Electrical and mechanical properties of carbon pellets from acid (HNO3)treated self-adhesive carbon grain from oil palm empty fruit bunch

Factors such as its natural properties, low cost and availability in large quantities as a by-product may give oil palm empty fruit bunches (EFB) a great potential as a candidate precursor for solid carbon products. Self-adhesive carbon grains (SACG) were prepared from EFB by a low temperature pre-carbonization process. Green pellets were prepared from SACG and SACG treated with nitric acid having concentration of 1, 3 and 5 Molar (M). Carbon pellets were produced by carbonization of green pellets up to 1000°C in a nitrogen environment using multi-step heating profile. Measurements on carbon pellets show that the electrical conductivity (), hardness (H) and Young's modulus (Y) follow the linear equations /[10^–3 × (m )^–1] = 0.57M + 4.74, H/[Vickers hardness] = 27M + 148 and Y/[GPa] = 2.6M + 5.0, respectively. This indicates that nitric acid systematically affected the properties of the product. The behavior that , H and Y increase linearly with M seems to be associated with the effect of acid treatment on the weight loss, lignocellulosic structure and particle size of the SACG.     

Thermal stability and flammability of coconut fiber reinforced poly(lactic acid) composites

This study examined the mechanical and thermophysical behavior of green composites. In the preparation procedure of the composite, a plasma treatment was applied to the surface of the coconut fibers to improve the interfacial adhesion between the fibers and matrix. The coconut fiber-reinforced PLA composites were prepared using the commingled yarn method. The mechanical properties of the composites, such as tensile strength, Young’s modulus, and elongation at break were examined, and the shrinkage and flame retardant properties of the specimens were measured. From these experiments, the effect of the plasma treatment on the mechanical and thermophysical behavior of the coconut fibers/PLA composites was identified. In addition, morphological analysis was performed using scanning electron microscopy.     

Viscoelastic and thermal behavior of woven hemp fiber reinforced poly(lactic acid) composites

This study examined the physical behavior of hemp/poly(lactic acid) (PLA) composites, particularly the thermal properties and viscoelastic behavior. Twill and plain woven hemp fabrics were used as reinforcements and hemp fabrics-reinforced PLA composites were produced using a film stacking method. The coefficient of thermal expansion of the composites decreased sharply with increasing the volume fraction of fiber. The twill structure was found to be suitable for reinforcing a PLA resin with higher impact strength and better mechanical properties than the plain woven. The viscoelastic properties of the composites including the storage modulus, loss modulus and loss tangent were also examined by dynamic mechanical analysis. In addition, morphological analysis was performed using scanning electron microscopy.     

Characterization of polyester composites from recycled polyethylene terephthalate reinforced with empty fruit bunch fibers

Unsaturated polyester resin (UPR) was synthesized from recycled polyethylene terephthalate (PET) which acted as a matrix for the preparation of UPR/empty fruit bunch fibers (EFB) composite. Chemical recycling on fine pieces of PET bottles were conducted through glycolysis process using ethylene glycol. The unsaturated polyester resin (UPR) was then prepared by reacting the glycolysed product with maleic anhydride. FTIR analysis of glycolyzed product and prepared UPR showed that cross-links between unsaturated polyester chain and styrene monomer occurred at the unsaturated sites which resulted in the forming of cross-linking network. The preparation of UPR/EFB composite was carried out by adding EFB into prepared UPR matrix. The effects of surface treatment on EFB with sodium hydroxide solution (NaOH), silane coupling agent and maleic anhydride (MA) were then studied. The experimental results showed that treated EFB have higher values of tensile and impact strength compared with untreated EFB. The best results were obtained for silane treatment followed by MA and NaOH treatments where the tensile strength was increased by about 21%, 18% and 13% respectively. SEM micrographs of the tensile fracture surfaces of UPR/EFB composite also proved that treatment on EFB has increased the interfacial adhesion between the fiber and UPR matrix compared to the untreated UPR/EFB composite.     

Comparative life cycle assessment (LCA) of bio-oil production from fast pyrolysis and hydrothermal liquefaction of oil palm empty fruit bunch (EFB)

This paper presents a life cycle assessment of two alternative processes for the production of bio-oil from Malaysian oil palm empty fruit bunch (EFB), namely, fast pyrolysis and hydrothermal liquefaction, in which limited studies have been reported in the literature. In this study, both processes were evaluated and compared in terms of their impacts to the environment, specifically based on the selected impact categories: global warming potential (GWP), acidification, eutrophication, toxicity, and photochemical-oxidant formation. The results indicated that fast pyrolysis process of EFB caused more severe impact on the environment compared to hydrothermal liquefaction process. Fast pyrolysis process caused almost 50 % more GWP impact compared to hydrothermal liquefaction process, due to both high energy demand in the drying process and high-temperature operation of fast pyrolysis. Other than that, the assessment on other environmental impacts indicated that hydrothermal liquefaction operation is more environmentally benign compared to fast pyrolysis due to the reduced energy consumption. Lastly, sensitivity analysis involving three scenarios (change in bio-oil yield, thermal efficiency of boilers, and thermal efficiency of dryers), respectively, were constructed and presented.     

碳纤维/聚乳酸复合材料的结晶性能和流变特性

以碳纤维（CF）作填料,制备了CF/聚乳酸（CF/PLA）复合材料,CF的质量比（CF∶PLA）为1%、3%、5%、10%和15%。研究了PLA及CF/PLA复合材料的结晶性能和流变特性。结果表明,质量比≤3%时,CF在基体中起到了异相成核的作用,提高了PLA的结晶性能,XRD衍射峰强度增强,CF/PLA复合材料结晶温度和结晶度分别提高到112.5℃和30.7%,流变特性与纯PLA相似。CF的质量比增加到5%时,达到"渗流阈值",黏度激增,限制了分子链段的自由运动,导致CF/PLA复合材料结晶性能下降。CF质量比为15%时,CF/PLA复合材料结晶温度降低至93.1℃,结晶度只有2.5%。     

Stress-transfer in microfibrillated cellulose reinforced poly(lactic acid) composites using Raman spectroscopy

Lyocell fibres were used to make microfibrillated cellulose (MFC) by combined homogenisation and sonication. A web-like structure was obtained with fibril diameters in the range of several micrometers to less than 80 nm. Composite samples with PLA resin reinforced with MFC networks were prepared using compression moulding. Young’s modulus and tensile strength of these composites increased by ～60% and 14% respectively, compared to the pure resin material. Raman spectroscopy was used to monitor the molecular deformation of networks and composite materials. A Raman band initially located at ～1095 cm^?1 was observed to shift towards a lower wavenumber position upon tensile deformation. The rate of Raman band shift with respect to strain for the composites was higher than for the pure MFC networks, indicating that the observed improvement in mechanical properties results from stress transfer from the PLA resin to the MFC fibrils.     

Agrofibre reinforced poly(lactic acid) composites: Effect of moisture on degradation and mechanical properties

Natural fibre reinforced PLA composites are a 100% biobased material with a promising mechanical properties profile. However, natural fibres are hygroscopic whereas PLA is sensitive to hydrolytic degradation under melt processing conditions in the presence of small amounts of water. Here, we determine the effect of water content in undried and dried natural fibres on semi crystalline grade PLA degradation during processing as well as on the composite’s mechanical performance. The fibres evaluated are ramie, flax and cotton, containing 6–9 mass% moisture in the undried state and 0.2–0.4 mass% in the dried state. Intrinsic viscosity and melt flow index analysis indicate that the effect of the different levels of moisture in the fibres have a similar and small effect on PLA degradation, PLA hydrolysis appears rather affected by fibre diameter. Morphology, flexural strength and stiffness and Charpy impact of the composites are not significantly affected by the water present in the undried fibres.     

Novel lightweight sandwich-structured bio-fiber-reinforced poly(lactic acid) composites

Novel bio-based lightweight sandwich-structured composites with both skin and core materials made from biofiber and poly(lactic acid) (PLA) matrix were developed. The composites contained 48 wt% cellulose fiber and 52 wt% PLA matrix. The fabrication process was simple and required no adhesive for the skin–core bonding. The effects of fiber weight fraction and density on the core compressive properties were evaluated experimentally. Fifty percent of fibers gave the best results among the three fiber weight fractions studied and was used in preparing cores for subsequent fabrication of the sandwich-structured composites. The flexural properties and failure modes of the sandwich-structured composites were assessed. The flexural properties of the composites met the published deflection requirements for automotive load floor applications. Since these biocomposites were made using natural renewable materials that are fully biodegradable and recyclable, they show potential to be used as environmentally friendly alternatives to the existing products.     

Study on short ramie fiber/poly(lactic acid) composites compatibilized by maleic anhydride

Short ramie fiber reinforced poly(lactic acid) (PLA) composites without and with maleic anhydride (MA) were developed. The influence of PLA-g-MA as a compatibilizer on the properties of the composites was studied. The tensile, flexural and impact strength of the composites have improvements with the addition of PLA-g-MA. The morphology of fracture surface evaluated by SEM indicates that the composites with the addition of PLA-g-MA can get better adhesion between the fiber and the matrix. And the Vicat softening temperature and the degradation temperature of the composites are increased with the addition of PLA-g-MA. However, PLA-g-MA leads the glass transition temperature (T_g) decrease according to the DSC results.     

Life cycle assessment of oil palm empty fruit bunch delignification using natural malic acid-based low-transition-temperature mixtures: a gate-to-gate case study

In future biorefineries, the development of cheap and environmentally friendly solvents for biomass pretreatment is highly desirable. In this sense, low-transition-temperature mixtures (LTTMs) have high potential to serve as green solvents for replacing conventional pretreatment technologies. In this study, a life cycle assessment of LTTMs pretreatment was conducted to determine the environmental impacts caused by biomass delignification. A gate-to-gate analysis which started with harvested oil palm empty fruit bunch and ended with lignin was selected. The environmental impacts such as acidification potential, global warming potential, eutrophication potential, photochemical ozone creation potential, human toxicity potential and volatile organic compounds emission were evaluated. The comparable environmental balances of commercial l-malic acid and cactus malic acid-based LTTMs pretreatment processes verified the suitability of the process with natural malic acid as the source of proton donor. This study concludes that biomass delignification using natural cactus malic acid-based LTTMs had promising features such as high delignification efficiency and environmentally friendly compared to commercial l-malic acid-based LTTMs. Based on environmental point of view, the overall process of biomass delignification using sucrose-based LTTMs had lower CO₂ emissions compared to the monosodium glutamate- and choline chloride-based LTTMs. These findings are important for verifying the greenness and sustainability of LTTMs to be applied at industrial scale.     

Effect of fiber surface-treatments on the properties of poly(lactic acid)/ramie composites

Ramie fiber reinforced poly(lactic acid) (PLA) composites were prepared by a two-roll mill. Ramie was treated by alkali and silane (3-aminopropyltriethoxy silane and γ-glycidoxypropyltrimethoxy silane). Effect of surface treatment on the properties of the composites was studied. The tensile, flexural and impact strength of the composites have a significant improvement. Dynamic mechanical analysis (DMA) results show that the storage moduli of the composites with treated ramie increase with respect to the plain PLA and the composites with untreated fiber whereas tangent delta decreases. The Vicat softening temperature of the composites with treated fiber is greatly higher than that of the composites with untreated fiber. The results of thermogravimetric analysis (TGA) show that fiber treatment can improve the degradation temperature of the composites. Moreover, the morphology of fracture surface evaluated by scanning electron microscopy (SEM) indicates that surface treatment can get better adhesion between the fiber and the matrix.     

Electrospinning highly oriented and crystalline poly(lactic acid) fiber mats

In recent years, there has been an increased focus on sustainable, green alternatives with similar properties to conventional petroleum-based polymers. Poly(lactic acid) (PLA) is a biodegradable biopolymer which exhibits mild piezoelectric properties and has good processability which gives it potential for use in numerous existing and novel applications. The purpose of this study was to produce highly oriented and crystalline PLA electrospun fiber mats for piezoelectric applications. In order to yield a high piezoelectric constant, high crystallinity and fiber orientation are necessary. A two parallel collector set up was used to mechanically orient the fibers in the space between two copper electrodes. Voltage and feed rate were adjusted to produce smooth, oriented fibers with average diameters ranging 0.73–1.19 μm. Crystallinity and orientation were increased via hot drawing of the fiber mats and were maximized between 40 and 50 % and greater than 50 %, respectively.     

Toughening mechanisms in poly(lactic) acid reinforced with TEMPO-oxidized cellulose

The mechanical properties of poly(lactic) acid (PLA) were modified by the addition of small amounts of cellulose, prepared from the mechanical disintegration of birch Kraft pulp following oxidation of the primary alcohol groups mediated by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO). The TEMPO-fibrillated cellulose (TOFC) was subsequently acetylated in acetic anhydride to degrees of substitution (DS) of 0.4 and 0.6 to enhance the compatibility between the polar cellulose and the non-polar polymer. The fracture behaviour of tensile specimens prepared from PLA film containing weight fractions of 1, 2 and 5 % of TOFC was considerably altered. The strain-to-failure of PLA modified by the incorporation of 1 wt% TOFC acetylated to a DS of 0.6 increased approximately 25-fold and the work of fracture by order of magnitude. The increase in the fracture properties were, nevertheless, accompanied by a reduction in Young’s modulus of around 60 % at both DS levels. At the higher TOFC addition levels, no toughening was observed, with the strains-to-failure and works of fracture both decreasing compared to pure PLA film. On the other hand, the Young’s modulus and tensile strength of films prepared from PLA incorporating TOFC esterified to a DS of 0.6 was found to be greater than that of pure PLA film. Possible mechanisms explaining the increase in toughness at 1 wt% are postulated.     

Effect of plasma treatment on mechanical properties of jute fiber/poly (lactic acid) biodegradable composites

Surface treatment of natural fibers is one of the important methods to improve the mechanical properties of the composite material. In this paper, plasma treatment (PT) for various exposure timings (30, 60, 90, and 120?s) was performed to study the mechanical properties of jute fiber and its composites using poly (lactic acid) (PLA) as the matrix. The results were compared with alkali (AT) and plasma treated (PT) fiber composites. Bundle fiber test was carried out for untreated, AT, and PT jute fiber composites. PT fiber composites showed superior properties compared to other treatments. Micro-droplet test results showed that the interfacial shear strength (IFSS) of PT fiber composite is higher than that of AT fiber composites. Mechanical properties and hardness were increased on subjecting the fiber to plasma treatment. Tensile strength, young’s modulus and flexural strength were increased in an order of 28, 17, and 20%, respectively, for plasma polymerized jute fiber composites. Moreover, plasma polymerization leads to increase (>20%) in the flexural strength than untreated fiber composites. It is inferred that plasma treatment improves the interfacial adhesion between the jute fiber and PLA. These results were also confirmed by scanning electron microscopy observations of the fractured surfaces of the composites. Overall, plasma polymerization is an effective and eco-friendly method for the surface modification of the lingo cellulosic fiber to increase the compatibility between the matrix (hydrophobic) and fiber (hydrophilic).     

A comparison of the mechanical characteristics of kenaf and lyocell fibre reinforced poly(lactic acid) (PLA) and poly(3-hydroxybutyrate) (PHB) composites

Cellulose fibre-reinforced poly(lactic acid) (PLA) and poly(3-hydroxybutyrate) (PHB) composites have become increasingly interesting with regard to their biodegradability and mechanical characteristics. The use of different matrices leads to variable composite characteristics. This study provides a comparison of the mechanical characteristics of compression-moulded 30 mass% lyocell and 40 mass% kenaf fibre-reinforced PLA and PHB. The results of the tensile tests showed that 30 mass% lyocell/PLA composites reached the highest tensile and bending strength with 89 and 148 N/mm², respectively. The highest Young’s modulus was also measured for 30 mass% lyocell/PLA with 9.3 GPa, and the highest flexural modulus was measured for 40 mass% kenaf/PHB with 7.1 GPa. By far, the best impact strength was determined for lyocell/PHB with 70 kJ/m², followed by lyocell/PLA with 52 kJ/m². The investigation of the Shore D hardness resulted in a higher value for the PLA matrix with 81.5. PHB achieved a hardness of 67.5. By adding fibres as reinforcement, the Shore D hardness increased up to 83.6 for lyocell/PLA and 73.1 for kenaf/PHB. Density measurements showed lower densities for the composites with higher fibre loads (kenaf/PLA and kenaf/PHB) in comparison to the theoretical density. This speaks for a higher proportion of air inclusion in the composites which could negatively affect the mechanical composite characteristics.     

Thermal and mechanical properties of chemically treated oil palm fiber filled acrylonitrile butadiene styrene composites

In this work, chemical surface treated oil palm fibers, including alkali, maleic and silane pre‐treatments are melt blended and hot compression molded with acrylonitrile butadiene styrene into varying compositions of polymer composites. The effectiveness of the chemical pre‐treatment and fiber dispersion are analyzed with the aid of Fourier‐transform infrared spectrometry and scanning electron microscope while the influences on thermal degradation and mechanical properties of the resulting composites are analyzed through thermal gravimetric analysis and tensile test respectively. Differential thermogravimetric analysis result show that alkali, maleic and silane pre‐treatments could lower the onset thermal degradation temperature of oil palm fiber filled acrylonitrile butadiene styrene composites. The tensile test results show that chemically treated oil palm fiber filled acrylonitrile butadiene styrene composites attained enhancement in tensile strength as compared to untreated counterpart. Scanning electron microscopy observations on fracture surfaces of oil palm fiber filled acrylonitrile butadiene styrene composites found that the reinforcing efficiency of chemically treated oil palm fiber could be further increased by improving interfacial bonding between oil palm fiber and acrylonitrile butadiene styrene.     

环境友好聚乳酸复合发泡材料的研究进展

聚乳酸(PLA)复合发泡材料是一类重要的环境友好新型可降解材料。该材料通常是以PLA高聚物为主要原料,以其它可降解物质(如脂肪族树脂、淀粉、天然纤维等)为辅助成分复合发泡而成。论述了近年来国内外环境友好PLA复合发泡塑料的研究进展;综述了PLA复合发泡体存在的问题;概述并展望了PLA复合发泡材料的应用领域与发展趋势。     

Study on sound absorption property of ramie fiber reinforced poly(l-lactic acid) composites: Morphology and properties

The effect of ramie fiber, flame retardant and plasticizer on sound absorption property of ramie fiber reinforced PLLA composites was investigated. We used press molding process to prepare the ramie fiber/PLLA composites, with short ramie fiber and ramie plain weave fabric as the reinforcement. The dispersivity of flame retardant ammonium polyphosphate (APP) was indirectly tested by thermogravimetric analysis (TGA). The result of sound absorption property measurement shows that the composites with short ramie fiber have better sound absorption property than the ramie fabric reinforced PLLA composites. And the addition of APP and plasticizer poly(butylene adipate-co-terephthalate) (PBAT) improves the sound absorption property of ramie fabric/PLLA composites. Moreover, morphological studies by scanning electron microscopy (SEM) demonstrate the micro-phase separation in the PBAT/PLLA composites and the porosity of the single ramie fiber bundle. The results suggest that these special structures are the main reason for the better sound absorption property.     

Compression and bending performances of carbon fiber reinforced lattice-core sandwich composites

To restrict debonding, carbon fiber reinforced lattice-core sandwich composites with compliant skins were designed and manufactured. Compression behaviors of the lattice composites and sandwich columns with different skin thicknesses were tested. Bending performances of the sandwich panels were explored by three-point bending experiments. Two typical failure mechanisms of the lattice-core sandwich structures, delaminating and local buckling were revealed by the experiments. Failure criteria were suggested and gave consistent analytical predictions. For panels with stiff skins, delamination is the dominant failure style. Cell dimensions, fracture toughness of the adhesives and the strength of the sandwich skin decide the critical load capacity of the lattice-core sandwich structure. The mono-cell buckling and the succeeding local buckling are dominant for the sandwich structures with more compliant skin sheets. Debonding is restricted within one cell in bending and two cells in compression for lattice-core sandwich panels with compliant face sheets and softer lattice cores.