The major hurdle in melt-processing of ultra-high molecular weight polyethylene (UHMWPE) nanocomposite lies on the high melt viscosity of the UHMWPE, which may contribute to poor dispersion and distribution of the nanofiller. In this study, UHMWPE/cellulose nanofiber (UHMWPE/CNF) bionanocomposites were prepared by two different blending methods: (i) melt blending at 150 °C in a triple screw kneading extruder, and (ii) non-melt blending by ethanol mixing at room temperature. Results showed that melt-processing of UHMWPE without CNF (MB-UHMWPE/0) exhibited an increment in yield strength and Young's modulus by 15% and 25%, respectively, compared to the Neat-UHMWPE. Tensile strength was however reduced by almost half. Ethanol mixed sample without CNF (EM-UHMWPE/0) on the other hand showed slight decrement in all mechanical properties tested. At 0.5% CNF inclusion, the mechanical properties of melt-blended bionanocomposites (MB-UHMWPE/0.5) were improved as compared to Neat-UHMWPE. It was also found that the yield strength, elongation at break, Young's modulus, toughness and crystallinity of MB-UHMWPE/0.5 were higher by 28%, 61%, 47%, 45% and 11%, respectively, as compared to the ethanol mixing sample (EM-UHMWPE/0.5). Despite the reduction in tensile strength of MB-UHMWPE/0.5, the value i.e., 28.4 ± 1.0 MPa surpassed the minimum requirement of standard specification for fabricated UHMWPE in surgical implant application. Overall, melt-blending processing is more suitable for the preparation of UHMWPE/CNF bionanocomposites as exhibited by their characteristics presented herein. A better mechanical interlocking between UHMWPE and CNF at high temperature mixing with kneading was evident through FE-SEM observation, explains the higher mechanical properties of MB-UHMWPE/0.5 as compared to EM-UHMWPE/0.5.
Biodegradable polymers are an exceptional class of polymers that can be decomposed by bacteria. They have received significant interest from researchers in several fields. Besides this, biodegradable polymers can also be incorporated with fillers to fabricate biodegradable polymer composites. Recently, a variety of ionic liquids have also been applied in the fabrication of the polymer composites. In this brief review, two types of fillers that are utilized for the fabrication of biodegradable polymer composites, specifically organic fillers and inorganic fillers, are described. Three types of synthetic biodegradable polymers that are commonly used in biodegradable polymer composites, namely polylactic acid (PLA), polybutylene succinate (PBS), and polycaprolactone (PCL), are reviewed as well. Additionally, the influence of two types of ionic liquid, namely alkylimidazolium- and alkylphosphonium-based ionic liquids, on the mechanical, thermal, and chemical properties of the polymer composites, is also briefly reviewed. This review may be beneficial in providing insights into polymer composite investigators by enhancing the properties of biodegradable polymer composites via the employment of ionic liquids.
We propose and demonstrate dendrimer-based coatings for a sensitive biochip surface that enhance the high-performance sorption of small molecules (i.e., biomolecules with low molecular weights) and the sensitivity of a label-free, real-time photonic crystal surface mode (PC SM) biosensor. Biomolecule sorption is detected by measuring changes in the parameters of optical modes on the surface of a photonic crystal (PC). We describe the step-by-step biochip fabrication process. Using oligonucleotides as small molecules and PC SM visualization in a microfluidic mode, we show that the PAMAM (poly-amidoamine)-modified chip's sorption efficiency is almost 14 times higher than that of the planar aminosilane layer and 5 times higher than the 3D epoxy-dextran matrix. The results obtained demonstrate a promising direction for further development of the dendrimer-based PC SM sensor method as an advanced label-free microfluidic tool for detecting biomolecule interactions. Current label-free methods for small biomolecule detection, such as surface plasmon resonance (SPR), have a detection limit down to pM. In this work, we achieved for a PC SM biosensor a Limit of Quantitation of up to 70 fM, which is comparable with the best label-using methods without their inherent disadvantages, such as changes in molecular activity caused by labeling.
Ethylene glycol dimethacrylate (EGDMA) is used as a crosslinker in poly(acrylonitrile (AN)-co-vinylbenzyl chloride (VBC)) to investigate the effect of long-chain crosslinker to the porosity of the terpolymer system. Poly(AN-co-EGDMA-co-VBC) is synthesized by using precipitation polymerization method and further hypercrosslinked by Friedel-Crafts reaction. FT-IR spectra of poly(AN-co-EGDMA-co-VBC) show that the absorption bands at ~1290 cm-1 that are assigned to the C-Cl vibrations are almost disappeared in hypercrosslinked (HXL) poly(AN-co-EGDMA-co-VBC) polymers, confirming that the hypercrosslinking reaction is successful. SEM images show that the morphologies of the polymers are retained through the hypercrosslinking reactions. Brunauer-Emmett-Teller (BET) analysis shows that hypercrosslinked polymers had a specific surface area up to 59 m2·g-1. The preliminary performance of the terpolymer adsorbent to capture polar analyte is evaluated by adsorbing salicylic acid and mefenamic acid from aqueous solution in a batch system. The maximum adsorption capacity of salicylic acid and mefenamic acid were up to 416.7 mg·g-1 and 625 mg·g-1, respectively, and the adsorption kinetic data obeyed pseudo-second-order rate equation.
Over the last few decades, processing and compatibility have become challenging and interesting investigation areas of polymer matrix nanocomposites. This study investigated the addition of maleic anhydride (MAH) at different ratios with graphene nanoplatelets (GnPs) in poly(lactic acid)/modified natural rubber/polyaniline/GnP (PLA/m-NR/PANI/GnP) nanocomposites via two processing methods: a two-step technique and a one-pot technique. The former technique involved first preparing a master batch of PLA grafted with MAH, followed by a second step involving the melt blending of the nanocomposite (T1) using MAH-g-PLA. On the other hand, the one-pot technique involved the direct mixing of MAH during the melt-blending process (T2). The mechanical, morphological and thermal properties of the prepared nanocomposites were investigated. The findings showed that adding MAH significantly improved the tensile strength and elongation at break by about 25% for PLA/m-NR/PANi/GnP nanocomposites, with an optimal ratio of 1:1 of MAH-g-PLA to GnP loading using the T1 technique. FTIR analysis confirmed the chemical interaction between MAH and PLA for T1 nanocomposites, which exhibited improved phase morphology with smoother surfaces. MAH-compatibilized nanocomposites had enhanced thermal stabilities when compared to the sample without a compatibilizer. The findings show that the compatibilized PLA nanocomposite is potentially suitable for bio-inspired materials.
The effect of crump rubber on the dry sliding wear behavior of epoxy composites is investigated in the present study. Wear tests are carried out for three levels of crump rubber (10, 20, and 30 vol.%), normal applied load (30, 40, and 50 N), and sliding distance (1, 3, and 5 km). The wear behavior of crump rubber-epoxy composites is investigated against EN31 steel discs. The hybrid mathematical approach of Taguchi-coupled Grey Relational Analysis (GRA)-Principal Component Analysis (PCA) is used to examine the influence of crump rubber on the tribological response of composites. Mathematical and experimental results reveal that increasing crump rubber content reduces the wear rate of composites. Composites also show a significant decrease in specific wear values at higher applied loads. Furthermore, the coefficient of friction also shows a decreasing trend with an increase in crump rubber content, indicating the effectiveness of reinforcing crump rubber in a widely used epoxy matrix. Analysis of Variance (ANOVA) results also reveal that the crump rubber content in the composite is a significant parameter to influence the wear characteristic. The post-test temperature of discs increases with an increase in the applied load, while decreasing with an increase in filler loading. Worn surfaces are analyzed using scanning electron microscopy to understand structure-property correlations. Finally, existing studies available in the literature are compared with the wear data of the present study in the form of a property map.
One of the approaches to prolong the service lifespan of polymeric material is the development of self-healing ability by means of embedded microcapsules containing a healing agent. In this work, poly(melamine-urea-formaldehyde) (PMUF) microcapsules containing a palm oil-based alkyd were produced by polymerization of melamine resin, urea and formaldehyde that encapsulated droplets of the suspended alkyd particles. A series of spherical and free-flowing microcapsules were obtained. The chemical properties of core and shell materials were characterized by Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and proton nuclear magnetic resonance spectroscopy (¹H-NMR). Differential scanning calorimetry (DSC) analysis showed a glass transition around -15 °C due to the alkyd, and a melting temperature at around 200 °C due to the shell. Thermogravimetric analysis (TGA) results showed that the core and shell thermally degraded within the temperature range of 200⁻600 °C. Field emission scanning electron microscope (FESEM) examination of the ruptured microcapsule showed smooth inner and rough outer surfaces of the shell. Flexural strength and microhardness (Vickers) of the cured epoxy compound were not affected with the incorporation of 1%⁻3% of the microcapsules. The viability of the healing reactions was demonstrated by blending small amounts of alkyd with epoxy and hardener at different ratios. The blends could readily cure to non-sticky hard solids at room temperature and the reactions could be verified by ATR-FTIR.
This study aims to develop chitosan-based voriconazole nanoparticles (NPs) using spray-drying technique. The effect of surfactants and polymers on the physicochemical properties, in vitro release, and permeation of NPs was investigated. The prepared NPs containing various surfactants and polymers (e.g., Tween 20 (T20), Tween 80 (T80), sodium lauryl sulfate (SLS), propylene glycol (PG), and Polyethylene glycol-4000 (PEG-4000)) were physiochemically evaluated for size, zeta potential, drug content, percent entrapment efficiency, in vitro release, and permeation across rats' skin. A Franz diffusion cell was used for evaluating the in vitro release and permeation profile. The voriconazole-loaded NPs were investigated for antifungal activity against Candida albicans (C. albicans). The prepared NPs were in the nano range (i.e., 160-500 nm) and positively charged. Images taken by a scanning electron microscope showed that all prepared NPs were spherical and smooth. The drug content of NPs ranged from 75% to 90%. Nanoparticle formulations exhibited a good in vitro release profile and transport voriconazole across the rat's skin in a slow control release manner. The NPs containing SLS, T80, and PG exhibited the best penetration and skin retention profile. In addition, the formulation exhibited a potential antifungal effect against C. albicans. It was concluded that the development of chitosan NPs has a great potential for the topical delivery of voriconazole against fungal infection.
Tissue engineering and regenerative medicine are generally concerned with reconstructing cells, tissues, or organs to restore typical biological characteristics. Liposomes are round vesicles with a hydrophilic center and bilayers of amphiphiles which are the most influential family of nanomedicine. Liposomes have extensive research, engineering, and medicine uses, particularly in a drug delivery system, genes, and vaccines for treatments. Exosomes are extracellular vesicles (EVs) that carry various biomolecular cargos such as miRNA, mRNA, DNA, and proteins. As exosomal cargo changes with adjustments in parent cells and position, research of exosomal cargo constituents provides a rare chance for sicknesses prognosis and care. Exosomes have a more substantial degree of bioactivity and immunogenicity than liposomes as they are distinctly chiefly formed by cells, which improves their steadiness in the bloodstream, and enhances their absorption potential and medicinal effectiveness in vitro and in vivo. In this review, the crucial challenges of exosome and liposome science and their functions in disease improvement and therapeutic applications in tissue engineering and regenerative medicine strategies are prominently highlighted.
Various swelling drug delivery devices are promising materials for control drug delivery because of their ability to swell and release entrapped therapeutics, in response to physiological stimuli. Previously, many mathematical models have been developed to predict the mechanism of drug release from a swelling device. However, some of these models do not consider the changes in diffusion behaviour as the device swells. Therefore, we used a two-phase approach to simplify the mathematical model considering the effect of swelling on the diffusion coefficient. We began by defining a moving boundary problem to consider the swelling process. Landau transformation was used for mitigating the moving boundary problem. The transformed problem was analytically solved using the separation of variables method. Further, the analytical solution was extended to include the drug release in two phases where each phase has distinct diffusion coefficient and continuity condition was applied. The newly developed model was validated by the experimental data of bacterial cellulose hydrogels using the LSQCURVEFIT function in MATLAB. The numerical test showed that the new model exhibited notable improvement in curve fitting, and it was observed that the initial effective diffusion coefficient of the swelling device was lower than the later effective diffusion coefficient.
This work is a pioneer attempt to fabricate quasi-solid dye-sensitized solar cell (QSDDSC) based on organosoluble starch derivative. Rheological characterizations of the PhSt-HEC blend based gels exhibited viscoelastic properties favorable for electrolyte fabrication. From amplitude sweep and tack test analyses, it was evident that the inclusion of LiI improved the rigidity and tack property of the gels. On the other hand, the opposite was true for TPAI based gels, which resulted in less rigid and tacky electrolytes. The crystallinity of the gels was found to decline with increasing amount of salt in both systems. The highest photoconversion efficiency of 3.94% was recorded upon addition of 12.5 wt % TPAI and this value is one of the highest DSSC performance recorded for starch based electrolytes. From electrochemical impedance spectroscopy (EIS), it is deduced that the steric hindrance imposed by bulky cations aids in hindering recombination between photoanode and electrolyte.
A starch-resorcinol-formaldehyde (RF)-lithium triflate (LiTf) based biodegradable polymer electrolyte membrane was synthesized via the solution casting technique. The formation of RF crosslinks in the starch matrix was found to repress the starch's crystallinity as indicated by the XRD data. Incorporation of the RF plasticizer improved the conductivity greatly, with the highest room-temperature conductivity recorded being 4.29 × 10-4 S cm-1 achieved by the starch:LiTf:RF (20 wt.%:20 wt.%:60 wt.%) composition. The enhancement in ionic conductivity was an implication of the increase in the polymeric amorphous region concurrent with the suppression of the starch's crystallinity. Chemical complexation between the plasticizer, starch, and lithium salt components in the electrolyte was confirmed by FTIR spectra.
In this paper, we review various novel/modified interfacial polymerization (IP) techniques for the fabrication of polyamide (PA) thin film composite (TFC)/thin film nanocomposite (TFN) membranes in both pressure-driven and osmotically driven separation processes. Although conventional IP technique is the dominant technology for the fabrication of commercial nanofiltration (NF) and reverse osmosis (RO) membranes, it is plagued with issues of low membrane permeability, relatively thick PA layer and susceptibility to fouling, which limit the performance. Over the past decade, we have seen a significant growth in scientific publications related to the novel/modified IP techniques used in fabricating advanced PA-TFC/TFN membranes for various water applications. Novel/modified IP lab-scale studies have consistently, so far, yielded promising results compared to membranes made by conventional IP technique, in terms of better filtration efficiency (increased permeability without compensating solute rejection), improved chemical properties (crosslinking degree), reduced surface roughness and the perfect embedment of nanomaterials within selective layers. Furthermore, several new IP techniques can precisely control the thickness of the PA layer at sub-10 nm and significantly reduce the usage of chemicals. Despite the substantial improvements, these novel IP approaches have downsides that hinder their extensive implementation both at the lab-scale and in manufacturing environments. Herein, this review offers valuable insights into the development of effective IP techniques in the fabrication of TFC/TFN membrane for enhanced water separation.
The bio-inspired structure (e.g., honeycomb) has been studied for its ability to absorb energy and its high strength. The cell size and wall thickness are the main elements that alter the structural ability to withstand load and pressure. Moreover, adding a secondary structure can increase the compressive strength and energy absorption (EA) capability. In this study, the bio-inspired structures are fabricated by fused deposition modelling (FDM) technology using polylactic acid (PLA) material. Samples are printed in the shape of a honeycomb structure, and a starfish shape is used as its reinforcement. Hence, this study focuses on the compression strength and EA of different cell sizes of 20 and 30 mm with different wall thicknesses ranging from 1.5 to 2.5 mm. Subsequently, the deformation and failure of the structures are determined under the compression loading. It is found that the smaller cell size with smaller wall thickness offered a crush efficiency of 69% as compared to their larger cell size with thicker wall thickness counterparts. It is observed that for a 20 mm cell size, the EA and maximum peak load increase, respectively, when the wall thickness increases. It can be concluded that the compression strength and EA capability increase gradually as the cell size and wall thickness increase.
Natural fibers have proven to be excellent reinforcing agents in composite materials. However, a critical disadvantage of natural fibers is their hydrophilic nature. In this study, banana trunk fibers were mechanically damaged using a high-speed blender, and the resulting fibers (MDBTF) were treated with (i) stearic acid (SAMDBTF) and (ii) calcium carbonate coated with 5% (wt/wt) stearic acid (SACCMDBTF). The moisture sorption, oil sorption and thermal properties of the fibers were determined. The morphology, roughness and the functional groups present were also investigated. Study data of the present study indicate that SACCMDBTF exhibited a faster oil sorption capacity than SAMDBTF. Fast uptake of the oil occurred during the first 5 min, whereby the quantity of oil sorbed in SAMDBTF and SACCMDBTF was 5.5 and 15.0 g oil g-1 fiber, respectively. The results of a used engine oil uptake study revealed that SAMDBTF and SACCMDBTF sorbed 9.5 and 18.3 g/g-1 fiber, respectively, at equilibrium. The obtained results suggest that the mechanically damaged process improved the thermal stability of the fibers. This work reveals that the inclusion of stearic-acid-coated calcium carbonate into the interstices of MDBTF yields is environmentally safe for green hydrophobic composites. SACCMDBTF are used as efficient adsorbents for the removal of spilled oil on aqueous media.
This work represents a study to investigate the mechanical properties of longitudinal basalt/woven-glass-fiber-reinforced unsaturated polyester-resin hybrid composites. The hybridization of basalt and glass fiber enhanced the mechanical properties of hybrid composites. The unsaturated polyester resin (UP), basalt (B) and glass fibers (GF) were fabricated using the hand lay-up method in six formulations (UP, GF, B7.5/G22.5, B15/G15, B22.5/G7.5 and B) to produce the composites, respectively. This study showed that the addition of basalt to glass-fiber-reinforced unsaturated polyester resin increased its density, tensile and flexural properties. The tensile strength of the B22.5/G7.5 hybrid composites increased by 213.92 MPa compared to neat UP, which was 8.14 MPa. Scanning electron microscopy analysis was used to observe the fracture mode and fiber pullout of the hybrid composites.
The granite processing industry generates large amounts of bottom granite dust waste every day. After the drying and heating process of concrete mixture production, the granite dust is blown and collected in the filtering nozzle. This very fine particle granite dry fly dust, with a particle size maximum distribution of 500 μm, can easily be blown away by wind and cause serious environmental impacts. The use of this waste material would be an effective way to reduce such impacts. Therefore, this paper presents an experimental study on the potential of granite dust as a filler in enhancing the mechanical performance of a hybrid basalt/glass (WB/GCSM) composite. The unhole and open hole tensile (UHT and OHT) properties, low velocity impact (LVI) properties, quasi-static indentations (QSI) properties, flexural properties, interlaminar shear stress (ILSS) properties, and morphology of the developed WB/GCSM composites were evaluated. To meet the objective of this study, composite specimens were produced using 1.5-60 μm granite fly dust at three (3) different loadings (1, 3 and 5 wt%). This granite fly dust was incorporated into polyurethane resin using a mechanical stirring technique. The production of FRP laminates then completed using a hand lay-up and vacuum bagging technique. Four types of the WB/GCSM composites systems, i.e., [WB/GCSM], [WB/GCSM/1GD], [WB/GCSM/3GD] and [WB/GCSM/5GD] were fabricated and compared. The analysis results for the mechanical tests revealed that the incorporation of granite dust of up to 3 wt% had increased the UHT, OHT, LVI, QSI, flexural and ILSS properties of all WB/GCSM composites systems. Higher levels of damage tolerance in UHT and OHT tests, and increased ductility index in the LVI test were obtained when granite dust was added up to 5 wt%. However, a remarkable improvement in all mechanical properties was noticed for [WB/GCSM/1GD], which recorded the highest mechanical performance among all WB/GCSM composite systems.
In this work, the optimum filler loading to prepare epoxy/organoclay nanocomposites by the in-situ polymerization method was studied. Bi-functionalized montmorillonite at different filler loading (0.5, 1.0, 2.0, 4.0 wt %) was dispersed in epoxy resin by using a high shear speed homogenizer. The effect on morphology, thermal, dynamic mechanical, and tensile properties of the epoxy/organoclay nanocomposites were studied in this work. Wide-angle X-ray scattering (WAXS) and field emission scanning electron microscope (FESEM) studies revealed that possible intercalated structures were obtained in epoxy/organoclay nanocomposites. Thermogravimetric analysis (TGA) shows that epoxy/organoclay nanocomposites exhibit higher thermal stability at the maximum and final decomposition temperature, as well as higher char content, compared to pristine epoxy. The dynamic mechanical analysis (DMA) indicate that storage modulus (E'), loss modulus (E″), cross-link density and glass transition temperature (Tg) of the nanocomposites were improved with organoclay loading up to 1 wt %. Beyond this loading limit, the deterioration of properties was observed. A similar trend was also observed on tensile strength and modulus. We concluded from this study that organoclay loading up to 1 wt % is suitable for further study to fabricate hybrid nanocomposites for various applications.
Polyhydroxyalkanoates (PHAs) are storage granules found in bacteria that are essentially hydroxy fatty acid polyesters. PHA molecules appear in variety of structures, and amongst all types of PHAs, polyhydroxybutyrate (PHB) is used in versatile fields as it is a biodegradable, biocompatible, and ecologically safe thermoplastic. The unique physicochemical characteristics of these PHAs have made them applicable in nanotechnology, tissue engineering, and other biomedical applications. In this review, the optimization, extraction, and characterization of PHAs are described. Their production and application in nanotechnology are also portrayed in this review, and the precise and various production methods of PHA-based nanoparticles, such as emulsion solvent diffusion, nanoprecipitation, and dialysis are discussed. The characterization techniques such as UV-Vis, FTIR, SEM, Zeta Potential, and XRD are also elaborated.
Biological macromolecules like polysaccharides/proteins/glycoproteins have been widely used in the field of tissue engineering due to their ability to mimic the extracellular matrix of tissue. In addition to this, these macromolecules are found to have higher biocompatibility and no/lesser toxicity when compared to synthetic polymers. In recent years, scaffolds made up of proteins, polysaccharides, or glycoproteins have been highly used due to their tensile strength, biodegradability, and flexibility. This review is about the fabrication methods and applications of scaffolds made using various biological macromolecules, including polysaccharides like chitosan, agarose, cellulose, and dextran and proteins like soy proteins, zein proteins, etc. Biopolymer-based nanocomposite production and its application and limitations are also discussed in this review. This review also emphasizes the importance of using natural polymers rather than synthetic ones for developing scaffolds, as natural polymers have unique properties, like high biocompatibility, biodegradability, accessibility, stability, absence of toxicity, and low cost.