| 1. |
- Arino Marine, Ruth, 1980, et al.
(författare)
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Barrier screw compounding and mechanical properties of EAA copolymer and cellulose fiber composite
- 2013
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Ingår i: International Polymer Processing. - : Walter de Gruyter GmbH. - 0930-777X .- 2195-8602. ; 28:4, s. 421-428
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Tidskriftsartikel (refereegranskat)abstract
- The difficulty of feeding cellulose fibers and thermoplastics into the extruder or injection molding machine is addressed, this being a serious problem in the production of cellulose fiber composites for industrial applications. Agglomerates consisting in cellulose fibers and ethylene-acrylic acid copolymer (EAA) with different cellulose contents and different fiber lengths were processed with two different screws in order to better understand how the dispersion of the fibers can be improved by melt extrusion. A conventional screw with a compression ratio of 4 : 1 and a screw with barrier flights were used at different screw rotation speeds. The fiber length and fiber content were measured and microscopic analyses were performed in order to estimate the number and size of the cellulose fiber aggregates in the final composites. It was concluded that the barrier screw was more effective than the conventional screw in breaking up the fiber aggregates and dispersing the fibers. More but smaller cellulose aggregates were observed when the barrier screw was used, and the reduction of length was significantly greater for long than for short fibers. In contrast to that was expected, the samples containing the shorter fibers had better mechanical properties, probably due to a better dispersion of the fibers.
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| 2. |
- Arino Marine, Ruth, 1980, et al.
(författare)
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Enhancing the electrical conductivity of carbon black/graphite nanoplatelets: Poly(ethylene-butyl acrylate) composites by melt extrusion
- 2016
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 133:3
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Tidskriftsartikel (refereegranskat)abstract
- The influence of processing parameters such as screw geometry, temperature profile, and screw speed on the electrical properties of hybrid composites consisting of graphite nanoplatelets and carbon black in ethyl butyl acrylate was studied. Two different screws were used to compound the hybrid composites at two different temperatures and two different screw speeds. A beneficial effect was noted with regard to the electrical properties when adding nanoplatelets to the filler system. The cause could be a synergistic effect due to the difference in particle shape of the two fillers. Lower percolation thresholds were obtained with the conventional screw due to less breakage of the graphite nanoplatelets compared to the barrier screw. No significant changes of the electrical properties were observed when changing the temperature profiles or the screw speeds. Furthermore, the melt viscosity of the compounds was not appreciably affected at the rather low filler contents used here.
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| 3. |
- Arino Marine, Ruth, 1980, et al.
(författare)
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Injection molding of beverage container caps made of a composite consisting of wood cellulose fiber and an ethylene-acrylic acid copolymer
- 2014
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Ingår i: International Polymer Processing. - : Walter de Gruyter GmbH. - 0930-777X .- 2195-8602. ; 29:4, s. 507-514
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Tidskriftsartikel (refereegranskat)abstract
- The influence of processing parameters on injection-molded bottle caps consisting of 20 wt% of cellulose fibers and an ethylene-acrylic acid copolymer was studied. The study included three cylinder barrel temperatures and three mold temperatures. For each combination of temperatures, the holding pressure time was varied and the mold sealing time was determined. High density polyethylene caps were also produced as reference material, and injection-molded tensile test bars were also produced in order to assess the tensile mechanical properties. The results showed no major differences in sealing time for the caps containing cellulose fibers, except for the highest melt and mold temperatures where a slightly longer time was observed. The viscosity of the composite material was higher than that of the polymeric matrix. For the highest temperature and high shear rates, the viscosity of the composite material was close to the viscosity of the matrix material. The moisture content of the injection-molded bars was less than 1%, showing that almost no water was absorbed during the compounding or after several months. The crystallinity decreased when the fibers were included but was not influenced by the mold temperature. Enhanced mechanical properties were obtained by using the fibers compared to the pure ethylene-acrylic acid copolymer, both in the tensile test bars and in the caps. The reference high density polyethylene had, however, a higher mechanical performance than the composite.
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| 4. |
- Arino Marine, Ruth, 1980, et al.
(författare)
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Melt processing of wood cellulose tissue and ethylene-acrylic acid copolymer composites
- 2013
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Ingår i: International Polymer Processing. - : Walter de Gruyter GmbH. - 0930-777X .- 2195-8602. ; 28:4, s. 429-436
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Tidskriftsartikel (refereegranskat)abstract
- The difficulty of feeding cellulose fibers together with the polymer into the melt processing equipment is a serious disadvantage for the production of cellulose-containing composites on a large scale. In the present work, a continuous method of feeding cellulose in the form of a tissue into a twin-screw extruder through an opening downstream of the extruder cylinder was studied. With this method, composites with different fiber contents were obtained. The tissues used were one made mainly of softwood fibers and another mainly of hardwood fibers. In order to better understand how to improve the fiber dispersion by melt mixing, a second extrusion was performed with a single screw extruder with a barrier-flighted screw and also with the twin-screw used to compound the tissue with the polymer. The compounds produced were then injection molded into test bars. The test bars containing the softwood tissue exhibited some fiber aggregates also after a second extrusion, whereas no fiber aggregates were observed in samples made with the tissue containing hardwood fibers and two passes through the twin screw. The fiber length was in general reduced by each melt processing stage and the shortest fiber length was observed after two extrusions with the twin-screw and injection molding. The tensile modulus increased with increasing fiber content. A higher stiffness was obtained with more softwood fibers in the tissue whereas more hardwood fibers gave a higher tensile strength and greater elongation at break.
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| 5. |
- Arino Marine, Ruth, 1980
(författare)
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On the processing and properties of cellulose-containing polymeric materials
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cellulose fibres have properties such as renewability, biodegradability, very good availability and low cost that make them very attractive as a reinforcement for thermoplastic polymers. Other more specific favourable properties are low density, high specific stiffness, low abrasive nature and their potential for modification. There are however, some drawbacks or limitations when processing cellulose-fibre-reinforced composites that need to be resolved in order to improve the mechanical properties of the composite. This work is focused on how to adapt the processing towards this goal and on a study of the mechanical properties of polymer composites with a high content of fibre reinforcement.Cellulose is not soluble in water or conventional organic solvents. Recently, it was found that ionic liquids (IL) are able to dissolve cellulose, opening many new possibilities. In this work, microcrystalline cellulose (MCC) was dissolved in two different imidazolium-based ionic liquids, and when a coagulation agent (CA) was added a gel structure was obtained. In this case, MCC was also modified to lauric acid cellulose ester (LACE) in order to study the effect of surface hydrophobisation. The thermal properties of the gels depended only on the type of cellulose whereas the absorption of CA during gelling depended on the types of IL as well as the type of cellulose. The gels showed linear viscoelastic behaviour in terms of the storage modulus G’ but not of the loss modulus G”. A higher concentration of cellulose gave stiffer gels whereas the gel network strength depended on the types of IL and CA. The difficulty of feeding the cellulose fibres into the processing equipment is a serious disadvantage, since continuous feeding is desired for industrial applications. In this work, three different continuous feeding techniques have been studied, more specifically the methods of pelletized cellulose fibres with polymer, the feeding of cellulosic tissue into the compounder and the feeding of wet cellulose masterbatch. Composites containing 20 to 35 wt% of cellulose fibres in ethylene-acrylic acid copolymer were obtained with the different processing techniques. In all cases, injection moulding was performed as a last step. It was shown that if the dispersion of cellulose fibres was performed solely by melt mixing, i.e. without compatibilisers, shorter fibres led to less fibre aggregates. Contrary to what was expected, shorter fibres resulted in composites with better mechanical performance showing the great importance of fibre dispersion together with a good adhesion fibre-matrix. The final fibre length depended on the processing technique and on the fibre concentration, but it was also observed that longer fibres were more affected by the melt processing. Finally, one of the cellulose composites studied was used for injection moulding of bottle caps, demonstrating an application of this type of composite material.
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| 6. |
- Arino Marine, Ruth, 1980
(författare)
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On the processing and properties of cellulose-containing polymeric materials
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- ABSTRACTCellulose fibres have properties that make them very attractive as a reinforcement for thermoplastic polymers. Renewability, biodegradability, very good availability and low cost are some general advantages. Other more specific favourable properties are low density, high specific stiffness, low abrasive nature and their potential for modification. There are however, some drawbacks or limitations when processing cellulose-fibre-reinforced composites that need to be resolved in order to improve the mechanical properties of the composite. This work is focused on how to adapt the processing towards this goal and on a study of the mechanical properties of polymer composites with a high content of fibre reinforcement.Cellulose is not soluble in water or conventional organic solvents. Recently it was found that ionic liquids (IL) are able to dissolve cellulose, and this opens many new possibilities. In this work, microcrystalline cellulose (MCC) was dissolved in two different imidazolium-based ionic liquids and when a coagulation agent (CA) was added, a gel structure was obtained. In this case, MCC was also modified to lauric acid cellulose ester (LACE) in order to study the effect of surface hydrophobisation. It was concluded that the thermal transition range of the cellulose gels was affected only by the type of cellulose and that the absorption of CA during gelling depended on the types of IL and cellulose. The rheological measurements with a stress-controlled parallel-plate rheometer showed linear vicoelastic behaviour in terms of the storage modulus G’ but not in the loss modulus G”. Gels having a high concentration of cellulose exhibited higher plateau values for G’ and the critical stress value for linearity depended on the type of IL and the type of CA. It was concluded that the G’ and G” of the gels were independent of the frequency. The difficulty of feeding the cellulose fibres into the extruder or injection moulding machine is a serious disadvantage, since continuous feeding is desired when processing this type of composite. Pelletizing the cellulose fibres made it possible to achieve continuous feeding, but this process resulted in a significant shortening of the fibre lengths and a consequent reduction in the mechanical properties of the composite. Cellulose pellets or agglomerates of cellulose in ethylene-acrylic acid copolymer (EAA) were processed with different techniques. Pellets with 30 and 70 wt% cellulose content were used. The 70 wt% cellulose content pellets were blended with additional EAA to a final cellulose content of 30 wt%. It was concluded that the melt processing after the initial agglomeration had a small or insignificant effect on the fibre length. Elongation dispersive mixing improved both stiffness and strength, probably because the number and size of the fibre aggregates were reduced.Keywords: cellulose fibres, ethylene-acrylic acid copolymer, compounding, dispersion, ionic liquids, gels, rheological properties
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| 7. |
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| 8. |
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| 9. |
- Arino Marine, Ruth, 1980, et al.
(författare)
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Processing and mechanical properties of thermoplastic composites based on cellulose fibers and ethylene-acrylic acid copolymer
- 2012
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Ingår i: Polymer Engineering and Science. - : Wiley. - 0032-3888 .- 1548-2634. ; 52:9, s. 1951-1957
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Tidskriftsartikel (refereegranskat)abstract
- The melt processing and the tensile mechanical properties of composites consisting of 30 wt% softwood kraft pulp cellulose fibers and ethylene-acrylic acid copolymer (EAA) with 7% acrylic acid content were studied. The compounding techniques used were extrusion mixing performed with a single screw extruder and elongation dispersive mixing performed with the injection-molding machine. All blends were injection-molded in a final step. Fiber length, fiber content, and mechanical properties were measured and the number and the size of the fiber aggregates were determined by microscopy analysis. It was concluded that two passes of elongation dispersive mixing had a beneficial effect on the mechanical properties, which could be related to the fewer and smaller amounts of aggregates. The different types of processing performed had a small or insignificant effect on the fiber length since the fiber lengths measured were within the same range as that of the starting material. POLYM. ENG. SCI., 52:1951-1957, 2012. © 2012 Society of Plastics Engineers Copyright © 2012 Society of Plastics Engineers.
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| 10. |
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