Three‐dimensional nonwoven flax fiber reinforced polylactic acid biocomposites

Three‐dimensional (3D) shell‐structured PLA/Flax biocomposites were fabricated using a novel method incorporating the 3D nonwoven web‐forming process. PLA and flax fibers were blended in the fiber opening stage and converted to webs on the 3D mold using the air‐laying principle. The 3D webs were then consolidated by through‐air thermal bonding. The compression molding technique was used finally to convert the 3D webs to the biocomposites. The relationship between the main process parameters and the properties of the biocomposites was investigated. The results show that with increasing flax fiber content, the crush failure load, total energy absorption, specific energy absorption, and crush efficiency increased. The crushing properties decreased with increased molding temperature, but the crushing properties are not significantly affected by the molding time. The physical properties of 3D biocomposites were also evaluated and the appropriate processing parameters for 3D biocomposites were established. POLYM. COMPOS., 35:1244–1252, 2014. © 2013 Society of Plastics Engineers     

Biodegradability of nonwoven flax fiber reinforced polylactic acid biocomposites

Biocomposites of flax reinforced polylactic acid (PLA) were made using a new technique incorporating an air‐laying nonwoven process. PLA and flax fibers were mixed and converted to the webs in the air‐laying process. Prepregs were then made from the fiber webs by thermal consolidation. The prepregs were finally converted to composites by compression molding. This study was investigated the biodegradability and water absorption properties of the composites. The composites were incubated in compost under controlled conditions. The percentage weight loss and the reduction in mechanical properties of PLA and biocomposites were determined at different time intervals. It was found that with increasing flax content, the mechanical properties of the biocomposites decreased more during the burial trial. The increasing of flax content led to the acceleration of weight loss due to preferential degradation of flax. This was further confirmed by the surface morphology of the biodegraded composites from scanning electron microscope image analysis. Morphological observations indicated severe disruption of biocomposites structure between 60 and 120 days of incubation. POLYM. COMPOS., 35:2094–2102, 2014. © 2014 Society of Plastics Engineers     

Development and characterization of flax fiber reinforced biocomposite using flaxseed oil‐based bio‐resin

In this study, acrylated epoxidized flaxseed oil (AEFO) resin is synthesized from flaxseed oil, and flax fiber reinforced AEFO biocomposites is produced via a vacuum‐assisted resin transfer molding technique. Different amounts of flax fiber and styrene are added to the resin to improve its mechanical and physical properties. Both flax fiber and styrene improve the mechanical properties of these biocomposites, but the flexural strength decreases with an increase in styrene content. The mass increase during water absorption testing is less than 1.5% (w/w) for all of the AEFO‐based biocomposites. The density of the AEFO resin is 1.166 g/cm³, which increases to 1.191 g/cm³ when reinforced with 10% (w/w) flax fiber. The flax fiber reinforced AEFO‐based biocomposites have a maximum tensile strength of 31.4 ± 1.2 MPa and Young's modulus of 520 ± 31 MPa. These biocomposites also have a maximum flexural strength of 64.5 ± 2.3 MPa and a flexural modulus of 2.98 ± 0.12 GPa. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41807.     

Statistical design of sustainable composites from poly(lactic acid) and grape pomace

Biocomposites from poly(lactic acid) (PLA) and grape pomace (GP) were created via injection molding to examine the effects of GP in a PLA matrix. To optimize the mechanical performance the biocomposites were compatibilized with maleic anhydride grafted PLA (MA-g-PLA). The objective of this work was to create a model that could accurately predict the mechanical properties of GP/PLA biocomposites. A region of feasibility for the biocomposites was determined using a statistical design of experiments. Linear regression was used to model the mechanical performance and predicted results with an error of 10% for both tensile and flexural strength and 16% for impact strength. The model was verified with a biocomposite of PLA/GP/MA-g-PLA with a ratio of 62/36/2. This biocomposite had a tensile strength, flexural modulus, and impact strength of 25.8 MPa, 40.0 MPa, and 18.4 J/m, respectively. It was found that a linear model can accurately predict the mechanical properties of PLA/GP/MA-g-PLA biocomposites.     

Effect of thermal annealing on the mechanical and thermal properties of polylactic acid–cellulosic fiber biocomposites

Polylactic acid (PLA) biocomposites were produced by a combination of extrusion and injection molding with three cellulosic reinforcements (agave, coir, and pine) and contents (10, 20, and 30%). In particular, some samples were subjected to thermal annealing (105 °C for 1 h) to modify the crystallinity of the materials. In all cases, morphological (scanning electron microscopy) and thermal (differential scanning calorimetry, dynamical mechanical thermal analysis) characterizations were related to the mechanical properties (Charpy impact, tensile and flexural tests). The results showed that annealing increased the crystallinity for all the materials produced, but different mechanical behaviors were observed depending on fiber type and content. For example, annealing increased the impact strength and flexural modulus of PLA and PLA biocomposites (agave, coir, and pine), while decreasing their flexural strength. But the main conclusion is that fiber addition combined with thermal annealing can substantially increase the thermal stability of the studied materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43750.     

Novel polylactide/triticale straw biocomposites: Processing,formulation, and properties

This article aims to the development of polylactide (PLA)/triticale straw biocomposites with focus on the relationship between triticale straw content, additive presence, processing, and final properties. Prior to melt compounding, the triticale straw used in this study was chopped using the paper process to produce triticale particles that were further pelletized to assure a consistent feed rate into the extrusion line. PLA/triticale straw biocomposites were obtained for different triticale contents from 10 up to 40%vol, without and with maleic anhydride grafted polylactide (PLA‐g‐MA) as a coupling agent. As a supplementary additive, a PLA‐specific branching agent was used in some selected formulations to minimize the reduction in PLA's molecular weight. The biocomposites were characterized in terms of rheology, thermal properties, morphology, mechanical properties (tensile, flexural, and impact), and recyclability. The PLA‐g‐MA increased the tensile strength of biocomposites by 10%, whereas boosted the tensile modulus about 2.5 times at 40%vol triticale content. For the same formulation, the flexural strength was raised by 15% and flexural modulus was doubled. However, a combination of PLA‐g‐MA and branching agent proved to be the best approach to enhance PLA/triticale straw mechanical properties. When 20%vol of triticale was used as reinforcement, the presence of branching agent increased the flexural strength about 25%. The results demonstrate that the triticale straw processed in this way could offer a similar reinforcement capability as the cellulosic fibers based on the agricultural and forestry resources and can be easily recycled without losing its mechanical properties. It has a good potential in the biocomposites field with promising applications in construction, common goods, and transportation industries. POLYM. ENG. SCI., 54:446–458, 2014. © 2013 Society of Plastics Engineers     

Influence of fly ash cenospheres on performance of coir fiber‐reinforced recycled high‐density polyethylene biocomposites

Recycled high‐density polyethylene (RHDPE)/coir fiber (CF)‐reinforced biocomposites were fabricated using melt blending technique in a twin‐screw extruder and the test specimens were prepared in an automatic injection molding machine. Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of fly ash cenospheres (FACS) in RHDPE/CF composites were investigated. It was observed that the tensile modulus, flexural strength, flexural modulus, and hardness properties of RHDPE increase with an increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % CF and 1 wt % MA‐g‐HDPE exhibited optimum mechanical performance with an increase in tensile modulus to 217%, flexural strength to 30%, flexural modulus to 97%, and hardness to 27% when compared with the RHDPE matrix. Addition of FACS results in a significant increase in the flexural modulus and hardness of the RHDPE/CF composites. Dynamic mechanical analysis tests of the RHDPE/CF/FACS biocomposites in presence of MA‐g‐HDPE revealed an increase in storage (E′) and loss (E″) modulus with reduction in damping factor (tan δ), confirming a strong influence between the fiber/FACS and MA‐g‐HDPE in the RHDPE matrix. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties in the composites when compared with RHDPE matrix. The main motivation of this study was to prepare a value added and low‐cost composite material with optimum properties from consumer and industrial wastes as matrix and filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42237.     

Mechanical properties of natural fiber hybrid composites based on renewable thermoset resins derived from soybean oil,for use in technical applications

Natural fiber composites are known to have lower mechanical properties than glass or carbon fiber reinforced composites. The hybrid natural fiber composites prepared in this study have relatively good mechanical properties. Different combinations of woven and non‐woven flax fibers were used. The stacking sequence of the fibers was in different orientations, such as 0°, +45°, and 90°. The composites manufactured had good mechanical properties. A tensile strength of about 119 MPa and Young's modulus of about 14 GPa was achieved, with flexural strength and modulus of about 201 MPa and 24 GPa, respectively. For the purposes of comparison, composites were made with a combination of woven fabrics and glass fibers. One ply of a glass fiber mat was sandwiched in the mid‐plane and this increased the tensile strength considerably to 168 MPa. Dynamic mechanical analysis was performed in order to determine the storage and loss modulus and the glass transition temperature of the composites. Microstructural analysis was done with scanning electron microscopy. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Processing and properties of solution impregnated carbon fiber reinforced polyethersulfone composites

Carbon fiber reinforced polymer composites are attractive because of their high stiffness and strength‐to‐weight ratios. In order to fully utilize the stiffness and strength of the reinforcement fiber, it is necessary to bring the polymer matrix and the reinforcement fiber together with homogeneous wetting. In this paper, a solution processing technique and the mechanical properties of carbon fiber reinforced polyethersulfone composites were investigated. The polymer was dissolved in cyclopentanone and fed onto a continuous carbon fiber tow using a drum winder. The solution‐processed composite prepregs were then layed up and compression molded into unidirectional composite panels for evaluation. The composite samples showed uniform fiber distribution and reasonably good wetting. The longitudinal flexural modulus was as high as 137 GPa, and longitudinal flexural strength 1400 MPa. In addition, the effects of polymer grade and processing conditions on the mechanical properties of the composites were discussed. It is suggested that the transverse properties and interlaminar fracture toughness could benefit from higher polymer matrix molecular weight. A careful design in the spatial distribution of the molecular weight would be necessary for practical applications.     

Reactive compatibilization and performance evaluation of miscanthus biofiber reinforced poly(hydroxybutyrate‐co‐hydroxyvalerate) biocomposites

Dicumyl peroxide (DCP) initiated reactive compatibilization of poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV)/miscanthus fibers (70/30 wt %) based biocomposite was prepared in a twin screw extruder followed by injection molding. In the presence of DCP, both the flexural and the tensile strength of the PHBV/miscanthus composites were appreciably higher compared with PHBV/miscanthus composite without DCP as well as neat PHBV. The maximum tensile strength (29 MPa) and flexural strength (51 MPa) were observed in the PHBV/miscanthus composite with 0.7 phr DCP. The enhanced flexural and tensile strength of the PHBV/miscanthus/DCP composites are attributed to the improved interfacial adhesion by free radical initiator. Unlike flexural and tensile strength, the modulus of the PHBV/miscanthus/DCP composites was found to slightly lower than the PHBV/miscanthus composite. The modulus difference in the PHBV/miscanthus composite with and without DCP has good agreement with the observed crystallinity. However, the flexural and tensile modulus of all the prepared biocomposites was at least two fold higher than the neat PHBV. The storage modulus value of the PHBV/miscanthus and PHBV/miscanthus/DCP biocomposites follows similar trend like tensile and flexural modulus. The melting temperature and crystallization temperature of PHBV/DCP and PHBV/miscanthus/DCP samples were considerably lower compared with the neat PHBV and PHBV/miscanthus composites. The surface morphology revealed that the PHBV/miscanthus/DCP composites have good interface with less fiber pull‐outs compared with the corresponding counterpart without DCP. This suggests that the compatibility between the matrix and the fibers is enhanced after the addition of peroxide initiator. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44860.     

The Preparation and Characterization of Silk/Gelatin Biocomposites

There is a growing interest in the use of composite materials. Silk fiber/gelatin biocomposites were fabricated using compression molding. The fiber content in the composite varied from 10–30 wt%. Composite containing 30 wt% silk showed the best mechanical properties. Tensile strength, tensile modulus, bending strength, bending modulus and impact strength, hardness of the 30% silk content composites were found 54 MPa, 0.95 GPa, 75 MPa and 0.43 GPa and 5.4 kJ/m², 95.5 Shore A, respectively. Water uptake properties at room temperature, accelerated weathering aging, irradiation, thermomechanical analysis, and degradation in soil were carried out in this experiment.     

基于阀体制造的先进树脂基复合材料性能研究

研究了不同改性方法对酚醛团状膜塑料（BMC）、酚醛片状膜塑料（SMC）、乙烯基SMC材料力学性能的影响,分析了树脂基与纤维相的改性作用机制,得到了三者中具有最佳力学性能的复合材料,并通过仿真分析验证了不同复合材料用于制造阀体的可行性。结果表明,3种材料的拉伸性能为乙烯基SMC>酚醛BMC>酚醛SMC,弯曲性能为酚醛BMC>乙烯基SMC>酚醛SMC,乙烯基SMC的综合力学性能最佳;成型温度为160 ℃、模压压力为9 MPa、保温时间为30 min时,乙烯基SMC的拉伸强度、拉伸模量、弯曲强度、弯曲模量分别达到148.26 MPa、4.50 GPa、92.33 MPa、2.39 GPa;阀体静力学分析结果表明,乙烯基SMC与酚醛BMC均满足阀体制造要求。     

Biocomposites developed using water‐plasticized wheat gluten as matrix and jute fibers as reinforcement

Biocomposites developed from wheat gluten using water without any chemicals as plasticizer and jute fibers as reinforcement have much better flexural and tensile properties than similar polypropylene composites reinforced with jute fibers. Wheat gluten is an inexpensive and abundant co‐product derived from renewable resources and is biodegradable but non‐thermoplastic. Previous attempts at developing biocomposites from wheat gluten have used plasticizers such as glycerol or chemical modifications to make gluten thermoplastic. However, plasticizers have a considerably negative effect on the mechanical properties of the composites and chemical modifications make wheat gluten less biodegradable, expensive and/or environmentally unfriendly. In the research reported, we developed composites from wheat gluten using water as a plasticizer without any chemicals. Water plasticizes wheat gluten but evaporates during compression molding and therefore does not affect the mechanical properties of the composites. The effect of composite fabrication conditions on the flexural, tensile and acoustic properties was studied in comparison to polypropylene composites reinforced with jute fibers. Wheat gluten composites had flexural strength (20 MPa), tensile strength (69 MPa) and tensile modulus (7.7 GPa) values approximately twice those of polypropylene composites. Water is an effective plasticizer for wheat gluten and could be used to develop various types of inexpensive and biodegradable wheat gluten‐based thermoplastics. Copyright © 2011 Society of Chemical Industry     

Thermal,Mechanical and Morphological Characterization of Jute/Gelatin Composites

Jute fabrics/gelatin biocomposites were fabricated using compression molding. The fiber content in the composite varied from 20–60 wt%. Composites were subjected to mechanical, thermal, water uptake and scanning electron microscopic (SEM) analysis. Composite contained 50 wt% jute showed the best mechanical properties. Tensile strength, tensile modulus, bending strength, bending modulus and impact strength of the 50% jute content composites were found to be 85 MPa, 1.25 GPa, 140 MPa and 9 GPa and 9.5 kJ/m², respectively. Water uptake properties at room temperature were evaluated and found that the composites had lower water uptake compared to virgin matrix.     

Formulation‐properties versatility of wood fiber biocomposites based on polylactide and polylactide/thermoplastic starch blends

This article discusses the interrelation between formulation, processing, and properties of biocomposites composed of a bioplastic reinforced with wood fibers. Polylactide (PLA) and polylactide/thermoplastic starch blends (PLA/TPS) were used as polymeric matrices. Two grades of PLA, an amorphous and a semicrystalline one, were studied. TPS content in the PLA/TPS blends was set at 30, 50, and 70 wt%. Two types of wood fiber were selected, a hardwood (HW) and a softwood (SW), to investigate the effect of the fiber type on the biocomposite properties. Finally, the impact of different additives on biocomposite properties was studied with the purpose to enhance the bioplastic/wood fiber adhesion and, therefore, the final mechanical performance. The biocomposites containing 30 wt% of wood fibers were obtained by twin‐screw extrusion. The properties of the biocomposites are described in terms of morphology, thermal, rheological, and mechanical properties. Furthermore, the biocomposites were tested for humidity and water absorption and biodegradability. An almost 100% increase in elastic modulus and 25% in tensile strength were observed for PLA/wood fiber biocomposite with the best compatibilization strategy used. The presence of the TPS in the biocomposites at 30 and 50 wt% maintained the tensile strength higher or at least equal as for the virgin PLA. These superior tensile results were due to the inherent affinity between the matrices and wood fibers improved by the addition of a combination of coupling and a branching agent. In addition to their outstanding mechanical performance, the biocomposites showed high biodegradation within 60 days. POLYM. ENG. SCI., 54:1325–1340, 2014. © Her Majesty the Queen in Right of Canada 2013 ¹      

Engineered poly(lactic acid)‐talc biocomposites for melt processing: Effects of co‐blending with poly(butylene succinate) and poly(butylene terephthalate) on thermal and mechanical behavior

This article deals with the design and manufacturing of a novel class of PLA‐based material specifically engineered for injection molding, suitable for food contact and characterized by a good balance of mechanical properties and thermal resistance. A commercial PLA grade was modified by blending it with microlamellar talc as reinforcing filler, poly(butylene succinate) (PBS), and poly(butylene terephthalate) (PBT) as secondary polymeric phases. Ternary blend/talc biocomposites were achieved. The different constituents of the biocomposites were compatibilized by reactive compounding extrusion using maleic anhydride (MAH) grafted PLA (PLA‐MA). The thermal properties of the compounds prior and after injection molding were characterized by differential scanning calorimetry. The mechanical response of the injection molded materials was evaluated by flat indentation and flexural tests. The mechanical properties of the PLA/talc‐based biocomposites and crystallinity of PLA can be controlled by fine tuning the blend by the addition of PBS and PBT in the formulation. In particular, biocomposites characterized by good strength and toughness can be obtained by injection molding, without affecting thermal stability. Based on the experimental findings, the PLA‐based formulations pose; therefore, solid bases for replacing oil‐based plastics in several markets, specifically in the segment of food and pharmaceutical packaging. POLYM. ENG. SCI., 59:264–273, 2019. © 2018 Society of Plastics Engineers     

Preparation and mechanical characterization of chicken feather/PLA composites

Green composites, a bio‐based polymer matrix is reinforced by natural fibers, are special class of bio‐composites. Interest about green composites is continuously growing because they are environment‐friendly. This study describes the preparation and mechanical characterization of green composites using polylactic acid (PLA) matrix including chicken feather fiber (CFF) as reinforcement. Extrusion and an injection molding process were used to prepare CFF/PLA composites at a controlled temperature range. CFF/PLA composites with fiber mass content of 2%, 5%, and 10% were manufactured. The effects of fiber concentration and fiber length on mechanical properties of CFF/PLA composites have been studied. Mechanical properties of composites were investigated by tensile, compression, bending, hardness, and Izod impact testing. The results of experiments indicated that Young's modulus, compressive strength, flexural modulus, and hardness of the PLA reinforced CFF composites are higher but tensile strength, elongation at break, bending strength and impact strength of them are lower than pure PLA. The results indicate that these types of composites can be used for various applications. POLYM. COMPOS., 38:837–845, 2017. © 2015 Society of Plastics Engineers     

Effect of a Small Amount of Synthetic Fiber on Performance of Biocarbon-Filled Nylon-Based Hybrid Biocomposites

Advanced hybrid biocomposites are engineered from nylon 6, waste wood biosourced carbon (biocarbon) with a low content of synthetic fiber for lightweight auto-parts uses. The novel engineering process through direct injection molding of only 2 wt% synthetic fibers in the form of masterbatch with 20 wt% biocarbon, results outstanding performance of the resulting nylon biocomposites. Such uniquely developed biocomposites show tensile strength of 105 MPa and tensile modulus of 5.14 GPa with a remarkable heat deflection temperature (HDT) of 206 °C. The direct injection molding of synthetic fiber retains the length ≈3 times higher as compared to traditional extrusion and injection molding; resulting greater degree of entanglement and composite reinforcement effectiveness in the hybrid biocomposites. Highly dimensionally stable nylon 6 biocomposites with a very low coefficient of linear thermal expansion results through reinforcing ability of the sustainable biocarbon and small amount of synthetic fiber.     

Development and application of triglyceride-based polymers and composites

Triglyceride oils derived from plants have been used to synthesize several different monomers for use in structural applications. These monomers have been found to form polymers with a wide range of physical properties. They exhibit tensile moduli in the 1–2 GPa range and glass transition temperatures in the range 70–120 °C, depending on the particular monomer and the resin composition. Composite materials were manufactured utilizing these resins and produced a variety of durable and strong materials. At low glass fiber content (35 wt %), composites produced from acrylated epoxidized soybean oil by resin transfer molding displayed a tensile modulus of 5.2 GPa, a flexural modulus of 9 GPa, a tensile strength of 129 MPa, and flexural strength of 206 MPa. At higher fiber contents (50 wt %) composites produced from acrylated epoxidized soybean oil displayed tensile and compression moduli of 24.8 GPa each, and tensile and compressive strengths of 463.2 and 302.6 MPa, respectively. In addition to glass fibers, natural fibers such as flax and hemp were used. Hemp composites of 20% fiber content displayed a tensile strength of 35 MPa and a tensile modulus of 4.4 GPa. The flexural modulus was ∼2.6 GPa and the flexural strength was in the range 35.7–51.3 MPa, depending on the test conditions. The flax composite materials had tensile and flexural strengths in the ranges 20–30 and 45–65 MPa, respectively. The properties exhibited by both the natural- and synthetic fiber-reinforced composites can be combined through the production of “hybrid” composites. These materials combine the low cost of natural fibers with the high performance of synthetic fibers. Their properties lie between those displayed by the all-glass and all-natural composites. Characterization of the polymer properties also presents opportunities for improvement through genetic engineering technology. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 703–723, 2001     

Poly(lactic acid) biocomposites reinforced with ultrafine bamboo‐char: Morphology,mechanical, thermal,and water absorption properties

In this study, ultrafine bamboo‐char (BC) was introduced into poly(lactic acid) (PLA) matrix to improve mechanical and thermal properties of PLA based biodegradable composites. PLA/BC biocomposites were fabricated with different BC contents by weight. Uniform dispersion of BC in the PLA matrix and good interaction via physical and chemical interfacial interlocks were achieved. The maximum tensile strength and tensile modulus values of 14.03 MPa and 557.74 MPa were obtained when 30% BC was used. Impact strength of the biocomposite with 30% BC was increased by 160%, compared to that of pure PLA. DSC analysis illustrated that PLA/BC biocomposites had a better thermal property. Crystallization temperature decreased and maximal crystallinity of 30.30% was observed with 30% BC load. We did not notice significant thermal degradation differences between biocomposites with different BC loadings from TGA. Better water resistance was obtained with the addition of BC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43425.