| 1. |
- Gupta, Bhuvanesh, et al.
(författare)
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Radiation-induced graft modification of knitted poly(ethylene terephthalate) fabric for collagen immobilization
- 2007
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Ingår i: Polymers for Advanced Technologies. - : Wiley. - 1042-7147 .- 1099-1581. ; 18:4, s. 281-285
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Tidskriftsartikel (refereegranskat)abstract
- Radiation-induced graft co-polymerization of methacrylic acid and N-vinyl-2-pyrrolidone mixture from poly(ethylene terephthalate) knitted fabrics were conducted using a preirradiation method. The influence of the graft conditions, such as irradiation dose, reaction time, monomer concentration and temperature on the degree of grafting was determined. It was found that there is a limiting irradiation dose of 40 kGy above which the degree of grafting does not increase. An increase in the monomer concentration from 20 to 40% and an increase in temperature from 60 to 80°C gave a higher initial rate of grafting as well as higher equilibrium graft levels. The characterization of the fabric was carried out by attenuated total reflectance infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The grafted fabric surface, carrying negatively charged carboxylate ions, was shown to attract collagen, being positively charged to provide bioreceptive surfaces.
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| 2. |
- Mohammed-Ziegler, Ildiko, et al.
(författare)
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Wettability and spectroscopic characterization of silylated wood samples
- 2006
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Ingår i: Polymers for Advanced Technologies. - : Wiley. - 1042-7147 .- 1099-1581. ; 17:11-12, s. 932-939
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Tidskriftsartikel (refereegranskat)abstract
- Surfaces of three European wood species (namely, English oak, Hungarian oak, and Scots pine) and two tropical wood species (namely, teak and cloves) were silylated with dichlorodimethylsilane (DDS), dichlorodiphenylsilane (DPS) and octadecyltrichlorosilane (OTS) in the first step, and with chlorotrimethylsilane (CTMS) as a monofunctional reagent in a second step. Attenuated total reflection-Fourier transform infrared (ATR-FT-IR) and electron spectroscopy for chemical analysis (ESCA) measurements were performed in order to characterize the surface composition of the treated samples. The progress of surface modification was also monitored by contact angle measurements of different test liquids (water, formamide and diiodomethane). The water contact angles were found to be in the range of 80� to 145�. The most hydrophobic surface was obtained by two-step silylation by OTS and CTMS (water contact angles were between 131� and 140�). Interestingly, the hydrophobicity of DDS-treated samples showed a significant decrease after additional silylation by CTMS. The surface free energy values were evaluated in terms of the Lifshitz-van der Waals/acid-base theory. The results obtained by the surface analytical methods (i.e. FT-IR and ESCA measurements) were compared with the contact angle data. These results suggest that in the case of DDS-treated samples, CTMS molecules substitute partly the DDS molecules, thus only physisorption of the silylating agents is supposed at room temperature.
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| 3. |
- Nederberg, Fredrik, et al.
(författare)
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Induced surface migration of biodegradable phosphoryl choline functional poly(trimethylene carbonate)
- 2005
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Ingår i: Polymers for Advanced Technologies. - : Wiley. - 1042-7147 .- 1099-1581. ; 16:2-3, s. 108-112
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Tidskriftsartikel (refereegranskat)abstract
- In this article the synthesis, characterization, and surface orientation property of a biodegradable and biomimetic polymer are introduced. This phospholipid mimetic biodegradable polymer is synthesized by combining poly(trimethylene carbonate) (PTMC) with zwitterionic phosphoryl choline (PC) in a three-step synthesis. Since the glass transition of the polymer is around -20°C this material holds elastic properties at ambient temperature. This characteristic was used to induce surface enrichment as the polar PC end-group was enriched at the surface while treating films in an aqueous media. Film properties of the PTMC-PC amphiphile product revealed surface enrichment behavior, as the polar PC head group is oriented towards the surface. In addition, surface depletion of polar PC groups was the result when treating films under vacuum. This was observed by both contact angle measurements and electron spectroscopy for chemical analysis
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| 4. |
- Zammarano, Mauro, et al.
(författare)
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Flammability reduction of flexible polyurethane foams via carbon nanofiber network formation
- 2008
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Ingår i: Polymers for Advanced Technologies. - : Wiley. - 1042-7147 .- 1099-1581. ; 19:6, s. 588-595
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Tidskriftsartikel (refereegranskat)abstract
- Untreated polyurethane flexible foams (PUFs) are prone to rapid fire growth due to their low density and low thermal conductivity. Furthermore, the low viscosity of the decomposition products generates severe dripping that increases the fire hazard related to the combustion of PUFs. In fact, this downward flow of flaming liquid often results in a pool-fire that promotes flame propagation and boosts the rate of heat release (HRR) due to a significant increase in the burning area and to feed-back between the flame on the pool-fire and the residual foam. In this work the effect of nartoparticles, i.e., clays and carbon nanofibers (CNFs), on the HRR is investigated with special attention given to melt dripping. A modified cone calorimeter test has been developed for this purpose. It is shown that CNFs form an entangled fiber network which eliminates melt dripping and decreases the HRR.
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| 5. |
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