Hot Press Moulding Research Articles

Thermal stability and anti-ablation performance of plasma spray coated-YSZ on Al2TiO5 modified novel ablative carbon-phenolic composites

Abstract Despite ongoing challenges, ablative thermal protection systems are among the most promising methods for safeguarding spacecraft during re-entry thermal protection systems (TPS). A novel aluminium titanate (Al2TiO5/AT) and a highly efficient thermal barrier of coating (TB/TBCs) made from yttria-stabilized zirconia (YSZ), powder, but deposited using the plasma spray technique on polyacrylonitrile (PAN)-based carbon fiber fabric(C)-reinforced with resorcinol phenol formaldehyde resin (RF) composites (C-RF)) would be a potential candidate for TPS applications. This study investigates the composites with varying wt.% of AT that were developed, namely 0 wt.% (YSZ-C-RF), 1 wt.%, 3 wt.%, and 5 wt.% (YSZ-AT-C-RF) by utilizing a hot press moulding machine. Thermal stability and ablation performance of unmodified C-RF with modified YSZ-C-RF and YSZ-AT-C-RF composites are examined through thermogravimetric analysis (TGA) and oxyacetylene torch test/OAT (4.0 MW/m2 for 60 sec). Also, the phase composition and microstructure of the ablated surface are determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The TBC of YSZ has an obvious influence on the residual weight ratios at high temperatures in C-RF and also plays a positive role in increasing thermal stability under nitrogen atmosphere for enhancing ablation resistance concerning YSZ-C-RF. The mass and linear ablation rates (MAR and LAR) of the composites after modifying the surface by YSZ-coated particles are reduced by 82.98% and 15.65%, respectively. Similarly, the introduction of AT particles and TBC of YSZ results in evidence of improving the thermal stability and the ablation resistance in varying wt.% of YSZ-AT-C-RF composites. The primary optimum AT weight loading for enhancing ablation resistance in YSZ-C-RF composites is 1wt.%. The modification of 1wt.% AT particles and YSZ-Coated particles reduce MAR and LAR by 54.79% and 61.94%, respectively. This work offers a meaningful method to remarkably enhance the ablation performance of the modified C-RF and YSZ-AT-C-RF composites.

Transverse energy absorption performance of sandwich tubes with various origami foldcores

Nowadays, composite sandwich tubes are extensively utilized in the civil and aerospace industries due to their superior strength-to-weight mechanical properties. Origami-based core offers a large enhancement of the mechanical properties, yet little study research focuses on the effect of various foldcore configurations on the transverse mechanical properties of sandwich tubes, necessitating the design method for applications. This study introduces an innovative approach by incorporating origami into the composite sandwich core to enhance the transverse energy absorption capacity. The quasi-static transverse mechanical properties of carbon fibre-reinforced polymer (CFRP) sandwich tubes with foldcores are studied under three-point bending-like local compression and transverse structural compression. A systematic geometric design framework and numerical modelling technique are provided. By integrating finite element analysis and experiments, the research investigates the effects of various origami foldcore configurations and geometric parameters on transverse energy absorption capacity. The experiment setup is provided by sandwich tubular specimens with a full-diamond configuration as the foldcore. The cylindrical tubes (foldcore) of the sandwich structures were manufactured using four plies [0°]4 of T700 (T300) woven CFRP with the hot press moulding (vacuum bag using female and male moulds) technique respectively. Then, the parametric study and damage mode analysis of eight different foldcore patterns (axial Miura, circumferential Miura, diamond, Kresling, and their curved-creased counterparts) were studied. The results showed the superior energy absorption performance of the sandwich tube with Miura-pattern foldcore over the origami-pattern counterparts, nested tube, and traditional honeycomb sandwich tube with CFRP or aluminium-made cores. Therefore, the structural parameters optimisation of the Miura pattern tube was carried out by the Response Surface method (RSM) and a design strategy for increasing the energy absorption capacity was found. The findings offer guidance for designing high-specific energy absorption tubular structures for future advanced engineering applications.

Effect of Zirconia and Graphene Nanoparticles Loading on Thermo-Mechanical Performance of Hybrid Polymer Nanocomposite

This study demonstrates the development of a unique hybrid thermoplastic composite using reduced Graphene oxide (rGO) content and Zirconia (ZrO2) nanoparticles into the Ultra-High Molecular Weight Polyethylene (UHMWPE) biomaterials for continuous loading conditions. Specimens with different loadings of rGO (0 to 1.5 wt.%) and ZrO2 (5 to 10 wt.%) were fabricated using liquid phase ultrasonication followed by the hot press moulding method. The samples were analyzed using Thermogravimetric Analysis (TGA), Impact (Izod) testing, and Dynamic Mechanical Analysis (DMA). The developed material feasibility was assessed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analyses. The findings revealed that the 1 wt.% rGO/5 wt.% ZrO2/UHMWPE sample improved the storage modulus by 66.15%, and the Impact absorbed energy by 11.33% compared to the pristine UHMWPE. The proposed nanocomposite could be endorsed for artificial joints, prostheses, and other Artificial Bio-Bearing (ABB) applications.

Physical Behaviour of Wood Plastice Composite Made of Recycled High-Density Polyethylene (HDPE)

This paper investigated the physical characteristics of wood–plastic composites, which were made using recycled high-density polyethylene (HDPE) and using wood flour from Pometia sp (Matoa), Intsia sp (Merbau) and Alstonia sp (Pulai) as filler. The sawdust was taken from local furniture industry and the HDPE was collected from recycled plastic bottles of mineral water. Composite panels were made from recycled HDPE through hot-press moulding produced excellent stability based on JIS and SNI Standard, especially for moisture content and swelling characteristics. The water absorption and targeted density were also measured. In this study we found that the water absorption and the density of the composite exceeded our expectation. The composites showed high variation average for water absorption. For the swelling behavior, the value is varied from 5.74% to 25.57% after 2 hours soaking and varied between 7.56% to 28.53% after 24 hours soaking. This study has shown the composites had a high possibility to be used for interior and non-structural purposes.

Influences on the mechanical and physical properties of hot-press moulding alkali-activated slag (HP-FRAASC) composite with various fibers

ABSTRACT In this study, we will apply the hot-press moulding method for the first time to the preparation of alkali-activated slag composites (AASC) and incorporate 1vol.-%, 3vol.-%, 5vol.-%, and 7vol.-% steel, copper, and carbon fibres into the matrix in order to investigate the characteristics of the HP-AASC and fibre reinforced (HP-FRAASC) in terms of compressive strength, flexural strength, impact toughness, and bulk density of HP-AASC and HP-FRAASC. Results show that the composites have good flexural strength, compressive strength, and impact toughness when the content of steel fibres is 5 vol.-%, copper fibres are 7 vol.-%, and carbon fibres are 1–3 vol.-%. It was observed from each sample of HP-FRAASC and HP-AASC that the HP-AASC samples had lower porosity, better density, and an easy preparation process, which can be used as a suitable preparation method for this material.

Study of mechanical properties of sustainable biocomposite panels using Jute-PLA and Sisal-PLA

In recent years, bio composites have experienced significant growth and have found applications in various sectors, like domestic use, aerospace, circuit boards, and automotive industries. Extensive research has been conducted on natural fibres to develop it as composite materials so that can compete with synthetic fibre composites. Jute and sisal fibres with Polylactic acid (PLA) means fully biodegradable and recyclable, offer an environmentally friendly solution. The fabrication of the bio-composite specimen involved the utilization of a hot press moulding machine. The maximum strength and bending properties, including ductility, were assessed through flexural and tensile tests following ASTM standards. Free vibration analysis was conducted to determine important characteristics like damping frequency, damping ratio, and natural frequency of the bio composites. The resonant set obtained for Sisal/PLA is inferior to Jute/PLA composites, which clearly demonstrates the influence of fibre in resonant behaviour of the composites. Further Sisal/PLA composites show 20% rise in damping performance at first two resonant sets and 30% in the third resonant. This free vibration characterization of most widely used to composites provides valuable insights into the practical usage under suitable environment conditions.

Thermal and tensile properties of 3D printed ABS-glass fibre, ABS-glass fibre-carbon fibre hybrid composites made by novel hybrid manufacturing technique

This study was an attempt to combine fused deposition modelling and hot press moulding technique to fabricate hybrid polymer composites using acrylonitrile butadiene styrene (ABS) polymer, woven glass fibre (GF) and woven carbon fibre (CF). The composite specimens were subjected towere subjected to mechanical and thermal characterization.Tensile strength of GF/ABS and GF/CF/ABS composite were far higher than the virgin ABS. GF/ABS composites displayedimproved thermal resistance by giving a final residue of 42.36%, followed by GF/CF/ABS hybrid composites as per the thermogravimetric analysis. Thermomechanical analysis revealed the coefficient of thermal expansion in the order: ABS > GF/ABS > GF/CF/ABS. The entropy obtained from the DSC curve was of higher value for composites than the ABS. The ABS based composites fabricated from this technique can be applicable to structural parts in the automobiles, aircrafts, shipping vessels, etc.

Interlaminar, free vibration, HDT and water absorption properties of braided flax woven fabric PLA biocomposites

The presented research investigates the influence of braided flax woven-fabric filled with polylactic acid (PLA) polymer on interlaminar shear strength (ILSS), free vibration, heat deflection temperature (HDT) and water absorption. For this purpose, flax fibre-braided yarn and its fabric are prepared using solid braiding and plain weaving techniques. Then, PLA biocomposites are developed by solution casting and hot-press moulding processes. Shear test results showed, the addition of braided flax fibre increased the ILSS of composites compared to unreinforced PLA. Natural frequencies of the composite beams are improved with the braided flax reinforcement. Composites filled with three fabric layers showed higher frequency due to higher structural strength and stiffness associated with these composites. Bio-composites HDT is enhanced with the addition of braided flax fibre from 61.78% to 132.97%. The results of a water absorption test in distilled and seawater revealed that the composites have a relatively high water uptake in distilled water.

Study on the Inter-Laminar Shear Strength and Contact Angle of Glass Fiber/ABS and Glass Fiber/Carbon Fiber/ABS Hybrid Composites

In recent days, the uses of 3D printing have been successfully implemented in various applications due to their advantages. Besides, the need for sustainable choice has created a demand for the augmented use of thermoplastic composites. Thus, additive manufacturing techniques have become the essence of composite fabrication to achieve an automated and flexible fabrication technique. The present study used fused deposition modelling (FDM) and hot press moulding technique to produce composite samples. The composite laminates were fabricated by using acrylonitrile butadiene styrene (ABS) as polymer and woven glass fiber (GF) and woven carbon fiber (CF) used as reinforcements. Further, the laminates were subjected to inter-laminar shear strength (ILSS) and contact angle. The inter-laminar shear strength and the contact angle of hybrid samples were compared with virgin ABS and pure glass fiber-reinforced composites. The study reported a maximum ILSS of 198.5MPa achieved by GF/CF/ABS hybrid composites, which was higher by 17% and 217% compared with GF/ABS and ABS samples, respectively. The contact angle results showed an increase due to the incorporation of fibers with ABS by 5% and 13% in GF/ABS and GF/CF/ABS, respectively, contributing to the adhesion. The contact angle values achieved were 100.5°, 105.15°, and 113.39° by ABS, GF/ABS and GF/CF/ABS making them hydrophobic in nature. These developed reinforced materials, such as carbon fiber, glass fiber and ABS matrix composites, could be used in automotive, aerospace and wind energy applications.

In-situ synthesis of high-performance Al2O3-based ceramic cores reinforced with core-shell structures

The complex structure of the ceramic cores is key to the preparation of an aero-engine hollow blade with excellent cooling performance. The traditional methods such as hot-press moulding are difficult to prepare complex-structured ceramic cores, and 3D printing technology provides a new idea for the preparation of complex-structured ceramic cores. Using SiO2 and Y2O3 as mineralizers in Al2O3-based ceramic cores, high-performance ceramic cores with a core-shell structure was successfully prepared by 3D printing. Additionally, the changes in microstructure and properties at different sintering temperatures were studied. The results showed that with an increase in the sintering temperature, a core-shell structure with Y2Si2O7 as the shell and Y2O3 as the core was formed, and the reinforced phases such as mullite were generated at the same time. The formation of core-shell particles suppressed the energy loss of cracks. The generation of the liquid phase led to the tight bonding of the Al2O3 particles. The synergistic effects of the core-shell structures and the reinforced phases enhanced the flexural strength. When the sintering temperature was 1380 °C, the comprehensive performance met the application requirements of the ceramic cores, and the flexural strength and porosity were 19.3 MPa (at 1500 °C) and 30.5%, respectively. The 3D-printed ceramic core by low-temperature sintering with a core-shell structure was successfully prepared, which promoted the wider application of DLP-3D printed ceramic cores technology in the field of precision casting. This is expected to reduce the energy consumption during the sintering process and promote the production of high-performance complex-structured ceramic cores.

Microscopic testing of carbon fiber laminates with shape memory epoxy interlayer

For the first time, microscopic testing has been performed on shape memory polymer composites (SMPCs) which were manufactured by commercial materials already used in aerospace. Results from micro-tests have been compared with those from conventional memory-recovery cycling on macro-scale. Two shape memory polymer composite (SMPC) laminates were fabricated with different shape memory (SM) interlayer: one in the form of an uncured epoxy powder and the other in the form of a thin epoxy foam. The latter, in particular has been studied to evaluate lightweight and stiff sandwich structures with SM properties. The assessment of the manufacturing process by a hot press moulding technique was assessed through micro scale analysis using SEM and MicroCT analysis. DMA analyses were carried out to understand the interaction mechanisms between raw constituents. A Vickers micro-indentation examination before and after heating was able to assess the shape recovery behaviour at the micro-scale level. A nano-instrumental indentation was used to characterise the shape memory response under different loads at elevated temperatures. Whilst an instrumented thermo-mechanical test allowed to investigate the shape memory behaviour at macro-scale level. Results allow identifying the recovery mechanisms at the micro-scale which are responsible for the shape memory performances at the macro-scale. The higher recovery ability of the SM foam is confirmed in comparison with bulk interlayers.

Effect of different currents and compositions of Cu, MoS2 and HBN on the coating thickness of mild steel substrate using electric discharge coating

The substrate deposited on the workpiece is used by surface coating for the achievement of various properties in terms of hardness, smoothness, tear or wear etc But various methods such as electro-plating, conversion coating or several, are less effective because of costly machine involvement, complexity during operation, complexity during work-surface installation, specific (high/low) temperatures and thick coating. To achieve better coating among all, a layer of the modified composite coated surface using Copper (Cu), Molybdenum disulfide (MoS2) and Hexagonal Boron Nitride (HBN) with the help of an Electrical Discharge Machine (EDM) with reverse polarity is formed. In this process, the effect of two variable parameters current and composition (powder mixing ratio) of Cu, MoS2 and HBN with a 50% duty factor on the thickness of the deposited layer is observed. During the deposition process, each green compact electrode is formed by mixing the powdered material in a mortar for approximately 2.5 h and after processing in a hot press moulding machine. The deposited layer of the coating has also been analyzed using FESEM, XRD and tribological properties, where the highest deposition or thickness of the coating has been achieved at a powder mixing ratio of 20/40/40 to Cu/HBN/MoS2 with a current of 10 A at the same duty factor. Overall, better coating with controllable thickness can be achieved by using EDC, which can be helpful in automobiles or other industries where metal-to-metal friction causes performance loss.

Investigation of the mechanical and thermal stability of ultra-high molecular weight polyethylene by using amide-multi-walled carbon nanotubes as a reinforcement material

In this research, an investigation of the thermal and mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) reinforced with pristine and modified multi- walled carbon nanotubes (Amide-MWCNTs)-MWCNTs nanocomposite was conducted. The nanocomposites were prepared by ultra-sonication mixing and hot press moulding methods. The MWCNTs surface was functionalised with amide group. The prepared nanocomposites were characterised based on structure, thermal, and mechanical properties by x-ray diffraction (XRD), differential scanning calorimeter (DSC), and universal testing machine, respectively. The crystallinity, crystal size, space between atomic lattice and lattice constant were calculated from the XRD patterns. Results showed the decrease in UHMWPE crystallinity without affecting the crystal structure of UHMWPE when adding pristine MWCNTs and Amide-MWCNTs (1−5 wt%). Tensile test results showed an increase in the composites stiffness for all percentages in the range of 19%–65%, while the elongation at break for the 3 wt% Amide-MWCNT nanocomposite increased up to 71%. This indicates that the interfacial adhesion was enhanced by the amide group.

Machine learning approaches for prediction of properties of natural fiber composites : Apriori algorithm

ABSTRACT The selection of materials with the required properties was developing rapidly. There is no single rule to choose suitable material for a particular product. The complexes interrelation among the properties of composites makes more difficult to suggest suitable material for material scientist. The forecasting of relationship among material properties with throughput screening methods can help for the discovery of novel materials. The conventional way of selection of material need more investigations and time consuming. Recently, machine learning approaches are widely used in mechanical domain. Hence in this work, machine learning-based method was proposed to discover the relationship between the properties of natural fibres composites. To apply machine learning approach, there are 26 different natural fibres composites of Coir, Jute, Banana etc. were taken in to consideration. These materials are reinforced with pure export with different manufacturing methods such as Hand layup, Spray layup, Hot press moulding, and Compression moulding to produce the samples as per ASTM standards. The properties like density, tensile strength, hardness etc. were measured and interrelation among them was recognised using proposed method.

The Role of Graphitic Carbon Nitride in the Formulation of Copper-Free Friction Composites Designed for Automotive Brake Pads

In this study, graphitic carbon nitride (g-C3N4, labelled as gCN) was tested in the formulation of copper-free (Cu-free) friction mixtures, which are potentially interesting for brake pad manufacturing. Three formulations of friction composites were prepared starting from a common Cu-free master batch: (i) without graphite, (ii) with graphite and (iii) with gCN. The mixtures were pressed in the form of pins by hot-press moulding. The friction-wear performance of the prepared pins was investigated using a pin-on-disc (PoD) test at room temperature (RT), high temperature (HT) (400 °C) and, again, at room temperature (H-RT). The values of the friction coefficient (µ) for the composites with gCN (or graphite) were as follows: (i) RT test, µRT = 0.52 (0.47); (ii) HT test, µHT = 0.37 (0.37); (iii) RT after the HT tests, µH-RT = 0.49 (0.39). With respect to wear resistance, the samples with graphite performed better than the samples without this solid lubricant. To the best of our knowledge, this is the first report regarding the evaluation of the role of gCN in friction composites designed for automotive brake lining applications. The results indicate the main role of gCN as a soft abrasive.

Experimental investigation of glass fiber reinforcement with nano materials

The development of reinforced composite fibre has received a lot of attention in recent years. Reinforced composite fibres have superior mechanical properties to glass and carbon fibre, such as stiffness, impact strength, durability, and modulus. Poor moisture tolerance and the formation of its forms during processing render it more difficult to use them in a specific application. The effect of adding silica nano particle content to a glass fiber-reinforced composite fabricated through hand lay-up followed by hot press moulding is investigated in this study, and mechanical properties such as tensile strength, flexural strength, and impact strength are evaluated. The findings showed that when 5 percent Nano-silica is applied to the glass fibre, optimum tensile and flexural strength is obtained, and that the addition of 1 percent Nano-silica has major effects on the Charpy impact behaviour.

Preparation and Characterization of Oxo-degradable Polypropylene Composites Containing a Modified Pro-oxidant

In this study, the changes in the properties of polypropylene (PP) after loading of modified pro-oxidant were studied. Different proportions of modified-cobalt stearate (CoSt) pro-oxidant were filled in PP, and composites were prepared in a twin-screw extruder through compounding technique. Five films of these composites were prepared using hot press moulding. The modified pro-oxidant loaded PP films were characterized for chemical, physical, thermal, and morphological properties (before and after the biodegradation test). The biodegradability of the modified pro-oxidant loaded PP films was measured according to ASTM D 5338, and the biodegradation intermediate products were evaluated for their eco-toxicological effect. The changes (with respect to PP) in FTIR spectra of modified pro-oxidant loaded PP were noticed before and after accelerated ageing. The tensile properties and thermal stability of modified pro-oxidant loaded PP films decreased as confirmed by universal testing machine (UTM) and thermogravimetric analysis (TGA). Using differential scanning calorimetry (DSC) and XRD analysis, it was found that the percentage crystallinity of modified pro-oxidant loaded PP films has decreased and this led to increased degradability of PP. After the biodegradability test, SEM results of modified pro-oxidant loaded PP films revealed rougher morphology than before the biodegradability test. The highest biodegradability (28.87%) was obtained in PP100T30 film containing 30 phr of modified pro-oxidant. All the eco-toxicity tests of the degraded product materials demonstrated that the degraded products were nontoxic. Hence, the prepared composites can be effectively used as biodegradable flexible packaging materials.

Development and Characterization of Environmentally Friendly Insulation Materials for the Building Industry from Olive Pomace Waste

This work is focused on the upgrading olive oil pomace to obtain high environmentally friendly insulation materials for the construction and building industry. Upgrading of these wastes has been carried out by using the wet-laid technology in combination with different thermoplastic binder fibers both from natural and synthetic origin. After the wetlaid process, the obtained veils or non-wovens were subjected to different processes: a hot-press moulding process or a continuous lamination process. The acoustic insulation properties were obtained by the Kundt’s tube while the thermal insulating properties were obtained through determining heat transmission resistance (R) and heat absorption parameter (?). These tests have revealed the excellent insulation properties of the olive pomace-derived materials, specifically, those based on high surface density non-wovens. The complementary process that follows wet-laid, i.e. hot-press moulding or continuous lamination process has a remarkable effect on insulation behaviour. In particular, the hot-pressed materials from olive pomace show better acoustic insulation while the continuously laminated materials offer the best thermal insulation properties.

Chitosan Modified Bio-Fibre Based Board as Antimicrobial and Anti-Crack Board

Bio-based products represent a key component of global bio-economic growth. In the process of forming a bamboo fibre-based bio board in this study begins with the preparation of bamboo fibres to make it compatible as a filling material in polyester polymers. The mixing of bamboo fibre is done by considering the composition of the fibre material with the polymer used, namely polyester at a ratio of 90%:10%, 80%:20% and 70%:30% of the total weight of the mixture. This mixture is added with a natural substance that has been investigated to have resistance to microbial contamination (anti-microbial), chitosan at a ratio of 1%, 3% and 5% by weight of the total mixture of all components. Bio board printing is carried out using a hot press (moulding) tool. The functionality of bio-based and conventional natural fibre-based materials was investigated for a series of bio boards. The tests include tensile, antimicrobial activity and morphological testing using Scanning Electron Microscopy (SEM). The overall test results put bio board with a ratio of 70%:30% with the addition of chitosan as much as 5% wt as the best sample with a tensile strength value of 147 Mpa, the flexural value of 0.09 kN. The sample shows a good interface appearance of the bond that occurs between the polymer and the filler under the electron microscope.

Low velocity impact behavior of carbon fibre composite curved corrugated sandwich shells

Composite thin-walled curved structures are widely used in aerospace, marine, automotive and building engineering application. In this paper we design and fabricate a series of carbon fibre composite axial and circular corrugated sandwich cylindrical panels (ACSCPs and CCSCPs) by an in-house hot press moulding method. Low velocity impact tests are carried out to evaluate the impact resistance and failure mechanisms of such structures. Furthermore, validated finite element analysis (FEA) models based on the Hashin failure criteria are adopted to study the effects of the relative density, impact energy and impact position on their impact responses. It is observed that generally the peak forces and absorbed energies of the specimens ascend with the increase of the relative density. The impact responses, especially the ultimate loads of the present structures are particularly dependent on the impact position, but insensitive to the increase of the impact energy. By comparison, the ACSCPs generally have a more excellent impact resistance and energy absorption properties than that of CCSCPs. In addition, the corresponding energy contribution of the components for the ACSCPs and CCSCPs under different impact energy is also revealed, which could be useful for the multifunctional design of such kinds of composite curved sandwich structures.