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  • 1.
    Butylina, Svetlana
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Polypropylene (PP)-Based Hybrid Biocomposites and Bionanocomposites2018In: Polypropylene-Based Biocomposites and Bionanocomposites / [ed] P. M. Visakh, Matheus Poletto, NJ, USA.: John Wiley & Sons, 2018, p. 113-144Chapter in book (Refereed)
    Abstract [en]

    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

  • 2.
    Butylina, Svetlana
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Geng, Shiyu
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Oksman, Kristiina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Properties of as-prepared and freeze-dried hydrogels made from poly(vinyl alcohol) and cellulose nanocrystals using freeze-thaw technique2016In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 81, p. 386-396Article in journal (Refereed)
    Abstract [en]

    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.

  • 3.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Hyvärinen, Marko
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    A study of surface changes of wood-polypropylene composites as the result of exterior weathering2012In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, no 3, p. 337-345Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Hyvärinen, Marko
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Accelerated weathering of wood-polypropylene composites containing minerals2012In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 43, no 11, p. 2087-2094Article in journal (Refereed)
    Abstract [en]

    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

  • 5.
    Butylina, Svetlana
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Mechanical Engineering, Lappeenranta University of Technology .
    Hyvärinen, Marko
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Weathering of wood-polypropylene and wood-wollastonite-polypropylene composites containing pigments in Finnish climatic conditions2015In: Pigment & Resin Technology, ISSN 0369-9420, E-ISSN 1758-6941, Vol. 44, no 5, p. 313-321Article in journal (Refereed)
    Abstract [en]

    Purpose The purpose of this paper is to study the resistance of wood-polypropylene and wood-wollastonite-polypropylene composites containing pigments to natural weathering. Design/methodology/approach Natural weathering of composites was conducted in Finnish climatic conditions for one year. The colour of the composites was determined with a spectrophotometer, the morphology of the composite surface was analysed by scanning electron microscopy (SEM), and the changes in the polymer structure in surface layer of the composites were analysed with differential scanning calorimetry (DSC). Charpy impact strength was determined with an impact tester. Findings The pigments used in this study reduced the colour change of the composites exposed to outdoor weathering as compared with the un-coloured composite. The carbon black pigment was more effective than the iron oxide pigment. Moreover, only the carbon black pigment was found to reduce the degradation of the surface layer of the composites. The addition of the carbon black pigment had a positive effect on the dimensional stability of the composites in a water absorption test. Only the combination of the carbon black pigment and wollastonite resulted in a composite which was capable to retain its Charpy impact strength both after one year of outdoor weathering and cyclic treatment. Research limitations/implications This study is a part of continuous research on the development of wood-polymer composites (WPUs) suitable for outdoor applications in Finnish climatic conditions. The first part of the study, which has been published earlier, showed the results of weathering of composites in accelerated tests in comparison with 1,000 hours outdoor exposure during summer time (June and July). Outdoor weathering limited to 1,000 hours cannot give an objective view on the weathering behaviour of composites in Finnish climatic conditions. The results of the current study were obtained from one-year outdoor exposure of composites. Originality/value The wood-polypropylene composite made with the combination of the carbon black pigment and wollastonite can be recommended for outdoor applications. The study provides useful information on the resistance of wood-polypropylene composites to weathering in Finnish climatic conditions.

  • 6.
    Butylina, Svetlana
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Mechanical Engineering, Lappeenranta University of Technology.
    Hyvärinen, Marko
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Weathering of wood-polypropylene composites containing pigments2012In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 70, no 5, p. 719-726Article in journal (Refereed)
    Abstract [en]

    Outdoor applications of composites have 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 durability of the composites was assessed by testing flexural strength and density. Scanning electron microscopy was applied to evaluate the surface degradation of the composites. The weathering resulted in considerable colour fading of the composites. The composites containing darker colour pigments had better colour stability. After weathering, the general trend was a decrease of the flexural strength and density of the composites. The decrease in flexural strength was found to be lower for the composites having higher density.

  • 7.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology, Finland.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology, Finland.
    Resistance to weathering of wood-polypropylene and wood-wollastonite-polypropylene composites made with and without carbon black2014In: Pigment & Resin Technology, ISSN 0369-9420, E-ISSN 1758-6941, Vol. 43, no 4, p. 185-193Article in journal (Refereed)
    Abstract [en]

    Purpose - The purpose of this paper is to study natural and accelerated weathering of wood-polypropylene (WF-PP) and wood-wollastonite-polypropylene composites made with and without carbon black.

    Design/methodology/approach - Natural weathering was conducted in Ruokolahti, Finland in the time of year when solar radiation was maximal. The accelerated weathering tests included exposure to a xenon-arc source with and without spray, and a cyclic test consisting of water immersion-freeze-thaw stages.

    Findings - Both the type of weathering and the formulation of the composite determined the degree of change in their properties. Weathering, including xenon-arc exposure with spray resulted in much higher changes of colour of non-pigmented composites compared to natural weathering or xenon-arc weathering without spray. Both UV irradiation and moisture had an adverse effect on the Charpy impact strength of non-pigmented composites. Carbon black containing composites performed better than non-pigmented composites.

    Research limitations/implications - This study is a part of an ongoing research on the development of wood-polymer composites (WPCs) suitable for outdoor applications in Finnish climatic conditions. Outdoor weathering limited to 1,000 h cannot be used for the prediction of the service life of composites and was used here solely for comparative purposes.

    Originality/value - This paper will help to understand the effect of different weathering factors on the behaviour of WF-PP and wood-wollastonite-polypropylene composites made with and without carbon black (as UV stabiliser). The study demonstrated that while accelerated weathering tests provided useful information on the resistance of WF-PP composites to different weathering factors, they cannot be used alone to predict the behaviour of WPCs meant for outdoor application

  • 8.
    Butylina, Svetlana
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Luque, Susana
    bDepartment of Chemical and Environmental Engineering, University of Oviedo.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Fractionation of whey-derived peptides using a combination of ultrafiltration and nanofiltration2006In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 280, no 1-2, p. 418-426Article in journal (Refereed)
    Abstract [en]

    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.

  • 9.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Martikka, Ossi
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Comparison of water absorption and mechanical properties of wood-plastic composites made from polypropylene and polylactic acid2010In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, no 3-4, p. 220-228Article in journal (Refereed)
    Abstract [en]

    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.

  • 10.
    Butylina, Svetlana
    et al.
    Mechanical Engineering, Lappeenranta University of Technology.
    Martikka, Ossi
    Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Mechanical Engineering, Lappeenranta University of Technology.
    Effects of water immersion-freeze-thaw cycling on the properties of wood-polypropylene composites containing pigments2011In: Pigment & Resin Technology, ISSN 0369-9420, E-ISSN 1758-6941, Vol. 40, no 6, p. 386-392Article in journal (Refereed)
    Abstract [en]

    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.

  • 11.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Martikka, Ossi
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Physical and mechanical properties of wood-polypropylene composites made with virgin and/or recycled polypropylene2011In: Polymer-plastics technology and engineering (Softcover ed.), ISSN 0360-2559, E-ISSN 1525-6111, Vol. 50, no 10, p. 1040-1046Article in journal (Refereed)
    Abstract [en]

    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.

  • 12.
    Butylina, Svetlana
    et al.
    Lappeenranta University of Technology.
    Martikka, Ossi
    Lappeenranta University of Technology.
    Kärki, Timo
    Lappeenranta University of Technology.
    Properties of wood fibre-polypropylene composites: Effect of wood fibre source2011In: Applied Composite Materials, ISSN 0929-189X, E-ISSN 1573-4897Article in journal (Refereed)
    Abstract [en]

    This study examined the effect of type of wood fibre source on the physical and mechanical properties of wood fibre-polypropylene composites. Wood flour, fibres of heattreated wood and pellets were used as sources of wood fibres in the manufacturing process. All studied wood fibre-polypropylene composites were made from 75% wood, 22% recycled polypropylene (PP) and 3% maleated polypropylene (MAPP). Wood fibrepolypropylene composites were compounded in a conical twin-screw extruder. Water absorption and thickness swelling were studied. Mechanical properties of the composites were characterised by tensile, flexural, and impact testing. Micromechanical deformation processes were investigated using scanning electron microscopy done on the fractured surfaces of broken samples. The durability of composites exposed to three accelerated cycles of water immersion, freezing and thawing was examined. The results showed that the density of the composites was a key factor governing water absorption and thickness swelling. A significant improvement in tensile strength, flexural strength, and Charpy impact strength was observed for composites reinforced with heat-treated fibre compared to composites reinforced with pellets and especially to wood flour reinforced composites. The flexural strength and dimensional stability performance reduced after exposure to freezethaw cycling for all composites, but the degree of these changes was dependent on the wood fibre source.

  • 13.
    Butylina, Svetlana
    et al.
    Lappeenranta University of Technology.
    Martikka, Ossi
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Thermal performance and optical properties of wood-polymer composites2013In: Journal of Thermoplastic Composite Materials, ISSN 0892-7057, E-ISSN 1530-7980, Vol. 26, no 1, p. 60-73Article in journal (Refereed)
    Abstract [en]

    The thermal performance and optical properties of wood-polypropylene composites made from untreated wood material with and without metal-containing pigments, and composites made from heat-treated wood material were studied. The thermal heat buildup and linear shrinkage were determined. The impact of the optical properties of the surface of the composites on the heat buildup was analysed. The wood-polypropylene composites made from untreated wood without pigment were found to have the lowest heat buildup; a similar composite containing grey pigment had the highest heat buildup. The linear shrinkage of the studied wood-polypropylene composites was in the range 0.05-0.16%

  • 14.
    Butylina, Svetlana
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Martikka, Ossi
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Weathering properties of coextruded polypropylene-based composites containing inorganic pigments2015In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 120, p. 10-16Article in journal (Refereed)
    Abstract [en]

    This study concerns the weathering properties of coextruded polypropylene-based composites containing pigments. Three different pigments were incorporated in the shell layer of the composites: iron oxide, titanium dioxide and zinc oxide. The surface colour, surface gloss and tensile properties were tested. In addition, the weathered surfaces were studied by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The surfaces of the composites containing inorganic pigments were found to have fewer cracks after 500 h of weathering than the surface of the reference composite. The results revealed that the composites containing titanium oxide pigment exhibited better colour stability than the composites made with the other pigments. In spite of its high colour stability in weathering, the tensile properties (strength, Young's modulus and elongation at break) of the composite containing titanium oxide were reduced by weathering. The FTIR analysis revealed that the composite containing zinc oxide had a stabilising effect on polypropylene photo-degradation, which correlates well with the results of mechanical testing, showing that this composite retained its mechanical properties after weathering

  • 15.
    Butylina, Svetlana
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Shataeva, Larisa K.
    bInstitute of Macromolecular Compounds, Russian Academy of Science.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Separation of nucleoprotein complexes with antioxidant activity from yeast Saccharomyces cerevisiae2007In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 53, no 1, p. 64-70Article in journal (Refereed)
    Abstract [en]

    In this study, complexes of nucleic acids and acidic nuclear proteins were isolated from baker's yeast cells of Saccharomyces cerevisiae by mild alkaline extraction followed by precipitation with acetic acid. The optimal composition of the buffer applied for extraction of nucleoprotein complexes was determined. The high and low molar mass fractions of the nucleoprotein complexes were separated using cross-flow microfiltration through track-etched membranes. The molar masses were determined by intrinsic viscosity measurements and the molar mass distribution in nucleoprotein complexes was studied by gel permeation chromatography. The protein component of the nucleoprotein complexes was purified on a strongly basic anion exchange resin. The high molar mass nucleoprotein complexes could induce the growth of culture cells of S. cerevisiae exposed to ultraviolet irradiation or treated with hydrogen peroxide

  • 16.
    Butylina, Svetlana
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Shataeva, Larisa K.
    Institute of Macromolecular Compounds, Russian Academy of Science.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Yeast nucleopeptide complexes and their biological effect2004In: Journal of Peptide Science, ISSN 1075-2617, E-ISSN 1099-1387, Vol. 10, p. 162-Article in journal (Refereed)
  • 17.
    Butylina, Svetlana
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Shataeva, Larisa K.
    Institute of Macromolecular Compounds, Russian Academy of Science.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Yeast nucleopeptide complexes and their biological effects2005In: Peptides 2004: Proceedings: Bridges Between Disciplines, Kenes Int. , 2005, p. 423-424Conference paper (Refereed)
  • 18.
    Butylina, Svetlana
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Turku, Irina
    Fiber Composite Laboratory, School of Energy Systems, Lappeenranta University of Technology, Lappeenranta, Finland.
    Biodegradation and Flame Retardancy of Polypropylene-Based Composites and Nanocomposites2018In: Polypropylene-Based Biocomposites and Bionanocomposites / [ed] P. M. Visakh, Matheus Poletto, NJ, USA.: John Wiley & Sons, 2018, p. 145-175Chapter in book (Refereed)
    Abstract [en]

    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.

  • 19.
    Huuhilo, Tiina
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Martikka, Ossi
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Butylina, Svetlana
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Impact of mineral fillers to the moisture resistance of wood-plastic composites2010In: Baltic Forestry, ISSN 1392-1355, E-ISSN 2029-9230, Vol. 16, no 1, p. 126-131Article in journal (Refereed)
    Abstract [en]

    The impact of mineral fillers to the moisture resistance of the wood-plastic composites (WPC) is studied. Five inorganic fillers were tested for the wood-plastic composites calcium carbonate, two different types of wollastonite, soapstone and talc. The amount of polypropylene, wood and mineral was held constant, only the mineral type was changed during the tests. The studied composites were also compared with a reference sample, which was manufactured without any mineral addition. All added minerals decreased the swelling and moisture absorption of the wood-plastic composite considerably. Also the density of the wood-plastic composites increased when minerals were added. Without any added mineral, clear openings could be seen in the composite structure in scanning electron microscope (SEM) pictures. These openings could work as pathways for water into the inner parts of the WPC and increase swelling. It could also be seen in the SEM pictures that when mineral was added, these pathways for moisture were closed. After three weeks soak/freeze/dry cycles, the bending strength of the reference sample decreased considerably more than the bending strength of the samples with added minerals. Of the studied minerals, talc was the most effective.

  • 20.
    Huuhilo, Tiina
    et al.
    Lappeenranta University of Technology, Department of Mechanical Engineering.
    Martikka, Ossi
    Lappeenranta University of Technology, Department of Mechanical Engineering.
    Butylina, Svetlana
    Lappeenranta University of Technology, Department of Mechanical Engineering.
    Kärki, Timo
    Lappeenranta University of Technology, Department of Mechanical Engineering.
    Mineral fillers for wood-plastic composites2010In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, no 1, p. 34-40Article in journal (Refereed)
    Abstract [en]

    Five mineral fillers were tested for wood-plastic composites (WPCs): calcium carbonate, two different types of wollastonite, soapstone and talc. The impact of the fillers on the mechanical properties of the composites was studied. The experiments included bending tests, tensile tests, Brinell hardness and scanning electron microscopy experiments. The amount of wood, mineral and plastic (polypropylene) was kept steady. Only the mineral type was changed during the tests. A control sample without any mineral added was also manufactured. The mineral addition improved the tensile strength of the WPCs. The hardness of the composite was also improved when the minerals were added, and along with the increasing mineral hardness, the hardness of the composite increased. The wollastonite acicular shape was crushed during the manufacturing process, so the phase of the process in which the minerals are added requires careful consideration.

  • 21.
    Hyvärinen, Marko
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Väntsi, Olli
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Butylina, Svetlana
    Department of LUT Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Ultraviolet light protection of wood-plastic composites a review of the current situation2013In: Advanced Science Letters, ISSN 1936-6612, E-ISSN 1936-7317, p. 320-324Article in journal (Refereed)
    Abstract [en]

    Wood-plastic composites (WPCs) have several exterior applications where they are easily exposed to ultraviolet (UV) radiation. The paper presents the current situation in a field of UV protection of WPCs, including the most commonly used protective agents and methods, such as UV absorbers and hindered amine light stabilizers (HALS). Surface dressing methods, such as painting, coating and film coating are not included. The focus of the paper is on the ways of how to integrate UV protection comprehensively over the material. The work is a literature review and practical experiments are not included.

  • 22.
    Keskisaari, Anna
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Butylina, Svetlana
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Use of construction and demolition wastes as mineral fillers in hybrid wood-polymer composites2016In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, no 19, article id 43412Article in journal (Refereed)
    Abstract [en]

    The recycling of construction materials has been the subject of much research in past years. In this study, the use of construction and demolition wastes (CDWs) as mineral fillers in hybrid wood-polymer composites was studied. Two types of waste materials were used as fillers in the composites: (1) a mixture consisting of waste mineral wool (MW) and plasterboard (PB) and (2) mixed CDWs. The performance of the composites was evaluated from their mechanical properties and water-absorption behavior. We found in the study that the addition of mineral fillers decreased the flexural strength and modulus values of the wood-polypropylene (PP) composites. On the other hand, the exchange of part of the wood with a mineral filler resulted in an increase in the impact strength of the composite. The composite manufactured with the combination of MW and PB had the lowest water absorption. The decrease in wood loading resulted in improved dimensional stability in the hybrid wood-mineral filler-PP composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43412.

  • 23.
    Martikka, Ossi
    et al.
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Huuhilo, Tiina
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    Butylina, Svetlana
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Mechanical Engineering, Lappeenranta University of Technology.
    Kärki, Timo
    Department of Mechanical Engineering, Lappeenranta University of Technology.
    The effect of mineral fillers on the thermal properties of wood-plastic composites2012In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 7, no 2, p. 107-114Article in journal (Refereed)
    Abstract [en]

    The thermal properties of wood-plastic composites with five different mineral fillers were studied. The tested mineral fillers were calcite (CaCO 3), two different qualities of wollastonite, soapstone, and talc. The amount of wood, mineral, and plastic (polypropylene) was kept constant. Only the mineral type has been changed during the tests. The thermal behavior of the samples was studied by using a differential scanning calorimeter, a thermogravimetric analyzer and by determining the heat build-up. The analyzed properties were compared with a reference sample made without adding any minerals. The results show that the addition of mineral fillers does not remarkably change the thermal stability of composites. All the studied mineral fillers except soapstone had a small effect on the heat build-up

  • 24.
    Nyström, Marianne
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Butylina, Svetlana
    Department of Chemical Technology, Lappeenranta University of Technology.
    Platt, Samantha
    Department of Chemical Technology, Lappeenranta University of Technology.
    NF retention and critical flux of small hydrophilic/hydrophobic molecules2004In: Membrane Technology, ISSN 0958-2118, E-ISSN 1873-4049, Vol. 10, p. 5-8Article in journal (Refereed)
    Abstract [en]

    This feature article provides details of a study in which small molar mass substances were used as model substances in nanofiltration using NF-270 and Desal-5 DL membranes. The hydrophobicities of the substances were calculated, and flux, retention and critical flux were measured for the filtration and related to flow conditions and characteristics of model compounds and membranes.

  • 25.
    Oksman, Kristiina
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Aitomäki, Yvonne
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mathew, Aji P.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Siquiera, Gilberto
    Applied Wood Materials Laboratory, Swiss Federal Laboratories for Materials Science and Technology (EMPA), CH-8600 Dübendorf.
    Zhou, Qi
    School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm.
    Butylina, Svetlana
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Tanpichai, Supachok
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Zhou, Xiaojian
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hooshmand, Saleh
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Review of the recent developments in cellulose nanocomposite processing2016In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 83, p. 2-18Article in journal (Refereed)
    Abstract [en]

    This review addresses the recent developments of the processing of cellulose nanocomposites, focusing on the most used techniques, including solution casting, melt-processing of thermoplastic cellulose nanocomposites and resin impregnation of cellulose nanopapers using thermoset resins. Important techniques, such as partially dissolved cellulose nanocomposites, nanocomposite foams reinforced with nanocellulose, as well as long continuous fibers or filaments, are also addressed. It is shown how the research on cellulose nanocomposites has rapidly increased during the last 10 years, and manufacturing techniques have been developed from simple casting to these more sophisticated methods. To produce cellulose nanocomposites for commercial use, the processing of these materials must be developed from laboratory to industrially viable methods.

  • 26.
    Platt, Samantha
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Mauramo, Marika
    Department of Chemical Technology, Lappeenranta University of Technology.
    Butylina, Svetlana
    Department of Chemical Technology, Lappeenranta University of Technology.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Retention of pegs in cross-flow ultrafiltration through membranes2002In: Desalination, ISSN 0011-9164, E-ISSN 1873-4464, Vol. 149, no 1-3, p. 417-422Article in journal (Refereed)
    Abstract [en]

    This work investigated the difference between membrane cut-offs measured with the CHARMME methods and the values quoted from the manufacturers. Four different membranes were characterised. The two regenerated cellulose membranes that according to the manufacturers had cut-offs of 5 and 10 kD had, in fact, the same cut-off of 2.5 kD. It was also found that the polyethersulfone membrane had a lower cut-off (3 kD) than that stated by the membrane manufacturers (5 kD). A cross-flow velocity of 2 m/s and a flux of 40 1/h/m2 was found to keep the mass transfer coefficient within a tolerable range for all PEGs used.

1 - 26 of 26
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