Film Stacking Method Research Articles

Exploring the mechanical, rheological, and thermal performance of self‐reinforced composites based on polyamides and multi‐walled carbon nanotubes

AbstractSelf‐reinforced composites (SRCs) based on different blends of PA6, PA12, and multi‐walled carbon nanotubes (MWCNTs) as matrices and a PA6.6 plain woven fabric as reinforcement were prepared by the film stacking method. The morphology of the SRCs was analyzed using optical and scanning electron microscopy, both on cryo‐fractured and included polished cross‐sections samples. Rheological measurements were performed to assess the materials microstructure and thermal stability. In addition, uniaxial tensile tests were carried out to determine mechanical properties such as stiffness, strength, strain at break, and tensile toughness. The assessment of failure mechanisms was performed through acoustic emission in situ during tensile tests. Furthermore, fracture tests were carried out to evaluate the impact of incorporating MWCNTs on SRCs failure and fracture behavior. The obtained results suggest a notable improvement in the mechanical properties of the SRCs compared with the matrices, that is, tensile strength increased by 132% for SRC‐0, 83% for SRC‐0.5, 54% for SRC‐2.5, and only by 13% for SRC‐8. This study indicates that these SRCs appear as promising materials for high performance applications, which also require multifunctional characteristics.

Recyclable and elastic highly thermally conductive epoxy-based composites with covalent-noncovalent interpenetrating networks.

High-power electronic architectures and devices require elastic thermally conductive materials. The use of epoxy resin in thermal management is limited due to its rigidity. Here, based on epoxy vitrimer, flexible polyethylene glycol (PEG) chains are introduced into covalent adaptable networks to construct covalent-noncovalent interpenetrating networks, enabling the elasticity of epoxy resins. Compared to traditional silicone-based thermal interface materials, the newly developed elastic epoxy resin shows the advantages of reprocessability, self-healing, and no small molecule release. Results show that, even after being filled with boron nitride and liquid metal, the material maintains its resilience, reprocessability and self-healing properties. Leveraging these characteristics, the composite can be further processed into thin films through a repeated pressing-rolling technique that facilitates the forced orientation of the fillers. Subsequently, the bulk composites are reconstructed using a film-stacking method. The results indicate that the thermal conductivity of the reconstructed bulk composite reaches 3.66 W m-1 K-1, achieving a 68% increase compared to the composite prepared through blending. Due to the existence of covalent adaptable networks, the inorganic and inorganic components of the composite prepared in this work can be completely separated under mild conditions, realizing closed-loop recycling.

“Film-stacking method as an alternative Agave tequilana fibre/PLA composite fabrication”

This paper presents the fabrication of an Agave tequilana Fibre (ATF) bio-composite by film stacking method and an experimental investigation on preliminary mechanical properties; namely tensile, flexural, impact, and water uptake. Randomly oriented bio-composite samples were made from both, untreated and surface treated ATF collected from a tequila distillery waste stream. The ATF were surface treated using NaOH, and Pectate lyase to improve fibre properties and adhesion. The samples were prepared using three fibre loadings, 20, 40 and 60 wt%. Randomly oriented ATF mats were pre-impregnated with poly (lactic acid) (PLA) before bio-composite stacking and press moulding. Untreated fibre samples were processed and kept as a reference. The morphology of the fracture surfaces was analysed through optical and environmental scanning electron microscopy (ESEM). The quasi-static tensile tests revealed that the modulus of the bio-based composite materials is up to ~10% lower than that of the neat PLA. Flexural strength values observed at 60 wt% of fibre content were within the ranges of 76.10–77.0 MPa for treated samples with a flexural modulus of 3.36–3.76 GPa, whereas impact strength presented a reduction of ~32–35%. Generally, all measured properties presented reduction in strength with the increase of fibre loading.

Natural jute fiber treated with silane coupling agent KH570 reinforced polylactic acid composites: mechanical and thermal properties

With the progress of society, fiber reinforced composites have become the subject of research in the field of composite materials, in which natural fibers are widely used in the enhancement and modification of thermoplastics due to their low density, biodegradation and most wide origins. However, the hydrophilicity of special fiber is the main factor that hinders its bonding with hydrophobic polymer matrix which leads to poor interface compatibility between the fiber/matrix interface. The coupling agent can increase the nonpolarity of the natural fiber and the compatibility between the fiber and the resin. In this study, the composites were fabricated by the film stacking method, and the surface of jute fiber was treated with silane coupling agent so as to prepare jute/polylactic acid composites with good mechanical and thermal properties. The mechanical and thermomechanical results show that the combination of the coupling agent can significantly improve the interfacial bond of the jute/polylactic acid composites, leading to an efficient enhancement of comprehensive performance.

Permanganate Treatment Optimization on Tensile Properties and Water Absorption of Kenaf Fiber-Polypropylene Biocomposites

Kenaf fiber has been studied for biocomposites reinforcement due to its renewable and carbon neutrality. Meanwhile, polypropylene sheets are easily processed and considered a prospective thermoplastic matrix source for biocomposites. Hence, the combination of both materials is expected to form an attractive biocomposite. This study aimed to optimize permanganate treatment on tensile properties and water absorption of kenaf-reinforced propylene biocomposites. It thermally tested kenaf fibers and PP using differential scanning calorimetry (DSC) before performing compression molding at 185°C and 70 bars using the film stacking method. The kenaf fiber variables were untreated, alkaline pre-treated, and alkaline-permanganate treated to low concentrations of 0.01 to 0.05 wt% of KMnO4. Furthermore, this study conducted Yarn tensile test and Weibull distribution to find a strength variability statistically. Composite tensile and burn tests were performed to obtain tensile strength, constituent materials, and void volume fractions. Composites fractography was implemented to examine the effect of permanganate on composite water uptake behavior using scanning electron microscopy. This study used low concentration in permanganate treatments than several previous studies. The results showed that biocomposites have a tensile strength of 125 MPa, higher than in previous studies that found a value less than 80 MPa. This study has contributed to the green optimization treatment using lower chemical concentrations but with better results on impregnation, interfacial, water absorption, and mechanical properties of kenaf or polypropylene composites.

Performance comparison of carbon fiber reinforced polyaryletherketone and epoxy composites: Mechanical properties, failure modes, cryo‐thermal behavior, and finite element analysis

AbstractHigh‐performance thermoplastic composites are gaining attention as potential replacement for thermoset composites in high‐end structural applications owing to their superior fracture toughness and recyclability. In this study, polyaryletherketone (PAEK) and carbon fabric (CF) reinforced PAEK are compared with epoxy and epoxy‐CF composites. PAEK‐CF composites are prepared by film stacking method followed by compression molding while hand lay‐up technique was used for epoxy‐CF composites. PAEK and PAEK‐CF composites possess superior tensile properties, flexural strength and fracture toughness compared to those prepared from epoxy. The incorporation of CF improved the wear resistance in both PAEK and epoxy and PAEK‐CF exhibited the lowest wear rate. The investigation of interlaminar shear strength of the composites was conducted and the highest value observed for PAEK‐CF composite. Wear and fracture surface analysis suggested ductile failure for PAEK and PAEK‐CF composites and brittle failure in epoxy composites, as indicated by interfacial bonding/debonding and fiber pullout, at the fracture surface. Cryo‐thermal cycling effects on the tensile properties, fracture toughness and fracture surface morphology of the composites are studied. The failure behavior obtained from experimental studies was corroborated with finite element method‐based simulation models of fracture toughness response in single edge notch bend test using Abaqus/Explicit.

Creep and heat deflection temperature (HDT) study of Pineapple leaf fibre (PALF) and Montmorillonite (MMT) nanoclay reinforced Poly-lactic acid (PLA) based laminated hybrid biocomposite

The objective of this paper is to evaluate the influence of Montmorillonite (MMT) nanoclay reinforcement on creep and heat deflection temperature (HDT) characteristics of pineapple leaf fibre (PALF)/poly-lactic acid (PLA) /MMT hybrid biocomposite. PLA/MMT films of 1 mm thickness were prepared using melt mixing and compounding by varying the MMT inclusion from 0,1,2 and 3 wt%. PLA/MMT films were arranged alternately with basket woven PALF. The film stacking method was used for the fabrication of laminated hybrid biocomposite. Temperature controlled compression moulding method was used for biocomposite fabrication. Impression creep test was used to study the creep behaviour and heat deflection temperature (HDT) as per ASTM D648 of the laminated hybrid biocomposite samples was carried out to evaluate the thermo-mechanical behaviour. Impression depth in millimetre was measured as a function of time and presented as creep plots. Short primary, prolonged secondary creep curves, and absence of tertiary stage of creep were observed. MMT inclusion of 2 wt% exhibited minimum impression depth and highest HDT results as compared to that of the rest of the samples. The SEM images reveals that at 2 wt% MMT nanoclay was evenly distributed and hence improved the fibre matrix-nano particle adhesion

Effect of silane treatment on tensile strength, moisture absorption and thermal property of unidirectional woven mat enset fibers reinforced polypropylene composite

ABSTRACT The aim of this paper is to study the effect of bis [3(triethoxysilyl) propyl] tetrasulfide (Si69) and 3-Glycidoxypropyl trimethoxy silane (GPS) on the properties of unidirectional enset fiber reinforced Polypropylene (PP) composite. For this purpose, enset fiber was weaved into the mat and treated with 1.5 wt% Si69 and 5 wt% GPS after which it was used to reinforce PP composites through the film stacking method followed by the compression molding. Fabricated composites were characterized by their tensile, thermal, water absorption, image of the fracture surface, and FTIR spectroscopy properties. Among the developed unidirectional reinforced PP composite, the surface-treated enset-woven mat with 1.5wt% Si69 gave the highest tensile strength with an increase of 267.1%, and 36.9% from untreated enset random (EvRa) and unidirectional fiber-reinforced PP composite (EvUnt) respectively. Moreover, 1.5 wt% Si69-treated enset fiber unidirectional reinforced PP composite reduced equilibrium water uptake percentage by approximately two folds, and thermal performance also improved by 12.9% from EvUnt composite. Notably, both silane treatment of enset fibers and composites increased elongation at break compared to EvUnt. Altogether, 1.5wt% Si69-treated enset fiber unidirectional reinforced polypropylene composite achieved a remarkable improvement of property and can be used for high mechanical and long-term performance applications.

Effect of Surface Treatment on the Mechanical Performance of Unidirectional Enset Fiber Reinforced Polypropylene Composite

ABSTRACT Natural fibers have recently become an alternative reinforcement for composite products owing to their light-weightiness, renewability and biodegradability. However, they have certain drawbacks including hygroscopic nature, low compatibility with the polymer matrices and inferior mechanical properties when compared to synthetic fibers. This study aims to develop a one-way enset fiber-reinforced polypropylene (PP) composite. In this study, long and aligned enset fibers were interlaced with PP yarns to form a woven mat. The mat was surface treated, and later the film stacking method was applied to develop the composite via hot pressing. The mechanical properties of the developed composites were characterized. The results showed that bis[3-(triethoxysilyl) propyl] tetrasulfide (1.5 wt% Si69) and 3glycidyloxy propyl trimethoxy silane (5 wt%GPs) treated unidirectional enset fiber woven mat showed the highest tensile strength which shows an increase of 266.98% and 218.14%, respectively, relative to the pure PP. In terms of flexural strength, enset fibers treated with NaOH (3.5 wt%) and EVsi69 (1.5 wt%) showed the greatest improvement of 218.14% and 151.64% respectively over pure PP. Therefore, the developed composite samples confirmed that enset fiber can be effectively reinforced with PP for the application of automotive and construction industries.

Improving the mechanical performance of resistance-welded green composite joints using different heating elements

This study investigates the tensile and compressive failure behavior of a single-lap joint of green composites obtained by resistance welding. The green composites composed of poly (lactic)acid (PLA) and bamboo fiber were fabricated in a hot compression by the film-stacking method. The different heating elements namely polypyrrole (conductive polymer), carbon fiber (CF) fabric, and stainless steel (SS) mesh were used to perform the resistance welding of nonconductive green composites. The heating time (30, 60, and 90 s) and the percentage of overlapping area covered by the heating element (35, 65, and 100%) were the other two welding parameters considered for experimental investigation. The effect of welding parameters on tensile and compressive failure loads was experimentally investigated through a full-factorial experimental design. The load vs. displacement and failure behavior of the welded specimen under different conditions was extensively investigated. The statistical analysis of the experimental data was performed to find the relative significance of the welding parameters. The type of heating element was found to be the most significant parameter as it has maximum statistical contribution in both tensile and compressive failure loads. The tensile and compressive failure loads were improved by 31% and 63% when CF fabric was used as a heating element as compared to the SS mesh heating element. Similarly, failure loads obtained by using CF fabric were improved by 187% (tensile) and 323% (compressive) when compared one-on-one with polypyrrole heating element.

Characterization and analyses of degradable composites made with needle-punched jute nonwoven and polylactic acid (PLA) membrane

Fiber reinforced composite materials can be seen everywhere in our daily life. The development speed of thermoplastic composites has gradually surpassed that of thermosetting materials because of their low density, recyclability and high production efficiency. Polylactic acid (PLA) and jute fibers are two of the most attractive research pursuits in the field of biodegradable materials nowadays. In this work, PLA films and jute nonwovens were made firstly, then biodegradable composite materials were produced combining PLA as the matrix with jute fiber as reinforcement using the film-stacking method. The mechanical properties of the prepared biodegradable materials were characterized by tensile testing and 3-point bending testing. The biodegradable composite materials have great potential applications in various fields with advantages of low cost, easy manufacture, low density and excellent mechanical properties.

Mechanical Characteristics Testing of Biodegradable Ramie Fiber Reinforced Polylactic Acid (PLA) Fabricated with Hot-Press Molding

In this research, composite material was fabricated from both renewable resources and biodegradable materials: ramie woven fabric as reinforcement and 3D printed polylactic acid (PLA) filament as resin matrix. The laminate composites were produced using a film stacking method and processed using hot-press molding. The mechanical properties of woven ramie fabric, PLA matrix, and laminate composites were investigated. It is shown that the breaking force of the plain woven ramie fabric in the warp direction was greater than in the weft direction. Further, the tensile and impact properties of laminate at warp direction higher than weft direction when ramie fabric reinforcement is used. In addition, scanning electron microscopy examination of laminate composite showed good bonding between ramie fiber and PLA matrix. In summary, laminated composites based on polylactic acid and woven ramie fabric display good performance capability, which can use for the development of engineering applications.

Experimental analysis of tensile and compressive failure load in single-lap adhesive joint of green composites

In this study, the tensile and compressive performance of adhesively bonded single-lap joint of green composites (bamboo fiber/Polylactic acid (PLA)) has been experimentally investigated. The green composites have been fabricated by film stacking method in compression molding. The important factors affecting the performance of the adhesively bonded joint such as overlapping length of the specimen (20, 40, and 60 mm) and width of the specimen (20, 26, and 32 mm) have been studied for epoxy, polyurethane, and parent polymer (PLA) used as bonding materials for joining of developed green composites. From the experimental analysis, it has been found that the higher levels of width and overlapping length of the joint specimen offer better tensile and compressive strength of the joint specimen. The failure loads of the joint specimens have been found to be more for epoxy as compared to PLA and polyurethane used for the purpose of joining. The relative significance of the chosen input parameters has also been found by performing analysis of variance (ANOVA). The most significant parameter has been found to be the width of the specimen for tensile failure load and type of bonding material for compressive failure load. The failure mode analysis has revealed that adhesive and cohesive failures are the major mode of failure of the adhesively bonded green composites under tensile and compressive loadings.

High performance thermoplastic polymer for the compressive behaviour of carbon fibre reinforced composites

Purpose This paper aims to study the effect of elevated temperature on the compression behaviour of carbon fibre polyphenylene sulphide (CF/PPS) laminates notched and unnotched specimens made by film stacking method (FSM). Design/methodology/approach The surface of CF was coated with a silane coupling agent to form an effective transition layer with PPS, so as to enhance the interfacial interaction between CF and PPS. Considering the influence of fabrication pressure, forming temperature and cooling rate on the properties of laminates to obtain a reasonable preparation process. Conducting a compressive experiment of notched and unnotched specimens at different temperatures, which failure modes were examined by scanning electron microscope and stereo microscope. Findings The experimental observations highlight that with the increase of temperature, the transition failure mode from fibre broken to kink-band appeared in unnotched specimens, which were closely attributed to the matrix state. The notched specimens appeared more complex failure mode, which can be attributed to the joint effect of temperature and opening hole. Research implications A simple way of FSM for composite material laminates has been developed by using woven CF and PPS films. Originality/value The outcome of this study will help to understand the compression response mechanism of composite materials made by FSM at different temperature.

Comparison of Properties of Carbon Fiber Reinforced Thermoplastic and Thermosetting Composites for Aerospace Applications

In the present study the properties of carbon fiber reinforced poly ether ketone (PEK) is compared with carbon fiber reinforced epoxy (EP) composite fabricated by compression moulding technique. PEK carbon fiber (PK-CF) composites are prepared by film stacking method whereas the epoxy carbon fiber (EP-CF) composites are prepared by conventional compression moulding route maintaining a constant 60wt% carbon fiber. The tensile properties analysis indicated that PK-CF composite possesses a tensile strength of 425MPa which was much higher than 311MPa recorded by EP-CF. The stress intensity factor (K IC ) values of PK-CF composites are found to be 10% higher than EP-CF counterparts. It is seen that the PK-CF composites possess higher glass transition temperature enabling them to be used at elevated temperatures. The investigation of flame retardant behaviour of the composite is conducted by Limiting Oxygen Index (LOI) test, and highest value is obtained for PK-CF composite.

Development of self-reinforced low-density polyethylene using γ-irradiation cross-linked polyethylene fibres

In this study, we investigated low-density polyethylene (LDPE) self-reinforced composites in which the fibres were irradiated with gamma rays prior to compression moulding. The tensile tests of the single fibres revealed that the hot air-assisted melt-spun fibres had better mechanical performance than the same LDPE matrix material. The irradiation cross-linked the fibres, which made it possible to widen the temperature window of the film-stacking method we applied for composite production. The irradiated fibres did not fuse at 120 °C, which was above their crystal melting temperature (Tm = 106 °C). The effect of irradiation on the mechanical properties of fibres themselves and the composites reinforced with these fibres were investigated. Based on the mechanical and crystalline properties we obtained, the fibres irradiated with an absorbed dose of 200 kGy were chosen as reinforcement for the composites. We performed dynamic mechanical analysis and creep tests on the composites and found that irradiation had a minor effect (10% increase) on storage modulus, while creep strain decreased greatly. The composites with non-irradiated fibres had a creep strain 60% higher at a stress of 2 MPa at the end of the test. LDPE composites with irradiated fibres did not only have improved mechanical performance but they retain the main advantage of self-reinforced composites, which is simple recycling.

Tensile Modulus of Film Stacked Palm Fibers-LDPE Sheet Composites

ABSTRACT Palm fiber-LDPE composites were prepared by a film-stacking method studying the effects of fibers content, their length, processing temperature and alkaline treatment on tensile modulus and modulus efficiency factor. It was found that up to 5 wt.% and processing temperature to 160°C in addition to alkaline treatment improved the tensile modulus and modulus efficiency factor to a certain limit due to an enhancement in load carrying and interfacial adhesion, also it was obvious that long fibers play a positive role in load transfer; improving the tensile modulus and its efficiency factor due to effective load transfer. Ductility was decreased due to the brittle behavior of the fibers.

On the analysis of compressive failure load of single-lap bolted joint of green composites

In the present study, bamboo fiber reinforced polylactic acid (PLA) composites have been fabricated by hot compression molding using film stacking method. The compressive failure load behavior of single lap bolted joint of the developed composites has been experimentally investigated. The influence of the geometric parameters of mechanical bolted joint such as width to diameter ratio (w/d), edge to diameter ratio (e/d) and bolt fastening torque on the compressive failure load has been statistically analyzed. Taguchi’s analysis has been performed to find the optimum level of geometric parameters to obtain higher compressive failure load of the bolted joint. The w/d and bolt fastening torque were found to be significant parameters influencing the compressive failure load of the bolted joint. The compressive failure load of the bolted joint is more at a higher value of w/d and bolt fastening torque.

Thermomechanical characterization of basalt fiber reinforced biodegradable polymers

AbstractIn the present study the effectiveness of two different biodegradable polymers, namely Polylactic acid (PLA) and ECOVIO (EC), a blend of a copolyester and PLA, as matrix materials for basalt fiber composites, prepared with the “film stacking method” has been investigated. Comparison with composites based on glass fiber mat has also been performed. The addition of basalt fibers, leads to a significant improvement in tensile and flexural strength and stiffness. The ECOVIO/basalt fiber composites exhibited the highest percentage enhancement, while the failure strain decreased dramatically. Therefore, the basalt fabrics appear to have a competitive mechanical performance with the glass fiber mats employed.

The Choice of Recycling Methods for Single-Polymer Polyester Composites

This work has described the production of single-polymer composites by the film-stacking method. Two types of single-polymer composites with different mass fractions of the polyester reinforcement phase (10% and 20%) and the PETG matrix were investigated. The produced composites were subsequently recycled by injection moulding, pressing, and extrusion. Selected properties of the processed composites were determined: density, viscosity-average molecular weight, impact resistance, and tensile strength. The work done in this paper has demonstrated the benefits and drawbacks of each recycling method for these materials. The selected properties of single-polymer polyester composites and single-polymer polyester composites that were recycled by extrusion have also been compared.