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Dr. Pratheep Kumar Annamalai
The University of Queensland

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0 Chemical Engineering
0 Nanocellulose
0 nano and functional materials
0 construction and building materials
0 Polymer chemistry and technology

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Nanocellulose

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Research article
Published: 08 June 2021 in ACS Applied Polymer Materials
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The incorporation of lignin into rigid polyurethane foam (RPUF) has been explored for the last two decades for replacing petrochemical polyols and producing sustainable high-performance insulation materials. However, to date, the issues associated with the dispersion of technical lignin in the commonly used polyols for RPUF have highly limited the improvement in mechanical and thermal insulation performance. This study reports the enhanced dispersion of kraft lignin (KL) up to 75 wt % in the glycerol-substituted aromatic polyester polyol blend. The influence of significantly well-dispersed KL on RPUF in terms of loading levels, the viscosity of the polyol, the microstructure, and the thermal and mechanical properties of RPUF is discussed. The KL incorporated (0.5–6.0 wt %) in polyol afforded a remarkable reduction in thermal conductivity (32%–34%) of the resultant RPUF with minimal variation in density and insignificant change in compressive strength. The scale of this improvement, to the best of our knowledge, has not been reported to date in lignin-incorporated RPUF systems. Furthermore, the presence of the KL in the RPUF also resulted in a mild improvement in the flame retardance performance. This study provides insights into producing KL-incorporated RPUF for thermal insulation application.

ACS Style

Hima Haridevan; Martyn S. McLaggan; David A.C. Evans; Darren J. Martin; Trent Seaby; Zhanying Zhang; Pratheep K. Annamalai. Dispersion Methodology for Technical Lignin into Polyester Polyol for High-Performance Polyurethane Insulation Foam. ACS Applied Polymer Materials 2021, 3, 3528 -3537.

AMA Style

Hima Haridevan, Martyn S. McLaggan, David A.C. Evans, Darren J. Martin, Trent Seaby, Zhanying Zhang, Pratheep K. Annamalai. Dispersion Methodology for Technical Lignin into Polyester Polyol for High-Performance Polyurethane Insulation Foam. ACS Applied Polymer Materials. 2021; 3 (7):3528-3537.

Chicago/Turabian Style

Hima Haridevan; Martyn S. McLaggan; David A.C. Evans; Darren J. Martin; Trent Seaby; Zhanying Zhang; Pratheep K. Annamalai. 2021. "Dispersion Methodology for Technical Lignin into Polyester Polyol for High-Performance Polyurethane Insulation Foam." ACS Applied Polymer Materials 3, no. 7: 3528-3537.

Research article
Published: 04 February 2021 in Biomacromolecules
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From a perspective of sustainable development and practical applications, there has been a great need for the design of advanced polylactide (PLA) biocomposites that are flame-retardant, ultraviolet (UV)-resistant, and mechanically strong by using biomass-derived additives. Unfortunately, the achievement of a desirable performance portfolio remains unsatisfactory because of improper design strategies. Herein, we report the design of lignin-derived multifunctional bioadditives (TP-g-lignin) with tunable chemical compositions through graft polymerization of a phosphorus-/nitrogen-containing vinyl monomer (TP). Our results show that the incorporation of 5.0 wt % of TP-g-lignin (at a lignin-to-TP ratio of 1:4 by mass) enables PLA to achieve a desirable flame retardancy rating meeting the UL-94 V-0 industrial standard requirements. Meanwhile, the final PLA composite exhibits an exceptional UV-shielding capability. Moreover, with 5.0 wt % of the bio-derived additive, the elastic modulus of PLA is increased by ∼26%, while mechanical strength is fully retained due to engineered favorable interfaces. This work offers an innovative and sustainable strategy for creating bio-based multifunctional additives by using industrial lignin waste and further the application of PLA in the areas of packaging, fabrics, electronics, automobiles, etc.

ACS Style

Haitang Yang; Bingbing Shi; Yijiao Xue; Zhewen Ma; Lina Liu; Lei Liu; Youming Yu; Zhanying Zhang; Pratheep K. Annamalai; Pingan Song. Molecularly Engineered Lignin-Derived Additives Enable Fire-Retardant, UV-Shielding, and Mechanically Strong Polylactide Biocomposites. Biomacromolecules 2021, 22, 1432 -1444.

AMA Style

Haitang Yang, Bingbing Shi, Yijiao Xue, Zhewen Ma, Lina Liu, Lei Liu, Youming Yu, Zhanying Zhang, Pratheep K. Annamalai, Pingan Song. Molecularly Engineered Lignin-Derived Additives Enable Fire-Retardant, UV-Shielding, and Mechanically Strong Polylactide Biocomposites. Biomacromolecules. 2021; 22 (4):1432-1444.

Chicago/Turabian Style

Haitang Yang; Bingbing Shi; Yijiao Xue; Zhewen Ma; Lina Liu; Lei Liu; Youming Yu; Zhanying Zhang; Pratheep K. Annamalai; Pingan Song. 2021. "Molecularly Engineered Lignin-Derived Additives Enable Fire-Retardant, UV-Shielding, and Mechanically Strong Polylactide Biocomposites." Biomacromolecules 22, no. 4: 1432-1444.

Journal article
Published: 14 November 2020 in Industrial Crops and Products
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Strong and tough nanocomposite materials based on natural rubber (NR) latex demonstrate increasing potential to be used in advanced engineering applications and personal care products. Among many approaches for improving the toughness of NR-based products, the use of renewable and bio-based nanofillers is persuaded by environmental and economic trends. In this study, we report the preparation and incorporation of nanoscale organosolv lignin (OSL) particles in NR latex to improve its mechanical properties. We showed that the tensile strength, toughness, and Shore hardness of NR films reinforced with 5 wt % nanoscale OSL were improved by 39 %, 53 % and 12 %, respectively, while retaining high elongation at break (∼1800 %). This substantially improved mechanical property profile can be attributed to the enhanced nanoscale dispersion of OSL and the associated favourable interfacial adhesion of OSL with the NR matrix. Furthermore, the impact of an industrially applicable leaching process on the toughness and thermo-oxidative stability of rubber films is also discussed. For an instance, after the leaching process, the tensile strength, elongation, and toughness of 1 wt % OSL/NR were increased by 27 %, 9 %, and 32 %, respectively.

ACS Style

Alireza Hosseinmardi; Nasim Amiralian; Amir Nemati Hayati; Darren J. Martin; Pratheep K. Annamalai. Toughening of natural rubber nanocomposites by the incorporation of nanoscale lignin combined with an industrially relevant leaching process. Industrial Crops and Products 2020, 159, 113063 .

AMA Style

Alireza Hosseinmardi, Nasim Amiralian, Amir Nemati Hayati, Darren J. Martin, Pratheep K. Annamalai. Toughening of natural rubber nanocomposites by the incorporation of nanoscale lignin combined with an industrially relevant leaching process. Industrial Crops and Products. 2020; 159 ():113063.

Chicago/Turabian Style

Alireza Hosseinmardi; Nasim Amiralian; Amir Nemati Hayati; Darren J. Martin; Pratheep K. Annamalai. 2020. "Toughening of natural rubber nanocomposites by the incorporation of nanoscale lignin combined with an industrially relevant leaching process." Industrial Crops and Products 159, no. : 113063.

Article
Published: 21 June 2020 in Batteries & Supercaps
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Potassium‐ion storage is being explored by researchers for its advantages in forming graphite‐based intercalation compounds, with cost‐effective production compared to lithium‐ion systems. However, its poor performance in graphite‐based platforms, owing to the volume expansion required for intercalation, has demanded alternative materials for reversible potassiation. Herein, we demonstrate a simple one‐step pyrolysis approach to develop an amorphous hard carbon material from commercial cellulose for high‐performance potassium‐ion batteries (KIB). The larger interlayer spacing (∼0.4 nm) alongside the electronegative oxygen functional groups promotes potassium‐ion storage. High capacity, good rate and long cycling performance with lower‐volume expansion could be credited to the amorphous carbon that possesses turbostratic nanodomains. Further, oxygen functional groups on the carbon material are identified in our experimental studies, and density functional theory simulations indicate that these are likely to enhance the potassium‐ion capacity of the materials.

ACS Style

Ashok Kumar Nanjundan; Rohit Ranganathan Gaddam; Amir H. Farokh Niaei; Pratheep K. Annamalai; Deepak P. Dubal; Dr. Darren James Martin; Dr. Yusuke Yamauchi; Dr. Debra J. Searles; Dr. Xiu Song Zhao. Potassium‐Ion Storage in Cellulose‐Derived Hard Carbon: The Role of Functional Groups. Batteries & Supercaps 2020, 3, 953 -960.

AMA Style

Ashok Kumar Nanjundan, Rohit Ranganathan Gaddam, Amir H. Farokh Niaei, Pratheep K. Annamalai, Deepak P. Dubal, Dr. Darren James Martin, Dr. Yusuke Yamauchi, Dr. Debra J. Searles, Dr. Xiu Song Zhao. Potassium‐Ion Storage in Cellulose‐Derived Hard Carbon: The Role of Functional Groups. Batteries & Supercaps. 2020; 3 (9):953-960.

Chicago/Turabian Style

Ashok Kumar Nanjundan; Rohit Ranganathan Gaddam; Amir H. Farokh Niaei; Pratheep K. Annamalai; Deepak P. Dubal; Dr. Darren James Martin; Dr. Yusuke Yamauchi; Dr. Debra J. Searles; Dr. Xiu Song Zhao. 2020. "Potassium‐Ion Storage in Cellulose‐Derived Hard Carbon: The Role of Functional Groups." Batteries & Supercaps 3, no. 9: 953-960.

Journal article
Published: 18 December 2019 in Polymer Degradation and Stability
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Polyethylene as a polymeric precursor for carbon fibre production has attracted much attention over recent years. Not only is it a low-cost commodity polymer, it has a higher theoretical carbon yield (at 100%) than polyacrylonitrile (at 67%) and is very readily melt processed into fibres. The challenge is to efficiently dehydrogenate and graphitize polyethylene fibres. This paper explores the use of bromine as a novel oxidant to functionalise polyethylene prior to carbonisation, leading to efficient cyclisation and carbonisation on heating. Through a process of low-temperature photo-induced liquid-phase bromination followed by dehydrobromination at moderate temperature and subsequent carbonisation to 800 °C, a carbonaceous product was obtained in high carbon yield (>90%). The effects of a range of process conditions, as well as the use of different types of polyethylene and polyethylene blends, were explored.

ACS Style

Bronwyn Laycock; Xiaoyu Wang; Ru-Fen Liu; Pratheep Kumar Annamalai; Jorja Cork; Chris Derstine; Michael Mills; Eric W. McFarland. Pyrolysis of brominated polyethylene as an alternative carbon fibre precursor. Polymer Degradation and Stability 2019, 172, 109057 .

AMA Style

Bronwyn Laycock, Xiaoyu Wang, Ru-Fen Liu, Pratheep Kumar Annamalai, Jorja Cork, Chris Derstine, Michael Mills, Eric W. McFarland. Pyrolysis of brominated polyethylene as an alternative carbon fibre precursor. Polymer Degradation and Stability. 2019; 172 ():109057.

Chicago/Turabian Style

Bronwyn Laycock; Xiaoyu Wang; Ru-Fen Liu; Pratheep Kumar Annamalai; Jorja Cork; Chris Derstine; Michael Mills; Eric W. McFarland. 2019. "Pyrolysis of brominated polyethylene as an alternative carbon fibre precursor." Polymer Degradation and Stability 172, no. : 109057.

Research article
Published: 04 June 2019 in ACS Omega
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Nanocellulose, as a biobased versatile nanomaterial that can be derived with tailorable surface functionalities, dimensions, and morphologies, has considerable implications for modifying the rheology, mechanical reinforcement, and influencing the carbonization efficiency in the production of polyacrylonitrile (PAN)-based carbon fibers. Herein, we report the influence of three different nanocellulose types, varying in the derivatization method, source, and aspect ratio, on the mechanical properties and thermal transformations of solution-spun PAN/nanocellulose nanocomposite fibers into carbon fibers. The incorporation of 0.1 wt % nanocellulose into solution-spun PAN fibers led to a 7–19% increase in tensile modulus and 0–27% increase in tensile strength in the solution-spun fibers, compared to a control PAN fiber. These improvements varied depending on the nanocellulose type. After low-temperature carbonization at 1200 °C, improvements in the mechanical properties of the nanocellulose-reinforced carbon fibers, compared with a PAN fiber, were also observed. In contrast to the precursor fibers, the improvement % in the carbonized fibers was found to be dependent on the nanocellulose morphology and was linearly correlated with increasing aspect ratio of nanocellulose. For example, in carbon fibers with a cotton-derived low-aspect-ratio cellulose nanocrystal and spinifex-derived high-aspect-ratio CNC and nanofiber, up to 4, 87, and 172% improvements in tensile moduli were observed, respectively. Due to the processing methods used, the nanocellulose aspect ratio and crystallinity are inversely related, and as such, the increase in the carbon fiber mechanical properties was also related to a decrease in crystallinity of the nanocellulose reinforcers. Raman spectra and electron microscopy analysis suggest that mechanical improvement after carbonization is due to internal reinforcement by highly ordered regions surrounding the carbonized nanocellulose, within the turbostratic carbon fibers.

ACS Style

Edward Jiang; Maxime Maghe; Nima Zohdi; Nasim Amiralian; Minoo Naebe; Bronwyn Laycock; Bronwyn L. Fox; Darren Martin; Pratheep K. Annamalai. Influence of Different Nanocellulose Additives on Processing and Performance of PAN-Based Carbon Fibers. ACS Omega 2019, 4, 9720 -9730.

AMA Style

Edward Jiang, Maxime Maghe, Nima Zohdi, Nasim Amiralian, Minoo Naebe, Bronwyn Laycock, Bronwyn L. Fox, Darren Martin, Pratheep K. Annamalai. Influence of Different Nanocellulose Additives on Processing and Performance of PAN-Based Carbon Fibers. ACS Omega. 2019; 4 (6):9720-9730.

Chicago/Turabian Style

Edward Jiang; Maxime Maghe; Nima Zohdi; Nasim Amiralian; Minoo Naebe; Bronwyn Laycock; Bronwyn L. Fox; Darren Martin; Pratheep K. Annamalai. 2019. "Influence of Different Nanocellulose Additives on Processing and Performance of PAN-Based Carbon Fibers." ACS Omega 4, no. 6: 9720-9730.

Journal article
Published: 01 December 2018 in Bioinspired, Biomimetic and Nanobiomaterials
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Natural polymers have greatly impacted the advancement of modern medicine. Natural polymer-based biomaterials are biodegradable. A significant advantage of natural polymers is that they can be broken down and removed from the body after they have served their function. A wide range of novel biomaterials from natural polymers has been investigated to meet new challenges in medical science. Chitosan is one of the natural polymers which have been widely used in the biomedical field. Nanotechnology is one of the most popular areas of current research. In the area of nanotechnology, polymer and metal/metal oxide nanoparticle matrix-based nanocomposites have generated a significant amount of attention in the recent literature. These bionanocomposites have wide-ranging applications in drug delivery and tissue engineering. This paper discusses polymer–metal/metal oxide nanoparticle matrix-based nanocomposite biomaterials and their applications in the biomedical field – that is, drug delivery and tissue engineering applications.

ACS Style

Sangeeta Kumari; Raj Pal Singh; Nayaku N. Chavan; Pratheep K. Annamalai. Chitosan-based bionanocomposites for biomedical application. Bioinspired, Biomimetic and Nanobiomaterials 2018, 7, 219 -227.

AMA Style

Sangeeta Kumari, Raj Pal Singh, Nayaku N. Chavan, Pratheep K. Annamalai. Chitosan-based bionanocomposites for biomedical application. Bioinspired, Biomimetic and Nanobiomaterials. 2018; 7 (4):219-227.

Chicago/Turabian Style

Sangeeta Kumari; Raj Pal Singh; Nayaku N. Chavan; Pratheep K. Annamalai. 2018. "Chitosan-based bionanocomposites for biomedical application." Bioinspired, Biomimetic and Nanobiomaterials 7, no. 4: 219-227.

Research article
Published: 27 November 2018 in ACS Omega
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The isolation of nanocellulose from lignocellulosic biomass, with desirable surface chemistry and morphology, has gained extensive scientific attention for various applications including polymer nanocomposite reinforcement. Additionally, environmental and economic concerns have driven researchers to explore viable alternatives to current isolation approaches, employing chemicals with reduced environmental impact. To address these issues, in this study, we have tuned the amphiphilic behavior of cellulose nanofibers (CNFs) by employing controlled alkali treatment, instead of in combination with expensive, environmentally unsustainable conventional approaches. Microscopic and spectroscopic analysis demonstrated that this approach is capable of tuning composition and interfacial tension of CNFs through a careful control of the quantity of residual lignin and hemicellulose. To elucidate the performance of CNF as an efficient reinforcing nanofiller in hydrophobic polymer matrices, prevulcanized natural rubber (NR) latex was employed as a suitable host polymer. CNF/NR nanocomposites with different CNF loading levels (0.1–1 wt % CNF) were prepared by a casting method. It was found that the incorporation of 0.1 wt % CNF treated with a 0.5 w/v % sodium hydroxide solution led to the highest latex reinforcement efficiency, with an enhancement in tensile stress and toughness of 16% to 42 MPa and 9% to 197 MJ m–3, respectively. This property profile offers a potential application for the high-performance medical devices such as condoms and gloves.

ACS Style

Alireza Hosseinmardi; Pratheep Kumar Annamalai; Benoit Martine; Jordan Pennells; Darren J. Martin; Nasim Amiralian. Facile Tuning of the Surface Energy of Cellulose Nanofibers for Nanocomposite Reinforcement. ACS Omega 2018, 3, 15933 -15942.

AMA Style

Alireza Hosseinmardi, Pratheep Kumar Annamalai, Benoit Martine, Jordan Pennells, Darren J. Martin, Nasim Amiralian. Facile Tuning of the Surface Energy of Cellulose Nanofibers for Nanocomposite Reinforcement. ACS Omega. 2018; 3 (11):15933-15942.

Chicago/Turabian Style

Alireza Hosseinmardi; Pratheep Kumar Annamalai; Benoit Martine; Jordan Pennells; Darren J. Martin; Nasim Amiralian. 2018. "Facile Tuning of the Surface Energy of Cellulose Nanofibers for Nanocomposite Reinforcement." ACS Omega 3, no. 11: 15933-15942.

Communication
Published: 16 October 2018 in Small
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Analysis of cellulose nanocrystals (CNCs) at low volume fractions in polymer nanocomposites through conventional electron microscopy still remains a challenge due to insufficient contrast between CNCs and organic polymer matrices. Herein, a methodology for enhancing the contrast of CNC, through atomic layer deposition (ALD) of alumina (Al2O3) on CNCs is demonstrated. The metal oxide coated CNC allows clear visualization by transmission electron microscopy, when they are dispersed in water and polyol. A coating of about 6 ± 1 nm thick alumina layer on the CNC is achieved after 50 ALD cycles. This also enables the characterization of CNC dispersion/orientation (at 0.2 wt% loading) in an amorphous cellular system rigid polyurethane foam (RPUF), using backscattered electron microscopy with energy‐dispersive X‐ray spectroscopy. Microscopic analysis of the RPUF with alumina‐coated CNC confirms that the predominant alignment of CNC occurs in a direction parallel to the foam rise.

ACS Style

Athanasia A. Septevani; David A. C. Evans; Alireza Hosseinmardi; Darren Martin; John Simonsen; John F. Conley Jr.; Pratheep K. Annamalai. Atomic Layer Deposition of Metal Oxide on Nanocellulose for Enabling Microscopic Characterization of Polymer Nanocomposites. Small 2018, 14, e1803439 .

AMA Style

Athanasia A. Septevani, David A. C. Evans, Alireza Hosseinmardi, Darren Martin, John Simonsen, John F. Conley Jr., Pratheep K. Annamalai. Atomic Layer Deposition of Metal Oxide on Nanocellulose for Enabling Microscopic Characterization of Polymer Nanocomposites. Small. 2018; 14 (46):e1803439.

Chicago/Turabian Style

Athanasia A. Septevani; David A. C. Evans; Alireza Hosseinmardi; Darren Martin; John Simonsen; John F. Conley Jr.; Pratheep K. Annamalai. 2018. "Atomic Layer Deposition of Metal Oxide on Nanocellulose for Enabling Microscopic Characterization of Polymer Nanocomposites." Small 14, no. 46: e1803439.

Journal article
Published: 01 July 2018 in Industrial Crops and Products
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Lignin, an inexpensive renewable biopolymer that offers both aliphatic and aromatic hydroxyl (OH) functional groups, is a potential raw material for the polyurethane industry. Contemporary approaches for incorporating lignin in rigid polyurethane foam (RPUF) involve mechanical mixing of microscale lignin powder under ambient conditions or at high loading levels, resulting in the RPUF with inferior compressive mechanical and thermal conductivity properties compared to petrochemical-based controls. Herein, we demonstrate a significant improvement in the dispersion of an industrial grade kraft lignin in a polyol mixture (96% sucrose/glycerine initiated polyether polyol and 4% glycerol) by dispersing at high-temperature (120 °C, 12 h) resulting in RPUF with enhanced performance. Through this methodology, the polyol/lignin dispersion with 5 wt.% lignin has afforded a simultaneous improvement in thermal insulation (by 5%) and compressive strength (by 4%) of RPUF compared to the control and such a property profile, to the best of our knowledge, has not yet been achieved in lignin substituted RPUF systems.

ACS Style

Amir Nemati Hayati; David Alwyn Charles Evans; Bronwyn Laycock; Darren Martin; Pratheep Kumar Annamalai. A simple methodology for improving the performance and sustainability of rigid polyurethane foam by incorporating industrial lignin. Industrial Crops and Products 2018, 117, 149 -158.

AMA Style

Amir Nemati Hayati, David Alwyn Charles Evans, Bronwyn Laycock, Darren Martin, Pratheep Kumar Annamalai. A simple methodology for improving the performance and sustainability of rigid polyurethane foam by incorporating industrial lignin. Industrial Crops and Products. 2018; 117 ():149-158.

Chicago/Turabian Style

Amir Nemati Hayati; David Alwyn Charles Evans; Bronwyn Laycock; Darren Martin; Pratheep Kumar Annamalai. 2018. "A simple methodology for improving the performance and sustainability of rigid polyurethane foam by incorporating industrial lignin." Industrial Crops and Products 117, no. : 149-158.

Journal article
Published: 01 February 2018 in Industrial Crops and Products
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The development of sustainable rigid polyurethane foam (RPUF) using biologically renewable materials remains a challenge in both academia and industry. This study focuses on the cellulose nanocrystal (CNC) reinforcement of a model RPUF based on a hybrid polyol system of 80:20 ‘polyether’ and palm-kernel oil based ‘polyester’ polyols (PKObP), in order to simultaneously enhance thermal insulation and/or mechanical properties. The addition of 0.4 wt.% CNC in the RPUF afforded a 2.4% improvement (i.e. reduction) in the thermal conductivity (from 24.1 ± 0.4 mW/mK to 23.5 ± 0.3 mW/mK). This is statistically insignificant improvement and the same order of magnitude reported by other studies investigating the effect of micro and nanofiller in RPUF. It was unexpected, as we have previously observed a 5% reduction in thermal conductivity with the same loading (0.4 wt.%) of acid-hydrolysed CNC in the RPUF formulation using the same polyether polyol alone due to improved nucleation. Microscopic and cell content measurements indicated that the presence of the PKObP, which has the basic structure of a non-ionic surfactant, prevented the CNC from acting as a nucleation agent. The nature of interaction between the CNC and PKObP has decreased the specific compressive strength both parallel (−12.0%) and perpendicular (−1.8%) to foam rise. However, the specific Young’s modulus perpendicular to foam rise was significantly improved (8.5%), and this was attributed to the alignment of the CNC in the direction of foam rise.

ACS Style

Athanasia A. Septevani; David A.C. Evans; Darren Martin; Pratheep K. Annamalai. Hybrid polyether-palm oil polyester polyol based rigid polyurethane foam reinforced with cellulose nanocrystal. Industrial Crops and Products 2018, 112, 378 -388.

AMA Style

Athanasia A. Septevani, David A.C. Evans, Darren Martin, Pratheep K. Annamalai. Hybrid polyether-palm oil polyester polyol based rigid polyurethane foam reinforced with cellulose nanocrystal. Industrial Crops and Products. 2018; 112 ():378-388.

Chicago/Turabian Style

Athanasia A. Septevani; David A.C. Evans; Darren Martin; Pratheep K. Annamalai. 2018. "Hybrid polyether-palm oil polyester polyol based rigid polyurethane foam reinforced with cellulose nanocrystal." Industrial Crops and Products 112, no. : 378-388.

Journal article
Published: 27 November 2017 in IEEE Transactions on Dielectrics and Electrical Insulation
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Short circuit (SC) strength of a power transformer is influenced by its winding clamping pressure. The required level of clamping pressure is selected at the design stage based on the maximum allowable SC current level of the transformer. Progressive loss of clamping pressure is a common problem in power transformers. Shrinkage and fading of the stiffness of solid insulation due to thermal degradation are the most common causes of this problem. It has also been identified that changes in the moisture content and repetitive compression cycles on pressboard during high current faults tend to change the winding clamping pressure. This study aims to investigate the effects of moisture and compression cycles on winding clamping pressure through a set of laboratory experiments and finite element analyses. Thickness change and compressive stress-strain curves of pressboard were measured under different moisture conditions. The results were then used to calculate changes in winding geometry and clamping pressure of a 100 kVA three phase, disc type transformer winding.

ACS Style

Lakshitha Naranpanawe; Chandima Ekanayake; Tapan Kumar Saha; Pratheep Kumar Annamalai. Influence of moisture dependency of pressboard on transformer winding clamping pressure. IEEE Transactions on Dielectrics and Electrical Insulation 2017, 24, 3191 -3200.

AMA Style

Lakshitha Naranpanawe, Chandima Ekanayake, Tapan Kumar Saha, Pratheep Kumar Annamalai. Influence of moisture dependency of pressboard on transformer winding clamping pressure. IEEE Transactions on Dielectrics and Electrical Insulation. 2017; 24 (5):3191-3200.

Chicago/Turabian Style

Lakshitha Naranpanawe; Chandima Ekanayake; Tapan Kumar Saha; Pratheep Kumar Annamalai. 2017. "Influence of moisture dependency of pressboard on transformer winding clamping pressure." IEEE Transactions on Dielectrics and Electrical Insulation 24, no. 5: 3191-3200.

Journal article
Published: 01 November 2017 in Industrial Crops and Products
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ACS Style

Athanasia A. Septevani; David A.C. Evans; Pratheep Kumar Annamalai; Darren Martin. The use of cellulose nanocrystals to enhance the thermal insulation properties and sustainability of rigid polyurethane foam. Industrial Crops and Products 2017, 107, 114 -121.

AMA Style

Athanasia A. Septevani, David A.C. Evans, Pratheep Kumar Annamalai, Darren Martin. The use of cellulose nanocrystals to enhance the thermal insulation properties and sustainability of rigid polyurethane foam. Industrial Crops and Products. 2017; 107 ():114-121.

Chicago/Turabian Style

Athanasia A. Septevani; David A.C. Evans; Pratheep Kumar Annamalai; Darren Martin. 2017. "The use of cellulose nanocrystals to enhance the thermal insulation properties and sustainability of rigid polyurethane foam." Industrial Crops and Products 107, no. : 114-121.

Original paper
Published: 26 June 2017 in Cellulose
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During the last two decades, work surrounding the preparation of a vast array of cellulose nanomaterials from both wood and non-wood based sources has steadily intensified. This study reports on the isolation of high aspect ratio nanocellulose from an arid grass source commonly called “spinifex”, Triodia pungens, via an optimised sulfuric acid hydrolysis protocol. The unique attributes of T. pungens have enabled pulping and bleaching under milder conditions than used in typically reported protocols, followed by relatively easy deconstruction into nanofibres with an unprecedentedly high aspect ratio. Hydrolysis of bleached T. pungens under these optimised processing conditions has yielded nanocellulose with a very high aspect ratio of 144 (average dimensions of 3.45 ± 1 nm × 497 ± 106 nm), a crystallinity of 73% and a production yield of 42%. Based on the spectroscopic and X-ray scattering analyses, an unusually high content of hemicellulose (42%) is correlated with both the ease of deconstruction and the retention of nanocellulose length. This high hemicellulose content also appears to give rise to a lower transverse stiffness than previously-reported values for wood sources.

ACS Style

Nasim Amiralian; Pratheep Kumar Annamalai; Christopher J. Garvey; Edward Jiang; Paul Memmott; Darren J. Martin. High aspect ratio nanocellulose from an extremophile spinifex grass by controlled acid hydrolysis. Cellulose 2017, 24, 3753 -3766.

AMA Style

Nasim Amiralian, Pratheep Kumar Annamalai, Christopher J. Garvey, Edward Jiang, Paul Memmott, Darren J. Martin. High aspect ratio nanocellulose from an extremophile spinifex grass by controlled acid hydrolysis. Cellulose. 2017; 24 (9):3753-3766.

Chicago/Turabian Style

Nasim Amiralian; Pratheep Kumar Annamalai; Christopher J. Garvey; Edward Jiang; Paul Memmott; Darren J. Martin. 2017. "High aspect ratio nanocellulose from an extremophile spinifex grass by controlled acid hydrolysis." Cellulose 24, no. 9: 3753-3766.

Journals
Published: 16 June 2017 in Nanoscale
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Remnant lignin and hemicellulose in the cellulose nanofibre (CNF) and a deep-eutectic-solvent pretreatment on CNF can enhace the tensile strength and toughness or natural rubber nanocomposites.

ACS Style

Alireza Hosseinmardi; Pratheep K. Annamalai; Lianzhou Wang; Darren Martin; Nasim Amiralian. Reinforcement of natural rubber latex using lignocellulosic nanofibers isolated from spinifex grass. Nanoscale 2017, 9, 9510 -9519.

AMA Style

Alireza Hosseinmardi, Pratheep K. Annamalai, Lianzhou Wang, Darren Martin, Nasim Amiralian. Reinforcement of natural rubber latex using lignocellulosic nanofibers isolated from spinifex grass. Nanoscale. 2017; 9 (27):9510-9519.

Chicago/Turabian Style

Alireza Hosseinmardi; Pratheep K. Annamalai; Lianzhou Wang; Darren Martin; Nasim Amiralian. 2017. "Reinforcement of natural rubber latex using lignocellulosic nanofibers isolated from spinifex grass." Nanoscale 9, no. 27: 9510-9519.

Journals
Published: 04 May 2017 in Sustainable Energy & Fuels
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Spinifex grass derived hard carbon is used as anodes for sodium-ion batteries. Extraordinary stability and capacity retention of ∼300 mA h g−1 on prolonged cycling against sodium was observed. The eco-friendly and low-cost synthesis procedure make the biomass derived carbon material promising for energy storage applications.

ACS Style

Rohit Ranganathan Gaddam; Edward Jiang; Nasim Amiralian; Pratheep K. Annamalai; Darren Martin; Nanjundan Ashok Kumar; X. S. Zhao. Spinifex nanocellulose derived hard carbon anodes for high-performance sodium-ion batteries. Sustainable Energy & Fuels 2017, 1, 1090 -1097.

AMA Style

Rohit Ranganathan Gaddam, Edward Jiang, Nasim Amiralian, Pratheep K. Annamalai, Darren Martin, Nanjundan Ashok Kumar, X. S. Zhao. Spinifex nanocellulose derived hard carbon anodes for high-performance sodium-ion batteries. Sustainable Energy & Fuels. 2017; 1 (5):1090-1097.

Chicago/Turabian Style

Rohit Ranganathan Gaddam; Edward Jiang; Nasim Amiralian; Pratheep K. Annamalai; Darren Martin; Nanjundan Ashok Kumar; X. S. Zhao. 2017. "Spinifex nanocellulose derived hard carbon anodes for high-performance sodium-ion batteries." Sustainable Energy & Fuels 1, no. 5: 1090-1097.

Research article
Published: 07 March 2017 in ACS Sustainable Chemistry & Engineering
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The energy requirements for the production of high quality carbon fiber and other carbon-based materials made by carbonization is a key factor limiting the commercial application of these materials. With the aim of enhancing the carbonization efficiency, we have prepared polyacrylonitrile (PAN) based precursor materials doped with high aspect-ratio cellulose nanofibers (CNF) derived from Australian spinifex grass (T. pungens). This was achieved by systematically investigating the rheology and electrospinning properties of composite fibers of PAN and CNF prepared at various CNF concentration levels and subsequently stabilized and carbonized. The carbon properties were characterized by X-ray diffraction and Raman spectroscopy. Upon carbonization, the incorporation of CNF into the PAN precursor led to changes in the crystallite and graphitic structure of the carbon materials, and these changes found to be closely related to the CNF concentration. CNF loadings of 0.5–2 wt % resulted in spinnable solutions with well-ordered carbon structures exhibiting a reduced Raman D/G ratio and an increased [002] band intensity by XRD. These spinifex CNF additives highlight a new approach for enhancing the energy efficiency of the carbonization process for PAN-based precursors.

ACS Style

Edward Jiang; Nasim Amiralian; Maxime Maghe; Bronwyn Laycock; Eric McFarland; Bronwyn Fox; Darren Martin; Pratheep K. Annamalai. Cellulose Nanofibers as Rheology Modifiers and Enhancers of Carbonization Efficiency in Polyacrylonitrile. ACS Sustainable Chemistry & Engineering 2017, 5, 3296 -3304.

AMA Style

Edward Jiang, Nasim Amiralian, Maxime Maghe, Bronwyn Laycock, Eric McFarland, Bronwyn Fox, Darren Martin, Pratheep K. Annamalai. Cellulose Nanofibers as Rheology Modifiers and Enhancers of Carbonization Efficiency in Polyacrylonitrile. ACS Sustainable Chemistry & Engineering. 2017; 5 (4):3296-3304.

Chicago/Turabian Style

Edward Jiang; Nasim Amiralian; Maxime Maghe; Bronwyn Laycock; Eric McFarland; Bronwyn Fox; Darren Martin; Pratheep K. Annamalai. 2017. "Cellulose Nanofibers as Rheology Modifiers and Enhancers of Carbonization Efficiency in Polyacrylonitrile." ACS Sustainable Chemistry & Engineering 5, no. 4: 3296-3304.

Book chapter
Published: 01 January 2017 in Hybrid Polymer Composite Materials
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ACS Style

B.T.S. Ramanujam; Pratheep Kumar Annamalai. Conducting polymer–graphite binary and hybrid composites. Hybrid Polymer Composite Materials 2017, 1 -34.

AMA Style

B.T.S. Ramanujam, Pratheep Kumar Annamalai. Conducting polymer–graphite binary and hybrid composites. Hybrid Polymer Composite Materials. 2017; ():1-34.

Chicago/Turabian Style

B.T.S. Ramanujam; Pratheep Kumar Annamalai. 2017. "Conducting polymer–graphite binary and hybrid composites." Hybrid Polymer Composite Materials , no. : 1-34.

Conference paper
Published: 01 January 2017 in AIP Conference Proceedings
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The increasing awareness of the environment and the economy of petroleum resources has driven the development of alternative processes and raw materials based on sustainable and renewable biomaterials with excellent properties. This study is aimed to use biologically renewable cellulose nanocrystals (CNC) as reinforcing agent to enhance the properties of polyurethane foams (PUF) based on solely palm-polyol. Rod-like shape cellulose nanocrystals (CNC) was successfully isolated from cotton based resources via strong acid hydrolysis with the average width, length and aspect ratio about 14.7 ± 4.9 nm, 167.7 ± 23.2 nm and 11.4, respectively. The crystallinity of CNC was confirmed by using X-ray diffraction (XRD) and differential scanning calorimetry (DSC) and was found at 82.8% and 83.8%, respectively. This obtained cellulose nanocrystals (CNC) at a loading of 0.4 wt. % was then incorporated via solvent-free sonication method in the model of palm based polyurethane foam. The preliminary results showed that the effect of CNC on the mechanical properties afforded a significant improvement on the compressive strength and modulus without affecting much their tensile strength. The results on thermal stability and thermal transitions were found unchanged whereas the storage modulus revealed substantial improvement with the presence of CNC with almost two fold from 0.7 MPa to 1.3 MPa (∼86 %).

ACS Style

Athanasia Amanda Septevani; Pratheep K. Annamalai; Darren J. Martin. Synthesis and characterization of cellulose nanocrystals as reinforcing agent in solely palm based polyurethane foam. AIP Conference Proceedings 2017, 1 .

AMA Style

Athanasia Amanda Septevani, Pratheep K. Annamalai, Darren J. Martin. Synthesis and characterization of cellulose nanocrystals as reinforcing agent in solely palm based polyurethane foam. AIP Conference Proceedings. 2017; ():1.

Chicago/Turabian Style

Athanasia Amanda Septevani; Pratheep K. Annamalai; Darren J. Martin. 2017. "Synthesis and characterization of cellulose nanocrystals as reinforcing agent in solely palm based polyurethane foam." AIP Conference Proceedings , no. : 1.

Research article
Published: 06 December 2016 in Langmuir
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Adhesive interactions between nanofibers strongly influence the mechanical behavior of soft materials composed of fibrous networks. We use atomic force microscopy in lateral force mode to drag a cantilever tip through fibrous networks, and use the measured lateral force response to determine the adhesive forces between fibers of the order of 100 nm diameter. The peaks in lateral force curves are directly related to the detachment energy between two fibers; the data is analyzed using the Jarzynski equality to yield the average adhesion energy of the weakest links. The method is successfully used to measure adhesion forces arising from van der Waals interactions between electrospun polymer fibers in networks of varying density. This approach overcomes the need to isolate and handle individual fibers, and can be readily employed in the design and evaluation of advanced materials and biomaterials which, through inspiration from nature, are increasingly incorporating nanofibers. The data obtained with this technique may also be of critical importance in the development of network models capable of predicting the mechanics of fibrous materials.

ACS Style

Grace K. Dolan; Gleb E. Yakubov; George W. Greene; Nasim Amiralian; Pratheep Kumar Annamalai; Darren J. Martin; Jason R. Stokes. Dip-and-Drag Lateral Force Spectroscopy for Measuring Adhesive Forces between Nanofibers. Langmuir 2016, 32, 13340 -13348.

AMA Style

Grace K. Dolan, Gleb E. Yakubov, George W. Greene, Nasim Amiralian, Pratheep Kumar Annamalai, Darren J. Martin, Jason R. Stokes. Dip-and-Drag Lateral Force Spectroscopy for Measuring Adhesive Forces between Nanofibers. Langmuir. 2016; 32 (50):13340-13348.

Chicago/Turabian Style

Grace K. Dolan; Gleb E. Yakubov; George W. Greene; Nasim Amiralian; Pratheep Kumar Annamalai; Darren J. Martin; Jason R. Stokes. 2016. "Dip-and-Drag Lateral Force Spectroscopy for Measuring Adhesive Forces between Nanofibers." Langmuir 32, no. 50: 13340-13348.