Thermal stability and dynamic mechanical properties of kenaf/bamboo fibre reinforced epoxy composites

An increased awareness of environmental concerns has increased the need for innovation to produce high performance engineering materials with natural renewable resources. In this study, 3 types of natural fibre (mat form) reinforced epoxy composites were prepared by the hand lay-up method, namely, kenaf (K)/Epoxy, bamboo (B)/Epoxy, and bamboo charcoal (BC)/Epoxy. The thermal stability of the specimens was investigated by thermogravimetric analysis (TGA) and the dynamic mechanical properties. Viscous elastic behaviour of the specimens was investigated via a dynamic mechanical analyzer (DMA). The TGA results revealed that the BC/Epoxy composite showed the highest thermal stability compared to K/Epoxy and B/Epoxy with the highest initial and final decomposition temperature at 348 °C and 463 °C, respectively. It also showed the highest charcoal content at 11.5%. From the DMA results, the K/Epoxy composite showed better dynamic mechanical properties with the highest complex modulus (E*) strength and the lowest damping behaviour (peak height of Tan δ). The DMA analysis also revealed that the glass transition temperature of the composites fell between 60 °C to 90 °C. This preliminary study may give a new path to develop a novel hybrid composite that offers unique properties unachievable in a single material system

Thermomechanical and dynamic mechanical properties of bamboo/woven kenaf mat reinforced epoxy hybrid composites

The dimensional stability and dynamic mechanical properties on bamboo (non woven mat)/kenaf (woven mat) hybrid composites was carried out in this study. The hybridization effect of bamboo (B) and kenaf (K) fibers at different weight ratio were studied at B:K:70:30, and B:K:30:70 while maintaining total fiber loading of 40% by weight. The coefficient of thermal expansion (CTE) and dynamic mechanical properties of composites were analyzed by thermomechanical anlayzer (TMA), and dynamic mechanical analyzer (DMA), respectively. Positive hybridization effects were observed on B:K:50:50 hybrid composite with lowest CTE and highest dynamic mechanical properties among all composites. The dimensional stability were strongly influence by the fiber orientation where all composites shows prominent expansion in the transverse fibers direction but relatively low expansion in longitudinal fibers direction. Dynamic mechanical properties in term of complex modulus (E*), storage modulus (E′), loss modulus (E″), Tan delta and Cole-Cole plot were studied. DMA results reveal that B:K:50:50 hybrid composite possess the highest complex modulus due to the strong fiber/matrix interfacial bonding which supported by the coefficient of effectiveness and Cole-Cole plot. Hence, it is concluded that 50:50 weight ratio of bamboo and kenaf fibers is the optimum mixing ratio to enhance both dimensional and dynamic mechanical properties of hybrid composites, and it can be utilized for automotive or building materials applications which demand high dimensional stability and dynamic mechanical properties

Evaluation of thermal properties of bamboo/kenaf fiber reinforced epoxy hybrid composites and nanocomposites

The awareness of environmental concerns has increased the need to produce high performance engineering materials with natural fiber-based materials. Hybridizing natural fibers with nanofiller modified polymeric composites is a potential alternative material that displays better mechanical and thermal properties for advanced applications. This research work focussed on the evaluation of the hybridization effects between non-woven bamboo mat (B) and woven kenaf mat (K) reinforced epoxy hybrid composites with further enhancement on the thermal properties by adding nanoclay. The hybrid composites were prepared by hand lay-up techniques. The epoxy/nanoclay mixture was prepared by in-situ polymerization by using a high shear speed homogenizer. Optimum fiber mixing ratio (B/K:30/70, B/K:50/50; B/K:70/30) were examine in terms of their thermal properties and resistance against environmental effects. The results reveal that increasing the bamboo fiber loading improved the thermal stability of the hybrid composites. The initial decomposition temperature of B/K:70/30 is about 10 ℃ higher than kenaf/epoxy composite. B/K:50/50 hybrid composites exhibit the highest dimensional stability and viscoelastic behaviour. It recorded the lowest thermal expansion percentage (1.14%) while B/Epoxy and K/Epoxy recorded the total thermal expansion at 2.33% and 1.47%, respectively. Besides, the durability of the hybrid composites against environmental effects was also studied by accelerated weathering test and soil burial test. B/K:50/50 hybrid composites presents a balance of resistance to environmental effects while maintaining the biodegradability characteristic. The organoclay loading (0.5, 1.0, 2.0, 4.0wt.%) epoxy nanocomposites were fabricated. The morphological, thermal, dynamic mechanical and tensile properties of the nanocomposites show optimum performance at 1wt.% loading. Further study was carried out by fabricating B/K/Nanoclay/Epoxy hybrid nanocomposites with bamboo and kenaf fiber ratio was fixed at 50:50 and nanoclay loading was fixed at 1wt.%. The effects on adding 3 different types of nanoclays: halloysite nanotube (HNT), montmorillonite (MMT) and organically modified MMT (OMMT) were compared. The morphological, thermal and flammability of the B/K/Nanoclay/Epoxy hybrid nanocomposites were characterized. The morphological study reveals that MMT/Epoxy and HNT/Epoxy are highly agglomerated while OMMT/Epoxy reveals a more uniform distribution morphology. The oxidative decomposition behaviour of the hybrid composites was studied with a thermogravimetry analyzer (TGA) under an oxygen atmosphere. The flammability properties were evaluated through Underwriters Laboratories 94 horizontal burning test (UL-94HB), limiting oxygen index (LOI), cone calorimetry and smoke density tester. The final decomposition temperature of B/K/OMMT recorded at 495 °C and it is 60 °C higher compare to B/K/Epoxy. The residue value of the hybrid nanocomposites at 800 ℃ is significantly increased by 196%, 175%, 269% with the addition of MMT, HNT and OMMT nanoclay, respectively. All hybrid nanocomposites achieved an HB40 rating in the UL-94HB test. With the addition of nanoclay, the LOI value increased from 20 to 28%. A significant reduction of total heat release and peak heat release rate between 36 – 43% was observed on nanoclay filled hybrid composites. Improvement of other fire indicators such as FIGRA (fire growth rate index), MARHE (maximum average rate of heat emission) and SMOGRA (smoke growth rate index) were noticed in all hybrid nanocomposites with excel performance observed on B/K/OMMT. The findings from this work can be utilized in preparing high-performance natural fibers reinforced epoxy hybrid composites with improvement in their dimensional stability and fire performance for automotive and building applications

The Effect of Bi-Functionalized MMT on Morphology, Thermal Stability, Dynamic Mechanical, and Tensile Properties of Epoxy/Organoclay Nanocomposites

In this work, the optimum filler loading to prepare epoxy/organoclay nanocomposites by the in-situ polymerization method was studied. Bi-functionalized montmorillonite at different filler loading (0.5, 1.0, 2.0, 4.0 wt %) was dispersed in epoxy resin by using a high shear speed homogenizer. The effect on morphology, thermal, dynamic mechanical, and tensile properties of the epoxy/organoclay nanocomposites were studied in this work. Wide-angle X-ray scattering (WAXS) and field emission scanning electron microscope (FESEM) studies revealed that possible intercalated structures were obtained in epoxy/organoclay nanocomposites. Thermogravimetric analysis (TGA) shows that epoxy/organoclay nanocomposites exhibit higher thermal stability at the maximum and final decomposition temperature, as well as higher char content, compared to pristine epoxy. The dynamic mechanical analysis (DMA) indicate that storage modulus (E′), loss modulus (E″), cross-link density and glass transition temperature (Tg) of the nanocomposites were improved with organoclay loading up to 1 wt %. Beyond this loading limit, the deterioration of properties was observed. A similar trend was also observed on tensile strength and modulus. We concluded from this study that organoclay loading up to 1 wt % is suitable for further study to fabricate hybrid nanocomposites for various applications

The effect of bi-functionalized MMT on morphology, thermal stability, dynamic mechanical, and tensile properties of epoxy/organoclay nanocomposites

In this work, the optimum filler loading to prepare epoxy/organoclay nanocomposites by the in-situ polymerization method was studied. Bi-functionalized montmorillonite at different filler loading (0.5, 1.0, 2.0, 4.0 wt %) was dispersed in epoxy resin by using a high shear speed homogenizer. The effect on morphology, thermal, dynamic mechanical, and tensile properties of the epoxy/organoclay nanocomposites were studied in this work. Wide-angle X-ray scattering (WAXS) and field emission scanning electron microscope (FESEM) studies revealed that possible intercalated structures were obtained in epoxy/organoclay nanocomposites. Thermogravimetric analysis (TGA) shows that epoxy/organoclay nanocomposites exhibit higher thermal stability at the maximum and final decomposition temperature, as well as higher char content, compared to pristine epoxy. The dynamic mechanical analysis (DMA) indicate that storage modulus (E′), loss modulus (E″), cross-link density and glass transition temperature (Tg) of the nanocomposites were improved with organoclay loading up to 1 wt %. Beyond this loading limit, the deterioration of properties was observed. A similar trend was also observed on tensile strength and modulus. We concluded from this study that organoclay loading up to 1 wt % is suitable for further study to fabricate hybrid nanocomposites for various applications

Effects of nanoclay on mechanical and dynamic mechanical properties of bamboo/kenaf reinforced epoxy hybrid composites

Current work aims to study the mechanical and dynamical mechanical properties of non-woven bamboo (B)/woven kenaf (K)/epoxy (E) hybrid composites filled with nanoclay. The nanoclay-filled BK/E hybrid composites were prepared by dispersing 1 wt.% nanoclay (organically-modified montmorillonite (MMT; OMMT), montmorillonite (MMT), and halloysite nanotube (HNT)) with high shear speed homogenizer followed by hand lay-up fabrication technique. The effect of adding nanoclay on the tensile, flexural, and impact properties of the hybrid nanocomposites were studied. Fractography of tensile-fractured sample of hybrid composites was studied by field emission scanning electron microscope. The dynamic mechanical analyzer was used to study the viscoelastic properties of the hybrid nanocomposites. BK/E-OMMT exhibit enhanced mechanical properties compared to the other hybrid nanocomposites, with tensile, flexural, and impact strength values of 55.82 MPa, 105 MPa, and 65.68 J/m, respectively. Statistical analysis and grouping information were performed by one-way ANOVA (analysis of variance) and Tukey method, and it corroborates that the mechanical properties of the nanoclay-filled hybrid nanocomposites are statistically significant. The storage modulus of the hybrid nanocomposites was improved by 98.4%, 41.5%, and 21.7% with the addition of OMMT, MMT, and HNT, respectively. Morphology of the tensile fracture BK/E-OMMT composites shows that lesser voids, microcracks and fibers pull out due to strong fiber–matrix adhesion compared to other hybrid composites. Hence, the OMMT-filled BK/E hybrid nanocomposites can be utilized for load-bearing structure applications, such as floor panels and seatbacks, whereby lightweight and high strength are the main requirements

Effects of nanoclay on physical and dimensional stability of bamboo/kenaf/nanoclay reinforced epoxy hybrid nanocomposites

The objective of current work is to evaluate the density, void content, water absorption, thickness swelling and thermal expansion of non-woven bamboo mat (B)/ woven kenaf mat (K)/nanoclay/epoxy hybrid nanocomposites. The natural fibers based hybrid nanocomposites were prepared by incorporation of montmorillonite (MMT), halloysite nanotube (HNT) and organically modified montmorillonite (OMMT) at 1 wt.% loading, through hand lay-up technique. Water absorption was investigated by soaking the samples with distilled water at room temperature until saturation point and the thickness swelling was also measured as per standard. Thermomechanical analyser (TMA) was used to study the dimensional stability caused by temperature variation. Addition of nanoclay increase the density, reduced the void content and suppress water uptake in all hybrid nanocomposites. B/K/OMMT hybrid nanocomposites exhibit better dimensional stability with regards to water absorptions and thermal expansion as compare to B/K/MMT and B/K/HNT. The improvement can be attributed by the uniformly dispersed and strong interfacial adhesion bonding between the OMMT and epoxy matrix. The develop nanocomposites in this work can be utilized for building and automotive application which required high dimensional stability property