane nanofibres are investigated using atomic force microscopy. It was found that the elastic modulus varies significantly with a change in fibre diameter and multiple experiments were performed to confirm this observation. An attempt was …
-
Revision-Polyurethane-Graphene Nanocomposites for Corrosion-Resistant Coatings
… ease of application could be greatly improved. Polyurethanes are commonly used as binders for coatings, so the fabrication and characterization of polyurethane-graphene nanocomposites for use in anticorrosive coatings was chosen as the premise for this project.</p> <p>A number of different …
-
Initiation of smoldering combustion in flexible polyurethane foams
Thesis (Mech.E)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.
Page 1 of 20