Load Transfer Efficiency Research Articles

Low-cost flash graphene from carbon black to reinforce cementitious composites for carbon footprint reduction

With the merits of high quality, cost-effectiveness, and high yield efficiency, flash Joule heating (FJH) emerges as an efficient means for mass production of flash graphene (FG). It creates prerequisites for the large-scale application of graphene in reinforcing cementitious composites, thus opening innovative possibilities for curbing carbon emissions and fostering the sustainable evolution of cementitious composites. In this study, two types of FGs, including high-purity FG (FG-G) and conductive FG (FG-D), are successfully synthesized via FJH process using carbon black as the carbon source. FG-G features a low ID/IG of 0.52, and exhibits higher graphitization and structural orderliness with fewer defects compared to the FG-D. The addition of 0.25 wt% FG-D increases the compressive strength, flexural strength, and flexural ultimate strain of cementitious composites by 16.48 MPa/16.8%, 1.43 MPa/37.2%, and nearly 2600 με/550%, respectively. The microstructure characterization results reveal that FG reduces the matrix defects, enhances both the matrix microstructure and calcium silicate hydrate gel nanostructure, which is advantageous for matrix refinement, inhibition of microcrack aggregation and propagation, and load transfer efficiency. Its disorderly stacked turbine structure also contributes to robust interface bonding and friction with cement matrix, thus facilitating the strengthening and toughening of cementitious composites. This study introduces a potential avenue to develop widely applicable and versatile silicon-based cementitious composites with high performance and low CO2 emission by using small carbon-based graphene as reinforcement.

SiC nanofiber-reinforced Ag matrix composites exhibiting high strength and ductility

In this work, we demonstrated an example of leveraging the intrinsic morphology features of one-dimensional SiC nanofiber (SiCnf) to design high-performance Ag-metal matrix composites (MMCs) using powder metallurgy techniques. To break up the SiCnf agglomerates and increase surface functionality while maintaining its integrity, the raw SiCnf underwent a specially developed surface modification process. Following a combination of hetero-agglomeration, spark plasma sintering and hot extrusion, the SiCnf was homogeneously dispersed and singly aligned throughout the Ag matrix. Microstructure observations revealed close contact between the SiCnf and the Ag matrix, resulting in a sawtooth-like SiCnf-Ag interface induced by the plastic flow of Ag. Thanks to the presence of strong mechanical anchors at SiCnf protrusions, the load transfer efficiency of the SiCnf-Ag interface reached 72 %. Consequently, the SiCnf/Ag composite exhibited a high tensile strength of 219 MPa and a substantial failure elongation of 39.2 %. This work underscores the importance of optimizing interfacial microstructures and offers the new insights of designing novel Ag-MMCs for applications in conductive devices.

Comprehensive evaluation of interfacial interactions optimization for CF reinforced high-performance thermoplastic composites by electrochemical deposition of conjugated polymers

The mechanical properties of carbon fiber (CF) reinforced high-performance thermoplastic composites are significantly compromised due to inadequate interface bonding between CF and matrix. In this study, electrochemical polymerization techniques were employed to modify CFs with polypyrrole (PPy), poly-aniline (PANI), and poly-o-phenylenediamine (PoPd), to systematically investigate the impact of conjugated polymers on the interfacial properties of CF/copoly (phthalazinone ether sulfone ketone)s (PPESK) composites through a combination of experimental and molecular dynamics (MD) approaches. The findings revealed distinct differences among these conjugated polymers in terms of their effects on both IFSS and ILSS for CF/PPESK composites. Among all tested laminates, PoPd@CF-60s/PPESK exhibited the highest IFSS, ILSS and flexural strength values of 39.8 MPa, 75.6 MPa, and 1494 MPa, respectively, 94.1 %, 20.6 %, and 47.6 % higher than those of CF-desized/PPESK, without compromising CFs strength and thermal resistance of CF/PPESK composites. MD simulations combined with fracture morphology analysis confirmed that compatibility between conjugated polymers and matrix played a pivotal role in enhancing interface properties for CF/PPESK composites. Furthermore, the AFM outcomes demonstrated that the PoPd layer could serve as the modulus transition layer between the CF phase and the PPESK phase, which effectively enhancing the load transfer efficiency between the two phases under external forces. To summarize, this work presents a straightforward yet non-destructive approach that effectively enhances the interface strength within advanced CF reinforced high performance thermoplastic polymer composites (CFRHPTPs).

Effect of Ni on the mechanical and corrosion properties of TiC-reinforced steel matrix composites

Particle-reinforced steel matrix composites typically lead to a decrease in corrosion resistance while enhancing mechanical properties. However, steel matrix composites for marine applications require superior mechanical properties and corrosion resistance. In this study, 8 vol% TiC/Fe–C composites were prepared using the master alloy method. The effects of Ni contents (0, 1.2 wt%, 1.6 wt%, 2.0 wt%, and 2.4 wt%) on the mechanical and corrosion properties of the composites were evaluated. Results indicated that the tensile strength, elongation, and corrosion resistance of the composites initially increased and then decreased with increasing Ni content. The σUTS and εf of Ni2.0 composites increased from 536 MPa and 4.1 % for Ni0 to 1100 MPa and 9.0 %, respectively. The icorr and corrosion rate of the Ni2.0 composite were 0.440 μA/cm2 and 0.0057 mm/year, respectively. The mechanical properties and corrosion resistance of TiC particle-reinforced steel matrix composites were simultaneously enhanced by the addition of 2.0 wt% Ni. The increase in strength is mainly attributed to changes in thermal mismatch resulting from Ni addition, solid solution strengthening of the Fe–Ni solid solution, and improved interface compatibility between the TiC particles and the matrix, thus enhancing load transfer efficiency. The increase in plasticity can be attributed to the significant improvement in interface deformation compatibility with Ni addition. The increase in corrosion resistance primarily results from the steel matrix alloying, uniform distribution of TiC particles, and strong interface bonding between the particles and the matrix.

Thermal-Mechanical Coupling Performance of Heat-Resistant, High-Strength and Printable Al-Si Alloy Antisymmetric Lattice Structure.

The unsatisfactory mechanical performance at high temperatures limits the broad application of 3D-printed aluminum alloy structures in extreme environments. This study investigates the mechanical behavior of 4 different lattice cell structures in high-temperature environments using AlSi12Fe2.5Ni3Mn4, a newly developed, heat-resistant, high-strength, and printable alloy. A novel Antisymmetric anti-Buckling Lattice Cell (ASLC-B) based on a unique rotation reflection multistage design is developed. Micro-CT (Computed Tomography)and SEM (Scanning Electron Microscope) analyses revealed a smooth surface and dense interior with an average porosity of less than 0.454%. Quasi-static compression tests at 25, 100, and 200°C showed that ASLC-B outperformed the other 3 lattice types in load-bearing capacity, energy absorption, and heat transfer efficiency. Specifically, the ASLC-B demonstrated a 51.56% and 44.14% increase in compression load-bearing capacity at 100 and 200°C compared to ASLC-B(AlSi10Mg), highlighting its excellent high-temperature mechanical properties. A numerical model based on the Johnson-Cook constitutive relationship revealed the damage failure mechanisms, showing ASLC-B's effectiveness in preventing buckling, enhancing load-transfer efficiency, and reducing stress concentrations. This study emphasizes the importance of improving energy absorption and mechanical performance for structural optimization in extreme conditions. The ASLC-B design offers significant advancements in maintaining structural integrity and performance under high temperatures.

Influence of pipe rocking on the effectiveness of the load transfer along the drillstring during slide drilling: A comprehensive experimental study

The application of surface rocking-pipe-assisted drilling (SRPAD) technology is largely dependent on the ability driller to transfer an appropriate amount of weight to the bit. However, the impact of surface torque oscillations on the longitudinal drag and frictional torque is not thoroughly understood. For this purpose, in this study, a novel experimental apparatus was developed to study the load transfer characteristics along a drillstring during SRPAD. In the experiment, the forces and torques at both ends of the simulated drillstring were recorded, and the mechanical responses at various positions on the drillstring are monitored using a strain-measuring method. The experimental results suggest that properly rocking the drillstring back and forth can help operators regain most of the friction-reducing performance of conventional rotating drillstrings. Furtherore, we found that, if the pipe-rocking parameters, including the rocking velocity, rocking angle, surface hookload, and holding time, are properly controlled, the load transfer efficiency can be effectively improved. In particular, the rocking angle and surface hookload should be increased to reduce the stick-slip effect and buckling distortion. The experimental results provide important guidance for improving the performance of SRPAD system, though the flowing of drilling fluid and the influence of bent-housing motors are not taken into consideration.

Achieving BNNSs intrinsic strengthening in Ti-based composite through reaction-interface engineering

For the purpose of achieving boron nitride nanosheets (BNNSs) intrinsic strengthening and relating microscopic interface characteristics to macroscopic mechanical behavior in BNNSSs/Ti composites, the BNNSs/Ti composites were fabricated by field-assisted hot pressing (FHP) and subsequent 923K, 1023K, 1123K or 1223K hot-rolling (HR). Herein, we succeeded in simultaneously maintaining the BNNSs intrinsic structure and considerable interfacial nano-sized TiBw. Interestingly, the superior tensile property (UTS: 1166MPa, El. 9.3%) was realized in 1123K as-rolled BNNSs/Ti composite, whereas the dramatic ductility deterioration exhibited in composite when the HR temperature setting at 1223K. BNNSs load transfer and interface failure behavior were investigated by direct in-situ tensile SEM observation. The nano-TiBw on partially reacted BNNSs played a predominant role on BNNSs load-transfer efficiency and contributed to the desirable ductility. These findings highlighted the untapped potential for improving mechanical properties in BNNSs reinforced metal matrix composite.

Microstructure, interfacial and mechanical properties of SiC interphase modified C/C-SiC composites prepared by reactive melt infiltration

Interfacial modification can effectively regulate the interfacial properties of ceramic matrix composites. This paper reports on the effect of SiC interphase thickness on the microstructure, interfacial and mechanical properties of C/C-SiC composites. As the SiC interphase thickness increased to 2 μm, the flexural strength and modulus of the C/C-SiC composites increased up to 252 MPa and 40 GPa, an increase of 36 % and 40 %, respectively. Because the SiC interphase protected the carbon fibers from the corrosion of liquid silicon, thereby increasing the effective fiber volume fraction. Furthermore, the increased interfacial shear strength (IFSS) measured by the fiber push-in test improved the load transfer efficiency. Raman spectrum and transmission electron microscopy indicated that the damage process of the interface with high IFSS after the fiber push-in test showed fiber/pyrolytic carbon interface debonding, release of thermal residual stress, and larger upward rebound protrusion of carbon fibers without interface crushing.

Effect of clamshell powder on the mechanical and damping properties of epoxy-bamboo composites

Compared to single natural fibre composites, hybridising natural fibres with filler particles presents a promising avenue for enhancing composites physical, mechanical, and damping properties. This study delves into incorporating clamshell powder, a filler derived from clams’ hard protective outer shells, into polymer composites. The focus is on investigating the potential of clamshell powder as a filler material to augment the mechanical and damping properties of epoxy-bamboo mat composites. The weight ratio of clamshell fillers varied from 0% to 9%, and the compression moulding method was used to fabricate the composites. As per ASTM standards, mechanical properties were evaluated by conducting tensile and flexural tests. Free vibration tests by impact hammer technique were employed to evaluate the natural frequency, damping ratio, and mode shapes of developed composites to measure damping properties. Results revealed that adding clamshell filler significantly improved composites tensile strength, flexural strength, and damping properties. The addition of clamshell elevated the tensile strength by 18.5%, and flexural strength by 24.2% for composite with 6 wt% filler, which can be attributed to the efficiency of load transfer and the interfacial bonding between fillers and epoxy matrix. SEM analysis supported the experimental results obtained. The highest damping value is received for 9 wt% filler, showing 30% enhancement compared to composites without clamshell filler. Modal analyses using ANSYS software further validated the positive impact of clamshell filler. This study underscores the potential of clamshell filler in enhancing the mechanical and damping properties of epoxy-bamboo composites, broadening their applicability in various fields.

RESEARCH ON APPLICATION OF FINITE ELEMENT METHOD TO ANALYZE LOAD TRANSFER EFFICIENCY ACCORDING TO DEFLECTION OF AIRPORT RIGID PAVEMENT

The load transfer between adjacent cement concrete slabs at expansion joint locations is affected by many different factors. The load-bearing capacity of the pavement will be limited and even lead to destruction if the load transmission ability of the dowel bars does not meet the requirements. Especially, for airports that have just been put into operation or have been in operation for a long time. In this article, the authors have researched and evaluated the effectiveness of load transfer according to deflection through the application of the 3D finite element method. The model utilizes material parameters and actual airport hard pavement structures and calculates for many types of aircraft commonly operating in Vietnam. Thereby calculating and evaluating the load transfer efficiency (LTE) according to deflection for each specific type of aircraft. The model also visually shows the deformation of the transmission dowel bars and concrete slabs at the expansion joint location. The authors tested the model's reliability through experiments conducted at Tan Son Nhat International Airport which is the largest-scale and oldest airport in Vietnam. The results of calculating LTE from the simulation and experimental models have a small error (3.39%) which shows that the model is highly reliable and can be used for similar research directions without being easily done through traditional methods.

A novel approach to achieve high strength, high plasticity and high conductivity of graphene/Cu composites with graphene core-shell structure

The synergy between mechanical strength and ductility as well as electrical conductivity (EC) is of great importance for the application of Cu matrix composites (CMCs). In this work, a Cu@reduced graphene oxide (RGO) core-shell structure was purposively constructed to prepare RGO/Cu composites. The results show that this core-shell structure prepared by electrostatic adsorption and chemical reduction is beneficial to the uniform distribution of RGO and the formation of Cu-O-C bonds at the RGO/Cu interface. Compared with pure Cu, the yield strength (YS) and ultimate tensile strength (UTS) of the RGO/Cu composite with only 1% RGO are improved by 119% and 40%, respectively. While it maintains high ductility and EC, almost consistent with that of pure Cu. The core-shell structure enhances the load transfer efficiency of the RGO/Cu interface, and reduces the interfacial obstruction of electron transport. This work achieves a good balance of mechanical strengthening and electrical conducting, which provides a new strategy for the development of graphene/Cu composites.

Study on Calculation Method of Bending Performance of Concrete Sandwich Composite Slab.

In order to explore the flexural behavior of a concrete sandwich panel under concentrated boundary conditions, based on Kirachhoff's elastic thin plate theory in this paper, the geometric deformation, physical conditions, and equilibrium relationship of a sandwich panel are deduced by constructing the layered analysis model of the sandwich panel, the basic differential equation of the flexural deformation of the concrete sandwich thin plate is obtained, and the mathematical expression of the internal force and displacement under the boundary condition of concentrated support is given. Combined with an engineering example, the proposed calculation method is verified. The results show that, in the arrangement of reliable connectors for concrete sandwich panels, the concrete wythes bear the load while the contribution of the core layer to the bending capacity of the structure can be ignored. When subjected to a laterally distributed load, the sandwich panel mainly experiences out-of-plane bending deformation, and the bending normal stress in the concrete panel layer shows a linear non-uniform distribution along the thickness direction of the panel. The bending deformation performance and bearing efficiency of a concrete sandwich slab with the change in concentrated support position have significant effects, and the load transfer efficiency can be improved by optimizing the arrangement of supports. Except for small local areas near the supports, the bending stress distribution and deformation behavior of the concrete sandwich panel can be accurately analyzed by the calculation method established in this paper.

Axial Load Peristaltic Transfer Mechanism of the Drillstring to Improve Penetration Rate

Summary During the drilling of long horizontal wells, the significant frictional resistance generated by the wellbore walls poses a challenge for the drillstring to efficiently transmit load to the drill bit, which eventually reduces drilling efficiency and restricts the extension distance achievable. Inspired by the structure and movement principle of an earthworm, we propose an earthworm-like load transfer method for the drillstring to address this issue. Specifically, the proposed method involves the installation of a pulse generator and multiple vibration subs within the same drillstring, decomposes the drillstring into multiple sections and modulates it to creep like an earthworm, thus facilitating load transfer. Experimental studies and numerical simulations were conducted in this paper to explore the fundamental mechanisms of earthworm-like crawling, aiming to enhance the efficiency of load transfer within the drillstring. The experimental results suggest that adopting earthworm-like excitation can increase the load transfer efficiency of the drillstring by 36–52% compared to conventional drilling methods. However, if the drillstring experiences helical buckling, there is a significant decrease in the efficiency of load transfer. Meanwhile, a dynamic model of the drillstring, considering the 3D wellbore trajectory, multipoint excitation, Stribeck friction, and penetration rate, has been developed. The simulated results from the proposed model align well with the experimental results obtained before the drillstring buckling, with an error of less than 5%. The simulation results for a 1000-m drillstring indicate that the earthworm-like excitation significantly enhances the efficiency of load transfer compared to conventional drilling methods. This improvement is attributed to the increase in the proportion of reverse-motion drillstring segments by 35.8–40.25%, which will greatly reduce the instantaneous total vector frictional force of the entire drillstring.

A Parametric Study Investigating the Dowel Bar Load Transfer Efficiency in Jointed Plain Concrete Pavement Using a Finite Element Model

Transverse joints are introduced in jointed plain concrete pavement systems to mitigate the risk of cracks that can develop due to shrinkage and temperature variations. However, the structural behaviour of jointed plain concrete pavement (JPCP) is significantly affected by the transverse joint, as it creates a discontinuity between adjacent slabs. The performance of JPCP at the transverse joints is enhanced by providing steel dowel bars in the traffic direction. The dowel bar provides reliable transfer of traffic loads from the loaded side of the joint to the unloaded side, known as load transfer efficiency (LTE) or joint efficiency (JE). Furthermore, dowel bars contribute to the slab’s alignment in the JPCP. Joints are the critical component of concrete pavements that can lead to various distresses, necessitating rehabilitation. The Swedish Transport Administration (Trafikverket) is concerned with the repair of concrete pavement. Precast concrete slabs are efficient for repairing concrete pavement, but their performance relies on well-functioning dowel bars. In this study, a three-dimensional finite element model (3D-FEM) was developed using the ABAQUS software to evaluate the structural response of JPCP and analyse the flexural stress concentration in the concrete slab by considering the dowel bar at three different locations (i.e., at the concrete slabs’ top, bottom, and mid-height). Furthermore, the structural response of JPCP was also investigated for several important parameters, such as the joint opening between adjacent slabs, mispositioning of dowel bars (horizontal, vertical, and longitudinal translations), size (diameter) of the dowel bar, and bond between the slab and the dowel bar. The study found that the maximum LTE occurred when the dowel bar was positioned at the mid-depth of the concrete slab. An increase in the dowel bar diameter yielded a 3% increase in LTE. Conversely, the increase in the joint opening between slabs led to a 2.1% decrease in LTE. Additionally, the mispositioning of dowel bars in the horizontal and longitudinal directions showed a 2.1% difference in the LTE. However, a 0.5% reduction in the LTE was observed for a vertical translation. Moreover, an approximately 0.5% increase in LTE was observed when there was improved bonding between the concrete slab and dowel bar. These findings can be valuable in designing and evaluating dowel-jointed plain concrete pavements.

Experimental Results and Analysis of Midrange Underwater Asymmetric Wireless Power Transfer

The eddy current loss caused by the conductivity of seawater results in a relatively low transfer efficiency of underwater wireless power transfer (WPT). And the transfer distance of the current WPT system is relatively short. Considering that most of the wireless power transfer devices in practical applications are asymmetric, few studies have explored the transfer characteristics of asymmetric midrange WPT in seawater. In this study, it is experimentally found that the load voltage and transfer efficiency of an asymmetric midrange WPT system with reduced primary balancing resistance in seawater are nearly twice as high as those of a symmetric one at a 50 cm transfer distance and a 410 kHz operation frequency with a 44.4 Ω load resistance. A new circuit model of the underwater WPT system with complex impedance and complex mutual inductance is then presented, and the load voltages predicted by the model are consistent highly with the experimental values; the model is then utilized for the explanation of the experimental observations. Changing the load resistance also improves the transfer efficiency of the system; however, the eddy current loss results in a relatively low transfer efficiency of 30.9% at an optimal load resistance of 90 Ω. The asymmetric midrange underwater WPT system can be applied in scenarios where the transfer distance is prioritized.

The mechanical and friction properties of 3D skeleton-reinforced copper matrix composites with Al2O3 decorated graphene oxide as the reinforcements

In this study, copper composite foams reinforced with Al2O3 decorated graphene oxide (AG) were prepared via chemical plating and electrodeposition. Subsequently, copper powders were filled into the pores of the composite foams and then spark plasma sintering (SPS) was employed to fabricate the 3D skeleton-reinforced composites. The tensile strength reached 365 MPa for AG/Cuf®Cu composites, which was 47.1%, 33.7%, and 13% higher compared with the pure copper, Cuf®Cu, and GO/Cuf®Cu composites, respectively. Additionally, improved friction properties with obviously decreased friction coefficient and wear rate were shown in the AG/Cuf®Cu composite. The structure study and strengthening mechanism analysis indicated that the decoration of Al2O3 on the graphene oxide resulted in enhanced interface bonding, higher load transfer efficiency for the mechanical and friction properties improvement.

Molecular-level network engineering of crosslinker towards high-performance carbon nanotube fiber

Intensive efforts are underway to integrate the distinct properties of individual carbon nanotubes (CNTs) into their assemblies and meet the growing demand for lightweight and strong materials. This study achieved CNT fibers (CNTFs) with high specific tensile strength (4.97 N/tex) and specific modulus (206.8 N/tex) by designing all-ring type bridges between CNTs. This reinforcement strategy involves suppressing the distortion of CNTs and promoting effective crosslinks within the fiber structure to increase the total inter-bundle interactions. The molecular-level network within the linking segment reduces vulnerability at the typically weak connection points and enhances load-transfer efficiency between crosslinked CNTs. In addition to improvements in mechanical properties, incorporating dopant groups in the bridge enhanced the electrical conductivity, reaching up to 2086 S m2/kg. This strategy provides straightforward access to multifunctional fibers beyond those of commercially accessible or literature-reported benchmark fibers.

Epitaxial growth of rare-earth yttrium on nanosheets to form semicoherent interface in zinc implant

Molybdenum disulfide (MoS2) nanosheet as nano reinforcement exhibits great advantages in zinc (Zn) implant due to its coordinated crystal slip and grain boundary strain effect. Nevertheless, the poor interface bonding restrains the coordination effect of MoS2. In this work, rare earth yttrium (Y) was used to epitaxial grow on the vacancy nucleation sites of MoS2 plane through a gas phase reduction method, and then introduced into Zn to improve their interface bonding. On one hand, rare earth Y could form a semicoherent interface with Zn due to the similar atomic arrangement and small lattice misfit between (101)Y plane (0.272 nm) and (002)Zn plane (0.248 nm). On the other hand, it could be tightly integrated together with sulfur element of MoS2 via covalent bond. As a result, the plastic strain of composites was improved from 6.1 % to 10.45 %. Simultaneously, the fracture energy was also increased to 201 × 103 J/m2, since rare earth Y considerably promoted load transfer efficiency from Zn matrix to MoS2 and thereby significantly activated slip systems. Encouragingly, the mechanical strength of the Zn-based biocomposite simultaneously reached 273.3 ± 10.9 MPa due to load transfer strengthening and grain refinement.

Analysis of the strength of joints in fabric/ unsaturated polyester composites

Fabric/unsaturated polyester composites have garnered significant attention due to their lightweight properties and superior mechanical characteristics. Despite these advantages, the strength of joints within these composites remains a crucial aspect requiring thorough investigation. This paper presents a study focused on comprehending the factors that influence joint strength in fabric/polymer composites, emphasizing the importance of effective load transfer and robust adhesion within the fabric/polymer matrix. The objective is to minimize stress concentration and enhance load distribution within the joint. The failure mechanism involves a combination of Bearing Failure and shear-out failure, particularly in single-fabric layer composites. The study establishes a linear relationship between composite bending stiffness and the enforcement fabric’s flexural rigidity. A comparison of tensile properties across various joining methods, such as bolts, adhesive bonding, and tongue grooves, reveals that bolt joints exhibit the highest strength and elongation, followed by tongue groove joints. Notably, bolt joints demonstrate elevated toughness, efficiency, and stiffness in samples of two-layer twill fabric when the twill lines are oriented perpendicular to each other. Under these conditions, joint properties are measured at 0.89%, 14804.65 Nm, and 20.46 J, respectively. Increased fabric flexural rigidity yields advantages in terms of load distribution, load transfer efficiency, and dimensional stability. This study deepens the understanding of factors influencing joint strength, contributing valuable insights for the development of optimized joint designs and manufacturing processes. These advancements aim to enhance the performance and reliability of fabric/unsaturated polyester composites in applications requiring high strength and structural integrity.

Synthesis, characterization, thermal and mechanical behavior of polypropylene hybrid composites embedded with CaCO<sub>3</sub> and graphene nano-platelets (GNPs) for structural applications

<abstract> <p>In this study, ultra-fine graphene nanoplatelets (GNPs) were employed as nanofillers to reinforce a polypropylene (PP) matrix. This was done in conjunction with a polypropylene grafted maleic anhydride (PP-MAH) compatibilizer and calcium carbonate (CaCO<sub>3</sub>), with the aim of improving the mechanical and thermal properties of the resulting hybrid composites. Formulations for the hybrid composites were fabricated by compounding the PP matrix with varying weight percentages of GNPs (x = 0.5, 1.0, 1.5, 2.0), 2 wt.% CaCO<sub>3</sub>, and 5 wt.% PP-MAH using a twin-screw extruder followed by injection molding. This research thoroughly investigates the mechanical and thermal characteristics. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR) results confirm the successful development of hybrid composites. The thermal stability, crystallization temperature, melting temperature, tensile strength, flexural strength, and impact resistance were evaluated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), universal testing machine, and low-velocity impact tester, respectively. The results indicated a significant improvement in the tensile strength of the PP matrix with the addition of GNPs, with the highest enhancement observed at 1.5 wt.% GNP loading, where the tensile strength reached a maximum of 40.54 MPa. This improvement was attributed to the proper interconnection, bonding, and compounding of PP with GNPs, thus leading to an increase in the load transfer efficiency.</p> </abstract>