Current Analytical Chemistry - Volume 14, Issue 3, 2018

Background: Phenolic resins received greater attention from academic researchers and made prestigious status among all thermoset resins. Several effective attempts have made to explore different synthesis processes of producing phenolic in more useful and advanced way. Since the date of innovation, huge varieties of biocomposites and composites products have been produced for various applications. Methods: Among all types of Phenolic resin related applications, Phenolic resin molding compounds have been used for highest utility products due to better mechanical strength, resistance, long-term reliability and cost effectiveness. Results: Currently, modified phenolic resins are broadly used in the fabrication of synthetic/natural fiber reinforced composites in order to replace metals and ceramics on industrial level owing to its superior mechanical, thermal and electrical properties. This review article is intended to present an overview on the phenolic chemistry, curing process, structure, synthesis and its properties. Conclusion: The present review article also aims to cover the reported research works on modified phenolic, and bio-phenolic resins, and their diverse industrial applications to support the ongoing research and development in green sustainable commercial products.

Background: Silver nanoparticle (Ag NP)-containing biolpolymer nanocomposites possess antibacterial activity, which is largely associated with the NP size, shape, surface area and medium. Methods: These biomaterials have been investigated as dressing for wounds and burns, treatment for infected areas, coatings for orthopaedic and dental implants and for water disinfection. Results: This broad-acting and potent antibacterial activity is likely due to a multifaceted mechanism of action that is not completely understood. Although the Ag NPs are useful against antibiotic resistant bacteria, their level of toxicity is not well established and requires further investigation. Conclusion: This review details the brief perspective, critical analysis of the currently available articles and discusses the future applications of these potentially life-saving nanocomposites.

Background: The usage of natural fibres as reinforcement in bioplastic polymer composite has garnered attention during the last few decades. This is due to limitations of biodegradable polymerbased materials which have an intractable nature, poor water-sensitivity, poor mechanical strength and are brittle. Natural fibres are preferred as they can be obtained naturally, be safely collected and can save costs compared to glass fibres. Moreover, natural fibres can be used to make various products including filters, brushes, mats, cushions, rope and shelter for fish breeding. However, many waste products are generated from fibres and fruits. Therefore, to reduce waste produced, many experiments have been conducted with the aim of maximizing the product while minimizing waste. Many studies focus on bionanocomposites, which are used with natural fibres due to their abundance and potential for replacing carbon fibre and fibresglass in the future. Nanocrystalline cellulose (NCCs) serves as a promising candidate for bionanocomposite due to its nano-scale cellulose fibre composition, high strength and stiffness, low weight and biodegrability, renewability and its production and application in the development of composite materials. Therefore, the aim of this paper is to review research related to NCCs and its various applications in polymer reinforcement. Methods: Research articles related to the use of nanocrystalline cellulose as reinforcement for polymeric matrix nanocomposites and its potential applications were reviewed. A summary of nanocrystalline cellulose reinforcement for various polymer matrices was provided. This article was separated into sections involving characterization, extraction and processing of NCCs from various plants, formation of cellulose nanocomposite and new application developments. Results: Studies highlighted in the article detailed suitable characteristics of NCCs for various nanocomposite applications such as for packaging, use as a drug excipient and in drug delivery, in automotive, optical, substitute/biomedical, pharmaceutical and construction industries. Conclusion: NCCs have gained substantial interest due to its unique features, such as cost effectiveness, high aspect ratio, and its light weight. In summary, this article reviewed several current research in NCCs from the preparation of nano-scale green particle material. Furthermore, this article reviewed mechanical nanocomposite properties, and the range of application potential of this green material.

Background: The present review deals with the recent development of kenaf hybrid composites. Kenaf reinforced polymer composites are made up of either thermoplastic or thermoset matrix, depending on their applications. The combination of kenaf fibre with more than two fibres in hybrid composites enhances the potential uses of kenaf in many applications. The well-known limitations of natural fibres, such as lack of thermal stability, strength degradation, water absorption and poor impact properties, encourage the exploration of hybridisation with high performance fibres. Methods: We review the researches on kenaf reinforced composites and kenaf reinforced hybrid biocomposites. This review covers the types of matrix used, methods applied in manufacturing the hybrid composites and the potential application of the hybrid composites. Results: Kenaf fibres are widely used in fibre reinforced composites. There are limitations in the use of kenaf in polymeric composites, including high moisture absorption, non-uniformity and poor mechanical properties. Hybridisation of kenaf fibre with other fibres resulted in the hybrid composites with comparable strength, stiffness, strength to weight ratio, resistance and other physical and mechanical properties. The selection of matrix materials also plays an important role in fibre reinforced composites materials. There will be an increase in the use of natural fibre hybrid composites in areas such as household products and automotives. Conclusion: Kenaf fibres play an important role in multi-application composites. This fibre is used solely in polymer matrix or in combination either with other natural fibres or with synthetic fibres. Kenaf hybrid composites are being developed as a potential alternative to reduce the use of synthetic fibres such as aramid or glass fibres.

Background: Natural and synthetic fibers are known for their low density, easier fabrication than metallic in several engineering applications. Furthermore, their structural rigidity is high and they can be used for advanced applications, such as aerospace applications and automotive industry sector. Methods: Owing to this in depth, studies had been conducted to evaluate its failure modes and process of fabrication for axial and lateral crushing behaviour to replace metallic materials. In this review paper, failure modes and geometrical designs such as shapes, triggering and geometry have been examined, where these factors are affected on crashworthiness parameters. The main aim of this review article is the reported work done in crushing behavior and failure modes of natural, synthetic and manufacturing technique process parameters on fibers reinforced composite tubes. Results: The results showed that the failure modes and crushing behavior in composite tubes depend on the type of material reinforced composite tubes and structure. Conclusion: The failure modes and crushing behavior in composite tubes depend on the type of material reinforced composite tubes and structure.

Background: The rising environmental awareness has driven efforts for the development of renewable materials for various end-use applications. The trend of using biopolymer in combination with organic or non-organic filler has increased rapidly in recent years. Seaweed is a versatile organism that produces various kinds of polysaccharides i.e. agar, carrageenan and alginate that are extensively used in the development of biopolymer. Biopolymers derived from seaweed polysaccharides possess promising features as they are renewable, biodegradable, biocompatible, and environment-friendly. The aims of this paper are to review research related to the seaweed and its biopolymers for various applications. Methods: Research articles related to the seaweed and its biopolymers are reviewed. The summary of seaweed composites and seaweed biopolymers modification are provided. Results: Seaweed has been used for various applications ranging from food, thickening agent, natural medicine, biofuel, biosorbent material, etc. Seaweed was also used as reinforcement to improve the mechanical properties of polymer composites. Various modifications have been done on seaweed biopolymer to improve the properties of the materials such as blending with other polymers, the addition of compatibilizer, and reinforcement with other materials. The potential of seaweed polymers i.e. agar, carrageenan, and alginate in various applications such as packaging and pharmaceutical show promising characteristics for applications. Conclusion: Seaweed is a highly potential source for renewable biopolymers. These biopolymers have shown great characteristics for various applications due to their unique film-forming ability and excellent mechanical properties. These properties can be further improved following various modification techniques i.e. reinforcement and blending. The potential of seaweed as filler in polymer composites provides evidence to improve the thermal, physical, and mechanical properties of the synthetic polymer matrix. It can be concluded that seaweed is a highly potential renewable resource for the development of biocompatible and environmentally friendly materials.

Background: In this study, scaffolds were fabricated using a desktop robot based rapid prototyping (DRBRP) system that was developed in-house. Poly lactic acid (PLA) and calcium carbonate (CaCO3) composites, doped with silver nanoparticles (nAg), were used for the scaffolds. The effect of injection parameters on the porosity rate of both, the single and hybrid scaffolds, were examined. Clearly, the incorporation of 1 wt% of CaCO3, and 0.5 wt% nAg, had no effect on the flow ability of the viscous polymer, and thus optimization was easy. Scanning electron microscopy (SEM) analysis aided in optimizing the process parameters, and therefore improving the surface morphology, and pore structure. Method: Compression tests were performed to understand the coupled effect of CaCO3 nanoparticles, and the porosity on the mechanical properties of the bulk scaffolds. Result: The compressive modulus of the PLA/CaCO3/nAg scaffolds reached values of 0.38 GPa, and 0.28 GPa, at porosities of 40 % and 50%, respectively. Conclusion: Despite the difficulty in reproducing scaffolds with exact porosities, it could be concluded that the stiffness of the hybrid scaffolds increased in comparison to the single PLA scaffolds, at equal porosities.

Background: Appropriate design and development (in terms of mechano-chemical properties) of scaffold is essentially important for scaffold-based tissue engineering. Methods: In this study, scaffolds were fabricated using a desktop robot based rapid prototyping (DRBRP) system that was developed in-house. Poly lactic acid (PLA) and calcium carbonate (CaCO3) composites, doped with silver nanoparticles (nAg), were used for the scaffolds. The effect of injection parameters on the porosity rate of both, the single and hybrid scaffolds, were examined. Results: Clearly, the incorporation of 1 wt% of CaCO3, and 0.5 wt% nAg, had no effect on the flow ability of the viscous polymer, and thus optimization was easy. Scanning electron microscopy (SEM) analysis aided in optimizing the process parameters, and therefore improving the surface morphology, and pore structure. Compression tests were performed to understand the coupled effect of CaCO3 nanoparticles, and the porosity on the mechanical properties of the bulk scaffolds. The compressive modulus of the PLA/CaCO3/nAg scaffolds reached values of 0.38 GPa, and 0.28 GPa, at porosities of 40 % and 50%, respectively. Conclusion: Despite the difficulty in reproducing scaffolds with exact porosities, it could be concluded that the stiffness of the hybrid scaffolds increased in comparison to the single PLA scaffolds, at equal porosities.

Background: The mechanical properties of novel flax fibre reinforced corrugated composite structures subjected to quasi-static and dynamic compression loading are investigated in this paper. Polypropylene (PP) and polylactic acid (PLA) have been used as thermoplastic matrices to enhance the recyclability of the composite material. Methods: The corrugations were manufactured using matched-die compression moulding and then used as cores in sandwich panels having facings of the same material. The effect of increasing the number of corrugations on the compressive properties of the sandwich panels was investigated by subjecting them to compression loading. Results: The results indicated a monotonic increase in the absorbed energy as the number of corrugations increased from two to five. All of the panels based on flax/PP composites showed a greater energy- absorbing capability compared to those made from flax/PLA. Conclusion: The cores exhibited progressive cell-wall buckling and cell wall folding, characteristic of a typical energy-absorbing structure. The predominant mode of failure was buckling, and then cell wall fracture for the flax/PP corrugations in contrast to interlaminar delamination, and fibre buckling for the flax/PLA cores. Failure maps indicate that the cell walls buckle at low relative densities (up to 0.01) with cell wall fracture occurring at higher relative densities. At the balanced relative density, where both buckling and fracture of the cell walls occur simultaneously, the corresponding stresses are 0.8 MPa for the flax/PLA composite and 0.6 MPa for flax/PP composite. The associated relative density is about 0.01 for both cases.

SPR System for On-Site Detection of Biological Warfare [Current Analytical Chemistry, 2017, 13(2), 144-149] The authors wish to add Lidia Mizak and Romuald Gryko to the author list of this article for his contributions to this article. The complete author list and contact details for Lidia Mizak and Romuald Gryko are as follows: Maciej Trzaskowski^a,*, Lidia Mizak^b, Romuald Gryko^b and Tomasz Ciach^aaDepartment of Biotechnology and Bioprocess Engineering, Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warsaw, Poland; ^bMilitary Institute of Hygiene and Epidemiology, Pulawy, Poland