Assessment of the Mechanical and Microstructural Performance of Waste Kraft Fibre Reinforced Cement Composite Incorporating Sustainable Eco-Friendly Additives

This study investigates the influence of limestone powder and metakaolin as sustainable eco-friendly additives on the properties and behavior of cementitious composite boards, with a focus on mechanical strength, physical properties, and microstructural characteristics. The experimental investigation begins with the characterization of the raw materials, including limestone powder, and metakaolin, to assess their particle sizes, elemental composition, and microstructural features. Cement composite boards were fabricated using an innovatively developed lab-simulated vacuum dewatering process, by varying the proportions of limestone powder and metakaolin as partial replacements for cement, along with waste kraft fibres as reinforcement. Mechanical testing was conducted to evaluate the flexural strength and behaviour of the composite boards according to standardized procedures. A microstructural analysis was performed using scanning electron microscopy (SEM) to examine the effect of additives on the cementitious matrix, fibrematrix interaction, and hydration products. The findings from the experimental study reveal insights into the influence of limestone powder and metakaolin on the mechanical properties and microstructure of waste kraft fibre-reinforced cement composite boards. Our analysis of the results shows that adding 9% limestone powder as partial cement replacement produces a 24% and 50% enhancement in flexural strength at 7 and 28 days of hydration, while that of metakaolin as partial cement replacement was optimum at 6% with an enhancement of 4% and 36%, respectively, at 7 and 28 days of hydration. The implications of these findings for the development of sustainable cementitious composite are discussed, including the potential benefits of using limestone powder and metakaolin as supplementary cementitious materials in waste kraft fibre-reinforced cement composite boards. Finally, recommendations for optimizing additive proportions are also provided to enhance the understanding and application of these materials in the construction and building industries

Fabrication and characterisation of short fibre reinforced elastomer composites for bending and twisting magnetic actuation

Polydimethylsiloxane (PDMS) films reinforced with short Nickel-coated Carbon Fibres (NiCF) were successfully fabricated, with the fibres aligned along different directions using an external magnetic field. The fibres were dispersed in the host matrix using sonication and mechanical mixing before being cured for 48 h in the magnetic field; thanks to the nickel functionalisation, the fibre orientation was achieved by a low intensity field (<0.2 T) which required an inexpensive experimental set-up. The main focus of this study was looking at the actuation potential of this magnetic composite material; successful actuation was achieved, showing its large displacement capability. The results confirm the presence of an instability controlled by the magnetic torque, as predicted by the introduced model. The composite films undergo a transition from a bending-only deformed configuration for the 0° fibre specimen, to a twisting-only configuration, achieved for fibres at 90°, whereas all the intermediate angles show both bending and twisting. This behaviour mirrors that which is used to propel a selection of marine mammals

Optical characterisation of polymeric nanocomposites using tomographic, spectroscopic and Fraunhofer wavefront assessment

Polymers are often embedded with specific nanofillers such that the functional characteristics and properties of the resulting polymeric nanocomposite (PNC) are enhanced. The degree to which these enhancements can be achieved depends not only on the level of particle loading of nanofillers, but most importantly on the resulting dispersion profile achieved within the matrix. Agglomeration (often referred to as clustering) is a result of the mixing process and very much depends on the chemistry between the polymer and nanofiller. Depending on the PNC type, different mixing processes can be applied but the general consensus is that such processes are not repeatable themselves. Not only it is quite difficult to achieve the desired level of dispersion, but in addition there is a limited number of characterization tools that can be employed to routinely check the homogeneity achieved within a produced sample. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques are usually employed, but they are very time consuming, expensive, require special sample preparation and treatment, often produce results that are difficult to interpret and can only analyse very small areas of sample. This work reports on the adaptation and development and three optical techniques that are non-destructive, can accurately characterize the dispersion achieved as a result of the mixing process and can analyse larger material areas. The techniques reported are based on static and dynamic visible and infra-red light scattering

Optimizing the mechanical properties of cement composite boards reinforced with cellulose pulp and bamboo fibers for building applications in low-cost housing estates

Africa is the third-richest continent in the world in terms of bamboo species. Despite these laudable natural resources, most African countries still use asbestos cement board as one of their major building materials. This is chiefly due to the high cost of equipment and technologies associated with non-asbestos-fiber cement board production. The current research seeks to underscore the possibility of utilizing these massive continent resources for non-asbestos-fiber cement board production by employing the existing production process in the asbestos cement industries via an innovatively developed laboratory-simulated Hatschek process. Non-asbestos-fiber cement boards incorporating kraft and bamboo fibers were successfully produced in the laboratory using this innovative method based on Hatschek technology, with natural fibre addition in the range of 2–6 wt.%. Experimental results revealed that the Flexural strength and deflection of the board improved significantly, producing optimum values of 10.41 MPa and 2.0 mm, respectively for composite board reinforced with 10 wt.% and 6 wt.% of kraft pulp and bamboo fibers, respectively. The SEM morphology of the fractured surfaces revealed the mode of composite fracture as well as good interaction at the fiber–matrix interface. Overall, the mechanical properties of the developed composite boards satisfy the minimum requirements of relevant standards based on fiber cement flat sheets and can be employed for internal building applications in low-cost housing estates in developing countries. The outcome of this research indicates that the current industrial production process based on Hatschek technology can be employed for non-asbestos-fiber cement board production using the studied natural fiber.This research was funded by the Tertiary Education Trust Fund (TETFund), Nigeria, through the Academic Staff Training and Development (AST&D) scholarship grant number TETF/ES/ UNIV/ONDO STATE/TSAS/2019/Vol.1

Manufacturing carbon fibres from pitch and polyethylene blend precursors: a review

Carbon fibres are one of the newer, emerging materials with multiple engineering applications, from automobiles to space vehicles. Carbon fibres have high mechanical strength, are lighter than metals with better chemical resistance. There have been reports on the use of polyethylene and pitch precursors for the production of carbon fibres, but there are few reports of how these blends could be used for carbon fibre preparation. Bearing in mind the myriad of benefits that using carbon fibres could bring, this paper reviews recent advances published in the literature on how mesophase pitch and polyethylene could be suitable precursors for carbon fibres. It also provides an introduction to the development of precursor blends that allow the properties of carbon fibres to be tailored to specific applications, including processing techniques, fibre parameters, fibre properties and fibre structur

Drawdown prepreg coating method using epoxy terminated butadiene nitrile rubber to improve fracture toughness of glass epoxy composites

Laminates of fibre-reinforced prepreg have excellent in-plane mechanical properties, but have inadequate performance in the through thickness direction. Here, we address this issue by application of epoxy-terminated butadiene nitrile (ETBN) liquid rubber between the prepreg laminae using an automatic draw bar coating technique. Test results reveal that by adding ETBN in small quantities in the range of 9.33–61.33 g/m2, the interlaminar critical energy release rates (GIc and GIIc) are improved by up to 122% in mode-I and 49% in mode-II. Moreover, this finding is further supported by the dynamic mechanical analysis thermograms that clearly indicate that coating has not altered the Tg of ETBN-coated samples. Scanning electron microscopic analysis of fracture surfaces showed that rubber particles formed micro cavitations in the epoxy, causing localised rubber rich regions. These resin-rich regions require more energy to fracture, resulting in increased toughness of the glass epoxy prepreg systems. </jats:p

Enhanced oral bioavailability and hepatoprotective activity of thymoquinone in the form of phospholipidic nano-constructs

Background: The poor biopharmaceutical properties of thymoquinone (TQ) obstruct its development as a hepatoprotective agent. To surmount the delivery challenges of TQ, phospholipid nanoconstructs (PNCs) were constructed. Method: PNCs were constructed employing microemulsification technique and systematic optimization by three-factor three level Box-Behnken design. Result: Optimized PNC composition exhibited nano size (90%), controlled drug release pattern, and neutral surface charge (zeta potential of −0.65 mV). After oral administration of a single dose of PNC, it showed a relative bioavailability of 386.03% vis-à-vis plain TQ suspension. Further, TQ-loaded PNC demonstrated significant enhanced hepato-protective effect vis-à-vis pure TQ suspension and silymarin, as evidenced by reduction in the ALP, ALT, AST, bilirubin, and albumin level and ratified by histopathological analysis. Conclusion: TQ-loaded PNCs can be efficient nano-platforms for the management of hepatic disorders and promising drug delivery systems to enhance oral bioavailability of this hydrophobic molecule

Natural Antimicrobial Nano Composite Fibres Manufactured from a Combination of Alginate and Oregano Essential Oil

Alginate is a linear biodegradable polysaccharide polymer, which is bio-renewable and widely used for various biomedical applications. For the next generation of medical textiles, alginate nanofibres are desirable for their use in wound dressings that are biocompatible, sustainable, and abundantly available. This study has developed a unique manufacturing process for producing alginate nanofibres with exceptional antimicrobial properties of oregano essential oil (OEO) as a natural antimicrobial agent. OEO with varying degrees of concentration was incorporated in an aqueous alginate solution. Appropriate materials and electrospinning process parameter selection allowed us to manufacture alginate fibres with a range of diameters between 38 and 105 nm. A unique crosslinking process for alginate nanofibres using extended water soaking was developed. Mechanical characterisation using micro-mechanical testing of nonwoven electrospun alginate/oregano composite nanofibres revealed that it was durable. An extensive antimicrobial study was carried out on alginate/oregano composite nanofibres using a range of Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA) and Listeria monocytogenes) and Gram-negative bacteria (Klebsiella pneumoniae and Salmonella enterica), which are common wound and food pathogens. The results indicated that increasing the concentration of OEO from 2 to 3 wt % showed improved antimicrobial activity against all pathogens, and activity was significantly improved against MRSA compared to a non-alginate-based control disk containing OEO. Therefore, our research suggests that all-natural alginate/oregano nanofibre composite textiles offer a new generation of medical textiles for advanced wound dressing technology as well as for food packaging applications