The Effect of Graphene Oxide and SEBS-g-MAH Compatibilizer on Mechanical and Thermal Properties of Acrylonitrile-Butadiene-Styrene/Talc Composite.

In this study, acrylonitrile butadiene styrene (ABS)/talc/graphene oxide/SEBS-g-MAH (ABS/Talc/GO/SEBS-g-MAH) and acrylonitrile butadiene styrene/graphene oxide/SEBS-g-MAH (ABS/GO/SEBS-g-MAH) composites were isolated with varying graphene oxide (0.5 to 2.0 phr) as a filler and SEBS-g-MAH as a compatibilizer (4 to 8 phr), with an ABS:talc ratio of 90:10 by percentage. The influences of graphene oxide and SEBS-g-MAH loading in ABS/talc composites were determined on the mechanical and thermal properties of the composites. It was found that the incorporation of talc reduces the stiffness of composites. The analyses of mechanical and thermal properties of composites revealed that the inclusion of graphene oxide as a filler and SEBS-g-MAH as a compatibilizer in the ABS polymer matrix significantly improved the mechanical and thermal properties. ABS/talc was prepared through melt mixing to study the fusion characteristic. The mechanical properties showed an increase of 30%, 15%, and 90% in tensile strength (TS), flexural strength (FS), and flexural modulus (FM), respectively. The impact strength (IS) resulted in comparable properties to ABS, and it was better than the ABS/talc composite due to the influence of talc in the composite that stiffens and reduces the extensibility of plastic. The incorporation of GO and SEBS-g-MA also shows a relatively higher thermal stability in both composites with and without talc. The finding of the present study reveals that the graphene oxide and SEBS-g-MAH could be utilized as a filler and a compatibilizer in ABS/talc composites to enhance the thermo-mechanical stability because of the superior interfacial adhesion between the matrix and filler.

Effect of Nanofillers on Tribological Properties of Polymer Nanocomposites: A Review on Recent Development.

Polymer nanocomposites with enhanced performances are becoming a trend in the current research field, overcoming the limitations of bulk polymer and meeting the demands of market and society in tribological applications. Polytetrafluoroethylene, poly(ether ether ketone) and ultrahigh molecular weight polyethylene are the most popular polymers in recent research on tribology. Current work comprehensively reviews recent advancements of polymer nanocomposites in tribology. The influence of different types of nanofiller, such as carbon-based nanofiller, silicon-based nanofiller, metal oxide nanofiller and hybrid nanofiller, on the tribological performance of thermoplastic and thermoset nanocomposites is discussed. Since the tribological properties of polymer nanocomposites are not intrinsic but are dependent on sliding conditions, direct comparison between different types of nanofiller or the same nanofiller of different morphologies and structures is not feasible. Friction and wear rate are normalized to indicate relative improvement by different fillers. Emphasis is given to the effect of nanofiller content and surface modification of nanofillers on friction, wear resistance, wear mechanism and transfer film formation of its nanocomposites. Limitations from the previous works are addressed and future research on tribology of polymer nanocomposites is proposed.

Mechanical and Morphological Properties of Bio-Phenolic/Epoxy Polymer Blends.

Polymer blends is a well-established and suitable method to produced new polymeric materials as compared to synthesis of a new polymer. The combination of two different types of polymers will produce a new and unique material, which has the attribute of both polymers. The aim of this work is to analyze mechanical and morphological properties of bio-phenolic/epoxy polymer blends to find the best formulation for future study. Bio-phenolic/epoxy polymer blends were fabricated using the hand lay-up method at different loading of bio-phenolic (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) in the epoxy matrix whereas neat bio-phenolic and epoxy samples were also fabricated for comparison. Results indicated that mechanical properties were improved for bio-phenolic/epoxy polymer blends compared to neat epoxy and phenolic. In addition, there is no sign of phase separation in polymer blends. The highest tensile, flexural, and impact strength was shown by P-20(biophenolic-20 wt% and Epoxy-80 wt%) whereas P-25 (biophenolic-25 wt% and Epoxy-75 wt%) has the highest tensile and flexural modulus. Based on the finding, it is concluded that P-20 shows better overall mechanical properties among the polymer blends. Based on this finding, the bio-phenolic/epoxy blend with 20 wt% will be used for further study on flax-reinforced bio-phenolic/epoxy polymer blends.

Recently Emerging Nanotechnological Advancements in Polymer Nanocomposite Coatings for Anti-corrosion, Anti-fouling and Self-healing.

Recent nanotechnological advancements have enabled novel innovations in protective polymer nanocomposites (PNC) coatings for anti-corrosion, anti-fouling and self-healing services on material surfaces. Nanotechnology encompases research, manufacturing, and application of nanoparticulate architectures, tubular structures, sheets or plates exhibiting sizes below 100 nanometers (nm) in at least a single dimension. Inclusions of nanoparticles into organic entities have demonstrated enhanced properties essential for attainiment of aesthetics, anti-corrosion, thermal stability for high-temperature performances, mechanical strength essential for resisting coating deterioration in harsh environments, nano-architectural cross-linking capable of hindering penetration of corrosive, and biofouling entities. Unlike previously published literature, this paper elucidates very recently emerging important advancements in novel techniques utilized in developing PNC coatings for applications in aerospace, packaging, automotive, biomedicine, maritime, and oil and gas industries for attaining superior anti-fouling, anti-corrosion, and self-healing behaviors on critical material surfaces. Emerging market structures and novel applications are also presented.

Mechanical and Thermal Properties of Montmorillonite-Reinforced Polypropylene/Rice Husk Hybrid Nanocomposites.

In recent years, there has been considerable interest in the use of natural fibers as potential reinforcing fillers in polymer composites despite their hydrophilicity, which limits their widespread commercial application. The present study explored the fabrication of nanocomposites by melt mixing, using an internal mixer followed by a compression molding technique, and incorporating rice husk (RH) as a renewable natural filler, montmorillonite (MMT) nanoclay as water-resistant reinforcing nanoparticles, and polypropylene-grafted maleic anhydride (PP-g-MAH) as a compatibilizing agent. To correlate the effect of MMT delamination and MMT/RH dispersion in the composites, the mechanical and thermal properties of the composites were studied. XRD analysis revealed delamination of MMT platelets due to an increase in their interlayer spacing, and SEM micrographs indicated improved dispersion of the filler(s) from the use of compatibilizers. The mechanical properties were improved by the incorporation of MMT into the PP/RH system and the reinforcing effect was remarkable as a result of the use of compatibilizing agent. Prolonged water exposure of the prepared samples decreased their tensile and flexural properties. Interestingly, the maximum decrease was observed for PP/RH composites and the minimum was for MMT-reinforced and PP-g-MAH-compatibilized PP/RH composites. DSC results revealed an increase in crystallinity with the addition of filler(s), while the melting and crystallization temperatures remained unaltered. TGA revealed that MMT addition and its delamination in the composite systems improved the thermal stability of the developed nanocomposites. Overall, we conclude that MMT nanoclay is an effective water-resistant reinforcing nanoparticle that enhances the durability, mechanical properties, and thermal stability of composites.

Enhanced Flexibility of Biodegradable Polylactic Acid/Starch Blends Using Epoxidized Palm Oil as Plasticizer.

The brittleness of polylactic acid (PLA) has always limited its usage, although it has good mechanical strength. In this study, flexibility of PLA/starch (PSt) blend was enhanced using epoxidized palm oil (EPO) as the green plasticizer. The PLA/starch/EPO (PSE) blends were prepared while using the solution casting method by fixing the content of starch and varying ratio of EPO. The thermal properties, such as glass transition temperature (Tg), melting temperature (Tm), and crystallization temperature (Tcc) were decreased by increasing the amount of EPO into PSt, indicating that EPO increases the chain mobility. Thermogravimetric analysis (TGA) showed that thermal degradation resistance of PSE was higher when compared to PSt. The mechanical testing revealed that EPO at all contents improved the mechanical properties, such as increment of the elongation-at-break and impact strength. Whereas, dynamic mechanical analysis showed that the addition of filler into PLA decreased the storage modulus of PLA. The carbonyl group of the aliphatic ester remained the same in the PSE blends. The morphological study verified the ductility of PSE blends surface when compared to the brittle surface of PSt. As for the soil burial tests, EPO accelerated the degradation of blends. From these results, it can be concluded that EPO improved the flexibility of PLA blends.

Exploring the effect of cellulose nanowhiskers isolated from oil palm biomass on polylactic acid properties.

In this work, polylactic acid (PLA) reinforced cellulose nanowhiskers (CNW) were prepared through solution casting technique. The CNW was first isolated from oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC) by using 64% H2SO4 and was designated as CNW-S. The optical microscopy revealed that the large particle of OPEFB-MCC has been broken down by the hydrolysis treatment. The atomic force microscopy confirmed that the CNW-S obtained is in nanoscale dimension and appeared in individual rod-like character. The produced CNW-S was then incorporated with PLA at 1, 3, and 5 parts per hundred (phr) resins for the PLA-CNW-S nanocomposite production. The synthesized nanocomposites were then characterized by a mean of tensile properties and thermal stability. Interestingly to note that incorporating of 3 phr/CNW-S in PLA improved the tensile strength by 61%. Also, CNW-S loading showed a positive impact on the Young's modulus of PLA. The elongation at break (Eb) of nanocomposites, however, decreased with the addition of CNW-S. Field emission scanning electron microscopy and transmission electron microscopy revealed that the CNW-S dispersed well in PLA at lower filler loading before it started to agglomerate at higher CNW-S loading (5phr). The DSC analysis of the nanocomposites obtained showed that Tg,Tcc and Tm values of PLA were improved with CNW-S loading. The TGA analysis however, revealed that incopreated CNW-S in PLA effect the thermal stability (T10,T50 and Tmax) of nanocomposite, where it decrease linearly with CNW-S loading.

Effect of hydrolysed cellulose nanowhiskers on properties of montmorillonite/polylactic acid nanocomposites.

Polylactic acid (PLA) nanocomposites reinforced with hybrid montmorillonite/cellulose nanowhiskers [MMT/CNW(SO4)] were prepared by solution casting. The CNW(SO4) nanofiller was first isolated from microcrystalline cellulose using acid hydrolysis treatment. PLA/MMT/CNW(SO4) hybrid nanocomposites were prepared by the addition of various amounts of CNW(SO4) [1-9 parts per hundred parts of polymer (phr)] into PLA/MMT nanocomposite at 5 phr MMT content, based on highest tensile strength values as reported previously. The biodegradability, thermal, tensile, morphological, water absorption and transparency properties of PLA/MMT/CNW(SO4) hybrid nanocomposites were investigated. The Biodegradability, thermal stability and crystallinity of hybrid nanocomposites increased compared to PLA/MMT nanocomposite and neat PLA. The highest tensile strength of hybrid nanocomposites was obtained by incorporating 1 phr CNW(SO4) [∼ 36 MPa]. Interestingly, the ductility of hybrid nanocomposites increased significantly by 87% at this formulation. The Young's modulus increased linearly with increasing CNW(SO4) content. This is due to the relatively good dispersion of nanofillers in the hybrid nanocomposites, as revealed by transmission electron microscopy. Fourier transform infrared spectroscopy indicated the formation of some polar interactions. In addition, water resistance of the hybrid nanocomposites improved and the visual transparency of neat PLA film did not affect by addition of CNW(SO4).

Partial replacement effect of montmorillonite with cellulose nanowhiskers on polylactic acid nanocomposites.

In this study, hybrid montmorillonite/cellulose nanowhiskers (MMT/CNW) reinforced polylactic acid (PLA) nanocomposites were produced through solution casting. The CNW filler was first isolated from microcrystalline cellulose by chemical swelling technique. The partial replacement of MMT with CNW in order to produce PLA/MMT/CNW hybrid nanocomposites was performed at 5 parts per hundred parts of polymer (phr) fillers content, based on highest tensile strength values as reported in our previous study. MMT were partially replaced with various amounts of CNW (1, 2, 3, 4 and 5phr). The tensile, thermal, morphological and biodegradability properties of PLA hybrid nanocomposites were investigated. The highest tensile strength of hybrid nanocomposites was obtained with the combination of 4phr MMT and 1phr CNW. Interestingly, the ductility of hybrid nanocomposites increased significantly by 79% at this formulation. The Young's modulus increased linearly with increasing CNW content. Thermogravimetric analysis illustrated that the partial replacement of MMT with CNW filler enhanced the thermal stability of the PLA. This is due to the relatively good dispersion of fillers in the hybrid nanocomposites samples as revealed by transmission electron microscopy. Interestingly, partial replacements of MMT with CNW improved the biodegradability of hybrid nanocomposites compared to PLA/MMT and neat PLA.

Encapsulation of nonmetallic fractions recovered from printed circuit boards waste with thermoplastic.

The present work includes a process for encapsulation by combining substantially simultaneously dry nonmetallic printed circuit boards (PCBs) powder and recycled high-density polyethylene (rHDPE) in an extruder to form a homogenous matrix. The extruded materials were then molded into standard tensile, flexural, and impact properties testing specimens. Nonmetallic PCB mainly consists of large amount of glass fiber-reinforced epoxy resin materials. Incorporation of 50 wt% nonmetallic PCB in rHDPE matrix had increased the flexural strength and modulus by 35% and 130%, respectively. Tensile strength reported to be constant without much improvement. However, the Young's modulus has increased by 180%, with incorporation of 50 wt% nonmetallic PCB. The addition of 6 phr (parts per hundred) maleated polyethylene (MAPE) resulted in 2-fold increase in tensile and flexural strength. Regarding the leaching properties, Cu was identified as the metal that leached at the highest level from the raw nonmetallic PCB, at 59.09 mg/L. However, after the nonmetallic PCB was filled in rHDPE/PCB composites, the concentration of Cu was reduced far below the regulatory limit, to only 3 mg/L. Thermal properties of composites were studied, and it was found out that incorporation of nonmetallic PCB fillers in rHDPE resulted in low thermal conductivity, whereas mechanical strength of the composites showed maximum improvements at 220 degrees C. Overall, the encapsulation technique using nonmetallic PCB waste has formed a monolithic waste form that provides a barrier to the dispersion of wastes into the environment. Implications: Nonmetallic materials reclaimed from waste PCBs were used to analyze the chemical composition, and it was found that nonmetalllic PCBs mainly consist of glass fiber-reinforced epoxy resin materials. With such millions of glass fibers in nonmetallic PCBs, there are mass-excellent supporting bodies that enhance the mechanical properties of composites. In fact, utilization of nonmetallic PCB waste as filler in composites can dramatically restrain the solubility of heavy metals in leachate solution, thus making it safe to be used in practical products.

Isolation and characterization of cellulose nanowhiskers from oil palm biomass microcrystalline cellulose.

The objective of this study is to compare the effect of two different isolation techniques on the physico-chemical and thermal properties of cellulose nanowhiskers (CNW) from oil palm biomass obtained microcrystalline cellulose (MCC). Fourier transform infrared analysis showed that there are no significant changes in the peak positions, suggesting that the treatments did not affect the chemical structure of the cellulose fragment. Scanning electron microscopy showed that the aggregated structure of MCC is broken down after treatment. Transmission electron microscopy revealed that the produced CNW displayed a nanoscale structure. X-ray diffraction analysis indicated that chemical swelling improves the crystallinity of MCC while maintaining the cellulose I structure. Acid hydrolysis however reduced the crystallinity of MCC and displayed the coexistence of cellulose I and II allomorphs. The produced CNW is shown to have a good thermal stability and hence is suitable for a range of applications such as green biodegradable nanocomposites reinforced with CNW.

Properties of polylactic acid composites reinforced with oil palm biomass microcrystalline cellulose.

In this work, polylactic acid (PLA) composites filled with microcrystalline cellulose (MCC) from oil palm biomass were successfully prepared through solution casting. Fourier transform infrared (FT-IR) spectroscopy indicates that there are no significant changes in the peak positions, suggesting that incorporation of MCC in PLA did not result in any significant change in chemical structure of PLA. Thermogravimetric analysis was conducted on the samples. The T50 decomposition temperature improved with addition of MCC, showing increase in thermal stability of the composites. The synthesized composites were characterized in terms of tensile properties. The Young's modulus increased by about 30%, while the tensile strength and elongation at break for composites decreased with addition of MCC. Scanning electron microscopy (SEM) of the composites fractured surface shows that the MCC remained as aggregates of crystalline cellulose. Atomic force microscopy (AFM) topographic image of the composite surfaces show clustering of MCC with uneven distribution.

Isolation and characterization of microcrystalline cellulose from oil palm biomass residue.

In this work, we successfully isolated microcrystalline cellulose (MCC) from oil palm empty fruit bunch (OPEFB) fiber-total chlorine free (TCF) pulp using acid hydrolysis method. TCF pulp bleaching carried out using an oxygen-ozone-hydrogen peroxide bleaching sequence. Fourier transform infrared (FT-IR) spectroscopy indicates that acid hydrolysis does not affect the chemical structure of the cellulosic fragments. The morphology of the hydrolyzed MCC was investigated using scanning electron microscopy (SEM), showing a compact structure and a rough surface. Furthermore, atomic force microscopy (AFM) image of the surface indicates the presence of spherical features. X-ray diffraction (XRD) shows that the MCC produced is a cellulose-I polymorph, with 87% crystallinity. The MCC obtained from OPEFB-pulp is shown to have a good thermal stability. The potential for a range of applications such as green nano biocomposites reinforced with this form of MCC and pharmaceutical tableting material is discussed.

Converting non-metallic printed circuit boards waste into a value added product.

The aim of this study was to investigate the feasibility of using nonmetallic printed circuit board (PCB) waste as filler in recycled HDPE (rHDPE) in production of rHDPE/PCB composites. Maleic anhydride modified linear low-density polyethylene (MAPE) was used as compatibilizer. In particular, the effects of nonmetallic PCB and MAPE on mechanical properties of the composites were assessed through tensile, flexural and impact testing. Scanning electron microscope (SEM) was used to study the dispersion of nonmetallic PCB and MAPE in the matrix. Nonmetallic PCB was blended with rHDPE from 0-30 wt% and prepared by counter-rotating twin screw extruder followed by molding into test samples via hot press for analysis. A good balance between stiffness, strength and toughness was achieved for the system containing 30 wt% PCB. Thus, this system was chosen in order to investigate the effect of the compatibilizer on the mechanical properties of the composites. The results indicate that MAPE as a compatiblizer can effectively promote the interfacial adhesion between nonmetallic PCB and rHDPE. The addition of 6 phr MAPE increased the flexural strength, tensile strength and impact strength by 71%, 98% and 44% respectively compared to the uncompatibilized composites.