Oligomeric composition of polyols from fatty acid methyl ester: the effect of ring‐opening reactants of epoxide groups

Commercial availability of fatty acid methyl ester (FAME) from palm oil targeted for biodiesel offers a good feedstock for the production of structurally well‐defined polyols for polyurethane applications. The effect of molecular weight (MW), odd and even carbon numbers, and the linear and branched structure reactants used in the ring‐opening reaction of epoxidized fatty acid methyl ester (E‐FAME) on the properties of polyols was investigated. Conversions of E‐FAME to PolyFAME polyols were confirmed by Fourier transform infrared analysis, oxirane oxygen content, and hydroxyl number. Gel permeation chromatography (GPC) calibrated against polyether polyols as a standard and vapor pressure osmometry were used for MW determination. GPC chromatograms of PolyFAME polyols clearly demonstrated the formation of oligomers during ring‐opening reactions. MW, and odd and even carbon numbers in a structure of linear diols and branched diol used in the syntheses of PolyFAME polyols did not have an effect on crystallinity, glass transition, or melt temperatures measured using Differential scanning calorimetry (DSC). PolyFAME polyols ring‐opened with water, methanol, and 1,2‐propanediol contained secondary hydroxyl groups, whereas PolyFAME polyols ring‐opened with linear diols contained a mixture of primary and secondary hydroxyl groups. It was found that the concentration of primary hydroxyl groups increased significantly by increasing the number of carbons from C2 to C3 in the linear diols. The viscosity of PolyFAME polyols also increased with the MW of linear diols used in the E‐FAME ring‐opening reaction. These findings would be beneficial for formulators in choosing the most cost effective polyols for polyurethane formulations

The Effects of Molecular Architecture on the Rheological and Mechanical Properties of Polymeric Systems

150 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2002.The roles of molecular architecture and end-group functionality on the surface segregation characteristics of branched polymers in blends with commercially available linear polymers were also investigated. In the blends of branched PEIs with polystyrene (PS), the surface migration of PEIs correlates with the changes in their molecular architecture with xAB. However, the effects of configurational entropy, which depends on the molecular architecture, on the surface migration properties of blends are minute in comparison to the enthalpic effects, which are affected by the end-group chemistry of HBPs. Therefore, in order to minimize the interfacial energy, it was observed that the PEI HBPs with lower surface energies than PS segregated to the low energy air-interface, in turn decreasing the surface energy of PS films. On the other hand, higher surface energy PEI HBPs concentrate near the substrate, inhibiting the dewetting of low molecular weight PS. The miscibility of HBPs with linear low density polyethylenes (LLDPE) was found to depend on the length and concentration of alkane end-groups on HBPs. However, the addition of small amounts of PEI HBPs to LLDPEs was found to have a negligible effect on the rheological and processing properties of LLDPEs.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Neutral or National Point of View? A Comparison of Srebrenica Articles across Wikipedia's Language Versions

Wikipedia puts forward that each article gains more quality over time as the process of consensus building results in a neutral point of view. In this study we analyze the same article across different Wikipedia language versions, comparing the article titles, templates, tables of contents, particular content details, talk pages, editors’ names and locations, references and images. For the contentious articles in existence for at least five years, we found that they could be said to express rather national than neutral points of view. In the case in question, the Srebrenica massacre, the Bosnian, Dutch and Serbian article’s respective viewpoints can be attributed to specific sets of editors contributing in their own language version, and the references they employ. Editors of the various language versions participate in the English version, which results in a continually contested article often referred to (in the Serbian) as western. The Serbo-­‐ Croatian strives to be anti-­‐nationalist and apolitical, employing a variety of means to unify the Bosnian and Serbian points of view. In general, the analysis provides footing for studying Wikipedia's language versions as cultural references