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Kim L. Pickering - One of the best experts on this subject based on the ideXlab platform.

  • Cellulose nanocrystal treatment of aligned short Hemp Fibre mats for reinforcement in polypropylene matrix composites
    Cellulose, 2021
    Co-Authors: Tom Sunny, Kim L. Pickering
    Abstract:

    Oriented short Hemp Fibre mats were produced using dynamic sheet forming (DSF) incorporating cellulose nanocrystals (CNCs) to improve their integrity. The CNCs were found to act as a binder and improve mechanical strength of the mats as well as the strength of polypropylene matrix composites produced with the mats. Improved thermal stability was also obtained for composites by using CNC treatment of Fibre mats.

  • Effect of stearic acid treatment on the properties of aligned short Hemp Fibre mats and their potential use as reinforcement in polypropylene matrix composites
    Cellulose, 2021
    Co-Authors: Kim L. Pickering, Tom Sunny
    Abstract:

    The main objective of this study was to assess the effect of stearic acid vapour treatment on Hemp Fibre mats produced using dynamic sheet forming, and the potential use of these treated mats as reinforcement in polypropylene matrix composites. Stearic acid was successfully applied through vapour treatment, appearing to form a layer on Fibre surfaces. It was found that the presence of stearic acid increased hydrophobicity and thermal stability of Fibre mats. It was also found to increase thermal stability of polypropylene matrix composites as well as their strength.

  • Alkali treatment of Hemp Fibres for the production of aligned Hemp Fibre mats for composite reinforcement
    Cellulose, 2020
    Co-Authors: Tom Sunny, Kim L. Pickering, Shen Hin Lim
    Abstract:

    The main objective of this study was to produce aligned Hemp Fibre mats from high strength Hemp Fibres using dynamic sheet forming (DSF). Alkali treatment of Hemp Fibre was carried out at ambient and high temperature to separate Fibres. Single Fibre tensile testing was used to assess the tensile properties of the Fibres. It was found that the highest tensile properties were exhibited by high temperature treated Fibre, whereas the tensile properties exhibited by ambient temperature treated Fibre were lower than for untreated Fibre. It was also found that Fibre granulated after high temperature treatment, was better separated than that granulated before high temperature treatment. This well-separated Fibre could successfully be formed into mats using DSF. The orientation of the formed mat was analysed using ImageJ (NIH, USA) software by which the potential of DSF to produce aligned Hemp Fibre mat was supported. The tensile properties of composite reinforced by these aligned Hemp Fibre mats were assessed.

  • comparison of harakeke with Hemp Fibre as a potential reinforcement in composites
    Composites Part A-applied Science and Manufacturing, 2014
    Co-Authors: M Aruan G Efendy, Kim L. Pickering
    Abstract:

    The objective of this study was to characterize the performance of untreated and chemically treated harakeke Fibre (a leaf Fibre from a plant native to New Zealand) and compare with Hemp Fibre to assess its use as potential reinforcement in composites. Alkali treatment is amongst the most popular treatments used to remove unwanted Fibre constituents such as pectin, hemicellulose and waxes; it can enhance Fibre properties, Fibre separation, interfacial bonding and Fibre dispersion within a composite. Physical and mechanical properties of untreated and alkali treated Fibres were assessed using single Fibre tensile testing, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis using thermogravimetric analysis (TGA). Untreated harakeke Fibre was found to be lower in tensile strength compared to untreated Hemp Fibre. It was also found that the tensile strength of harakeke and Hemp Fibres treated with 5 wt% NaOH/2 wt% Na2SO3 and 5 wt% NaOH was not significantly affected and these Fibres had good Fibre separation. However, alkali treatment was found to lead to higher crystallinity index (Ic) and better thermal stability for harakeke as well as Hemp Fibres.

  • effect of Fibre treatments on interfacial shear strength of Hemp Fibre reinforced polylactide and unsaturated polyester composites
    Composites Part A-applied Science and Manufacturing, 2011
    Co-Authors: Moyeenuddin Ahmad Sawpan, Kim L. Pickering, Alan Fernyhough
    Abstract:

    Surface treatment of Hemp Fibres was investigated as a means of improving interfacial shear strength (IFSS) of Hemp Fibre reinforced polylactide (PLA) and unsaturated polyester (UPE) composites. Fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane. A combined treatment using sodium hydroxide and silane was also carried out. IFSS of PLA/Hemp Fibre samples increased after treatment, except in the case of maleic anhydride treatment. Increased IFSS could be explained by better bonding of PLA with treated Fibres and increased PLA transcrystallinity. The highest IFSS was 11.4 MPa which was obtained for the PLA/alkali treated Fibre samples. IFSS of UPE/Hemp Fibre samples increased for all treated Fibres. This is believed to be due to the improvement of chemical bonding between the treated Fibres and the UPE as supported by FT-IR results. The highest IFSS (20.3 MPa) was found for the combined sodium hydroxide and silane treatment Fibre/UPE samples.

Hom Nath Dhakal - One of the best experts on this subject based on the ideXlab platform.

  • machinability of natural Fibre reinforced polymer composites conventional vs ultrasonically assisted machining
    Composites Part A-applied Science and Manufacturing, 2019
    Co-Authors: Dong Wang, Ivan Popov, Sikiru Oluwarotimi Ismail, Hom Nath Dhakal, P Y Onawumi, Vadim V Silberschmidt
    Abstract:

    Abstract Natural-Fibre-reinforced polymer (NFRP) composites are becoming a viable alternative to synthetic Fibre based composites in many industrial applications. Machining is often necessary to facilitate assembly of parts in a final product. This study focuses on a comparative experimental analysis of the effects of conventional drilling (CD) and a hybrid ultrasonically-assisted drilling (UAD) of a Hemp Fibre-reinforced vinyl ester composite laminate. The results obtained indicate that UAD is more efficient when compared to CD for a range of drilling conditions. It yields lower cutting forces and energy resulting in reduced machining-induced damage in the composite, including diminished burr formation and Fibre pull-outs. The holes drilled with UAD exhibit improved surface finish and hole quality when compared to those produced with CD. The study demonstrates the applicability of UAD as a viable machining process for improved machinability of heterogeneous NFRP composite materials.

  • Comprehensive study on machinability of sustainable and conventional Fibre reinforced polymer composites
    Engineering Science and Technology, an International Journal, 2016
    Co-Authors: Sikiru Oluwarotimi Ismail, Hom Nath Dhakal, Ivan Popov
    Abstract:

    The conventional homogeneous materials can no longer effectively satisfy the growing demands on product capabilities and performance, due to the advancement in products design and materials engineering. Therefore, the Fibre reinforced composites (FRCs) with better properties and desirable applications emerged. These enhanced qualities of the FRCs have emphasized the need for analysing their machinability for further improvement of performance. Hence, this paper presents a comprehensive investigation on the machinability effects of drilling parameters (feed rate, cutting speed and thrust force), drill diameters and chips formation mainly on delamination and surface roughness of Hemp Fibre reinforced polymer (19/HFRP) and carbon Fibre reinforced polymer (MTM 44-1/CFRP) composite laminates, using high speed steel (HSS) drills under dry machining condition. The results obtained depict that an increase in feed rate and thrust force caused an increase in delamination and surface roughness of both samples, different from cutting speed. Also, increased drill diameter and types of chips formation caused an increase in both delamination and surface roughness of both samples, as the material removal rate (MRR) increased. Evidently, the minimum surface roughness and delamination factor of the two samples for an optimal drilling are associated with feed rates of 0.05–0.10mm/rev and cutting speed of 30m/min.

  • Effects of drilling parameters and aspect ratios on delamination and surface roughness of lignocellulosic HFRP composite laminates
    Journal of Applied Polymer Science, 2016
    Co-Authors: Sikiru Oluwarotimi Ismail, Hom Nath Dhakal, Johnny Beaugrand, Eric Dimla, Ivan Popov
    Abstract:

    Hemp Fibre-reinforced polycaprolactone (HFRP) composite has inherent good mechanical properties and benefits which include remarkably high specific strength and modulus, low density, and renewability. No doubt, these properties have attracted wider applications of HFRP composite in engineering applications. This paper presents an investigation on the influence of drilling parameters and Fibre aspect ratios, AR (0, 19, 26, 30, and 38) on delamination damage factor and surface roughness of HFRP composite laminates utilising high speed steel twist drills under dry machining condition. Taguchi's technique was used in the design of experiment. The results obtained show that increase in cutting speed reduces delamination factor and surface roughness of drilled holes, whereas increase in feed rate causes increase in both delamination factor and surface roughness. Feed rate and cutting speed had the greatest influence on delamination and surface roughness respectively when compared with aspect ratio, while an increase in Fibre aspect ratios leads to a significant increase in both delamination factor and surface roughness. The optimum results occurred at cutting speed and feed rate (drilling parameters) of 20 mm/min and 0.10 mm/rev, respectively, when drilling sample of AR 19. (C) 2015 Wiley Periodicals, Inc.

  • effect of basalt Fibre hybridisation on post impact mechanical behaviour of Hemp Fibre reinforced composites
    Composites Part A-applied Science and Manufacturing, 2015
    Co-Authors: Hom Nath Dhakal, Fabrizio Sarasini, Jacopo Tirillo, Carlo Santulli, Zhongyi Zhang, V Arumugam
    Abstract:

    A major limitation to the spreading of natural Fibre reinforced composites in semi-structural components is their unsatisfactory impact performance. As a potential solution, the production of synthetic/plant Fibre hybrid laminates has been explored, trying to obtain materials with sufficient impact properties, while retaining a reduced cost and a substantial environmental gain. This study explores the effects of hybridisation of basalt Fibre on post-impact behaviour and damage tolerance capability of Hemp Fibre reinforced composites. All reinforced laminates were impacted in a range of energies (3, 6, and 9 J) and subjected to both quasi-static and cyclic flexural tests with a step loading procedure. The tests have also been monitored by acoustic emission (AE), which has confirmed the existence of severe limitations to the use of natural Fibre reinforced composites even when impacted at energies not so close to penetration and the enhanced damage tolerance offered by the hybridisation with basalt fibers.

  • low velocity impact response of non woven Hemp Fibre reinforced unsaturated polyester composites influence of impactor geometry and impact velocity
    Composite Structures, 2012
    Co-Authors: Hom Nath Dhakal, Zhongyi Zhang, Nick Bennett, P N B Reis
    Abstract:

    In this study, the influence of varying impactor geometries on the impact damage characteristics of Hemp Fibre reinforced unsaturated polyester composites were subjected to a low-velocity impact loading using an instrumented falling weight impact test setup. The three varying tup geometries: hemispherical, 30° and 90°, at four different impact velocity levels: 2.52 m/s, 2.71 m/s, 2.89 m/s and 2.97 m/s were assessed. The experimental results to investigate the influence of impactor geometry suggest that HFRUP composites were able to withstand higher loads when tested with hemispherical impactor and also absorbed more energy than that for 90° and 30° shaped tup geometry. The post impact damage patterns and failure mechanisms of impacted samples were further characterised by ultrasonic (UT) inspection. Impact induced damage characterised by scanning electron microscope (SEM) suggests that damage induced by the impact included a typical failure mechanisms showing matrix cracking, Fibre breakage and Fibre pullout. As the impact velocity increases the damage to back face of the laminate increased for laminates tested with a hemispherical impactor while it decreased to certain extent for laminates tested with 90° and 30° impactor geometries.

Fabrizio Sarasini - One of the best experts on this subject based on the ideXlab platform.

  • Durability of Basalt/Hemp Hybrid Thermoplastic Composites
    MDPI AG, 2019
    Co-Authors: Claudia Sergi, Maria Carolina Seghini, Fabrizio Sarasini, Jacopo Tirillo, Vincenzo Fiore, Tommaso Scalici
    Abstract:

    The Achilles heel of thermoplastic natural Fibre composites is their limited durability. The environmental degradation of the mechanical properties of Hemp and Hemp/basalt hybrid-reinforced high-density polyethylene (HDPE) composites has been investigated with a special focus on the effects of water ageing and accelerated ageing, including hygrothermal and UV radiation. Modification of the matrix was carried out using a maleic anhydride high-density polyethylene copolymer (MAPE) as a compatibilizer. Hybridization of Hemp Fibres with basalt Fibres and the incorporation of MAPE were found to significantly decrease the water uptake (up to 75%) and increase the retention of mechanical properties after accelerated ageing. Secondary crystallization phenomena occurring in the composites, as confirmed by differential scanning calorimetry (DSC) analysis, were able to counteract the severe combined effects of hygrothermal stress and UV radiation, with the exception of Hemp-Fibre composites where permanent damage to the Fibres occurred, with 2% and 20% reduction in tensile strength and modulus, respectively, for a 30 wt % Hemp Fibre-reinforced HDPE

  • effect of basalt Fibre hybridisation and sizing removal on mechanical and thermal properties of Hemp Fibre reinforced hdpe composites
    Composite Structures, 2018
    Co-Authors: Fabrizio Sarasini, Claudia Sergi, Maria Carolina Seghini, Luca Cozzarini, Jacopo Tirillo, Nina Graupner
    Abstract:

    Abstract Despite the advantages offered by natural Fibre-based thermoplastic composites in terms of environmental impact and cost, their mechanical performance is generally lower than that of synthetic counterparts. Hybridisation with mineral Fibres (basalt) can broaden the industrial applications of natural Fibre reinforced composites. The present study focused on the performance of injection-moulded short basalt Fibre, Hemp Fibre and Hemp/basalt Fibre hybrid high density polyethylene (HDPE) composites. Effects of a maleated coupling agent on the thermal and mechanical properties of the resulting composites were evaluated as a function of the Fibre mass fraction. Hybridisation of Hemp Fibres with basalt Fibres was found to significantly increase the mechanical properties and the crystallinity of Hemp-Fibre reinforced composites thus suggesting that short Hemp/basalt Fibre hybrid HDPE composites are promising candidates for semi-structural applications. Additionally, a sizing removal procedure mimicking the conditions experienced in an end-of-life composite thermal recycling process was defined and discussed in terms of residual mechanical properties of basalt/HDPE composites.

  • effect of basalt Fibre hybridisation on post impact mechanical behaviour of Hemp Fibre reinforced composites
    Composites Part A-applied Science and Manufacturing, 2015
    Co-Authors: Hom Nath Dhakal, Fabrizio Sarasini, Jacopo Tirillo, Carlo Santulli, Zhongyi Zhang, V Arumugam
    Abstract:

    A major limitation to the spreading of natural Fibre reinforced composites in semi-structural components is their unsatisfactory impact performance. As a potential solution, the production of synthetic/plant Fibre hybrid laminates has been explored, trying to obtain materials with sufficient impact properties, while retaining a reduced cost and a substantial environmental gain. This study explores the effects of hybridisation of basalt Fibre on post-impact behaviour and damage tolerance capability of Hemp Fibre reinforced composites. All reinforced laminates were impacted in a range of energies (3, 6, and 9 J) and subjected to both quasi-static and cyclic flexural tests with a step loading procedure. The tests have also been monitored by acoustic emission (AE), which has confirmed the existence of severe limitations to the use of natural Fibre reinforced composites even when impacted at energies not so close to penetration and the enhanced damage tolerance offered by the hybridisation with basalt fibers.

  • impact and post impact damage characterisation of hybrid composite laminates based on basalt Fibres in combination with flax Hemp and glass Fibres manufactured by vacuum infusion
    Composites Part B-engineering, 2015
    Co-Authors: Roberto Petrucci, Fabrizio Sarasini, Jacopo Tirillo, Debora Puglia, Luigi Torre, C Santulli, E Nisini, Giangiacomo Minak, J M Kenny
    Abstract:

    Abstract The impact and flexural post-impact behaviour of ternary hybrid composites based on epoxy resin reinforced with different types of Fibres, basalt (B), flax (F), Hemp (H) and glass (G) in textile form, namely FHB, GHB and GFB, has been investigated. The reinforcement volume employed was in the order of 21–23% throughout. Laminates based exclusively on basalt, Hemp and flax Fibres were also fabricated for comparison. Hybrid laminates showed an intermediate performance between basalt Fibre reinforced laminates on the high side, and flax and Hemp Fibre reinforced laminates on the low side. As for impact performance, GHB appears to be the worst performing hybrid laminate and FHB slightly overperforms GFB. In general, an increased rigidity can be attributed to all hybrids with respect to flax and Hemp Fibre composites. The morphological study of fracture by SEM indicated the variability of mode of fracture of flax and Hemp Fibre laminates and of the hybrid configuration (FHB) containing both of them. Acoustic emission monitoring during post-impact flexural tests confirmed the proneness to delamination of FHB hybrids, whilst they were able to better withstand impact damage than the other hybrids.

  • influence of low velocity impact on fatigue behaviour of woven Hemp Fibre reinforced epoxy composites
    Composites Part B-engineering, 2014
    Co-Authors: Davi Silva De Vasconcellos, Fabrizio Sarasini, Jacopo Tirillo, C Santulli, Fabienne Touchard, Laurence Chocinskiarnault, Monica Francesca Pucci, Salvatore Iannace, Luigi Sorrentino
    Abstract:

    Abstract The purpose of this work is to study the resistance to low velocity impact of woven Hemp/epoxy matrix composites and the influence of impact damage on their residual quasi-static tensile and cyclic fatigue strengths. Impact characteristic parameters were evaluated and critically compared to those found in the literature for other similar composites. Damage mechanisms were analysed by using AE monitoring and microscopic observations. An analytical model is used to predict the fatigue lifetime of impacted specimens. Moreover a damage scenario is proposed, reduced to two phases in post-impacted fatigue behaviour, instead of three phases for non impacted specimens.

Alan Fernyhough - One of the best experts on this subject based on the ideXlab platform.

  • influence of loading rate alkali Fibre treatment and crystallinity on fracture toughness of random short Hemp Fibre reinforced polylactide bio composites
    Composites Part A-applied Science and Manufacturing, 2011
    Co-Authors: Kim L. Pickering, Moyeenuddin Ahmad Sawpan, Jeevan Jayaraman, Alan Fernyhough
    Abstract:

    Abstract Plane-strain fracture toughness (KIc) of random short Hemp Fibre reinforced polylactide (PLA) bio-composites was investigated along with the effect of loading rate, Fibre treatment and PLA crystallinity. Fracture toughness testing was carried out at loading rates varying from 0.5 to 20 mm/min using single-edge-notched bending specimens with 0 to 30 wt.% Fibre. KQ (trial KIc) of composites decreased as loading rate increased, until stabilising to give KIc values at a loading rate of 10 mm/min and higher. The reduction of crazing and stress whitening, as well as a more direct crack path observed in PLA samples combined with reduced plastic deformation observed in composites provided explanation for this reduction. KIc of composites was found to decrease with increased Fibre content and Fibre treatment with sodium hydroxide. Studies controlling the degree of PLA crystallinity by heat treatment or “annealing” showed that reduction of KIc can be attributed to increased crystallinity.

  • effect of Fibre treatments on interfacial shear strength of Hemp Fibre reinforced polylactide and unsaturated polyester composites
    Composites Part A-applied Science and Manufacturing, 2011
    Co-Authors: Moyeenuddin Ahmad Sawpan, Kim L. Pickering, Alan Fernyhough
    Abstract:

    Surface treatment of Hemp Fibres was investigated as a means of improving interfacial shear strength (IFSS) of Hemp Fibre reinforced polylactide (PLA) and unsaturated polyester (UPE) composites. Fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane. A combined treatment using sodium hydroxide and silane was also carried out. IFSS of PLA/Hemp Fibre samples increased after treatment, except in the case of maleic anhydride treatment. Increased IFSS could be explained by better bonding of PLA with treated Fibres and increased PLA transcrystallinity. The highest IFSS was 11.4 MPa which was obtained for the PLA/alkali treated Fibre samples. IFSS of UPE/Hemp Fibre samples increased for all treated Fibres. This is believed to be due to the improvement of chemical bonding between the treated Fibres and the UPE as supported by FT-IR results. The highest IFSS (20.3 MPa) was found for the combined sodium hydroxide and silane treatment Fibre/UPE samples.

  • improvement of mechanical performance of industrial Hemp Fibre reinforced polylactide biocomposites
    Composites Part A-applied Science and Manufacturing, 2011
    Co-Authors: Moyeenuddin Ahmad Sawpan, Kim L. Pickering, Alan Fernyhough
    Abstract:

    Abstract In this work, mechanical properties of chemically treated random short Fibre and aligned long Hemp Fibre reinforced PLA composites were investigated over a range of Fibre content (0–40 wt.%). It was found that tensile strength, Young’s modulus and impact strength of short Hemp Fibre reinforced PLA composites increased with increased Fibre content. Alkali and silane Fibre treatments were found to improve tensile and impact properties which appears to be due to good Fibre/matrix adhesion and increased matrix crystallinity. A 30 wt.% alkali treated Fibre reinforced PLA composite (PLA/ALK) with a tensile strength of 75.5 MPa, Young’s modulus of 8.18 GPa and impact strength of 2.64 kJ/m2 was found to be the best. However, plane-strain fracture toughness and strain energy release rate decreased with increased Fibre content. The mechanical properties of the PLA/ALK composites were increased further due to alignment of long Fibres.

Tom Sunny - One of the best experts on this subject based on the ideXlab platform.