| 1. |
- Butylina, Svetlana, et al.
(författare)
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A study of surface changes of wood-polypropylene composites as the result of exterior weathering
- 2012
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Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 97:3, s. 337-345
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Tidskriftsartikel (refereegranskat)abstract
- Outdoor applications of composites raised questions about their durability. In this study, the effects of outdoor weathering on the properties of wood-polypropylene composites with and without pigments were examined. The composites were placed outdoors for one year, and their colour changes were evaluated after 1, 3, 6, 9 and 12 months of weathering. The weathering resulted in considerable colour fading of the composites. Composites containing darker colour pigments had better colour stability. Scanning electron microscopy analysis revealed that surface cracks caused by weathering in a wood-polypropylene composite having a higher polypropylene content were less abundant, and the deterioration of the surface layer was lower compared to composites containing less polymer. Measurements of melting temperatures by differential scanning calorimetry gave a consistent picture of polypropylene degradation in the surface layer. After weathering, a decrease in Charpy impact strength was found for composites characterised by higher moisture absorption.
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| 2. |
- Butylina, Svetlana, et al.
(författare)
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Accelerated weathering of wood-polypropylene composites containing minerals
- 2012
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Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier. - 1359-835X .- 1878-5840. ; 43:11, s. 2087-2094
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Tidskriftsartikel (refereegranskat)abstract
- Accelerated weathering tests were carried out on wood-polypropylene composites containing minerals. Three different mineral fillers were studied: calcium carbonate, wollastonite and talc. Colour changes were evaluated after distinct periods; the total time of exposure of the composites to UV irradiation was 2000 h. The weathering resulted in significant colour fading of the composites. The composites containing mineral fillers had higher changes of colour (lightness) than the reference composite. Scanning electron microscopy analysis revealed deterioration of the polymer surface layer in all weathered composites. Exposure of the reference composite to UV irradiation resulted in the disappearance of the polypropylene surface layer and disclosure of wood fibres, which led to a higher drop in the lignin content of this composite compared to mineral-containing composites. A substitution of part of the wood with mineral fillers resulted in decreased water absorption and thickness swelling of mineral-containing composites, compared to the reference composite. Exposure to water immersion-freeze-thaw cyclic treatment and UV irradiation led to a decrease in the Charpy impact strength of the composites, except for the composite containing talc
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| 3. |
- Butylina, Svetlana, et al.
(författare)
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Biodegradation and Flame Retardancy of Polypropylene-Based Composites and Nanocomposites
- 2018
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Ingår i: Polypropylene-Based Biocomposites and Bionanocomposites. - NJ, USA. : John Wiley & Sons. - 9781119283560 - 9781119283621 ; , s. 145-175
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Bokkapitel (refereegranskat)abstract
- This chapter summarizes information about the biodegradation and flame retar- dancy of PP-based biocomposites and nano composites obtained from highly ranked journals published during the last two decades. The first part of this chapter deals with the biodegradation of PP-based composites. The second part of this chapter begins with a short description of the specific flammability of PP, followed by an overview of fire retardants and flame testing methods and standards. PP composites reinforced with commonly applied cellulosic fillers, such as wood, flax and others, as well as rarely used wool fibers are considered. The effect of different nanometric fillers alone or in combination with conventional fire retardants on the flammability of composites is also described. Along with comparative analysis of different fire retardants regarding their ability to decrease the flammability of PP matrix composites, the mechanism action and their possible synergy effects are highlighted.
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| 4. |
- Butylina, Svetlana, et al.
(författare)
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Cellulose Nanocomposite Hydrogels : From Formulation to Material Properties
- 2020
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Poly(vinyl alcohol) (PVA) hydrogels produced using the freeze-thaw method have attracted attention for a long time since their first preparation in 1975. Due to the importance of polymer intrinsic features and the advantages associated with them, they are very suitable for biomedical applications such as tissue engineering and drug delivery systems. On the other hand, there is an increasing interest in the use of biobased additives such as cellulose nanocrystals, CNC. This study focused on composite hydrogels which were produced by using different concentrations of PVA (5 and 10%) and CNC (1 and 10 wt.%), also, pure PVA hydrogels were used as references. The main goal was to determine the impact of both components on mechanical, thermal, and water absorption properties of composite hydrogels as well as on morphology and initial water content. It was found that PVA had a dominating effect on all hydrogels. The effect of the CNC addition was both concentration-dependent and case-dependent. As a general trend, addition of CNC decreased the water content of the prepared hydrogels, decreased the crystallinity of the PVA, and increased the hydrogels compression modulus and strength to some extent. The performance of composite hydrogels in a cyclic compression test was studied; the hydrogel with low PVA (5) and high CNC (10) content showed totally reversible behavior after 10 cycles.
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| 5. |
- Butylina, Svetlana, et al.
(författare)
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Comparison of water absorption and mechanical properties of wood-plastic composites made from polypropylene and polylactic acid
- 2010
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 5:3-4, s. 220-228
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the water absorption and mechanical properties of composites made from softwood sawdust and plastics, such as virgin and recycled polypropylene and polylactic acid (PLA). The composites were processed by extrusion, and their properties were investigated by a water immersion test, mechanical tests and a cyclic test for moisture resistance. Scanning electron microscopy was used to study the morphology of the fracture surfaces of the composites. The composites made with recycled polypropylene had the lowest water absorption and thickness swelling of the studied composites. The PLA composites made with heat-treated sawdust showed the highest flexural strength. Of the polypropylene based composites, virgin polypropylene resulted in composites with higher flexural strength. The Charpy impact strength of the composites was found to have an inverse trend compared to flexural strength. Cyclic treatment of the studied composites resulted in 20-60% loss of flexural strength, depending on type of composite.
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| 6. |
- Butylina, Svetlana, et al.
(författare)
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Effects of water immersion-freeze-thaw cycling on the properties of wood-polypropylene composites containing pigments
- 2011
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Ingår i: Pigment & Resin Technology. - : Emerald Group Publishing Limited. - 0369-9420 .- 1758-6941. ; 40:6, s. 386-392
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to study the effects of water immersion-freeze-thaw treatment on the physical properties, flexural strength (FS) and morphology of wood-polypropylene composites containing pigments. Design/methodology/approach - Wood-polypropylene composites containing brown, green and grey pigments were compounded in a conical twinscrew extruder. A composite manufactured without any pigment addition was used as a reference. The amount of pelletized wood, polypropylene and coupling agent (MAPP) was kept constant. The moisture content, thickness swelling (TS), FS and surface colour of the composites were measured before and after water immersion-freeze-thaw cycling. Scanning electron microscopy (SEM) was used to study the morphology of the composites. Findings - FS and dimensional stability were reduced after exposure to water immersion-freeze-thaw cycling for all composites. The surface properties (colour and roughness) of the composites also changed after exposure to water immersion-freeze-thaw cycling. The degree of change depended on the presence of pigment and the type of polypropylene (neat or recycled), however. Research limitations/implications - This study is a part of an ongoing study on weathering of wood-polymer composites (WPC) containing different additives. The results of this study were obtained from accelerated laboratory experiments. Practical implications - Inorganic pigments are widely used as additives in plastics, because they have an excellent UV absorption, good IR-reflective properties and heat stability. The research revealed that metal-containing pigments had an effect on degradation in quality of wood-polypropylene composites exposed to water immersion-freeze-thaw cyclic treatment. The addition of metal-containing pigments to composite formulation resulted in a higher susceptibility of wood-polypropylene composites to water absorption, and as a consequence to a higher drop of FS compared to composites made without pigment. The polymer matrix plays an important role in the protection of WPC against weathering. Originality/value - This paper will help in understanding possible problems in the durability of wood-polypropylene composites compounded with metal-based pigments when they are exposed to water immersion-freeze-thaw cyclic treatment.
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| 7. |
- Butylina, Svetlana, et al.
(författare)
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Fractionation of whey-derived peptides using a combination of ultrafiltration and nanofiltration
- 2006
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Ingår i: Journal of Membrane Science. - : Elsevier. - 0376-7388 .- 1873-3123. ; 280:1-2, s. 418-426
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the fractionation and further isolation and characterisation of peptides and proteins present in sweet whey by means of ultrafiltration using a regenerated cellulose membrane with a nominal molar mass cut-off value of 10 kg/mol and nanofiltration through sulphonated polyether sulphone membrane with a cut-off of 1 kg/mol. The concentration of whey proteins was done below the critical flux. The sieving coefficients for the whey components (proteins, lactose and salts) were estimated. Whey proteins were completely rejected by the ultrafiltration membrane. Size exclusion chromatography (SEC) and matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry were used to evaluate the molar masses of the peptide fractions that were present in the whey permeates. Nanofiltration of whey permeates obtained after ultrafiltration was conducted at two pH values (9.5 and 3.0) that corresponded to the different charged states of the membrane and of the peptides. The transmission of peptides, amino acids and lactose was found to be mainly affected by the permeability of the fouling layer. The selectivity of the nanofiltration membranes toward peptides compared to lactose was calculated as 0.82 and 6.81 at pH 9.5 and 3.0, respectively.
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| 8. |
- Butylina, Svetlana, et al.
(författare)
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Physical and mechanical properties of wood-polypropylene composites made with virgin and/or recycled polypropylene
- 2011
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Ingår i: Polymer-plastics technology and engineering (Softcover ed.). - : Taylor & Francis. - 0360-2559 .- 1525-6111. ; 50:10, s. 1040-1046
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Tidskriftsartikel (refereegranskat)abstract
- The physical and mechanical properties of wood-polymer composites made with virgin or recycled polypropylene, or a mixture of these were studied. The composites made with recycled polypropylene had higher density, lower porosity, and higher dimensional stability compared to the composites made with virgin polypropylene. Although the composites made with recycled polypropylene exhibited lower tensile strength than those made with virgin polypropylene, they had higher Charpy impact strength. Scanning electron microscopy analysis of the fractured surfaces of the composites showed no significant differences in the fracture mechanisms of the studied composites. The degree of crystallinity was estimated to be higher for the virgin polypropylene than for the recycled one.
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| 9. |
- Butylina, Svetlana
(författare)
-
Polypropylene (PP)-Based Hybrid Biocomposites and Bionanocomposites
- 2018
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Ingår i: Polypropylene-Based Biocomposites and Bionanocomposites. - NJ, USA. : John Wiley & Sons. - 9781119283560 - 9781119283621 ; , s. 113-144
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Bokkapitel (refereegranskat)abstract
- Hybrid biocomposites and particularly hybrid bionanocomposites are relatively recent additions to the composite family. Biocomposites are composite materials which include parts of biological origin. Hybridization is very useful because it makes it possible to tailor the composite properties according to the desired structure. This chapter deals with the preparation methods applied for PP-based hybrid biocomposites and bionanocomposites. The mechanical and thermal properties as well as the weathering properties and fire performance of various hybrid composites are summarized. The properties of hybrid biocomposites depend on the nature, size and loading of the filler and its interaction with the PP matrix. In most cases, commercial use of biocomposites has been limited to nonstructural or semistructural applications due to low stiffness, impact and thermal properties. Hybridization helps to overcome these problems. Nanofillers can improve the thermal stability, flame retardancy and durability, and therefore give rise to new applications and extend the existing applications of PP-based biocomposites
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| 10. |
- Butylina, Svetlana, et al.
(författare)
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Properties of as-prepared and freeze-dried hydrogels made from poly(vinyl alcohol) and cellulose nanocrystals using freeze-thaw technique
- 2016
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 81, s. 386-396
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Tidskriftsartikel (refereegranskat)abstract
- Poly(vinyl alcohol), PVA hydrogels are potential materials for biomedical and biotechnogical applications. However, their low mechanical properties restrict their use. In this study, the effect of PVA concentration, addition of nanocrystalline cellulose, CNC, number of freeze-thaw cycles and freeze-drying stage on properties of resulting hydrogels were investigated. The results showed that increase in PVA concentration and the addition of CNC improved the compressive properties of the hydrogels. Overall, increase in number of freeze-thaw cycles from 3 to 5 did not show any improvements in properties of hydrogels. Concentration of PVA had great effect on morphology of freeze-dried hydrogels. The CNC reduced crystallinity of PVA/CNC hydrogels as compared to PVA hydrogels. Rehydrated PVA and PVA/CNC hydrogels had higher compressive characteristics than their as-prepared analogues. In general, an improvement of compressive properties of hydrogels was achieved via reduction of their water content. In case of 5% PVA hydrogel, an addition of CNC was found to be beneficial because it increased degree of swelling and water content on rehydration.
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