Fiber Loading Research Articles

Investigation of Mechanical Properties of Short Sisal Fiber Reinforced Phenol Formaldehyde and Vinyl Ester Composites

Composite materials are replacing standard Engineering metals and alloys for many applications. Here in this work, Sisal fiber is used as reinforcement. Since it is abundantly available in nature and majority of it is getting wasted without being used as reinforcement in engineering applications. Short Sisal fiber reinforced Phenol Formaldehyde and Vinyl Ester resin composites are prepared with varied fiber lengths (5 mm and 10 mm) and for varied weight fraction (20%, 25% and 30%) of the fibers. The short Sisal fibers are treated with 5% of Sodium Hydroxide (NaOH) solution. In the present work, the effect of the fiber treatment, fiber length and fiber loading on the mechanical properties are investigated. The results show that the Alkali Treated Sisal fiber reinforced composites have better mechanical properties than untreated composites. The 10 mm fiber length reinforced composite shown improved mechanical properties than 5 mm fiber length reinforced composite. Increase in mechanical properties is seen when the fiber content in the composite is increased from 20% to 25% and 25% to 30%. The 30% weight of the Sisal fiber reinforced composite has shown higher values of mechanical properties.

Investigating the effect of polypropylene fibres and curing parameters on the workability and mechanical properties of concrete

Polypropylene fibers possess certain characteristics that make them an ideal counterpart to attain explicit advantages when used for building works, more specifically, when added to concrete. In this investigation, polypropylene fibers were added by weight of cement (0.25%, 0.5%, and 0.75%) in M20 grade of concrete and their impact on workability, compressive strength, and flexural strength were assessed and analyzed. The slump test revealed that as the polypropylene fiber loading in the concrete mix was increased, the workability of the mixture continued to decrease; the workability decreased by 11.11%, 19.44%, and 45.83% upon the addition of 0.25 %, 0.5%, and 0.75% fibers respectively in the concrete. The compressive strength, as well as the flexural strength of the concrete, increased monotonously with an increase in the curing time and fiber loading. For instance, in the case of acidic water curing, the compressive strength enhanced from 19.08 MPa to 22.85 MPa upon increasing the fiber content from 0.25% to 0.75%. Adding 0.25% polypropylene fiber resulted in an increase in the flexural strength of conventional concrete mix by 15.78% and 10.29% when cured in normal water for 28 days and 56 days, respectively. Both the compressive and flexural strength of the samples cured in normal water was found to be higher than the samples cured in acidic water and it was observed that the fibre-reinforced concretes were more resistant to acids than the normal unreinforced concrete.

Facile fabrication of 3D-printed cellulosic fiber/polylactic acid composites as low-cost and sustainable acoustic panels

This work presents a green, cost-effective and eco-friendly strategy to reduce noise pollution by developing biopolymer-based 3D-printed acoustic panels. We successfully fabricated two series of composites by varying the weight percentage (wt%) of cellulose fibers of water hyacinth (WH) and pineapple leaf (PAL), with polylactic acid (PLA) as the matrix via the heat-press method. All samples were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Physico-mechanical properties, including hardness, tensile, and impact strength, were improved with increasing fiber loading. Filaments of 1 wt% water hyacinth fibers (WHFs) in PLA (1 WHF/PLA) and 1 wt% pineapple leaf fibers (PALFs) in PLA (1 PALF/PLA) were prepared and tested for 3D printability. The sound absorption coefficients (α) of the 3D-printed panels were investigated from 500 to 5000 Hz sound frequency range. The 3D-printed 1 WHF/PLA and 1 PALF/PLA acoustic panels achieve a maximum α (α-max) of 0.55 and 0.83 at 5000 and 4000 Hz, respectively, featuring the first work to report α-max > 0.5 at low fiber loadings in the high-frequency sound range. The tensile strength of the 3D-printed versions is significantly higher than non-3D-printed counterparts and commercial acoustic absorbers. Our data suggest the prepared 3D-printed panels are excellent candidates for acoustic applications at high-frequency noises. This study exhibits a facile, environmentally benign and sustainable approach to construct highly efficient and mechanically robust biopolymer-based 3D-printed sound-proof panels, which have promising potential as green engineering materials. Interestingly, this research also proposes a mitigation technology for the freshwater invader, Eichhornia crassipes (water hyacinths).

Acoustic Emission based determination of delamination initiation in GFRP laminates

Acoustic Emission (AE) has the potential to identify delamination initiation in quasi-static Mode I fracture tests on glass fiber-reinforced polymer-matrix (GFRP) laminates. It had been shown that a combined AE activity and intensity criterion yields critical Mode I delamination resistance values GIC for an AS4/PEEK carbon fiber thermoplastic composite that are comparable to those from data analysis according to ASTM D5528. However, the AE historic index also allows for detection of delamination initiation under Mode I and Mode II loading of carbon fiber reinforced thermoplastics and thermosets. In the present study, these AE criteria for initiation under Mode I, Mode II and Mixed Mode I/II loading of GFRP epoxy laminates are compared with AE signal energy as additional initiation criterion. Initiation under Mode II and Mixed Mode I/II at a ratio of 4:3 was determined with two different set ups for each Mode. For some test configurations noise signals make unambiguous initiation detection difficult. Determination by means of AE energy or AE activity and intensity yields more conservative GC values compared with the AE historic index or criteria defined in the standards, however, with similar repeatability.

Effect of fiber loading on the mechanical, morphological, and dynamic mechanical characteristics of Calamus tenuis fiber reinforced epoxy composites

AbstractThis research delves into incorporating Calamus tenuis fibers as reinforcing material in polymer composites, conducting a thorough analysis of their viscoelastic, mechanical, and morphological attributes. Employing the hand layup method, Calamus tenuis fiber‐reinforced epoxy composites were crafted across a range of fiber loadings from 0 to 25 wt% with 5 wt% increments. Results highlight significant enhancements in mechanical attributes upon the incorporation of Calamus tenuis fibers into the matrix. Notably, the composite with 10 wt% Calamus tenuis fibers emerges as the top performer, showcasing unparalleled mechanical strength compared to neat epoxy. It achieves the highest tensile strength (21.08 ± 1.03 MPa) and tensile modulus (2.84 ± 0.09 GPa), along with the utmost flexural strength (63.31 ± 1.05 MPa) and flexural modulus (3.12 ± 0.16 GPa). Furthermore, it demonstrates remarkable impact strength (9.40 ± 0.40 J/cm2), emphasizing its resilience. Scanning electron microscopy (SEM) analysis confirms enhanced fiber‐matrix adhesion in the 10 wt% composite. Additionally, dynamic mechanical analysis (DMA) results reveal enhancements in storage and loss modulus, with the 10 wt% composites exhibiting the highest values. However, the damping factor decreases with the inclusion of Calamus tenuis fibers. Overall, a 10 wt% fiber loading is deemed ideal for enhancing the mechanical and dynamic properties of epoxy composites.Highlights Utilized Calamus tenuis fibers as reinforcing materials in epoxy composites. Investigated the mechanical, morphological, and viscoelastic properties. Calamus tenuis fibers boost epoxy composite mechanical traits significantly. SEM confirms improved fiber‐matrix adhesion in 10 wt% composite. DMA highlights elevated storage and loss modulus in 10 wt% composites.

Mechanical characterizations of waste face masks reinforced polyester composites: Recycling wastes into resources

Face masks are made of non-decomposable thin polypropylene sheets. People are discarding them in parks, beaches, drains, landfills, and roadsides because of a deficiency in recycling efforts. It poses health and environmental risks through soil, water, and air pollution, as well as implanting microplastics into aquatic and different active organisms via food chains. Therefore, the environment and ecosystem become unsustainable. This study explored the potential of recycling waste face masks (WFM) into composite materials. In this sense, WFM-reinforced three distinct polyester composites are developed with a 20 % fiber loading in the compression molding machine and employing shredded, parallel, and crisscross patterns of WFM. The tensile, flexural, and impact strengths of composites are assessed as per ASTM guidelines and contrasted with NFRP (natural fiber-reinforced polymer) composites. Besides, void contents and morphological features are investigated using the Field Emission Scanning Electronic Microscope (FE-SEM) to confirm the interaction between WFM and polyester. The maximum tensile and flexural strengths of 32.06 and 41.13 MPa, respectively, are found in the crisscross pattern WFM composite. The maximum impact strength of 0.053 J/mm is found in parallel, and the least void content of 0.63 % is found in crisscross WFM composites. Compared to NFRP composites, the mechanical strengths, void contents, and morphological properties of WFM composites are found promising. It proclaimed that WFM is an appropriate candidate for recycling into composites. It will deter environmental pollution and microplastic insinuation into living things, elevate sustainable development goals, and develop a circular economy by generating resources from WFM.

Enhancement of mechanical and structural characteristics through the hybridization of carbon fiber with Cordia‐dichotoma/polyester composite

AbstractSingle fiber polymer composites containing either natural or artificial fibers may not deliver the desired characteristics. The current study used the hand‐layup technique to make a hybrid composite by incorporating the natural fiber, Cordia‐dichotoma (CD) and artificial fiber, carbon fibers (CF) in a polyester matrix and compressing the mixture for the desired size. The current study investigates the influence of carbon fiber loading (0, 5, 10, and 15 wt%) on the mechanical, structural, and crystalline properties of CD/polyester composites keeping the total fiber loading at 20 wt%. Mechanical properties are investigated with a universal testing machine, and impact strength using Izod impact apparatus. Better mechanical properties (tensile strength‐457.38 MPa; flexural strength‐290.09 MPa and impact strength‐346.46 J/m) were obtained for the pure carbon fiber composite arranged in four layers (CF/CF/CF/CF), followed by hybrid composite (CF/CD/CD/CF) (tensile strength‐319.24 MPa; flexural strength‐253.03 MPa and impact strength‐291.34 J/m) whereas pure CD fiber (CD/CD/CD/CD) composite yielded the lowest values (tensile strength‐117.96 MPa; flexural strength‐164.99 MPa and impact strength‐118.11 J/m). Composites undergo hybridization, which improves their mechanical properties, lowers their cost, and makes them more environmentally friendly. The characteristics of the specimens were examined using Fourier Transform Infrared Spectroscopy (FTIR), X‐ray Diffraction Analysis (XRD), Atomic Force Microscope (AFM), and Scanning Electron Microscopy (SEM). According to findings, crystallinity index is increased from 77.94% for CD/CD/CD/CD composite and increased to 78.21% for CF/CD/CD/CF composite. Highest crystallinity index of 82.46% was obtained for CF/CF/CF/CF composite. These hybrid composites may be used for applications involving medium loads.Highlights In this study, Cordia‐dichotoma natural fibers are extracted and treated with alkali (NaOH) to reduce the biodegradability. To lower the cost and enhance mechanical and biodegradable properties Carbon and cordia‐dichotoma fibers have been hybridized. Mechanical Properties such as tensile, flexural and impact properties are evaluated for the prepared hybrid composites. Hybrid composites were analyzed using FTIR, AFM, XRD, and SEM to assess their suitability to various applications.

Upcycling Post-Consumer Paint Pail Plastic Waste.

The need for ending plastic waste and creating a circular economy has prompted significant interest in developing a new family of composite materials through recycling and recovery of waste resources (including bio-sourced materials). In this work, a family of natural fiber-reinforced plastic composites has been developed from paint pail waste recycled polypropylene (rPP) and waste wool fibers of different diameter and aspect ratio. Composites were fabricated by melt processing using polypropylene-graft-maleic anhydride as a compatibilizer. The internal morphology, interfacial and thermal characteristics, viscoelastic behavior, water sorption/wettability, and mechanical properties of composites were studied using electron microscopy, high-resolution synchrotron Fourier transform infrared microspectroscopy, thermal analysis, rheology, immersion test, contact angle measurement, tensile test and flexural test. The composite matrix exhibited an internal morphology of coalescent micro-droplets due to the presence of polyethylene and dry paint in the rPP phase. In general, the rheological and mechanical properties of the composites comprising higher-aspect-ratio (lower diameter) fibers exhibited relatively superior performance. About an 18% increase in tensile strength and a 39% increase in flexural strength were measured for composites with an optimal fiber loading of 10 wt.%. Interfacial debonding and fiber pull-out were observed as the main failure mechanism of the composites. The developed composites have potential for applications in automotive, decking, and building industries.

Bridging Behavior of Palm Fiber in Cementitious Composite

This study addresses the growing need for sustainable construction materials by investigating the mechanical properties and behavior of palm fiber-reinforced cementitious composite (FRCC), a potential eco-friendly alternative to synthetic fiber reinforcements. Despite the promise of natural fibers in enhancing the mechanical performance of composites, challenges remain in optimizing fiber distribution, fiber–composite bonding mechanism, and its balance to matrix strength. To address these challenges, this study conducted extensive experimental programs using palm fiber as reinforcement, focusing on understanding the fiber–matrix interaction, determining the pullout load–slip relationship, and modeling fiber bridging behavior. The experimental program included density calculations and scanning electron microscope (SEM) analysis to examine the surface morphology and diameter of the fibers. Single fiber pullout tests were performed under varying conditions to assess the pullout load, slip behavior, and failure modes of the palm fiber, and a relationship between the pullout load and slip with the embedded length of the palm fiber was constructed. A trilinear model was developed to describe the pullout load–slip behavior of single fibers, and a corresponding palm-FRCC bridging model was constructed using the results from these tests. Section analysis was conducted to assess the adaptability of the modeled bridging law calculations, and the analysis result of the bending moment–curvature relationship shows a good agreement with the experimental results obtained from the four-point bending test of palm-FRCC. These findings demonstrate the potential of palm fibers in improving the mechanical performance of FRCC and contribute to the broader understanding of natural fiber reinforcement in cementitious composites.

Microplastic assessment in remote and high mountain lakes of Gilgit Baltistan, Pakistan

Microplastic (MP) pollution is a critical environmental challenge worldwide, however limited research is reported in remote lakes of Pakistan. This study assessed MPs (>5 mm) prevalence, distribution and risk perspective in water and sediment of eight remote and high-altitude lakes (>1500 m above sea level) of Gilgit Baltistan, Pakistan. The lakes exhibited an average abundance of 152.6 ± 104.6 to 12.1 ± 7 MP/kg of dry sediments and 2 ± 0.9 to 17.1 ± 17.2 MP/L of surface water. MPs <200 μm dominated in both matrices. Surface water predominantly contained polyester and polypropylene, while polypropylene and polyethylene dominated in sediments. The gradient of elevation did not show any pronounced impact on the fiber loading or MP count in both matrices. Backward air mass trajectory revealed that air masses vastly travelled from western-Asia, Arabian sea and Bay of Bengal with an average transmission distance of 2500–3500 km (500 m a.s.l) that can be a potential deposition MP source in the area. Pollution Load Index of the lakes were >1 exhibiting pollution. All other lakes except Batura and Borith manifested a moderate hazard index. Naltar lake along with aforementioned two lakes also manifested high polymer toxicity. Further research should emphasize understanding the mechanisms and biotic interactions in high-mountain ecosystems.

Comparative study of natural fiber-Reinforced composites for sustainable thermal insulation in construction

Natural fiber-reinforced composites are increasingly recognized as sustainable alternatives in construction materials due to their environmentally friendly properties and ability to increase thermal insulation. This study conducts an in-depth comparative study between palm fiber (DPF) composites and other natural fiber-reinforced composites, including hemp and jute, with a focus on their application as insulation that provides insight into their thermal properties, performance, and mechanical properties to inform sustainable construction practices. The research methodology involves constructing and producing composite samples using date palm, hemp, and jute fibers, each combined into a common base material. Composites are mold-made, ensuring consistent and reproducible samples for testing. Through a systematic investigation, we explore these composites' thermal, and mechanical properties. Testing covers a specific range of fiber loadings, from 10 wt % – 30 wt %. Specific characterization techniques, including compression test, bending test, impact, FT-IR, and DSC, were used to evaluate the behavior of the composites under various conditions. Our results show that the thermal conductivity of the composites ranges from 0.0514 – 0.084 W/m. K for different fiber loading is affected by the fiber content.Furthermore, at maximum fiber concentration (30 by weight), the highest heat capacity of the hemp composite was 1674 J/Kg.K. The 30 wt % of jute and date palm composites achieved a maximum compressive strength of (70 MPa) and (64 MPa) respectively.In summary, this comprehensive study demonstrates the potential of natural fiber-reinforced composites as sustainable and fully bio-based alternatives for construction-related applications. Superior thermal properties and improved mechanical strength highlight their viability in thermal insulation applications.

The effects of fiber load and frictional work on fatigue behavior of water hydraulic artificial muscles in underwater environment

Water Hydraulic Artificial Muscles (WHAMs) exhibit characteristics of high pressure and substantial load capacity. In previous work, the fatigue life of WHAMs under elastic load has been investigated, and experimental results have indicated that the fatigue life is related to both fiber load and frictional work. To individually investigate the impact of fiber load and frictional work on the fatigue life of WHAMs, an experimental scheme was designed to test the fatigue life under different levels of fiber load and frictional work. Meanwhile, the working pressure and contraction range were determined for various working conditions, in order to assess their effects on the fatigue life of WHAMs. The W-test confirms that the fatigue life of WHAMs under each working condition follows a normal distribution. Based on the experimental results, the influence of fiber load and frictional work on fatigue life was analyzed. And the experimental results indicate that the impact of fiber load on the fatigue life of WHAMs is approximately three times greater than that of frictional work. Furthermore, substituting aramid 1414 fiber with aramid 3 fiber in the fiber sleeve led to a substantial increase in fatigue life, elevating the average fatigue life to more than 4 times. Based on the power-law model, a fatigue model of WHAM is established with fiber load and frictional work as factors. The relative error between the fatigue model and experimental results in previously published work demonstrates that the new fatigue model can accurately predict the fatigue life of WHAMs.

Influential reinforcement parameters, elemental mapping, topological analysis and mechanical performance of lignocellulosic date palm/epoxy composites for improved sustainable materials

The value of biomaterials for green products has begun to develop more ecofriendly and renewable sustainable materials for a better circular economy and to reduce carbon footprints. This work presents integrated investigations of the lignocellulosic date palm/epoxy composites at various reinforcement condition parameters for sustainable structural materials where elemental mapping, topological analysis, and mechanical performance have been performed. Mapping energy dispersive X-ray spectroscopy was utilized to assess the composite composition properly. Elemental mapping and a scanning electron microscope were employed to evaluate the chemical composition of the composites. The mechanical performance of the produced composites was also explored in terms of ultimate tensile strength, tensile modulus, elongation at break, and impact energy properties. The effects of fiber loading, fiber length, and fiber width (as long fiber, short fiber, and long-thin fiber) were investigated for the date palm fiber/epoxy composites. Results have revealed that the composite behavior was affected by several influential reinforcement parameters. The energy dispersive X-ray spectroscopy maps by C–K, O–K, Si–K, K-K, and Ca-K demonstrated that the composites contain mainly carbon, silicon, and oxygen. It was evident that the modulus of elasticity property of short fiber composites exhibits an increasing trend with higher fiber content, even at 35 wt%. Moreover, the enhancement of tensile strength for the short fiber size composites reached 72.5 %. However, such tensile strength of thin fiber size/epoxy composites achieved 135.7 % at 25 wt% indicating superior development of this mechanical property. The long date palm fiber composites demonstrated the best value of modulus of elasticity and the maximum impact energy of 15.3 kJ/m2 attained at 25 wt%, which is about 112.5 % enhancement. Scan electron microscope was capable of confirming that broken fibers were not separated from the matrix indicating the good adhesion between the fiber and the matrix that supports their good mechanical performance.

Determining the mechanical properties of biomaterial-based economic thermoplastic composites reinforced with hemp fibres

In this study, continuous reinforcement materials of hemp fibres and matrix polymers (staple polylactic acid (PLA), staple bicomponent PLA) were carded in a conventional carding machine. Various proportions of the hemp fibre reinforcement material, ranging from 20%, 30%, 40%, 50%, and 60% were used in the production of biocomposite structures. We have further studied the effect of several carding passages (up to 3 passages) on the strength performance of both the staple PLA and the staple bicomponent PLA matrix. To obtain composite samples, the carded webs were further consolidated in the hot press machine. Further mechanical performance analysis was carried out in both the cross direction as well as parallel to the machine direction. It was observed that the introduction of reinforcing hemp fibre shows an increase in tensile strength up to the critical fibre loading amount and a decrease in tensile strength after the critical fibre loading amount. The highest tensile strength of 35.84 MPa was obtained for (40HEMP / 60PLA / M / P3), applied to the composite structures in the machine production direction, while the lowest value was 14.70 MPa (60HEMP / 40BPLA / M / P1), respectively.

Mechanical and Dynamic Mechanical Characterization of Epoxy Composites Reinforced with Casuarina Leaf Bio Fibre

This study investigates the influence of casuarina leaf biofibre on the mechanical and morphological characteristics of epoxy resin composites. Composites were prepared using the hand-layup method, incorporating varying volume fractions of the biofibre (4%, 8%, 12%, 16%, 20% and 24% v/v). Mechanical and dynamic mechanical tests were carried out to assess the impact of the biofibre on the composite material. Mechanical testing revealed significant enhancements in tensile strength of 29.2 MPa, particularly at a biofibre volume fraction of 12% and the composite with the highest impact and flexural strengths measured at 2621 J/m2 and 41.1 MPa, respectively for the 16%v/v fibre loading. Dynamic mechanical analysis (DMA) results demonstrated improved viscoelastic properties attributed to the presence of the biofibre. Scanning electron microscopy (SEM) examination of tensile tested samples provided insights into interfacial bonding and filler dispersion within the composite matrix. Overall, the findings highlight the potential of casuarina leaf biofibre to enhance specific mechanical properties and viscoelastic behaviour of epoxy casuarina composites. Optimizing the biofibre volume fraction offers possibility to tailor composite properties for specific application requirements. This research advances the development of bio-based composite materials, contributing valuable insights for the creation of sustainable and high-performance engineering materials.

Evaluation of the mechanical properties of hybrid composites reinforced with plant fibers

The incorporation of plant fibers into the matrix plays an interesting role. Natural fibers have been widely used as reinforcements in polymer matrix composites. Among all reinforcing fibers, natural fiber-based hybrid composites have attracted the attention of researchers as high-potential reinforcing materials for composite materials. These fibers are easily available in the form of agricultural products. Natural fibers are inexpensive, durable and lightweight materials for composite applications. In this experimental work, sisal fibers and date palm fibers were used as reinforcement in different ratios to fabricate hybrid composites by compression molding technique while maintaining a total fiber loading of 20 % by weight. Tensile tests, flexural tests, and impact tests were carried out, water absorption was also determined. The results obtained show that the composite composed of a combination of 16% sisal fibers and 8% date palm fibers has better tensile properties with a stress value of 6.88 N/mm2 and a value of Izod impact of 43.218 J/m. As well as both composites showed a better bending stress value of 67.29 N/mm2, the water absorption test was carried out for four days with 120 hours analysis. This research focuses on the fact that specimen-2 containing 16% sisal and 8% date palm fibers absorbs less water than other composites.

Synthesis and characteristics of natural fiber reinforced nano hybrid composite – an experimental study

Abstract Recently, research on natural hybrid composites has occupied a significant role in the materials science sector. Due to the low density, high specific strength, dimensional stability, and biodegradability, natural fiber composite has become a predominant research area. The present study deals with the fabrication of a jute–banana fiber hybrid composite using the hand layup method with compression molding. A fixed concentration of 5 % carbon nanotubes (CNT) is included over the fiber surfaces as an additional reinforcement material to improve their thermal and electrical conduction properties. The prepared composite material is subjected to different fiber loading (0, 10, 20, and 30 wt.%) with jute and banana weight ratios of 1:1, 1:3, and 3:1. The investigation is conducted for testing the physical, mechanical, and thermal properties of the prepared composites along with morphological studies. Final results revealed a maximum longitudinal tensile strength of 68.8 MPa, 67.0 MPa, and 86.7 MPa and the maximum transverse tensile strength of 41.2 MPa, 40.5 MPa, and 48.0 MPa at 30 wt.% with respective fiber ratio of 1:1, 1:3, and 3:1. The maximum longitudinal flexural strength of this hybrid composite is noticed as 94 MPa, 90 MPa, and 103 MPa for the weight ratio of 1:1, 1:3, and 3:1. Higher impact energy is obtained for the composition ratio of 1:3 (JBC 1:3) which has more banana fiber than the other two. A new attempt at adding carbon nanotubes has improved their thermal conductivity compared to regular composites of jute–banana.

Biocompatibility, thermal and mechanical properties of glass fiber‐reinforced polybenzoxazine composites as a potential new endodontic post

AbstractA novel dental fiber post from glass fiber‐reinforced polybenzoxazine (PBZ) composites was developed in this work. The essential properties, that is, chemical characteristics, thermal and biological properties of the PBZ composites were investigated for various glass fiber loadings (10.5, 23.7, 41.2 and 65.1 vol%). Finite element analysis (FEA) was also utilized to observe mechanical behaviors of the tooth model repaired with PBZ composite posts compared to a natural tooth model. The findings reveal that for the fiber‐reinforced PBZ composites not only their thermal properties were significantly improved, but they also showed enhanced cytocompatibility; we found a coefficient of thermal expansion of 12.8 ppm/°C and cell viability of 91.55 for the 65.1 vol% glass fiber‐reinforced PBZ composite. Moreover, samples reinforced with higher glass fiber loadings effectively resulted in the reduction of stress distribution in dentin observed from FEA suggesting protection againt root fractures. Restoration using the PBZ composite post showed the same stress patterns in the dentin‐composite resin‐post interface of the repaired tooth as in the natural tooth model. The results revealed that the glass fiber‐reinforced PBZ composites possess good thermal properties and mechanical behaviors which renders them suitable candidates for biocompatible dental materials.Highlights The glass fiber/polybenzoxazine (GF/PBZ) composites had nontoxic properties as evidenced through cell viability, growth and morphology studies. The thermal expansion of the GF/PBZ composite was similar to that of dentin, promoting adaptation at the dentin‐post interface. Mechanical behaviors evaluated by FEA of tooth model restored with GF/PBZ composite post were similar to those restored with commercial glass fiber post. The biocompatible GF/PBZ composite with good thermal and mechanical properties is a promising new candidate material as dental fiber post.

Injection molded lightweight composites from tea-stem fiber and polypropylene: Effect of fiber loading on forming properties and cell structure

China boasts abundant tea resources and substantial production output. To facilitate the high-value utilization of by-products generated during tea production, such as tea stems, thereby reducing resource wastage, this study pioneered the preparation of tea-stem fiber-reinforced polypropylene (TF/PP) composites through microcellular injection and conventional molding processes. The effects of tea-stem fiber (TF) content on the formability of foamed and unfoamed composites were compared and analyzed. The findings reveal that the inclusion of TFs fostered the crystallization of polymer chains, decreased the flowability of the composites in their molten state, and enhanced the density, surface hydrophilicity, and thermal stability of the molded composites. In the unfoamed state, composites with 20 wt%, 40 wt%, and 30 wt% TF content exhibited optimal tensile (35.92 MPa), flexural (58.43 MPa), and impact (6.49 KJ/m2) strength, respectively. Upon foaming, composites with TF contents of 30 wt%, 40 wt%, and 30 wt% demonstrated superior tensile (32.84 MPa), flexural (51.31 MPa), and impact (6.94 KJ/m2) strength, respectively. A 30 % TF content in foamed composites yielded the best reinforcement effect, creating an ideal balance of internal interactions. This resulted in mechanical properties that were close to or even exceeded those of unfoamed PP while reducing the density by nearly 6 %. The results from this study contribute towards the high-value application of tea by-products, promoting the development of the global tea economy.

Chemical treatment, fibre length, and fibre loading affecting the mechanical and morphological characteristics of flax fibre/polylactic acid (PLA) green composites developed by injection moulding

AbstractThis paper presents the parametric investigation and optimization of various chemical treatment parameters that affect the mechanical performance of the green composite. The injection moulding method was used to produce the green composites using flax fibre (FF) and polylactic acid (PLA). The chemical parameters chosen to investigate their effects are chemical type (sodium hydroxide, sodium carbonate, and potassium hydroxide), chemical concentrations (1 %, 2 %, and 3 % (w/v)), and duration for fibre treatment (2 h, 4 h, and 6 h). The mechanical performance of the green composites was assessed by evaluating the various properties namely strength, modulus, and elongation under tensile, share, flexural, and compression loading conditions. The morphological study was also performed to examine the failure behavior of the composite after mechanical testing. The effect of fibre length (2 mm, 3 mm, 4 mm, 5 mm, and 6 mm) and fibre loading (10 wt.%, 20 wt.%, and 30 wt.%) on the performance of the flax fibre (FF)/polylactic acid (PLA) composite was also investigated. The fibre dispersion, fibre orientation, and fibre length retention were investigated to assess the characteristics of fibre during injection moulding of the developed flax fibre (FF)/polylactic acid (PLA) composite.