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Showing 1 to 20 of 42 for “"Chain scission"”.
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The Effects of Electron Radiation on the Glass Transition Temperature of a Polyetherimide
… for a dose of 100 MGy. The cross-link and chain scission densities in the irradiated PEI were determined using infrared spectroscopy. The cross-link density increased with dose for all doses investigated. The chain scission density increased with dose for doses up to 75 MGy, but was lower …
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Mechanically mediated trithiocarbonate addition to commodity polymers for a more circular economy
… to be. Great levels of mechanical force cause chain-scission and lower product value while simultaneously only working once, maybe twice before the material is useless. Studies to harness the chain-scission with functional groups have proved possible but limited. This study shows the effect of …
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The effects of ionising radiation on polypropylene
… are used to measure the radiationyield for chain scission G (s). Irradiation at room temperature causes significantly more chain scission than at 195K. Additional chain scission occurs on storage following irradiation at 195 K. Free radical concentrations are determined by electron spin …
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Oxidation and stabilisation chemistry of metallocene-based polyolefins during melt processing
… can be synthesized with exactly controlled short chain branches and stereo-regular microstructure. The unique properties of these polymers have led to their applications in many areas. As a result, it is important to have a good understanding of the oxidation mechanism of m-LLDPE during melt …
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An investigation of the factors affecting the degradation of cellulose acetate artefacts in museum collections
… of oxalate in degraded samples indicates chain scission occurring and high levels of acetate indicate deacetylation is occurring. Non-destructive and destructive sampling for ion chromatography have been used to explore if this is a viable screening process to identify artefacts in the …
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Functionalisation of polymers: reactive processing, structure and performance characteristics
… of GMA and the crosslinking of NR or chain scission of PP were identified as the main side reactions that competed with the desired grafting reaction in the polymers. At high concentrations of the peroxide T-101 (>0.02 mr) cross linking of NR and chain scission of PP became dominant …
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Ionic liquids as additives for biodegradable polyactic acid
… from rate constants calculated from random chain scission statistics and activation energies from thermogravimetric analysis, and accelerated its hydrolytic degradation, but to a lesser extent than the decanoate based IL. The catalytic role of the decanoate anion in hydrolytic degradation …
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Model Development and Parameter Estimation for Styrene Polymerization
… at 100 °C. Simulations are used to show that chain-end degradation reactions are not important in the temperature range of interest. The model is then extended to include industrially-relevant dicumyl peroxide and biphenyl peroxide chemical initiation. Additional peroxide-induced mid-chain …
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The Development of a Diesel Injector Experiment to Study the Combined Effects of Oxidation and Shear on Lubricating Oil Viscosity
… high molecular weight compounds is evidence of chain scission. The results show that cycling a 128 ml volume of oil 12 times has no effect on fresh, unaltered lubricating oils, even at low oxidation times up until 48 hours. However, the results show that heavily degraded lubricating oils near …
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Ultrasonically Aided Extrusion of Rubber Nanocomposites and Rubber Blends
… their properties, due to the dominant effect of chain scission. The ultrasonic treatment of SBR/CB and SBR/CNT nanocomposites led to a decrease of the electrical percolation threshold of their vulcanizates due to the ultrasonically induced uneven distribution of fillers as observed by the optical …
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Uranium Enrichment Signatures of Fluorinated Epoxy
… glass transition temperature is likely due to chain scission, which degrades the polymer chains and results in less energy being needed to allow movement in the molecular structure. The change in 𝑇𝑔 can then be related to uranium enrichment and production. This potentially allows a way to fill …
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Analytical studies of the degradation of cellulose nitrate artefacts
… in degraded artefacts also indicated that chain scission is occurring during deterioration. Later work using gel permeation chromatography confirmed this. Work has also involved the use of accelerated ageing tests to study the effect of sulphate in the degradation and also the influence of …
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Constitutive equations and failure criteria for amorphous polymeric solids
… with large plastic stretches and subsequent chain scission and a brittle mode of fracture.
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Degradation studies on recycled Polyethylene terephthalate
… ordered structure after the UV radiation due to chain scission by Norrish Type I and II mechanism. Carboxylic acid is formed as a result of degradation and increases with the extent of UV exposure in both types of weathering, the formation of carboxylic acid by Norrish II is dominated over …
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Radiation induced degradation of elastomers.
… PDMS elastomer degraded thermally by hydrolytic scission of the main chain and chain reformation by condensation of the silanol chain end groups. However,predominant chain reformation was observed during thermal degradation studies and it was believed that this was a consequence of the …
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The thermal degradation of polystyrene.
… of peroxidic links incorporated into the polymer chains. However such links do reduce the thermal stability of the polymer. The degradation pattern of polystyrenes containing initiator fragments at the chain-ends is different from that of thermally-initiated or anionic samples. The results are …
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Phase separation spinning of porous polypropylene hollow fibers
… pertinent literature led to the conclusion that chain scission of the polymer molecules was being catalyzed by contact of the polymer with certain metals (e.g. copper and iron) during solution preparation. However, with the use of a non-metallic mixing vessel and stirrer, the use of a nitrogen …
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The effects of space radiation on a chemically modified graphite- epoxy composite material
… Irradiation was found to cause crosslinking and chain scission in the polymer. The latter produced low molecular weight products which plasticize the material at elevated temperatures and cause apparent material stiffening at low stresses at room temperature.
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Chemistry of the Degradation of Vinyl Polymers to give Carbon Fibre Precursors
… of condensed pyrinoid and 4«pyridone sequences. Chain scission also occurs but hydrogen bonding through the 4=pyridone species prevents loss of orientation and damage to the fibre structure.
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Mid-IR Imaging and Multivariate Analysis of Dynamic Processes in Pharmaceutically Relevant Microparticles
… chromatography (GPC) results indicate a chain scission based degradation in PLGA upon γ exposure. The distribution of lactic acid is probed with IR during the hydrolysis of a PLA microparticle for the first time, showing a diffusional pathway from the degrading microparticle outwards into …
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