| 1. |
- Nordström, Ylva, et al.
(författare)
-
Mechanical characterization and application of Weibull statistics to the strength of softwood lignin-based carbon fibers
- 2013
-
Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 130:5, s. 3689-3697
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanical characterization of the first generation of softwood kraft lignin-based carbon fibers (CF) was carried out. The single fiber tensile tests of filaments with different diameters and length were performed to evaluate stiffness and strength of carbon fibers. The average mechanical properties were measured as follows: tensile strength of approximately 300 MPa, the elastic modulus of 30 GPa and a strain at failure within interval of 0.7-1.2%. The fiber strength data was evaluated by the two-parameter Weibull statistics and parameters of this distribution were obtained. Although strength of the produced fibers is still significantly lower than that of commercially available, the experimental results and predictions based on Weibull statistics show a fairly good fit.
|
|
| 2. |
- Al-Maqdasi, Zainab, 1986-, et al.
(författare)
-
Conductive Regenerated Cellulose Fibers by Electroless Plating
- 2019
-
Ingår i: Fibers. - Basel : MDPI. - 2079-6439. ; 7:5
-
Tidskriftsartikel (refereegranskat)abstract
- Continuous metallized regenerated cellulose fibers for advanced applications (e.g. multi-functional composites) are produced by electroless copper plating. Copper is successfully deposited on the surface of cellulose fibers using commercial cyanide-free electroless copper plating package commonly available for manufacturing of printed wiring boards. The deposited copper is found to enhance the thermal stability, electrical conductivity and resistance to moisture uptake of the fibers. On the other hand, involved chemistry results in altering the molecular structure of the fibers as is indicated by the degradation of their mechanical performance (tensile strength and modulus).
|
|
| 3. |
- Andersons, J., et al.
(författare)
-
Scale effect of the tensile strength of flax-fabric-reinforced polymer composites
- 2011
-
Ingår i: Journal of reinforced plastics and composites (Print). - : SAGE Publications. - 0731-6844 .- 1530-7964. ; 30:23, s. 1969-1974
-
Tidskriftsartikel (refereegranskat)abstract
- The development of UD natural fiber composites, considered for application as structural materials, necessitates evaluation of the scale effect of their strength. Alignment of the fibers in flax bast fiber composites can be achieved by employing textile reinforcement, such as yarns and fabrics. Cutting specimens for mechanical tests out of such textile-reinforced composite plates results in a complex non-uniform reinforcement structure at their edges, which may affect the strength of specimens. Scale effect of the tensile strength in the fiber direction of flax-fabric-reinforced composites is studied in the current work. A model accounting for both volume and edge effect of the specimens on their tensile strength is proposed. © The Author(s) 2011.
|
|
| 4. |
- Ansari, Farhan, et al.
(författare)
-
Experimental evaluation of anisotropy in injection molded polypropylene/wood fiber biocomposites
- 2017
-
Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier. - 1359-835X .- 1878-5840. ; 96, s. 147-154
-
Tidskriftsartikel (refereegranskat)abstract
- Although the anisotropy of wood fibers is reasonably well established, the anisotropy of injection molded wood fiber composites is not well understood. This work focuses on chemo-thermomechanical pulp (CTMP) reinforced polypropylene (PP) composites. A kinetic mixer (Gelimat) is used for compounding CTMP/PP composites, followed by injection molding. Effects from processing induced orientation on mechanical properties are investigated. For this purpose, a film gate mold was designed to inject composites in the shape of plates so that specimens in different directions to the flow could be evaluated. Observations from tensile tests were complemented by performing flexural tests (in different directions) on discs cut from the injected plates. SEM was used to qualitatively observe the fiber orientation in the composites. At high fiber content, both modulus and tensile strength could differ by as much as 40% along the flow and transverse to the flow. The fiber orientation was strongly increased at the highest fiber content, as concluded from theoretical analysis.
|
|
| 5. |
- Edgren, Fredrik, et al.
(författare)
-
Failure of NCF Composites Subjected to Combined Compression and Shear Loading
- 2006
-
Ingår i: Composites Science And Technology. - : Elsevier BV. - 0266-3538 .- 1879-1050. ; 66:15, s. 2865-2877
-
Tidskriftsartikel (refereegranskat)abstract
- Earlier studies have shown that formation of kink bands is the mechanism that is likely to govern failure of compression loaded non-crimp fabric (NCF) composite laminates. Because of this, a failure criterion for prediction of failure caused by kinking under multiaxial (axial compression and shear) loading has been adapted to a NCF composite system. The criterion has been validated for compression tests of quasi-isotropic laminates tested in uniaxial compression. By performing compression tests of the laminate at different off-axis angles, it was possible to vary the ratio of compressive axial stress/shear stress in the specimens. The test results proved that the criterion works well for predictions of kinking governed failure for the present material system. Detailed fractographic studies confirmed that formation of kink bands was the mechanism responsible for specimen failure. Kink bands were also found to develop at loads significantly lower than load at specimen failure.
|
|
| 6. |
- Engström, Jonas, et al.
(författare)
-
Characterization of carbon nanotube doped carbon fiber prepreg laminate
- 2012
-
Ingår i: Proceedings of the 15th European Conference on Composite Materials. - Venice : European Conference on Composite Materials, ECCM. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- The current paper reports results from a preliminary study on PREGCYL™ NC R2HM-01 which is a carbon nanotube doped prepreg produced by Nanocyl. The work consisted of sample manufacturing in autoclave, microcopy analysis with XHR-SEM and mechanical testing. The mechanical testing consisted of tensile tests of unidirectional (in longitudinal direction) and cross-ply laminates. Test of unidirectional laminates showed that stiffness of the PREGCYL material is slightly higher than that of MTM55 composites (111GPa vs 102GPa). The results from tests of cross-ply laminates indicated that damage (transverse cracks) initiation is delayed in PREGCYL composites compare to the MTM55 material. Damage accumulation also seems to be slower in nano-doped composites.
|
|
| 7. |
- Fernberg, Patrik, et al.
(författare)
-
Carbon nanotube treated carbon fibre preforms for improved properties of aeronautical grade composites
- 2012
-
Ingår i: ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials. - Padova : European Conference on Composite Materials, ECCM. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- The current paper reports work on development of enhanced carbon fibre composites manufactured by resin transfer moulding (RTM). In particular, the possibility to obtain a toughened composite through deposition of carbon nanotubes (CNT) on the fibres is investigated. The hypothesis is that deposition of CNT on the fibre surface has two major advantages: a) filtering problems during manufacturing are eliminated and b) CNT can contribute to a local toughening in the vicinity of fibres, where stress concentrations often are high. Unidirectional and multi-axial composites, with and without CNT-modification, were manufactured using conventional RTM-technique and HexFlow®RTM6 epoxy resin. The composites were characterized by means of mechanical testing (interlaminar shear strength, ILSS) and microscopy. Significant improvements by 13 to37 % in ILSS values were achieved with the addition of CNT. Stiffness degradation tests were also performed. The results from these tests were not completely conclusive. Some treatments promoted stiffness degradation whereas others had no apparent effect.
|
|
| 8. |
- Fernberg, Patrik, et al.
(författare)
-
Piezoresistive performance of long-fiber composites with carbon nanotube doped matrix
- 2009
-
Ingår i: Journal of Intelligent Materials Systems and Structures. - 1045-389X .- 1530-8138. ; 20:9, s. 1017-1023
-
Tidskriftsartikel (refereegranskat)abstract
- The electrical and mechanical properties of carbon nanotube (CNT) doped epoxy resin and composites based on this matrix were studied. The investigation was carried out on neat nanocomposites and on structural composites i.e., when the nanocomposite is used as matrix in composite materials reinforced with long continuous fibers. Tensile tests showed that CNT doped epoxy exhibited clear piezoresistive behavior. It was, however, also shown that geometrical changes of the specimen also contribute significantly to resistance changes during tensile loading. Particular effort was made to establish the relations between transverse cracking in glass fiber cross-ply laminates with nanotube doped matrix and changes of electrical resistance. It was shown that changes of electrical resistance during tensile loading of composites containing CNT doped matrix gives highly relevant information about the damage state of the material. In an unloaded state the resistance change is proportional to the relative change of stiffness. This work demonstrates that there are three different mechanisms, which contribute to changes of electrical resistance of a composite specimen subjected to tensile strain. These three mechanisms are: (a) geometrical changes of the specimen (b) piezoresistive material response, and (c) accumulation of micro-damage.
|
|
| 9. |
- Fernberg, Patrik, et al.
(författare)
-
Strain and damage sensing during loading of carbon nanotube doped composites
- 2009
-
Ingår i: ICCM International Conferences on Composite Materials. - London : IOM Communications.
-
Konferensbidrag (refereegranskat)abstract
- This work explores the possibility to use resistance changes in a carbon nanotube (CNT) doped composites to monitor deformations and damage. Most other studies in the field are done on simplified uniaxial loading whereas current work also evaluates the possibilities to monitor strain in more complex loading case, such as bending.
|
|
| 10. |
- Gong, Guan, et al.
(författare)
-
Development of polyethylene/nanoclay masterbatch for use in wood-plastic composites
- 2013
-
Ingår i: Plastics, rubber and composites. - 1465-8011 .- 1743-2898. ; 42:4, s. 167-175
-
Konferensbidrag (refereegranskat)abstract
- In this work, organoclay reinforced high density polyethylene (HDPE) nanocomposites were prepared at laboratory scale using a batch mixer. Processing conditions, maleic anhydride modified polyethylene (MAPE) type and MAPE/clay weight ratio were optimised. The microstructure of the resultant nanocomposites was analysed by X-ray diffraction and melt rheology tests, and flexural properties and thermal stability were evaluated. Three types of MAPEs with different melt flow indices (MFI) and maleic anhydride contents all improved the interaction between HDPE and clay and promoted clay dispersion. Nanocomposites where the MAPE with MFI most similar to HDPE was used showed the best exfoliation of clay and the strongest HDPE/clay interface. Mechanical properties were slightly improved, while thermal stability was distinctly enhanced in these HDPE nanocomposites compared with neat HDPE and HDPE nanocomposite without MAPE. The prepared HDPE nanocomposites show the potential to improve the thermal stability of wood-plastic composites for structural applications. © 2013 Institute of Materials, Minerals and Mining.
|
|
