| 1. |
- Wikant, A. W., et al.
(författare)
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Suboptimal light curing and direct exposure to water of two contemporary composites: degree of conversion, sorption, solubility, and Knoop hardness
- 2020
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Ingår i: European Journal of Oral Sciences. - : Wiley. - 0909-8836 .- 1600-0722. ; 128:4, s. 345-353
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Tidskriftsartikel (refereegranskat)abstract
- The water sorption and solubility of two polymer resin-based dental composite materials were assessed in order to evaluate the effects of immediate post-cure water exposure on the water sensitivity of the composites. Each material was tested with two different light curing setups. The radiant exposure of the two curing setups differed by a factor of 5. After exposure to water and subsequent drying, the Knoop surface hardness was measured. The change in the degree of conversion in both water and air storage medium within the first 24 h after curing was monitored by Raman spectroscopy. No significant differences in the degree of conversion were detected 24 h after curing. Samples exposed to the lower irradiation dose showed higher solubility and a lower surface hardness than the samples exposed to the higher irradiation dose. Early exposure to water did not cause detectable differences in the ongoing polymerization process. Increase in radiant exposure reduced the fraction of unbound constituents and increased the crosslink density, thereby reducing the plasticity of the material.
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| 2. |
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| 3. |
- Gedde, Ulf W, et al.
(författare)
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Applied polymer science
- 2021. - 1
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This companion volume to "Fundamental Polymer Science" (Gedde and Hedenqvist, 2019) offers detailed insights from leading practitioners into experimental methods, simulation and modelling, mechanical and transport properties, processing, and sustainability issues. Separate chapters are devoted to thermal analysis, microscopy, spectroscopy, scattering methods, and chromatography. Special problems and pitfalls related to the study of polymers are addressed. Careful editing for consistency and cross-referencing among the chapters, high-quality graphics, worked-out examples, and numerous references to the specialist literature make "Applied Polymer Science" an essential reference for advanced students and practicing chemists, physicists, and engineers who want to solve problems with the use of polymeric materials.
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| 4. |
- Gedde, Ulf W
(författare)
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Essential Classical Thermodynamics
- 2020
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Ingår i: SpringerBriefs in Physics. - Cham : Springer Nature. ; , s. 1-101
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Gedde, Ulf W, et al.
(författare)
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Mass and charge transport in polyethylene – Structure, morphology and properties
- 2023
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Ingår i: Polymer. - : Elsevier BV. - 0032-3861 .- 1873-2291. ; 266
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Forskningsöversikt (refereegranskat)abstract
- Polyethylene is a model for semicrystalline polymers that provides the option to vary crystallinity within wide ranges and then to establish relationships between structure and mass and charge transport properties. Three different topics are covered: diffusion of n-hexane in polyethylene, extensive penetrant uptake kinetics, swelling and the design of a novel sensor, and finally electrical conduction in polyethylene, a field important to modern distribution of electric power (HVDC). This feature article presents past and ongoing studies at KTH Royal Institute of Technology using a variety of experimental methods and computer-aided simulation and modelling.
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| 6. |
- Gubanski, Stanislaw, 1950, et al.
(författare)
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Polymer composition and electrical devices
- 2021
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- The invention relates to a polymer composition comprising a polymer (a) and a nanoparticle filler (b), wherein the polymer composition comprises a volume percentage (vol. %) of the nanoparticle filler (b), which is Dvol vol. %, and has a center-to-center average distance, in nanometer (nm), in two dimensions (2D) and with a free radius, from one nanoparticle to its nearest nanoparticle neighbour, which is R1st nm, and wherein the polymer composition shows a dependency between said center-to-center average distance to nearest neighbour, R1st, and said volume percentage, Dvol vol. %, which is R1st=E/(Dvol+0.3)+F, wherein Dvol1≤Dvol≤Dvol2, E1≤E≤E2, F1≤F≤F2, and Dvol1 is 0.010 and Dvol2 is 4.4, E1 is 100 and E2 is 280, and F1 is 50 and F2 is 140; an electrical device, e.g. a power cable; and a process for producing an electrical device.
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| 7. |
- Nilsson, Fritjof, Docent, 1978-, et al.
(författare)
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Nanocomposites and polyethylene blends: two potentially synergistic strategies for HVDC insulation materials with ultra-low electrical conductivity
- 2021
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Ingår i: Composites Part B: Engineering. - : Elsevier BV. - 1359-8368 .- 1879-1069. ; 204
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Tidskriftsartikel (refereegranskat)abstract
- Among the various requirements that high voltage direct current (HVDC) insulation materials need to satisfy, sufficiently low electrical conductivity is one of the most important. The leading commercial HVDC insulation material is currently an exceptionally clean cross-linked low-density polyethylene (XLPE). Previous studies have reported that the DC-conductivity of low-density polyethylene (LDPE) can be markedly reduced either by including a fraction of high-density polyethylene (HDPE) or by adding a small amount of a well dispersed, semiconducting nanofiller such as Al2O3 coated with a silane. This study demonstrates that by combining these two strategies a synergistic effect can be achieved, resulting in an insulation material with an ultra-low electrical conductivity. The addition of both HDPE and C8–Al2O3 nanoparticles to LDPE resulted in ultra-insulating nanocomposites with a conductivity around 500 times lower than of the neat LDPE at an electric field of 32 kV/mm and 60–90 °C. The new nanocomposite is thus a promising material regarding the electrical conductivity and it can be further optimized since the polyethylene blend and the nanoparticles can be improved independently.
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