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Browsing Journal Articles by browse.metadata.impactarea "Advanced Polymer Composites"
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Item Antibiotic 3D printed Materials for healthcare applications(Elsevier Inc, 2020-05) Mokhena, Teboho C; John, Maya J; Mochane, MJ; Sadiku, ER; Motsoeneng, TS; Mtibe, Asanda; Tsipa, PC; Kokkarachedu, V; Kanikireddy, V; Sadiku, RSince its introduction in the past 25 years, three-dimensional (3D) printing has been a major research topic owing to its potential to overcome the limitations of conventional 3D manufacturing techniques, that is, to control the overall architecture toward various applications. In the third (2013–present) decade, 3D printing enters a new phase in which researchers fabricate clinical constructs that benefit the current society. In this chapter, we briefly discuss the recent progress of 3D printing and challenges related to the antibiotic materials and manufacturing process for biomedical applications.Item Application of electrospun materials in oil–water separations(Scrivener Publishing LLC, 2020-04) Mokhena, Teboho C; John, Maya J; Mochane, MJ; Tsipa, PC; Boddula, RI; Ahamed, MI; Asiri, AMThere has been ever-increasing pressure to come up with novel strategies for oily wastewater treatment since it affect the available water sources, crop production, aquatic life and human health. Electrospun nanofibrous materials with attractive attributes, such as interconnected porous structure, large surface-to-area ratio, malleable mechanical properties, tuneable wettability, and porosity have a huge potential for oily wastewater treatment. In this chapter, the recent progress of oil/ water separation using electrospun nanofibrous materials is reviewed. The challenges and future prospects of this new field are also described.Item Bioelectricity generation by natural microflora of septic tank wastewater (STWW) and biodegradation of persistent petrogenic pollutants by basidiomycetes fungi: An integrated microbial fuel cell system(2021-01) Thulasinathan, B; Jayabalan, T; Sethupathi, M; Kim, W; Muniyasamy, Sudhakar; Sengottuvelan, N; Nainamohamed, S; Ponnuchamy, K; Alagarsamy, AThe microbial fuel cell is a unique advantageous technology for the scientific community with the simultaneous generation of green energy along with bioelectroremediation of persistent hazardous materials. In this work, a novel approach of integrated system with bioelectricity generation from septic tank wastewater by native microflora in the anode chamber, while Psathyrella candolleana with higher ligninolytic enzyme activity was employed at cathode chamber for the biodegradation of polycyclic aromatic hydrocarbons (PAHs). Six MFC systems designated as MFC1, MFC2, MFC3, MFC4, MFC5, and MFC6 were experimented with different conditions. MFC1 system using natural microflora of STWW (100%) at anode chamber and K3[Fe(CN)6] as cathode buffer showed a power density and current density of 110 ± 10 mW/m2 and 90 ± 10 mA/m2 respectively. In the other five MFC systems 100% STWW was used at the anode and basidiomycetes fungi in the presence or absence of individual PAHs (naphthalene, acenaphthene, fluorene, and anthracene) at the cathode. MFC2, MFC3, MFC4, MFC5, and MFC6 had showed power density of 132 ± 17 mW/m2, 138 ± 20 mW/m2, 139 ± 25 mW/m2, and 147 ± 10 mW/m2 respectively. MFC2, MFC3, MFC4, MFC5, and MFC6 had showed current density of 497 ± 17 mA/m2, 519 ± 10 mA/m2, 522 ± 21 mA/m2 and 525 ± 20 mA/m2 respectively. In all the MFC systems, the electrochemical activity of anode biofilm was evaluated by cyclic voltammetry analysis and biofilms on all the MFC systems electrode surface were visualized by confocal laser scanning microscope. Biodegradation of PAHs during MFC experimentations in the cathode chamber was estimated by UV-Vis spectrophotometer. Overall, MFC6 system achieved maximum power density production of 525 ± 20 mA/m2 with 77% of chemical oxygen demand removal and 54% of coulombic efficiency at the anode chamber and higher anthracene biodegradation (62 ± 1.13%) at the cathode chamber by the selected Psathyrella candolleana at 14th day. The present natural microflora - basidiomycetes fungal coupled MFC system offers excellent opening towards the simultaneous generation of green electricity and PAHs bioelectroremediation.Item Cellulose nanocrystals-based composites(Scrivener Publishing LLC, 2020-01) Mokhena, Teboho C; John, Maya J; Mochane, MJ; Mtibe, Asanda; Motsoeneng, TS; Mokhothu, TH; Tshifularo, CA; Jamil, N; Kumar, P; Batool, RCellulose nanocrystals and cellulose nanocrystals-based composites with their unique features, such as abundance, renewability, high strength and stiffness, eco-friendliness, and relatively low density received unprecedented interest from both academia and industries as replacement of conventional petroleum-based materials, since conventional petroleum-based materials create ecological threats such as global warming and pollution. In this chapter, critical factors in the manufacturing of cellulose nanocrystals-based composites with regard to preparation methods, morphology, barrier and mechanical behaviour are comprehensively discussed. It concludes with the recent developments and future trends of cellulose nanocrystals reinforced biopolymers.Item Cellulose nanomaterials: New generation materials for solving global issues(2020-02) Mokhena, Teboho C; John, Maya JThis review describes the recent advances in the production and application of cellulose nanomaterials. Cellulose nanomaterials (CNMs), especially cellulose nanocrystals and cellulose nanofibers, can be produced using different preparation processes resulting in materials with unique structures and physicochemical properties that are exploited in different fields such as, biomedical, sensors, in wastewater treatment, paper and board/packaging industry. These materials possess attractive properties such as large surface area, high tensile strength and stiffness, surface tailor-ability via hydroxyl groups and are renewable. This has been a driving force to produce these materials in industrial scale with several companies producing CNMs at tons-per-day scale. The recent developments in their production rate and their applications in various fields such as medical sector, environmental protection, energy harvesting/storage are comprehensively discussed in this review. We emphasize on the current trends and future remarks based on the production and applications of cellulose nanomaterials.Item Design and development of cellulosic bionanocomposites from forestry waste residues for 3D printing applications(2021-06) Mathew, Maya J; Dyanti, Nokuzola; Mokhena, Teboho C; Agbakoba, Victor; Sithole, Bishop BThis paper deals with the development of cellulose nanofibres (CNFs) reinforced biopolymers for use in packaging applications. Cellulose nanofibres were extracted from sawdust by a combination of chemical and mechanical treatments. The extracted cellulose nanofibres were chemically modified (fCNFs) and characterised by Fourier Transform Infrared Spectroscopy (FTIR). Bionanocomposites were prepared from biopolymers polylactic acid/polybutylene succinate (PLA/PBS) and cellulose nanofibres by compounding in a twin-screw extruder followed by injection moulding. The developed bionanocomposites were subjected to mechanical and thermal characterisation. As part of product development, CNF-biopolymer pellets were also extruded into filaments which were then 3D printed into prototypes. This work is a successful demonstration of conversion of waste residues into value-added.Item Effect of clay nanofillers on the mechanical and water vapor permeability properties of xylan–alginate films(2020-10) Naidu, Darrel S; Mathew, Maya JIn this study, xylan–alginate-based films were reinforced with nanoclays (bentonite or halloysite) by the solvent casting technique. The effect of the nanoclay loadings (1–5 wt %) on various properties—mechanical, optical, thermal, solubility, water sorption, and water vapor permeability (WVP)—of the xylan–alginate films were examined for their application as food packaging materials. A 5 wt % loading of either bentonite or halloysite resulted in a 49% decrease of the WVP due to the impermeable nature of the silicate layers that make up both bentonite and halloysite. Thermal stability and solubility of the nanocomposite films were not significantly influenced by the presence of the nanoclays, whereas the optical properties were significantly improved when compared to neat xylan–alginate blend. In general, films reinforced with bentonite exhibited superior mechanical and optical properties when compared to both halloysite-based nanocomposite and neat films.Item Engineered transparent wood composites: A review(2023-05) Jele, Thabisile B; Andrew, Jerome E; Mathew, Maya J; Sithole, BruceWood is a versatile resource due to its inherent properties such as low density, good weight to strength ratio, unique hierarchical structure, microscale pores, and ease of processing, including its biodegradability and renewability. In the building and construction industry, engineered transparent wood (ETW) may serve as a sustainable replacement for glass which is environmentally unfriendly in its manufacture and application. Natural wood is non transparent due to its low optical transmittance, therefore, lignin and chromophores are modified or eliminated, and a polymer is infiltrated in order to achieve transparency. Engineered transparent wood (ETW) exhibits excellent optical properties (transmittance>80%), high haze (haze>70%), thermal insulation (thermal conductivity less than 0.23Wm-1 K-1), unique hierarchical structure, good loadbearing performance with tough failure behaviour (no shattering) and ductility. These properties extend wood applications to optical components such as solar cells, screens, windows, magnetic materials, and luminescent and decorative materials. This review details the production of ETW and how the wood density, wood thickness, wood type, wood direction, cellulose volume fraction, extent and type of delignification, polymer type, functionalisation of ETW affect the morphological, functional, optical, thermal, photodegradation and mechanical properties of ETW.Item Engineered transparent wood with cellulose matrix for glass applications: A review(2024-06) Simelane, Nontobeko P; Olatunji, OS; Mathew, Maya J; Andrew, Jerome EEngineered transparent wood (ETW), derived from the modification of natural wood, presents a sustainable and aesthetically pleasing alternative to traditional glass. This review comprehensively explores the burgeoning field of ETW as a novel material for applications in the glass industry. A comprehensive overview of the various methodologies employed in the engineering of transparent wood, encompassing delignification, polymer infiltration, and other innovative techniques is provided. Additionally, the optical, mechanical, and thermal properties of ETW are systematically examined, highlighting its potential advantages over conventional glass materials. The review also discusses recent advancements, challenges, and future considerations of ETW. Furthermore, the review discusses key applications in the glass industry where ETW has demonstrated promising performance, including windows, facades, and decorative elements. Essentially, this review aims to enhance understanding of ETW's potential in glass applications by critically analyzing current research and advancements. It seeks to pave the way for future developments in this innovative and eco-friendly technology.Item Esterified cellulose nanofibres from saw dust using vegetable oil(2020-04) Mokoena, Teboho P; Mathew, Maya JIn this work, cellulose nanofibres (CNFs) were extracted from sawdust, which is an underutilized by-product from the wood and timber industry. The extracted CNFs by chemical and mechanical treatments had a web-like structure with diameters ranging between 2 nm and 27 nm and lengths reaching a few microns. The obtained CNFs were further chemically modified with vegetable canola oil using two different esterification processes. In order to compare the effect of the surface modification of CNFs, the nanopapers were prepared from their prospective suspensions through solvent evaporation method, and then characterize with Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis spectroscopy and tensile tester. FTIR results indicated that both methods led to a successful grafting of the long chain hydrocarbon structure onto the CNFs, and became more hydrophobic when compared to unmodified CNFs-based nanopapers. The crystallinity, mechanical, light transmittance and thermal properties were significantly affected primarily by the esterification method employed, thus the degree of substitution. It was found that high degree of substitution adversely affected the crystallinity, light transmittance, mechanical and thermal properties. The crystallinity decreased from 70% to <40% when the degree of substation was about 0.8.Item Influence of nucleation and growth mechanisms on the heat deflection temperature of a reactively processed polypropylene nanocomposite(2021-02) Bandyopadhyay, Jayita; Mekoa, Raphaahle C; Makwakwa, Dimakatso M; Skosana, Sifiso; Ray, Suprakas SThe development of a reactively processed polypropylene nanocomposite (PPNC) with consequential improvements in the heat deflection temperature (HDT), Vicat softening temperature (VST), and crystallization peak temperature (Tc) is reported herein. Neat PP without nanoclay was also reactively processed to elucidate the effects of fillers on the improvement in physical properties. The results show a considerable improvement in the HDT of PPNC (77.9 °C) compared to those of neat PP (62.6 °C) and reactively processed branched PP (BPP; 69.2 °C). Moreover, the Tc of PP in PPNC improved by ~14% compared to that of neat PP. Various models of nonisothermal crystallization kinetics were employed to elucidate the nucleation and crystal growth mechanisms, and to correlate them with the observed HDT improvement in PPNC. Thermal transitions investigated by modulated differential scanning calorimetry explained the changes observed in the VSTs of all the samples. To the best of our knowledge, this is the first report on a significant improvement in HDT along with a marked increase in Tc. Such simultaneous improvements in HDT, VST, and Tc are highly desirable for applications involving the use of PP-based materials in rigid packaging.Item Mechanical and shape memory properties of 3D-Printed Cellulose Nanocrystal (CNC)-reinforced polylactic acid bionanocomposites for Potential 4D applications(2022-09) Agbakoba, Victor C; Hlangothi, P; Andrew, Jerome E; Mathew, Maya JThere is a growing need for diversified material feedstock for 3D printing technologies such as fused deposition modelling (FDM) techniques. This has resulted in an increased drive in the research and development of eco-friendly biopolymer-based composites with wide applications. At present, bionanocomposites of polylactic acid (PLA), biopolymer, and cellulose nanocrystals (CNCs) offer promising technical qualities suitable for FDM 3D printing applications due to their biodegradability and wide-ranging applications. In this work, the applicability of the PLA/CNCs bionanocomposites in 4D applications was investigated by studying its shape-recovery behaviour. Tensile and dynamic mechanical analysis (DMA) was used to elucidate the mechanical and flexural properties of the 3D-printed specimens. The results revealed improvement in the deflection temperature under load (DTUL), creep deformation, and recovery of the PLA/CNCs bionanocomposites. Tensile and static 3-point bending analyses of the bionanocomposites revealed improved tensile strength and modulus of the 3D printed parts. The potential 4D application of the PLA/CNCs bionanocomposites was also investigated by successfully printing PLA/CNC bionanocomposites directly onto a nylon fabric. The PLA/CNCs-fabric prototype included a foldable cube and grid-patterned designs. Additionally, the heat-induced shape memory behaviour of these prototypes was demonstrated.Item Morphology, thermal, and thermomechanical properties of cellulose nanocrystals reinforced polyactide/poly[(butylene succinate)-co-adipate] blend composite foams(2020-10) Motloung, Mpho P; Zungu, Simphiwe; Ojijo, Vincent O; Bandyopadhyay, Jayita; Ray, Suprakas SThis study examines the influence of cellulose nanocrystal (CN) particles on the morphological, thermal, and thermo-mechanical properties of polylactide (PLA)/poly [(butylene succinate)-co-adipate] (PBSA) blend foams prepared by casting and particulate leaching method using fructose as porogen particles. The morphological analysis showed an interconnected open-cell structure, with porosity above 80%. The crystallinity of the prepared foams was disrupted by the inclusion of CN particles as observed from XRD analyses, which showed a decrease in PLA crystal peak intensity. With regards to neat blend foam, the onset thermal degradation increased with the addition of CN particles, which also increased the thermal stability at 50% weight loss. Furthermore, CN acted as a reinforcing agent in improving the stiffness of the prepared blend foam. Overall, completely environmentally friendly foams were successfully prepared, as a potential material that can replace the current existing foam materials that pose many environmental concerns. However, there is a need to develop an environmentally friendly processing technique.Item Nanomaterials: Types, synthesis and characterization(Springer, 2020-03) Mokhena, Teboho C; John, Maya J; Sibeko, MA; Agbakoba, VC; Mochane, MJ; Mtibe, Asanda; Mokhothu, TH; Motsoeneng, TS; Phiri, MM; Mofokeng, Tladi G; Srivastava, M; Srivastava, N; Mishra, PK; Gupta, VKNanoparticles are generally defined as particles having one or more dimensions of sizes ranging from 1 to 100 nm. Nanoparticles can be classified into organic, inorganic and carbon-based materials. In comparison with conventional micro-size particles, nanoparticles show enhanced properties, such as high reactivity, strength, surface area, sensitivity and stability due to their nanosize. Various preparation methods, viz. physical, chemical and mechanical, have been employed to synthesize different nanoparticles. This chapter presents an overview on nanoparticles and their types, properties, synthesis methods and application in bioconversion of biomass into biofuels.Item Optimization of media components and culture conditions for polyhydroxyalkanoates production by Bacillus megaterium(2020-07) Mohanrasu, K; Guru Raj Rao, R; Dinesh, GH; Zhang, K; Siva Prakash, G; Song, D; Muniyasamy, Sudhakar; Pugazhendhi, A; Jeyakanthan, A; Arun, APolyhydroxybutyrate (PHB) accumulating Bacillus megaterium was isolated from marine water. To increase the PHB productivity by Bacillus megaterium, steps were taken to evaluate the effects of carbon sources (arabinose, glucose, glycerol, lactose, lactic acid, mannitol, sodium acetate, starch and sucrose at a level of 20 g/L), nitrogen sources (ammonium chloride, ammonium sulphate, glycine, potassium nitrate, protease peptone and urea at a level of 2 g/L) and different pH. A maximum yield of 2.74 g/L of PHB was achieved for glucose as the carbon source and ammonium sulphate as the nitrogen source at pH 7. The optimized conditions were further used for batch fermentation throughout 72 h. Significantly maximum PHB of 5.61 g/L was obtained in a laboratory scale bioreactor at 64 h. The extracted polymer was compared with the authentic PHB and was confirmed to be PHB using FTIR, 1H NMR, DSC and TGA analysis, respectively.Item Preparation of cellulose nanocrystal (CNCs) reinforced polylactic acid (PLA) bionanocomposites filaments using biobased additives for 3D printing applications(2023-08) Agbakoba, Victor C; Hlangothi, P; Andrew, Jerome E; Mathew, Maya JThis work presents the experimental steps taken towards the preparation of 3D printable bionanocomposites using polylactic acid (PLA) biopolymer containing 0.1, 0.5 and 1 wt% CNCs. Optimized amounts of bio-based additives were added to improve the processability and flexibility of the bionanocomposites. The 3D printable bionanocomposite filaments were drawn using a single screw extruder. The bionanocomposites filament was used to 3D print prototypes and test specimens for dynamic mechanical analysis (DMA). Characterization of the CNCs and bionanocomposites was performed using Fourier Transform Infrared Spectroscopy (FTIR) analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The nucleating effect of CNCs enhanced the crystallization behaviour of bionanocomposites by 5%, 15% and 11%, for the different CNCs loadings. The TGA analysis revealed a 20 °C improvement in the thermal stability of the bionanocomposites. Meanwhile, the tensile analysis showed a =48% increase in the tensile strength of the bionanocomposites filaments which was attributed to the reinforcing effects of CNC. The addition of CNCs significantly increased the melt viscosity, storage and loss modulus of PLA. In summary, the bionanocomposite filaments produced in this study exhibited excellent processibility and superior mechanical and thermal properties. This work presents the experimental steps taken towards the preparation of 3D printable bionanocomposites using polylactic acid (PLA) biopolymer containing 0.1, 0.5 and 1 wt% CNCs.Item Recycling of plastics and composites materials and degradation technologies for bioplastics and biocomposites(Woodhead Publishing, 2021-01) Muniyasamy, Sudhakar; Dada, OS; Nayak, R; Patnaik, APlastic becomes a necessity for our day-to-day life, since it has been widely used in all major sectors including the textile industry. However, the tackling of these recalcitrant plastic-based products wastes is becoming the most challenging part around the world contributing severe environmental pollution and greenhouse gas emission. Currently, the paradigm shifts from the use of conventional oil-based plastics to biobased plastics from renewable sources as a solution to environmental pollution and reduces carbon footprint. Biobased materials provide as a green alternative through the recycling of plastic wastes along with biogenic capitals that are available within our ecosystems across the globe. In this chapter, the biodegradation propensities, biodegradation technologies, and mechanisms of bioplastics and biocomposites were highlighted. Diverse certification systems to ensure environmental safety and sustainability of bioplastic and biocomposites in our environment were also presented. This chapter presents the potential and opportunities for manufacturing biobased plastics and biocomposites to offer considerable benefits in the circular economy concept and high environmental significance to replace conventional plastics.Item Sequential extraction of carbohydrates and lignin from agricultural waste and their structural characterization(2022-07) Mtibe, Asanda; John, Maya J; Andrew, Jerome E; Mokhena, TCThis work reports on the extraction and characterization of carbohydrates such as cellulose, cellulose nanofibres, hemicellulose, and lignin from agricultural waste, i.e. maize stalks and sugarcane bagasse. The chemical compounds were extracted by hot water extraction (HWE) followed by alkaline extraction with 10 wt.% of sodium hydroxide (NaOH). Cellulose nanofibres (CNF) were isolated by mechanical grinding the cellulose fraction using a supermass colloider. The characteristics of the different fractionated components were investigated using nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and X-Ray diffraction (XRD). The removal of the hemicellulose, lignin and extractives were confirmed quantitatively by TAPPI standard methods. It was observed that the cellulose content and its crystallinity increased after treating maize stalks and sugarcane bagasse with hot water extraction and alkali treatment. The thermal stability of cellulose also improved after treatments. Transmission Electron Microscopy (TEM) results confirmed that web-shaped CNF were successfully extracted from the cellulose obtained from sugarcane bagasse and maize stalks. The dimensions of the CNF ranged from 5 to 30 nm in width and a few microns in length. In future studies, the fractionated hemicellulose, lignin and (micro and nano) cellulose will be used as reinforcements in the development of biocomposite materials.Item Structure and properties of lignin-based biopolymers in polymer production(Scrivener Publishing LLC, 2020) Motsoeneng, TS; Mochane, MJ; Mokhena, Teboho C; Mathew, Maya J; Jamil, N; Kumar, P; Batool, RLignin can be extracted from a variety of plants such as soft and hard wood which account for the different functional groups and contents as well as number average molecular weights. Different chemical treatments have been employed to isolate lignin. In order to improve the applicability of lignin, researchers have blended it with different polymeric matrices. Lignin-based blends are predominantly prepared by mechanical and solution mixing to enhance interfacial adhesion of the components of the blends for the envisaged structure, properties and applications. In addition, lignin can be chemically treated using either acid or base to reduce particle size and to improve its interaction with another polymer matrix. The structure and properties of the lignin-based blends are key features in the material applications and the ultimate usability of the blends. In this chapter, the different structures of lignin extracted from lignocellulosic fibers of various plant species are discussed. The chemical treatment of lignin biopolymer prior incorporation into polymers is also addressed. Succinctly, the chapter outlines the factors that control interfacial adhesion between the components of lignin-based blends to widen the applicability in the environment for antimicrobial activity as well as future remarks.Item Transitioning from conventional plastic to more sustainable alternative materials: Evidence from South Africa(2022-10) Oelofse, Suzanna HH; Nahman, Anton; Russo, Valentina; Stafford, William HL; Muswema, Aubrey P; Mathew, Maya J; Muniyasamy, SudhakarThe Council for Scientific and Industrial Research in partnership with UNIDO and the University of the Witwatersrand, with funding from the Japanese government, undertook research to identify and implement opportunities for sustainable alternative materials, including biodegradable plastic in South Africa. The project aims are twofold: 1) to develop an action plan to support sustainable transition to alternative materials and 2) to strengthen plastic recycling through encouraging waste separation at source and integration of informal waste collectors in a circular economy. This paper reports on the findings from research activities to determine the most appropriate alternative materials for consideration when transitioning to more sustainable alternatives. The results include that of the LCA study, availability of end-of-life treatment options for alternative materials, demonstration of the identified technologies/materials, the potential to produce alternative materials locally, and the Action Plan for South Africa to make the transition.