Mechanical and morphological properties of injection-molded rice husk polypropylene composites

In this work, the investigation of the physical, mechanical, and morphological properties of the rice husk flour/polypropylene composites was performed utilizing various filler loadings and coupling agent. Five levels of filler loading (35, 40, 45, 50, and 55 wt%) were designed. In addition, to help the interaction between fiber and polypropylene matrix, struktol coupling agent was added to the composites. All of tensile strength, Young's modulus, flexural strength, flexural modulus, and impact strength properties of the composites were carried out. Moreover, the 50 wt% filler-loaded composites had optimum tensile strength, flexural strength, and flexural modulus, whereas the 35 wt% of filler loading case was the best regarding Young's modulus, flexural strength, flexural modulus, and impact strength. Furthermore, the scanning electron microscope results demonstrate that as filler loading increases, more voids and fiber pullout occur.     

Mechanical Behavior of Unidirectional Curaua Fiber and Glass Fiber Composites

Summary: This work intends to promote the use of natural fibers by comparing the behavior of isophthalic polyester matrix composites reinforced with unidirectional curaua fibers with that of unidirectional glass fiber composites. The composites were produced varying the reinforcement angle (0°, 15°, 30°, 45°, 60°, 75° and 90°) with the aim of studying the fiber orientation effect on composite strength. Composites were also made varying the fiber volume fraction (10%, 20%, 30%, 40% and 50%). The efficiency of an alkaline (5% NaOH) surface treatment of the curaua fiber was also evaluated. The unidirectional composites were characterized using tensile, flexural and short beam tests as per ASTM standards. The properties of a lamina reinforced with either glass or curaua fibers were also studied using theoretical micromechanical approach available in commercial software. The curaua fiber alkaline treatment produced higher tensile strength results compared with untreated fibers. The increase in reinforcement angle significantly decreased strength and modulus of the composites, as expected, and the glass fiber composites showed a more pronounced dependence with fiber orientation. Although the glass fiber laminas showed the best mechanical performance, the results obtained with the curaua fibers were considered similar for angles greater than 45°.     

Additive manufacturing of continuous carbon fiber reinforced poly-ether-ether-ketone with ultrahigh mechanical properties

Continuous carbon fiber reinforced poly-ether-ether-ketone (CCF/PEEK) composites have attracted significant interests in mission-critical applications for their exceptional mechanical properties and high thermal resistance. In this study, we additively manufactured CCF/PEEK laminates by the Laser-assisted Laminated Object Manufacturing technique, which was recently reported by the authors. The effects of laser power and consolidation speed on the flexural strength of the CCF/PEEK composites were studied to obtain the optimal process parameters. Hot press postprocessing was performed to further improve the mechanical properties of the composites. Various fiber alignment laminates were prepared, and the flexural and tensile properties were characterized. The hot press postprocessing 3D printed unidirectional CCF/PEEK composites exhibited ultrahigh flexural modulus and strength of 125.7 GPa and 1901.1 MPa, respectively. In addition, the tensile modulus and strength of the composites reached 133.1 GPa and 1513.8 MPa. The results showed that the fabricated CCF/PEEK exhibited superior mechanical performance compare to fused filament fabrication (FFF) printed carbon fiber reinforced thermoplastics (CFRTP).     

Influence of Nanoclay on the Mechanical Performance of Wild Cane Grass Fiber-Reinforced Polyester Nanocomposites

Natural fiber-reinforced nanocomposites were prepared by incorporating wild cane grass fiber and organically modified montmorillonite (MMT) nanoclay into polyester resin. The composites were formulated up to a maximum volume of fiber of approximately 40% and their mechanical properties were investigated. The mean tensile strength and tensile modulus of nanoclay-filled wild cane grass fiber composites are 6.3% and 18.3% greater than those of wild cane grass fiber composites, respectively, without addition of nanoclay at maximum percentage volume of fiber. The mean flexural strength of nanocomposites at maximum percentage volume of fiber was increased to a maximum of 221 Mpa and flexural modulus to 4.2 Gpa. The mean impact strength of nanoclay-filled wild cane grass fiber composites was increased to 376.7 J/m at maximum percentage volume of fiber. The weight loss of nanoclay-filled wild cane grass fiber/polyester composites was 30% and 22% less than that of composites without nanoclay at maximum percentage volume of fiber. The results indicated that the use of nanoclay showed significant improvement in all the mechanical properties of wild cane grass fiber-reinforced composites.     

Study of the carbon fiber–Poly(Ether–Ether–Ketone) (PEEK) interfaces, 4: influence of fiber–matrix adhesion on the mechanical properties of unidirectional composites

The aim of the last part of this general study is to analyze the influence of the interfacial properties and, more precisely, the adhesion energy, between carbon fibers and PEEK on the final performance of unidirectional composites. A set of mechanical properties, i.e. interlaminar shear strength, longitudinal tensile and compressive and transverse tensile properties, of different unidirectional laminates with the same content (60% by volume) of carbon fibers is determined. It is first shown that the interlaminar shear strength is constant, whatever the type of materials. Therefore, this test is not appropriate to characterize the strength of the fiber–matrix interface in PEEK-based composites. On the contrary, in agreement with previous work on other systems, it appears that the ultimate properties (longitudinal tensile and compressive as well as transverse tensile strengths and strains) of the laminates increase with the interfacial adhesion energy, whereas the stiffness of these composites remains unaffected in all cases.     

Investigation on Physical and Mechanical Properties of WPC from Corn stalk (Lignocellulosic Fiber) and HDPE

Summary: This study has tried to use HDPE and the coupling agent consistent MAPP and cornstalk fibers, create wood plastic composite material and its physical and mechanical properties such as tensile modulus, flexural modulus and humidity absorption is measured. After determining the percentage of 20, 30 and 40% of corn stalk fibers in the product and the use of two longitudinal mesh levels of 40 and 80 of them and using the 5% MAPP coupling agent testing was done and it was shown that increasing fiber length and percent increase in product humidity is absorbed. This is while the declines by increasing the fiber length changes of samples were during the tensile tests. In the bending test also increased fiber length and flexural modulus was increased.     

Press forming of short natural fiber-reinforced biodegradable resin: Effects of fiber volume and length on flexural properties

The effects of the volume fraction and length of natural fibers on flexural properties of biodegradable composites were investigated. Kenaf and bagasse were mixed with corn-starch biodegradable resin, and composite flexural specimens were fabricated by press forming. Cox's model that incorporates the effect of fiber compression in the cross section was applied to calculate the flexural modulus. Bagasse was found to be more compressible than kenaf due to the difference structure in the cross section. For up to 60% volume fraction kenaf and 66% bagasse composites, the flexural modulus increased with increase in fiber volume fraction, and these results were in good agreement with the calculated values. However, above 60% fiber volume fraction kenaf and 66% bagasse, the flexural modulus decreased due to insufficient resin. Moreover, the decrease of the flexural modulus occurred at fiber lengths 2.8 mm kenaf and 3.2 mm bagasse. Above these fiber lengths, there was no change in the flexural modulus of the composite specimens. This trend was also identified by the calculation.     

A study of PP/PET composites: Factorial design,mechanical and thermal properties

Due to the economic importance of polypropylene (PP) and polyethylene terephthalate (PET), and the large amount of composites made with PP matrix and recycled PET as reinforcing material; an investigation was performed regarding the mechanical and thermal behavior of PP composites containing recycled polyethylene terephthalate fibers (rPET). Interfacial adhesion between the two materials was achieved by adding a compatibilizer, maleic anhydride grafted polypropylene, PP-g-MA. Mechanical behavior was assessed by tensile, flexural, impact and fatigue tests, and thermal behavior by HDT (Heat Deflection Temperature). Fractured surfaces and fiber were investigated by scanning electron microscopy. Multiple regression statistical analysis was performed to interpret interaction effects of the variables. Tensile strength, tensile modulus, flexural strength, flexural modulus and HDT increased after rPET fiber incorporation while strain at break, impact strength and fatigue life decreased. Addition of compatibilizer increased tensile strength, flexural strength and flexural modulus, fatigue life and HDT while tensile modulus, strain at break and impact strength decreased. However, at low fiber content, the impact strength increased, probably due to nucleation effects on PP.     

Three‐dimensional printing of poly(lactic acid) bio‐based composites with sugarcane bagasse fiber: Effect of printing orientation on tensile performance

The cellulose fiber was extracted from the abandoned crop sugarcane bagasse (SCB) by means of chemical treatment methods. Poly(lactic acid) (PLA) bio‐based composites with SCB were prepared through fused deposition modeling (FDM) 3D‐printing technology, and the morphologies, mechanical properties, crystallization properties, and thermal stability of 3D‐printed composites were investigated. Compared with the neat PLA, the incorporation of SCB into PLA reduces the tensile strength and flexural strength of 3D‐printed samples but increases the flexural modulus. The difference in tensile performance and bending performance is that the tensile strength of 3D‐printed samples is best when the SCB content is 6 wt%, while the flexural modulus continuously decreases as the SCB content increases. Furthermore, the effects of various printing methods on the tensile performance of 3D‐printed samples were explored via modifying G‐code of 3D models. The results indicate that the optimum SCB fiber content is identical for all printing methods except method “vertical.” Due to the fibers and molecular chains are oriented to varying degrees with altering raster angle in 3D‐printed samples, the fully oriented sample printed by method “parallel” has a better tensile strength. Besides, SCB exhibits enough high thermal decomposition temperature to meet requirements for melt extrusion processing of PLA composites, and SCB fiber is capable of promoting the crystallization of PLA.     

Biodegradable polyesters reinforced with surface-modified vegetable fibers

Flax fibers are investigated as reinforcing agents for biodegradable polyesters (Bionolle and poly(lactic acid) plasticized with 15 wt.-% of acetyltributyl citrate, p-PLLA). The composites are obtained either by high temperature compression molding fiber mats sandwiched between polymer films, or by batch mixing fibers with the molten polymer. Fibers in composites obtained by the latter method are much shorter (140-200 microm) than those of the mats (5,000 microm). Flax fibers are found to reinforce both p-PLLA and Bionolle (i.e. tensile modulus and strength increase) when composites based on fiber mats are investigated. Conversely, analogous composites obtained by batch mixing show poor mechanical properties. The observed behavior is attributed to the combined effect of fiber length and fiber-matrix adhesion. If flax fibers with a modified surface chemistry are used, the strength of short fiber composites is seen to improve significantly because the interface strengthens and load is more efficiently transferred. Appropriate surface modifications are performed by heterogeneous acylation reactions or by grafting poly(ethylene glycol) chains (PEG, molecular weight 350 and 750). The highest tensile strength of p-PLLA composites is reached when PEG-grafted flax fibers are used, whereas in the case of Bionolle the best performance is observed with acylated fibers.     

Preparation of starch-based biocomposites reinforced with mercerized lignocellulosic fibers: Evaluation of their thermal,morphological, mechanical,and biodegradable properties

In the present paper, starch-based biocomposites have been prepared by reinforcing corn starch matrix with mercerized Abelmoschus esculentus lignocellulosic fibers. The effect of fiber content on mechanical properties of composite was investigated and found that tensile strength, compressive strength, and flexural strength at optimum fiber content were 69.1%, 93.7% and 105.1% increased to that of cross-linked corn starch matrix, respectively. The corn starch matrix and its composites were characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric (TGA) analysis. The fiber reinforced composites were found to be highly thermal stable as compared to natural corn starch and cross-linked corn starch matrix. Further, water uptake and biodegradation studies of matrix and composites have also been studied.     

Mechanical properties of surface treated UHMWPE fiber and SiO2 filled PMMA composites

The hybrid reinforcement effect of surface‐treated UHMWPE fiber and SiO₂ on the mechanical properties of PMMA matrix composites was investigated. When UHMWPE fiber is introduced, the tensile strength of UHMWPE fiber‐reinforced composites sharply increases. The flexural modulus was enhanced with an increase in filler loading. Flexural modulus of the treated UHMWPE/SiO₂/PMMA composites was higher than that of the UHMWPE/PMMA and UHMWPE/SiO₂/PMMA composites. The outcome of the better interfacial bonding between the filler and the matrix is reflected in the improvement of the mechanical properties of the treated UHMWPE/SiO₂/PMMA composites. Copyright © 2017 John Wiley & Sons, Ltd.     

Effect of surface treatment with potassium permanganate on ultra-high molecular weight polyethylene fiber reinforced natural rubber composites

The effects of surface treatment using potassium permanganate on ultra-high molecular weight polyethylene (UHMWPE) fibers reinforced natural rubber (NR) composites were investigated. The results showed the surface roughness and the oxygen-containing groups on the surface of the modified fibers were effectively increased. The NR matrix composites were prepared with as-received and modified UHMWPE fibers added 0–6 wt%. The treated fibers increased the modulus and tensile stress at a given elongation. The tear strength increased with increasing fiber mass fraction, attained maximum values at 4 wt%. The hardness of composites exhibited continuous increase with increasing the fiber content. The dynamic mechanical tests showed that the storage modulus and the tangent of the loss angle were decreased in the modified UHMWPE fibers/NR composites. Several micro-fibrillations between the treated fiber and NR matrix were observed, which meant the interfacial adhesion strength was improved.     

Effect of Silane Coupling Agent and Compatibilizer on Properties of Short Rossells Fiber/Poly(propylene) Composites

Rossells fiber reinforced polypropylene composites were prepared by melt mixing. The fiber content was 20 wt%. Octadecyltrimethoxysilane (OTMS) and maleic anhydride grafted polypropylene (MAPP) were used to improve the adhesion between poly(propylene) (PP) and the fiber. The mechanical, rheological, and morphological properties, and heat distortion temperature (HDT) of the composites were investigated. Tensile strength, impact strength, flexural strength and HDT of MAPP modified PP composites increased with an increase in MAPP content. However, no remarkable effect of MAPP content on the Young's modulus of the composites was found. OTMS resulted in small decreases of tensile strength and Young's modulus, and increase in impact strength. Scanning electron micrographs revealed that MAPP enhanced surface adhesion between the fiber surface and PP matrix.     

Experimental investigation on the mechanical properties of Cyperus pangorei fibers and jute fiber-based natural fiber composites

The present era uses natural fibers as a partial replacement for synthetic fibers, thereby utilizing eco-friendly materials in a number of automotive applications (namely, bumpers, wind shields, doors, ceilings, etc.). Although there are many research findings related to natural fiber composites, in this work, a new sandwich layer of Cyperus pangorei fibers and jute fiber epoxy hybrid composites is developed using the hand lay-up technique and compared with the pure Cyperus pangorei fiber and pure jute fiber epoxy composites. The mechanical properties like tensile, flexural, compressive, impact, and hardness are performed as per ASTM standards for the developed composites. The test results show that Cyperus pangorei hybrid composite 3 had a tensile strength of 50.2 MPa, flexural strength of 301.48 N mm^?2, ultimate compression load of 15.03 KN, impact energy of 6.34 J, and Shore D hardness of 82.7, which are superior by 1.1–1.5 times to all the other developed composites. The microstructural characterizations are performed using scanning electron microscope which played a vital role in analyzing the failure morphology of the composites.     

Mechanical properties of plasma‐treated carbon fiber reinforced PTFE composites with CNT

This paper is concerned with the effects of the plasma surface treatment and the addition of CNT on the mechanical properties of carbon fiber/polytetrafluoroethylene (PTFE) composite. The tensile and flexural strength of composites containing CNT and plasma‐treated carbon fibers improved. The flexural strength first decreases with respect to the CF content. The flexural strength increases to 179 MPa for the plasma‐treated composite as compared with 167 MPa for the neat carbon fiber composites. The overall improvement is thus nearly 8%.     

表面复合纳米SiO_2和碳纳米管玻璃纤维增强尼龙6的结构与性能

利用静电相互作用在玻璃纤维(GF)表面分别复合纳米二氧化硅(SiO2)和多壁碳纳米管(MWNTs),制备了GF-SiO2、GF-MWNTs复合增强体,并通过转矩流变仪制备了尼龙6(PA6)/GF-SiO2和尼龙6(PA6)/GF-MWNTs复合材料.利用扫描电子显微镜(SEM),示差扫描量热仪(DSC),热机械分析仪(DMA)等手段研究了复合材料的微观结构、热学及力学性能.结果表明,静电复合的方法可以使纳米二氧化硅(nano-SiO2)、多壁碳纳米管(MWNTs)在GF表面达到均匀吸附,复合增强体能加快尼龙6的结晶速度,并使材料的玻璃化温度、动态模量、拉伸强度、结晶温度等明显提高,其中GF-MWNTs对复合材料性能的提高最明显,拉伸强度提升了21%,模量提高了28%.     

Effect of fiber length and loading on the properties of Schumannianthus dichotomus (murta) fiber–reinforced epoxy composites

The present work was aimed at preparing composite materials using epoxy matrix and murta fibers of varying lengths and weight percentages. The composites were analyzed on the basis of density, thermal gravimetric analysis, infrared spectroscopy, scanning electron microscopy, tensile strength, flexural strength, Izod impact strength, and Rockwell hardness studies. Twenty-five weight percent of randomly oriented fibers of 25 mm length rendered the best mechanical properties to the composite. The tensile strength of the composite was analyzed using the Hirsch model. The characterization of the composite reveals that murta fiber is a good candidate for polymer reinforcement.     

Effects of Rice Straw Powder (RSP) Size and Pretreatment on Properties of FDM 3D-Printed RSP/Poly(lactic acid) Biocomposites

To develop a new kind of environment-friendly composite filament for fused deposition modeling (FDM) 3D printing, rice straw powder (RSP)/poly(lactic acid) (PLA) biocomposites were FDM-3D-printed, and the effects of the particle size and pretreatment of RSP on the properties of RSP/PLA biocomposites were investigated. The results indicated that the 120-mesh RSP/PLA biocomposites (named 120#RSP/PLA) showed better performance than RSP/PLA biocomposites prepared with other RSP sizes. Infrared results showed that pretreatment of RSP by different methods was successful, and scanning electron microscopy indicated that composites prepared after pretreatment exhibited good interfacial compatibility due to a preferable binding force between fiber and matrix. When RSP was synergistically pretreated by alkaline and ultrasound, the composite exhibited a high tensile strength, tensile modulus, flexural strength, and flexural modulus of 58.59, 568.68, 90.32, and 3218.12 MPa, respectively, reflecting an increase of 31.19%, 16.48%, 18.75%, and 25.27%, respectively, compared with unmodified 120#RSP/PLA. Pretreatment of RSP also improved the thermal stability and hydrophobic properties, while reducing the water absorption of 120#RSP/PLA. This work is believed to provide highlights of the development of cost-effective biocomposite filaments and improvement of the properties of FDM parts.     

Properties Investigation of novel nitrile rubber composites with rockwool fibers

Rockwool is an inorganic fiber with interesting properties obtained from basaltic rocks. It can possibly be used in rubber technical products which work under critical conditions in several industries. This study aims to investigate properties of three short rockwool fibers/nitrile rubber composites. Ten formulations were prepared with 10, 25 and 40 phr of rockwool fibers with different length and modification. The composites were assessed on its morphological aspects, thermal, rheological, and mechanical behaviors. The results remarked that the rockwool fiber with chemical modification had better interfacial interaction with the polymer enhancing modulus at 100% of deformation, Shore A hardness, tear strength, Payne effect and stress relaxation under a compressive regime. An outstanding result was observed for the composite with 10 phr of fiber with chemical modification that had less stress relaxation when compared with the unfilled NBR indicating an excellent possibility of use of this fiber in materials that work under compressive forces. The difference in length of the rockwool fibers (125 μm–300 μm) did not interfere significantly on most of the results.