Fiber Reinforced Polypropylene Composites Research Articles

Multiscale analysis of the mechanical properties and interface damage mechanisms of carbon fiber reinforced polypropylene composites

AbstractIn this article, the mechanical properties of carbon fiber reinforced polypropylene (CF/PP) composites at different carbon fiber (CF) mass fractions were systematically investigated. A comprehensive examination is provided through the integration of experimental testing, numerical simulation, and theoretical analysis, revealing the enhancement effects of CF on the polypropylene (PP) matrix across multiple scales. Experimental results demonstrated that the incorporation of CF significantly impedes crack propagation and enhances the fracture resistance of the composites. Specifically, at a CF mass fraction of 15%, the elastic modulus of the composites is enhanced by 21.7% compared with pure PP, while the tensile strength increases by 40.9%–43.2%. The addition of maleic anhydride grafted polypropylene (MAH‐g‐PP) as a compatibilizer significantly improves the interfacial compatibility between CF/PP. Furthermore, finite element simulations revealed the damage evolution process at the CF/PP interface during tensile loading. Based on the Mori‐Tanaka model, the elastic modulus was predicted, aligning well with experimental and simulated results. This research offers a scientific basis for the design and application of CF/PP composites and contributes to the advancement of high‐performance composites.Highlights CF/PP composites show enhancements in mechanical properties with CF addition MAH improves interfacial adhesion between CF and PP, boosting tensile strength Multiscale experimental and FEA studies reveal CF/PP interface damage mechanisms Mori‐Tanaka model accurately predicts the elastic modulus of CF/PP composites

Effects of Consolidation Parameters on Flexural Behavior of Polypropylene/Glass Fiber Thermoplastic Composites

In this study, the flexural behavior of glass fiber-reinforced polypropylene (GFR-PP) composites was systematically investigated under three-point bending conditions to evaluate the impact of key production parameters. Composite plates with a thickness of 4 mm were fabricated using a stepped mold under varying pressure levels (10, 20, and 30 bar) and durations under pressure (5, 10, and 20 minutes). The specimens were prepared according to ASTM standards to ensure consistency and reliability. The primary objective of this study was to understand how production parameters influence the mechanical properties of GFR-PP composites. The results indicated that the combination of low pressure (10 bar) and longer durations (20 minutes) led to superior flexural strength and enhanced fiber-matrix adhesion due to optimized consolidation, with a maximum flexural strength exceeding 500 MPa. In contrast, higher pressure levels (30 bar) resulted in fiber deformation and reduced mechanical performance. This work provides critical insights into the optimization of production parameters to achieve high-performance GFR-PP composites, with potential applications in aerospace and other lightweight structural components requiring high mechanical strength and durability.

Improved fracture toughness of glass fibers reinforced polypropylene composites through hybridization with polyolefin elastomers and polymeric fibers for automotive applications

AbstractPolypropylene‐reinforced composites mostly exhibit a trade‐off between stiffness and toughness. In this study, the impact of incorporating polyolefin elastomer (POE) and Polyvinyl Alcohol (PVA) fibers as individual and hybrid reinforcement to glass fiber‐reinforced polypropylene composite in the presence of a compatibilizer was explored. The main focus was on achieving an optimal stiffness/toughness balance. Several ternary and quaternary hybrid composite systems were developed and analyzed. All components were melt‐blended using a twin‐screw extruder and then injection molded for subsequent mechanical and morphological analysis. A significant stiffness of approximately 2.4 GPa Young's modulus, and notched izod impact strength ranges between 250 and 400 J/m can be attained with the quaternary hybrid system, PP/GF/POE/PVA fibers. Its performance can be controlled by altering the POE/PVA fibers ratio to achieve the targeted stiffness/toughness balance. These values represent a remarkable increase, with Young's modulus being 120% higher and the izod impact strength surpassing that of the control sample by over 800%. The achieved results aligned with the requirements of the automotive industry, so the developed composites could have a high potential for automotive parts.Highlights Ternary and quaternary hybrid systems were fabricated by a twin‐screw extruder. An improvement of 120% in stiffness and 800% in toughness was observed. Distinct micromechanical deformation mechanisms were identified. Remarkable stiffness‐toughness balance was achieved. Reduction in weight makes the system suitable for automotive applications.

Development of an Automotive-Relevant Recycling Process for Paper Fiber-Reinforced Polypropylene Composites

The automotive industry is under growing pressure from regulatory agencies to improve the recyclability of its plastic components. Simultaneously, manufacturers are adopting natural fiber composites in vehicles to reduce their carbon footprint and decrease reliance on petroleum-based materials. This presents a challenge at vehicle end-of-life, however, as natural fiber-reinforced polymers are substantially more difficult to recycle than their unreinforced counterparts. This study investigated the development of a mechanical recycling process for paper fiber-reinforced polypropylene composites, focusing on the impact of injection molding parameters—specifically, injection temperature and rate—on the thermal, mechanical, and water uptake properties of the composites. The results showed that processing temperature had a greater influence on composite performance than injection rate, with some limited interaction effects between the two. Higher processing intensity damaged the paper fibers, increasing the number of nucleation sites and resulting in greater polypropylene crystallinity. These structural changes reduced tensile properties at higher intensities, while flexural properties improved. Objective function analysis was applied to identify optimal processing conditions, balancing these competing trends. Overall, the findings demonstrate that paper fiber-reinforced polypropylene composites can be recycled into automotive-relevant injection molding compounds using conventional plastic manufacturing techniques, though careful tuning of processing parameters is essential to achieve optimal performance.

Effect of soft and hard segments ratio of waterborne polyurethane on the properties of modified basalt fiber reinforced polypropylene composites

Effect of soft and hard segments ratio of waterborne polyurethane on the properties of modified basalt fiber reinforced polypropylene composites

Influence of Lignin Type on the Properties of Hemp Fiber-Reinforced Polypropylene Composites.

Increasing environmental awareness has boosted interest in sustainable alternatives for binding natural reinforcing fibers in composites. Utilizing lignin, a biorenewable polymer byproduct from several industries, as a component in polymer matrices can lead to the development of more eco-friendly and high-performance composite materials. This research work aimed to investigate the effect of two types of lignin (lignosulfonate and soda lignin) on the properties of hemp fiber-reinforced polypropylene composites for furniture applications. The composites were produced by thermoforming six overlapping layers of nonwoven material. A 20% addition of soda lignin or lignosulfonate (relative to the nonwoven mass) was incorporated between the nonwoven layers made of 80% hemp and 20% polypropylene (PP). The addition of both types of lignin resulted in an increase in the tensile and bending strength of lignin-based composites, as well as a decrease in the absorbed water percentage. Compared to oriented strand board (OSB), lignin-based composites exhibited better properties. Regarding the two types of lignin used, the addition of lignosulfonate resulted in better composite properties than those containing soda lignin. Thermal analysis revealed that the thermal degradation of soda lignin begins long before the melting temperature of polypropylene. This early degradation explains the inferior properties of the composites containing soda lignin compared to those with lignosulfonate.

Optimization of Compression Molding Parameters and Lifecycle Carbon Impact Assessment of Bamboo Fiber-Reinforced Polypropylene Composites.

Driven by global carbon neutrality goals, bamboo fiber-reinforced PP composites have shown significant potential for automotive applications due to their renewability, low carbon emissions, and superior mechanical properties. However, the environmental complexities associated with compression molding process parameters, which impact material properties and carbon emissions, pose challenges for large-scale adoption. This study systematically optimized the compression molding process of bamboo fiber-reinforced PP composites through a three-factor, five-level experimental design, focusing on preheating temperature, preheating time, and holding time. Additionally, an innovative life cycle assessment (LCA) was conducted to evaluate the environmental impact. The results indicated that at a preheating temperature of 220 °C, preheating time of 210-240 s, and holding time of 40-50 s, the material achieved a tensile strength of 35 MPa and a flexural strength of 45 MPa, with a 15% reduction in water absorption. The LCA further highlighted energy consumption, the compression molding process, and material composition as the primary contributors to carbon emissions and environmental impacts, identifying key areas for future optimization. This study provides an optimized framework for compression molding bamboo fiber-reinforced PP composites and establishes a theoretical foundation for their low-carbon application in the automotive industry. Future work will explore the optimization of bamboo fiber content and process parameters to further enhance material performance and reduce environmental impact.

Comparative Analysis of Mechanical and Morphological Properties of Cordenka and Ramie Fiber-Reinforced Polypropylene Composites.

The depletion of conventional materials and their adverse environmental impacts have prompted a shift toward sustainable alternatives in composite materials engineering. In pursuit of this objective, this study investigated the mechanical properties of polypropylene matrix composites reinforced with Cordenka, an artificial cellulose fiber, and compared them to those reinforced with ramie, a natural cellulose fiber. Continuous strand composites were developed using the Multi-Pin-assisted Resin Infiltration (M-PaRI) process. The strands were subsequently sectioned into 15 mm lengths and injection-molded into dumbbell and strip specimens for mechanical characterization. The results showed that 20 wt% Cordenka/PP composites exhibited a tensile strength of 68.7 MPa, 2.04 times higher than neat PP and 1.66 times greater than the 20 wt% ramie/PP composites. Impact testing further demonstrated that Cordenka/PP composites absorbed 2 to 2.5 times more impact energy than ramie/PP composites, regardless of the presence of notches. Fiber length analysis indicated that Cordenka fibers maintained their length beyond the critical fiber length, allowing for efficient stress transfer and acting as a more effective reinforcement compared to ramie fibers, which were below this threshold. Consequently, the Cordenka/PP composites exhibited significantly enhanced mechanical performance. Scanning electron microscopy (SEM) analysis revealed fewer fiber pullouts in ramie-reinforced composites, suggesting superior interfacial adhesion to the PP matrix, although it did not translate to higher mechanical properties. These findings underscore the potential of Cordenka as a sustainable alternative to synthetic, non-biodegradable fibers in PP composites, providing improved mechanical properties and promising prospects for advanced composite applications.

Temperature and rate dependent shear characterization and modeling of spread-tow woven Flax/PP composite laminates

This paper investigates the in-plane shear behavior of spread-tow woven structured flax fiber-reinforced polypropylene composites, focusing on temperature and displacement rate effects. For this aim, the study includes bias-extension experiments to characterize the shear behavior of the material. Several experiments were conducted at different displacement rates and temperature levels. The temperature levels were chosen to encompass the material's behavior during solid and molten-state thermoforming, given the melting and decomposition temperatures acquired from differential scanning calorimetry and thermogravimetric analysis tests, respectively. A new fixture was designed and manufactured to allow pre-heating of the oven and rapid placement of the samples, which in turn, prevents their degradation for the time duration required to reach a uniform temperature distribution in the oven. During the experiments, the 3D digital image correlation technique accurately measured local deformations and strains on the specimen's surface under varying conditions. Further, a finite element model is developed, incorporating a fiber reorientation algorithm with a hypo-elastic shear model to simulate the material's temperature and rate-dependent behavior. The finite element shear angle distributions, as well as the shear angle-force and shear angle-displacement curves, are compared with the Digital Image Correlation (DIC) data and load measurements for different test conditions, showing good agreement between the numerical and experimental approaches.

Influence of Processing Parameters in Injection Molding on the Properties of Short Carbon and Glass Fiber Reinforced Polypropylene Composites

Short-fiber reinforcement is a potent approach to improving the material properties of injection-molded parts. The main consideration in such reinforced materials is to preserve the fiber length, as this is the major influence on the properties of a given composite. The aim of this work was to investigate the different influencing parameters in injection molding processing on the properties of short carbon and glass fiber-reinforced polypropylene. We investigated parameters like melt temperature and back pressure, but also machine size and pre-heating regarding their influence on the tensile properties. We found that adjustments of melt temperature and back pressure only yield small improvements in the fiber length and the tensile properties, also depending on machine size, but a pre-heating step of the granules can significantly improve the properties.

Forming performance and environmental impact of bamboo fiber reinforced polypropylene composites based on injection molding process for automobiles

AbstractTo explore the potential application of plant fiber reinforced composites for automotive component applications, this study prepared bamboo fiber (BF)/nano‐talc/polypropylene (PP) composites based on the injection molding process, comprehensively evaluated the effect of reinforcement materials on the forming properties of composites, including thermal performance, mechanical properties, water absorption, etc. Furthermore, taking a certain automotive injection molded interior part as the object, a life‐cycle assessment from production to the gate was conducted based on the real energy and material consumption during the composite preparation process. The results indicate that adding BF and talc powder increased the thermal stability, density, hardness, viscosity, and crystallinity of the composites while reducing the water contact angle on the surface. Surface‐modified BF and PP showed good compatibility. Talc powder exhibited good dispersibility in PP, and the synergistic effect of BF and talc powder effectively enhanced the composite performance. The tensile, flexural, and impact strength of the composites were improved by 40.64%, 51.48%, and 66.51%, respectively, compared with pure PP. The modulus of the composite increased nearly 2 times compared with pure PP. Additionally, the composite demonstrated good friction and wear properties. The environmental impact of the BF composite manufacturing process was significantly higher than that of pure PP. The substantial consumption of electricity, chemicals, and water resources in the extraction and modification processes of BF were the main factors. The findings of this study contribute to achieving green, high‐performance BF composite manufacturing and the expansion of its applications.Highlights Composites have a higher environmental impact compared to PP. BF and talc can synergistically enhance the performance of composites. BF shows good compatibility with PP. Composites exhibit good friction and wear characteristics.

Study on the effect of fiber orientation on the elastic constants of carbon fiber reinforced polypropylene composites

In order to predict the effects of different fiber orientations on the elastic constants of composites, this paper takes carbon fiber reinforced polypropylene composites as an example, and adopts the Mori-Tanaka method to establish the Random Volume Element (RVE) model of fiber composites with five different fiber orientations, namely, 0 °, 30 °, 45 °, 60 °, and 90 °, and investigates the effects of the fiber The effects of fiber orientation and fiber volume fraction on their elastic constants were investigated to obtain the required data by this method instead of experiment. By improving the Halpin-Tsai model, the value of the orientation factor was determined on the basis of the random orientation factor, and the original shape factor was modified to an exponential shape factor, the orientation degree factor was introduced, and finally, the relationship equations between the modified exponential shape factor and the volume fraction and orientation degree were obtained. The results show that for the same fiber orientation and volume fraction, the smaller the value of shape factor, the higher the elastic modulus. The fitting errors of the four values of elastic constants were also analyzed, and it was found that the improved Halpin-Tsai model could be used to predict the elastic constants of carbon fiber-reinforced polypropylene composites in a certain range, thus providing a method to study the prediction of the elastic constants of composites by fiber orientation.

Microstructure-sensitive investigation on the plastic deformation and damage initiation of fiber-reinforced polypropylene composite

This study presents a comprehensive multi-scale analysis of damage mechanisms in short fiber-reinforced polypropylene composites. The study covers different fiber orientations and loading conditions, revealing distinct contributions from each damage phenomenon. Fiber/matrix interface decohesion and crack propagation across interfaces appear to be the predominant factors leading to material failure, irrespective of fiber orientation and loading mode. Mechanical tests highlight the importance of the interface of fiber/matrix in damage initiation, with local plasticity of the matrix under quasi-static loading. One can note that fiber pull-out is the predominant phenomenon. Moreover, the same damage mechanisms have been observed under 3-point fatigue loading. The results provide valuable insights for understanding and predicting damage evolution in fiber-reinforced composites. Notably, the material undergoes a consistent sequence of damage states, irrespective of monotonic or cyclic loading, highlighting the possibility of using monotonic loading data to predict fatigue lifetime.

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.

Repercussion of fiber content on the mechanical, thermal, and thermomechanical properties of natural fibers reinforced thermoplastic composites for automotive application

Natural fibers are becoming very popular as a reinforcement in composite materials owing to their benefits, such as low-price, lightweight, availability, and environmental friendliness. In this study, abaca fiber-reinforced polypropylene (PP) and high-density polyethylene (HDPE) composites were created with the help of the injection molding method. Prior to composite fabrication, abaca fibers were chemically treated with a 5 wt% caustic soda (NaOH) solution to improve the bonding between the abaca fibers and the matrix and to enhance their properties. Scanning electron microscopy (SEM) was utilized to assess the fiber surface microstructures before as well as after the chemical treatment, along with the fractured surfaces of tensile specimens. The mechanical properties, such as tensile, bending, and impact strength, of abaca/PP and abaca/HDPE composites were evaluated and compared. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods were utilized to investigate the thermal behavior of composites. Also, the dynamic mechanical analysis (DMA) method was utilized to explore the thermomechanical properties of the fabricated composites. The outcomes of the experimental findings showed that abaca/PP composite with 10 and 20 wt% fibers is the best choice of material to be used in the automobile industry.

Assessing Intra-Bundle Impregnation in Partially Impregnated Glass Fiber-Reinforced Polypropylene Composites Using a 2D Extended-Field and Multimodal Imaging Approach.

This study evaluates multimodal imaging for characterizing microstructures in partially impregnated thermoplastic matrix composites made of woven glass fiber and polypropylene. The research quantifies the impregnation degree of fiber bundles within composite plates manufactured through a simplified compression resin transfer molding process. For comparison, a reference plate was produced using compression molding of film stacks. An original surface polishing procedure was introduced to minimize surface defects while polishing partially impregnated samples. Extended-field 2D imaging techniques, including polarized light, fluorescence, and scanning electron microscopies, were used to generate images of the same microstructure at fiber-scale resolutions throughout the plate. Post-processing workflows at the macro-scale involved stitching, rigid registration, and pixel classification of FM and SEM images. Meso-scale workflows focused on 0°-oriented fiber bundles extracted from extended-field images to conduct quantitative analyses of glass fiber and porosity area fractions. A one-way ANOVA analysis confirmed the reliability of the statistical data within the 95% confidence interval. Porosity quantification based on the conducted multimodal approach indicated the sensitivity of the impregnation degree according to the layer distance from the pool of melted polypropylene in the context of simplified-CRTM. The findings underscore the potential of multimodal imaging for quantitative analysis in composite material production.

Effect of matrix modification and fiber surface treatment on the properties of basalt fiber reinforced polypropylene composites

With a focus on sustainable natural fiber reinforced polypropylene composites in varied industries like automotive and aerospace, this study investigates the impact of matrix modification and surface treatment of basalt fibers on the thermomechanical properties of basalt fiber reinforced heterophasic polypropylene composites. Polypropylene matrix modification was achieved by adding maleic anhydride grafted polypropylene (PP-g-MA), resulting in composites that exhibited a 133 % improvement in the tensile strength and 256 % improvement in the tensile modulus at 30 % fiber weight compared to neat polypropylene. The short basalt fibers underwent a silane treatment; However, the thermal treatment used to strip the default manufacturer's sizing resulted in a fluffy fibres texture, which led to agglomeration and feeding issues during processing. Although the silane treatment helped establish a better fiber-matrix interphase, no significant improvement in tensile strength was observed. However, the tensile modulus saw a 343 % improvement at 30 % fiber weight as compared to neat polypropylene. Resizing short basalt fibers following fiber recovery at the end-of-life stage of the composite would be challenging due to the fluffy nature of the fibers. Therefore, any fiber treatment should be done at the initial fiber manufacturing stage, and surface treatment at later stages requires detailed study.

Paper fiber-reinforced polypropylene composites from nonwoven preforms: A study on compression molding optimization from a manufacturing perspective

This work optimizes compression molding manufacturing for wet-formed nonwoven paper and polypropylene fiber mats. A central composite designed experiment investigated the effects of fiber reinforcement concentration, compression molding temperature, pressure, and time on composite laminate performance. We assess the composites’ density, panel thickness, water uptake, flexural behavior, and Izod impact strength. Models predicted and optimized composite performance using objective function analysis with penalties applied for undesirable conditions, such as processing time or low reinforcement concentration. Paper fiber content has the largest impact on composite properties, followed by processing time, molding pressure, and temperature. Composite optimization depends on penalty conditions; low fiber content penalties favor low fiber content panels with short processing times, while high fiber content penalties favor high fiber content panels with long processing times. This work suggests that molding composites with a greater fraction of renewable feedstock requires a commensurate increase in processing intensity.

Tribological Assessment of As-Built and Annealed Carbon Fiber-Reinforced Polypropylene Composites Fabricated Through FDM with Varying Layer Thicknesses

Tribological Assessment of As-Built and Annealed Carbon Fiber-Reinforced Polypropylene Composites Fabricated Through FDM with Varying Layer Thicknesses

Mechanical, Dielectric and Flame-Retardant Properties of GF/PP Modified with Different Flame Retardants.

With the rapid development of electronic information technology, higher requirements have been put forward for the dielectric properties and load-bearing capacity of materials. In continuous glass fiber-reinforced thermoplastic composites, polypropylene matrix is a non-polar polymer with a very low dielectric constant and dielectric loss, but polypropylene is extremely flammable which greatly limits its application. Aiming at the better application of flame retardant-modified continuous glass fiber-reinforced polypropylene composites (FR/GF/PP) in the field of electronic communication, the effects of four different kinds of flame retardants (Decabromodiphenyl ethane (DBDPE), halogen-free one-component flame retardant (MONO), halogen-free compound flame retardant (MULTI), and intumescent flame retardant (IFR)) on the properties of FR/GF/PP were compared, including the mechanical properties, dielectric properties and flame-retardant properties. The results showed that among the FR/GF/PP, IFR has the highest performance in mechanical properties, MULTI has better performance in LOI, DBDPE and IFR have better performance in flame retardant rating, and DBDPE and IFR have lower dielectric properties. Finally, gray relational analysis is applied to propose an approach for selecting the optimal combination (flame retardant type and flame-retardant content) of comprehensive performance. In the application exemplified in this paper, the performance of IFR-3-modified GF/PP is optimized.