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A review of weathering studies in plastics and biocomposites— Effects on mechanical properties and emissions of volatile organic compounds (VOCs)
(2024-04) Nzimande, Monwabisi C; Mtibe, Asanda; Tichapondwa, S; Mathew, Maya J
Polymeric materials undergo degradation when exposed to outdoor conditions due to the synergistic effects of sunlight, air, heat, and moisture. The degradation can lead to a decline in mechanical properties, fading, surface cracking, and haziness, attributed to the cleavage of the polymer chains and oxidation reactions. Accelerated weathering testing is a useful technique to evaluate the comparative photodegradation of materials within a reasonable timeframe. This review gives an overview of the different degradation mechanisms occurring in conventional plastics and bio-based materials. Case studies on accelerated weathering and its effect on the mechanical properties of conventional plastics and biocomposites are discussed. Different techniques for analysing volatile organic emissions (VOCs) have been summarized and studies highlighting the characterization of VOCs from aged plastics and biocomposites after aging have been cited.
Algae infused enhancement of PBAT stiffness: Investigating the influence of algae content on mechanical and thermal properties
(2024) Letwaba, J; Motloung, Mpho P; Muniyasamy, Sudhakar; Mavhungu, L; Mbaya, R; Okpuwhara, R
This study investigates the impact of algae loading on the properties of PBAT/algae bio-composites produced through a melt extrusion process. The integration of algae as a filler demonstrated a reinforcing effect on the PBAT matrix,leading to an increase in modulus with higher algae loading. Concurrently, the tensile strength and maximum tensile strain of PBAT decreased with an increase in algae content. The thermal stability of PBAT was affected by adding algae, resulting in bio-composites exhibiting an intermediate behavior compared with their neat precursors. The optimal formulation is achieved with 20 wt.% of algae incorporated into the PBAT matrix. The produced PBAT/algae bio-composites, demonstrated versatile applications across a wide range of products.
Analytical techniques to quantify modifiers in bitumen for the South African asphalt pavement industry
(2021-07) Makhari, A; Hawes, Nomashaka BN; Mturi, George AJ; Ojijo, Vincent O
Modifying bitumen is currently a common practice in South Africa. The asphalt pavement industry has seen an increase in use of different types of modifiers in an attempt to improve or extend the properties of bitumen. Common modifiers used in South Africa include plastomers (e.g. ethylene vinyl acetate or EVA), elastomers (e.g. styrene-butadiene-styrene or SBS) and warm mix additives (e.g. waxes). Bitumens are already complex materials which can be represented mechanically and rheologically with mathematical models. Recently, the need to also characterise the in situ structural and chemistry effect of modifiers within bitumen has been appreciated, in order to determine their influence on modified bitumen performance. This paper explores the analysis of bitumen with various modifiers using Fourier Transform Infra-Red (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC). Special attention is paid to quantification of these modifiers in bitumen as a quality control and forensic investigative tool, due to the current asphalt failure challenges facing the industry. The aim is to accurately determine the extent of modification through analytical techniques as a monitoring tool for the better construction of asphalt pavement roads. The paper shows such analytical scientific techniques have the potential to quantify locally used modifiers in South African bitumen.
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, R
Since 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.
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, AM
There 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.
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, A
The 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.
Carbon-metal sulfide nanomaterial photocatalysts for environmental remediation
(Elsevier, 2024) Hlekelele, Lerato; Mdlalosem, Lindani M; Nomadolo, Elizabeth N; Mtibe, Asanda; Chauke, Vongani; Makgwane, Peter R; Kumar, Naveen
The combination of transition metals and sulfides creates a class of elite semiconductor materials that are capable of forming important electrochemical reactions under reasonable conditions. These electrochemical reactions have been shown to be beneficial in environmental remediation and other applications. Some metal sulfides have been shown to have an edge over metal oxides, including their narrow band gaps and their sulfur edges with lone pairs which is suitable for photocatalytic reactions. However, metal sulfides have problems associated with photocorrosion and the short lifetime span of the photogenerated charge carriers. There are various ways scientists have implemented to increase the viability of metal sulfides as photocatalysts, in particular, using carbonaceous materials. The formation of hybrid heterostructures between metal sulfides and carbonaceous materials (graphitic carbon nitride) is one of the most studied methods of increasing the separation of charge carriers. The most studied types of heterostructures are Type-I, Type-II, and the p-n junctions, all with their advantages and disadvantages. Characterization techniques such as photoluminescence and transient photocurrent are usually used to demonstrate the usefulness of forming these types of heterojunctions. Apart from the formation of heterojunctions is compositing metal sulfides with conducting carbonaceous materials that do not have a band gap. In this instance, the carbon nanomaterials act as sinks for the photoinduced electrons. In this regard, different types of carbon nanomaterials have been shown to effectively increase the lifespan of the electron and hole pairs including carbon nanotubes, carbon nanofibers, graphene oxide (GO), reduced GO, and biochar, among others.
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, R
Cellulose 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.
Cellulose nanomaterials: New generation materials for solving global issues
(2020-02) Mokhena, Teboho C; John, Maya J
This 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.
The Circular Economy as Development Opportunity: Exploring Circular Economy Opportunities across South Africa’s Economic Sectors
(CSIR, 2021-12) Godfrey, Linda K; Nahman, Anton; Oelofse, Suzanna HH; Trotter, Douglas; Khan, Sumaya; Nontso, Zintle; Magweregwede, Fleckson; Sereme, Busisiwe V; Okole, Blessed N; Gordon, Gregory ER; Brown, Bernadette; Pillay, Boyse; Schoeman, Chanel; Fazluddin, Shahed; Ojijo, Vincent O; Cooper, Antony K; Kruger, Daniel M; Napier, Mark; Mokoena, Refiloe; Steenkamp, Anton J; Msimanga, Xolile P; North, Brian C; Seetal, Ashwin R; Mathye, Salamina M; Godfrey, Linda K
The intention of this book is to present the CSIR’s position and interpretation of the circular economy, and to use it to drive discussions on where immediate circular economy opportunities are achievable in South Africa. Opportunities that can be harnessed by business, government and civil society. These circular economy opportunities are framed in this book within the context of the current challenges facing various economic sectors. The CSIR has selected seven, resource intensive sectors – mining, agriculture, manufacturing, human settlements, mobility, energy and water – for further assessment. Many of these economic sectors have seen significant declines over the past years, with agriculture, manufacturing, transport and construction all showing negative growth pre-COVID. These are all sectors under economic stress and in need of regeneration. South Africa stands on the threshold of profound choices regarding its future development path. Transitioning to a more circular economy provides the country with the opportunity to address many national priorities including manufacturing competitiveness, food security; sustainable, resilient and liveable cities; efficient transport and logistics systems; and energy and water security, while at the same time decarbonising the economy. The transition to a circular economy provides the country with an opportunity for green and inclusive development to be the cornerstone of a post-COVID economic recovery. The titles of this book chapters are the following: Chapter 1: Driving economic growth in South Africa through a low carbon, sustainable and inclusive circular economy. Chapter 2: Placing the South African mining sector in the context of a circular economy transition. Chapter 3: Supporting food security and economic development through circular agriculture. Chapter 4: Supporting the development of a globally competitive manufacturing sector through a more circular economy. Chapter 5: Creating resilient, inclusive, thriving human settlements through a more circular economy. Chapter 6: Facilitating sustainable economic development through circular mobility. Chapter 7: Decoupling South Africa’s development from energy demand through a more circular economy. Chapter 8: Decoupling South Africa’s development from water demand through a circular economy.
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 B
This 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.
Design of 3D printable boehmite alumina/thermally exfoliated reduced graphene oxide-based polymeric nanocomposites with high dielectric constant, mechanical and thermomechanical performance
(2024-09) Botlhoko, Orebotse J; Makwakwa, Dimakatso M; Muniyasamy, Sudhakar
In this study, melt-blending was employed to blend 80 wt% poly(lactic acid) and 20 wt% poly(ε-caprolactone) (80 %PLA/20 %PCL) with boehmite alumina-thermally exfoliated reduced graphene oxide (BA-TERGO) as nanofillers. Herein, we present a novel synergy effect of BA/TERGO particles on improving the dielectric constant while maintaining dielectric loss at lower magnitudes. Also, improving the thermomechanical properties of tough PLA/PCL nanocomposite through the incorporation of a dual-filer system strategy. Consequently, remarkable increase in dielectric constant was achieved for BA-TERGO/blend nanocomposite. In particular, the blend exhibited dielectric constant of about 2.91, while the BA-TERGO/blend nanocomposite exhibited dielectric constant of about 4.93 at a frequency of 2.0 ×106 Hz and a temperature of 190 ºC. On the other hand, tensile modulus of the BA-TERGO/blend nanocomposite increased from 1908.5 MPa to 2505.2 MPa and the tensile strength increased from 70.48 MPa to 96.3 MPa when compared to that of the neat blend. BA-blend and BA-TERGO/blend nanocomposites provided the improved storage modulus and thermal stability. This finding renders PLA-based biodegradable materials suitable for tough 3D printable material with potential for integrated circuits applications.
Development of sustainable biobased polymer and bio-nanocomposite materials using nanocellulose obtained from agricultural biomass
(Routledge, 2020-07) Mtibe, Asanda; Muniyasamy, Sudhakar; Motaung, TE; Godfrey, Linda K; Görgens, JF; Roman, H
Biobased polymer and bio-nanocomposites have provided significant improvement in material science, moving towards the development of green materials to replace petro-based materials. The present study investigated the value-added utilisation of agriculturalbiomass residues derived from sugar cane bagasse and maize stalks for the development of biobased polymer and bio-nanocomposite materials for specific applications. In this study, extraction of cellulose and nanocellulose of environmentally friendly polymeric materials and their composite peoducts were studied. The study showed that the incorporation of nanocellulose into biopolymer matrix could produce bio-nanocomposites for specific uses in various applications, mainly in the biomedical and green packaging sectors.
Durable PLA Bioplastics
(Elsevier, 2024) Sinha Roy, Jayita; Ray, Suprakas S
Bioplastics are special plastics manufactured from biobased polymers and can potentially contribute to the circular plastics economy. In this direction, polylactic acid or polylactide (both abbreviated as PLA) is the most important commercially available polymer whose monomeric unit, lactic acid, can be produced from renewable resources. PLA has good thermal plasticity and mechanical properties and can be readily molded. During the manufacturing of PLA-based plastic products, the carbon footprint is approximately 75% lower than that of conventional plastic products. In the context of life cycle assessment and the eco-profile (input and output from the manufacturing process) of PLA, benefits and drawbacks, strategies for overcoming the drawbacks, and the trend of applications, it is worthy to develop PLA-based durable products considering regenerative technical approach. Therefore, this chapter reports recent progress in developing durable PLA bioplastics for various applications. Various strategies have been critically summarized, such as plasticization, copolymerization, and melt blending with different tough polymers, rubbers, thermoplastic elastomers, and nanomaterials. Changing the processing technology, modification of PLA by chemical methods or cross-linking and grafting, and annealing can improve the properties of PLA, which are also discussed in this chapter.
Effect of clay nanofillers on the mechanical and water vapor permeability properties of xylan–alginate films
(2020-10) Naidu, Darrel S; Mathew, Maya J
In 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.
Elucidating the local structure and electronic properties of a highly active overall alkaline water splitting NixCo1-xO/hollow carbon sphere catalyst
(2024) Mashindi, V; Terban, MW; Motta Meira, D; Moreno, BD; Morongoa, Prettier M; Rikhotso-Mbungela, Rirhandzu S; Marx, G; Olivier, J; Barrett, DH; Moloto, N
A NixCo1-xO/HCS catalyst with superior water-splitting is presented. High water-splitting reaction kinetics and enhanced durability were observed. The structure-function relationship was investigated with XPS, which demonstrated the presence of dominant Ni2+ and Co2+ species and a functionalized HCS support where nucleation of small metal oxide nanoparticles occurred. The PDF showed broadened Nickel/Cobalt-oxide bonds and expansion of the metal-metal pair distances. The alteration of the Metal-Oxide and Metal-Metal-Oxide bonds favored better HER and OER electrocatalysis, also as supported by DFT. EXAFS showed the existence of the bimetallic oxide catalyst and the stretching of the Ni–O bonds due to the coordination of the Ni–O with the Co. The composite exhibited higher activity and enhanced electrocatalytic mechanism towards water splitting through higher exchange current densities (0.615 and 0.886 mA cm−2) and low charge transfer resistance (14 and 10 Ω) respectively. Chronoamperometry proved the catalyst's stability during prolonged electrolysis.
Emerging Technologies in Polymer Processing
(Hanser, 2024-12) Ray, Suprakas S; Banerjee, Ritima; Bandyopadhyay, Jayita; Orasugh, Jonathan T; Bhattacharya, Satinath
Resting on the foundation of fundamental concepts, polymer processing has undergone phenomenal progress, beginning from the basic operations of mixing and molding, and evolving into advanced manufacturing techniques, such as 4D printing and nanocellular foaming. The use of cutting-edge technologies, such as computational modeling, have revolutionized even conventional processing techniques. Existing processing techniques have been modified, and new methods have been developed to meet application-specific requirements. The book “Emerging Technologies in Polymer Processing” is carefully structured to provide readers with a comprehensive understanding of the dynamic field of polymer processing innovation, covering a wide range of topics. This pioneering work is organized into several chapters, each meticulously crafted to look into specific facets of emerging technologies, their implications, and their applications within the polymer industry. The introductory chapter (Chapter 1) serves as the gateway to this exploration, setting the stage by delineating the evolution of polymer processing techniques. It offers a historical overview of traditional methods while elucidating the pressing need for innovation in response to evolving industry demands. Moreover, it candidly addresses the challenges inherent in conventional polymer processing techniques, laying the groundwork for the subsequent discussion on emerging technologies. Chapter 2 extensively reviews the role of rheology in the processability of polymeric materials: An in-depth understanding of the rheological characteristics of polymeric materials can help select the right materials and/or grades and processing conditions to achieve superior processability in various emerging processing operations. In Chapter 3, we emphasize the fundamentals of the conventional injection molding of polymeric materials with process control technologies, critical drivers of the market and restraints on them, recent trends, factors influencing precision, and advances in precision injection molding, including process control and material aspects. Chapter 4 provides a broad perspective on the manufacturing processes, the history of additive manufacturing, its economic feasibility, market and technology trends, and fundamentals of the different additive manufacturing processes. In Chapter 5, the fundamental principles governing electrospinning and the influence of solution properties, electric fields, and other processing parameters on nanofibers’ morphology are discussed. Chapter 6 complements Chapter 5, providing a thorough description of the various other processing methods used to prepare polymer fibers, as well as the most recent advancements in these processing methods. It also lists some of the benefits and drawbacks of each production process. Chapter 7 provides a comprehensive overview of the use of ultrasound in various polymer processing operations, highlighting its significant benefits. By shedding light on these advantages, the chapter aims to equip readers with a deeper understanding of the potential of ultrasound in polymer processing, fostering a sense of awareness and informed decision-making. In Chapter 8, we provide an overview of the fundamentals of plasma treatment technology and the use of plasma treatment in the surface modification of polymeric materials. Chapter 9 begins with a brief introduction to polymer foams and foam manufacturing techniques. After discussing the thermal insulation property of polymer foams, it then offers insight into recent advances in the development of nanocellular foams of superior properties, with a special focus on thermal insulation and mechanical properties.
Engineered transparent wood composites: A review
(2023-05) Jele, Thabisile B; Andrew, Jerome E; Mathew, Maya J; Sithole, Bruce
Wood 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.
Engineered transparent wood with cellulose matrix for glass applications: A review
(2024-06) Simelane, Nontobeko P; Olatunji, OS; Mathew, Maya J; Andrew, Jerome E
Engineered 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.
Esterified cellulose nanofibres from saw dust using vegetable oil
(2020-04) Mokoena, Teboho P; Mathew, Maya J
In 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.

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