Papers by Keyword: Biodegradable Composite

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Authors: Stefan Berger, Jürgen Weisser, Eberhard Müller, Matthias Schnabelrauch
Abstract: Composite systems composed of nanocrystalline apatites and oligolactide-based polymer networks were prepared resulting in malleable and even injectable formulations which can be cured to compact materials at body temperature. Porous devices with inter-connective porosity were obtained after addition of suitable foaming agents to the composite mixtures. Setting time, porosity and mechanical properties of the composites can be properly adjusted by varying the educt composition. The determined compressive strengths and Young’s moduli of the porous composites perfectly match the mechanical characteristics of cancellous bone material. Preliminary in vitro cell culture experiments with compact composite materials demonstrated their good cytocompatibility. Based on these findings, the synthesized nano-structured composites represent promising candidates for the development of new biomaterials usable in hard tissue regeneration.
Authors: Ana Rita Campos, António M. Cunha, Alberto Tielas, António Mateos
Abstract: The interest of the automotive industry on biodegradable and green composites is increasing dramatically due two environmental legislation that obliges automakers to reduce the disposal of waste from vehicles [1]. As an answer to this recent demand several research groups are working on the development of these composites. This work shows the development of a loudspeaker front made of two different biodegradable composites: PLA (polylactic acid) and SCA (blend of starch and cellulose acetate) reinforced with different percentages of cellulose spent fibres. The composites were previously extruded on a counter-rotating twin screw extruder and injection moulded into tensile specimens. The mechanical properties of the produced tensile specimens were assessed with an Instron Universal Testing Machine as well as the morphological aspects of the materials, studied with optical and scanning electron microscopies. After these preliminary set of tests, the best composites were chosen to produce the final parts (loudspeaker front). These parts were injection moulded on a Ferromatik Milacron K85 injection moulding machine (850 kN clamping force) and subjected to a wide set of automotive tests to evaluate their performance. The best materials for this application proved to be the PLA reinforced composites, although there is still a large window for improvement of properties, based on the engineering of the matrix/reinforcement interface and also on the improvement of the thermal properties of the PLA material.
Authors: Yong Cao, Shinichi Shibata, Koichi Goda
Abstract: Biodegradable composites made from bagasse fiber and biodegradable resin were prepared and the biodegradation were investigated by the soil burial test in terms of the effects of fiber content, alkali treatment to bagasse fiber and different soil. The biodegradable resin showed some extent biodegradation. The addition of bagasse fiber caused the acceleration of weight loss of the fiber reinforced composites in comparison with the neat biodegradable resin. The weight loss of the composites increased with the increase in the fiber content, which could attribute to the preferential degradation of bagasse fiber and the resin around the fiber. However there was no significant difference in weight loss between untreated and alkali treated fiber composites. Furthermore, it is noted that the weight loss drastically increased in the case of the composites buried in the microorganism enriched soil. This results from the increase of bacteria and fungi in soil. The photographs and SEM micrographs showed the degradation of the resin and the composites.
Authors: Hitoshi Takagi, Akira Asano
Abstract: Environment-friendly “green” composites were fabricated from a starch-based, dispersion-type biodegradable resin and cellulose nanofibers. The mixture of the dispersion-type biodegradable resin and cellulose nanofibers were blended well by using a home-use mixer and a stirrer, and then dried in air or in a vacuum. Composites were prepared by conventional hot pressing at a constant temperature of 140°C and at pressures from 10 to 50 MPa. Their flexural strength as well as flexural modulus increased with increasing the molding pressure, and were also affected by preparation methods and conditions. Their mechanical properties such as strength and modulus had a good correlation with their density. Especially it can be seen that there is significant effectiveness in a stirrer mixing process, which results in the improved uniform dispersion of nanofibers.
Authors: Esmeralda Uribe Lam, María Gabriela Gutiérrez Pliego, Víctor Gerardo Martínez Pérez, Alejandro Manzano Ramirez
Abstract: Flexion tests were performed (ASTM D790) for two biodegradable composites, the first one made of pine resin as matrix and henequen fibers as reinforcement, varying the percentage reinforcement. The second composite made of a matrix of cellulose obtained from a mixture of recycled paper and water and reinforced with maize bract fibers (the leaves that cover the corn cob) and infiltrated with pine resin. Five samples were evaluated for each compound in an Instron universal machine (load cell: 5 kN). For the henequen fibers and pine resin composite specimens were prepared according to standard by the method of hot casting resin, henequen fibers both short and long (127mm, 10mm) were included prior to discharge the matrix. The drying was at room temperature for 1 minute. Tests were conducted with different compositions of matrix / reinforcement by varying the amount of fiber in 26%, 20% and 14% of the specimen. The long fibers longitudinally traverse the specimen (127mm) and short fibers (10 mm) are dispersed in the mixture. The second composite is produced from corn fiber preforms and cellulose by the method of compression molding, dried in oven at 100 ° C for 2 hours. The preforms were infiltrated with pine resin by compressed air (25 psi). We analyzed the effect of corn fiber content in weight percentages of 10%, 30% and 50% with respect to cellulose and two lengths of corn fiber (22.25μm and 487 μm). Under study conditions, corn fiber generates a negative effect on the flexural strength of the compound. By increasing the fiber content of corn and its size, the bending strength decreased in almost all cases, is attributed to a lack of uniformity in the distribution of corn fibers. However, flexural strength values obtained were similar to materials such as wood, found in the literature. This projects the potential of the compound to replace, in certain applications, non-sustainable material
Authors: Yi Qiang Wu, Zhi Yong Qin, Yan Qing, Xin Gong Li
Abstract: Biodegradable composites of polylactic acid reinforced with wood fiber were fabricated by using twin screw extruder followed by the injection molding machine. The effects of different pretreatments of wood on mechanical properties of the biodegradable composite were discussed. The nature of composites were also examined through scanning electron microscope and Infrared Spectrum Analysis, the results reveal that both acid and stearic acid could be used as effective surface modifier for wood fiber/polylactic acid system, the composite system by adding Benzoic acid, the tensile strength has improved greatly, and about stearic acid composite system, the impact strength has improved significantly; After alkali treatment, coupling agent treatment and combination of alkali treatment and coupling agent treatment, and the use of alkali treatment and the coupling agent treatment is the best, follow by alkali treatment.
Authors: Kleber de Arruda Almeida, Alvaro Antonio Alencar de Queiroz
Authors: Ming Hui Guo, Yuan Yuan
Abstract: In our research, a commercial poly (lactic acid) (PLA) film was used in combination with wood fiber matrix to generate biodegradable composites by a film stacking technique and hot-press. The results showed the flexural properties and water resistance increased with the increasing of PLA addition. Silane-treated wood fiber composites significantly improved the flexural properties compared to untreated composites. In experiment range, the physical and mechanical properties of composites were better in higher hot-press temperature. The optimal parameters are determined by PLA addition 20%, silane addition 3%, the hot-press temperature 190°C, the hot-press time 10min.Under these parameters, the flexural properties of composites exceeded the requirement of the outdoor boards’ standard, but the water resistance was a little low.
Authors: Hitoshi Takagi
Abstract: Environmentally friendly cellulose nanofiber green composites were newly developed by combining two dispersion-type biodegradable resins: polylactic acid (PLA) and chemically modified starch, and cellulose nanofibers of two kinds. The nanoscale cellulose fibers were prepared by homogenization of wood pulp. The 10–100 nm diameter nanoscale cellulose fibers have a web-like network microstructure. The mixture of dispersion-type biodegradable resin and cellulose nanofibers was dried in an air-circulating oven to make composite preform sheets. Cellulose nanofiber composite samples were fabricated by press-forming of the preform sheets. Their mechanical properties were evaluated using room-temperature tensile tests. The composite composed of PLA-based resin and highly homogenized cellulose nanofibers showed higher mechanical properties than those of starch-based resin and coarse cellulose fibers. It is suggested that coarse cellulose fibers act as a defect, resulting in low mechanical properties. Maximum tensile strength reaches approximately 90 MPa at fiber weight contents of 60% by weight. This mechanical property is comparable to that of conventional glass-fiber-reinforced plastics.
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