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•“Hybrid” composites were manufactured using PLA through extrusion and injection moulding.•Sisal and hemp fibres were hybridized to develop sustainable composites.•Mechanical and ...thermal properties of the hybrid composites were evaluated.
Natural polymers based composites offers significant advantages over synthetic fibre reinforced petroleum matrix based composites with regard to biodegradability, biocompatibility, design flexibility and sustainability. This work reports for the first time manufacturing of hybrid fibre reinforced biodegradable composites using sisal and hemp fibre with polylactic acid employing melt processing and injection moulding techniques. Granulated sisal and hemp fibres were blended and hybrid composites were manufactured using aliphatic polyester made up of lactic acid (PLA) through extrusion and injection moulding and their performance was evaluated. Experimental results revealed that density, elongation at break and water absorption capacity of hybrid composites were 1.14 ± 0.07 g/cm3, 0.93 ± 0.35% and 1.06 ± 0.18% respectively. The achieved mean tensile strength (46.25 ± 6.75 MPa), Young’s modulus (6.1 ± 0.58 GPa) and specific tensile strength (38.86 ± 5.0) of hybrid fibre reinforced PLA composites were improved compared to neat PLA. The flexural strength (94.83 ± 11.21 MPa), flexural modulus (6.04 ± 0.55 GPA) and specific flexural strength (79.76 ± 8.80) of hybrid fibre composites also showed better performance than those of neat PLA. Incorporation of sisal and hemp fibre with polylactide remarkably increased the impact strength of composites. Overall, the hybrid composites demonstrated good performance suggesting that they have great potential for use as an environmentally friendly alternative material in automotive, packaging, electronics, interiors and agricultural applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Biomedical materials constitute a vast scientific research field, which is devoted to producing medical devices which aid in enhancing human life. In this field, there is an enormous demand for ...long-lasting implants and bone substitutes that avoid rejection issues whilst providing favourable bioactivity, osteoconductivity and robust mechanical properties. Hydroxyapatite (HAp)-based biomaterials possess a close chemical resemblance to the mineral phase of bone, which give rise to their excellent biocompatibility, so allowing for them to serve the purpose of a bone-substituting and osteoconductive scaffold. The biodegradability of HAp is low (Ksp ≈ 6.62 × 10
) as compared to other calcium phosphates materials, however they are known for their ability to develop bone-like apatite coatings on their surface for enhanced bone bonding. Despite its favourable bone regeneration properties, restrictions on the use of pure HAp ceramics in high load-bearing applications exist due to its inherently low mechanical properties (including low strength and fracture toughness, and poor wear resistance). Recent innovations in the field of bio-composites and nanoscience have reignited the investigation of utilising different carbonaceous materials for enhancing the mechanical properties of composites, including HAp-based bio-composites. Researchers have preferred carbonaceous materials with hydroxyapatite due to their inherent biocompatibility and good structural properties. It has been demonstrated that different structures of carbonaceous material can be used to improve the fracture toughness of HAp, as they can easily serve the purpose of being a second phase reinforcement, with the resulting composite still being a biocompatible material. Nanostructured carbonaceous structures, especially those in the form of fibres and sheets, were found to be very effective in increasing the fracture toughness values of HAp. Minor addition of CNTs (3 wt.%) has resulted in a more than 200% increase in fracture toughness of hydroxyapatite-nanorods/CNTs made using spark plasma sintering. This paper presents a current review of the research field of using different carbonaceous materials composited with hydroxyapatite with the intent being to produce high performance biomedically targeted materials.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this study, the effects of interleaved nanofibre veils on the Mode I and Mode II interlaminar fracture toughness (ILFT) of autoclave cured unidirectional carbon/epoxy composite laminates were ...investigated. Various electrospun nanofibre veils consisting of a range of different polymer types, fibre diameters and veil architectures were placed in the laminate mid-planes, which were subsequently subjected to double cantilever beam and end-notch flexure tests. It was found that the polymer type and veil areal weight were the most important factors contributing to laminate performance. A 4.5g/m2 PA66 veil provided the best all-round performance with fracture toughness improvements of 156% and 69% for Mode I and Mode II, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Industrial hemp fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane to investigate the influence of treatment on the fibre structure and tensile properties. It ...was observed that the average tensile strength of sodium hydroxide treated fibres slightly increased compared with that of untreated fibres, which was believed to be as a result of increased cellulose crystallinity. The average tensile strength of acetic anhydride, maleic anhydride, silane and combined sodium hydroxide and silane treated fibres slightly decreased compared with that of untreated fibres, which was believed to be as a result of decreased cellulose crystallinity. However, the average Young’s modulus of all treated fibres increased compared with untreated fibres. This was considered to be as a result of densification of fibre cell walls due to the removal of non-cellulosic components during treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The main goal of this study was to improve the mechanical performance of polypropylene (PP) matrix composites through high hemp fibre content. In order to achieve high fibre content, the ...possibilities of different polymer sheet thicknesses and stacking arrangements were investigated. It was found that decreasing the overall thickness of fibre mats between two polymer sheets within the stacking arrangements of composites and so decreasing the distance the polymer needs to travel improved the fibre wetting and therefore improved the tensile properties. The strongest composite produced had a fibre content of about 60 wt%. At this fibre content, tensile strength and Young’s modulus of the composites were found to be 3.0 and 6.9 times, respectively, higher than the control samples (polymer only samples), while figures for flexural strength and flexural modulus were 3.4 and 3.6, respectively.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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/m
2 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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Cellulose is one of the most versatile biopolymers found in nature. Its use is now transitioning from sustainability-focused development to provide technical solutions across a wide range of ...applications. This review paper describes the use of cellulose as reinforcement in biocomposites and recent related advances in 3D printing technologies, including 4D (responsive/smart) printing and current/future applications. Relevant aspects such as the origin and intrinsic/structural properties of cellulose and cellulose/matrix interaction during processing are discussed. A particular focus is directed to identify opportunities for the development of new cellulose-based composites, formulation requirements for 3D/4D printing, and comprehension of the interplay between rheology, chemistry, and processing. Overall, new materials and technologies based on cellulose have shown promising results for real-life applications, opening new scientific development opportunities and a new generation of sustainable and advanced materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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