This research demonstrates a one-step modification process of biopolymer carrageenan active sites through functional group substitution in κ-carrageenan structures. The modification process improves the electronegative properties of κ-carrageenan derivatives, leading to enhancement of the material's performance. Synthesized succinyl κ-carrageenan with a high degree of substitution provides more active sites for interaction with analytes. The FTIR analysis of succinyl κ-carrageenan showed the presence of new peaks at 1068 cm-1, 1218 cm-1, and 1626 cm-1 that corresponded to the vibrations of C-O and C=O from the carbonyl group. A new peak at 2.86 ppm in 1H NMR represented the methyl proton neighboring with C=O. The appearance of new peaks at 177.05 and 177.15 ppm in 13C NMR proves the substitution of the succinyl group in the κ-carrageenan structure. The elemental analysis was carried out to calculate the degree of substitution with the highest value of 1.78 at 24 h of reaction. The XRD diffractogram of derivatives exhibited a higher degree of crystallinity compared to pristine κ-carrageenan at 23.8% and 9.2%, respectively. Modification of κ-carrageenan with a succinyl group improved its interaction with ions and the conductivity of the salt solution compared to its pristine form. This work has a high potential to be applied in various applications such as sensors, drug delivery, and polymer electrolytes.
Conventionally, panel boards are produced with material flex or microparticle with P.U. or U.F. as adhesives. However, in this study, nanoparticle with epoxy resin as an adhesive was used to produce nanoboard. Coconut shell nanoparticle composite with epoxy resin as an adhesive was prepared using a compression molding technique. The coconut shell particles were originally 200 mesh size and then milled mechanically with a ball mill for the duration of 10, 20, 30, and 40 h (milling times) to produce nanoparticles. The composition ratio of the composite is 85 vol.% of coconut shell and 15 vol.% of epoxy resin. The formation of nanoparticles was observed with transmission electron microscopy (TEM). The mechanical, physical, and microstructure properties of the composite were examined with X-ray diffraction, scanning electron microscopy, atomic force microscopy, and universal testing machine. The results established that the properties of the composite (microstructures, mechanical, and physical) are influenced by the duration of milling of coconut shell particles. The modulus and flexural strength of the composite improved with an increase in the milling time. The density, thickness swelling, and porosity of the composite were also influenced by the milling times. The result suggested that the composite properties were influenced by the particle size of the coconut shell. The coconut shell nanoparticle composite can be used in the manufacturing of hybrid panels and board.
The incorporation of kenaf fiber fillers into a polymer matrix has been pronounced in the past few decades. In this study, the effect of multiwalled carbon nanotubes (MWCNTs) with a short kenaf fiber (20 mesh) with polypropylene (PP) added was investigated. The melt blending process was performed using an internal mixer to produce polymer composites with different filler contents, while the suitability of this melt composite for the injection molding process was evaluated. Thermogravimetric analysis (TGA) was carried out to investigate the thermal stability of the raw materials. Rheological analyses were conducted by varying the temperature, load factor, and filler content. The results demonstrate a non-Newtonian pseudoplastic behavior in all samples with changed kenaf fillers (10 to 40 wt %) and MWCNT contents (1 to 4 wt %), which confirm the suitability of the feedstock for the injection molding process. The addition of MWCNTs had an immense effect on the viscosity and an enormous reduction in the feedstock flow behavior. The main contribution of this work is the comprehensive observation of the rheological characteristics of newly produced short PP/kenaf composites that were altered after MWCNT additions. This study also presented an adverse effect on the composites containing MWCNTs, indicating a hydrophilic property with improved water absorption stability and the low flammability effect of PP/kenaf/MWCNT composites. This PP/kenaf/MWCNT green composite produced through the injection molding technique has great potential to be used as car components in the automotive industry.
Collagen (Col) is a naturally available material and is widely used in the tissue engineering and medical field owing to its high biocompatibility and malleability. Promising results on the use of Col were observed in the periodontal application and many attempts have been carried out to inculcate Col for gingival recession (GR). Col is found to be an excellent provisional bioscaffold for the current treatment in GR. Therefore, the aim of this paper is to scrutinize an overview of the reported Col effect focusing on in vitro, in vivo, and clinical trials in GR application. A comprehensive literature search was performed using EBSCOhost, Science Direct, Springer Link, and Medline & Ovid databases to identify the potential articles on particular topics. The search query was accomplished based on the Boolean operators involving keywords such as (1) collagen OR scaffold OR hybrid scaffold OR biomaterial AND (2) gingiva recession OR tissue regeneration OR dental tissue OR healing mechanism OR gingiva. Only articles published from 2015 onwards were selected for further analysis. This review includes the physicochemical properties of Col scaffold and the outcome for GR. The comprehensive literature search retrieved a total of 3077 articles using the appropriate keywords. However, on the basis of the inclusion and exclusion criteria, only 15 articles were chosen for further review. The results from these articles indicated that Col promoted gingival tissue regeneration for GR healing. Therefore, this systematic review recapitulated that Col enhances regeneration of gingival tissue either through a slow or rapid process with no sign of cytotoxicity or adverse effect.
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.
This paper investigated the static behaviour of glass fibre reinforced polymer (GFRP) built-up hollow and concrete filled built-up beams tested under four-point bending with a span-to-depth ratio of 1.67, therefore focusing their shear performance. Two parameters considered for hollow sections were longitudinal web stiffener and strengthening at the web-flange junction. The experimental results indicated that the GFRP hollow beams failed by web crushing at supports; therefore, the longitudinal web stiffener has an insignificant effect on improving the maximum load. Strengthening web-flange junctions using rectangular hollow sections increased the maximum load by 47%. Concrete infill could effectively prevent the web crushing, and it demonstrated the highest load increment of 162%. The concrete filled GFRP composite beam failed by diagonal tension in the lightweight concrete core. The finite element models adopting Hashin damage criteria yielded are in good agreement with the experimental results in terms of maximum load and failure mode. Based on the numerical study, the longitudinal web stiffener could prevent the web buckling of the slender GFRP beam and improved the maximum load by 136%. The maximum load may be further improved by increasing the thickness of the GFRP section and the size of rectangular hollow sections used for strengthening. It was found that the bond-slip at the concrete-GFRP interface affected the shear resistance of concrete-GFRP composite beam.
Natural product extraction is ingenuity that permits the mass manufacturing of specific products in a cost-effective manner. With the aim of obtaining an alternative chitosan supply, the carapace of dead horseshoe crabs seemed feasible. This sparked an investigation of the structural changes and antioxidant capacity of horseshoe crab chitosan (HCH) by γ-irradiation using 60Co source. Chitosan was extracted from the horseshoe crab (Tachypleus gigas; Müller) carapace using heterogeneous chemical N-deacetylation of chitin, followed by the irradiation of HCH using 60Co at a dose-dependent rate of 10 kGy/hour. The average molecular weight was determined by the viscosimetric method. Regarding the chemical properties, the crystal-like structures obtained from γ-irradiated chitosan powders were determined using Fourier transfer infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analyses. The change in chitosan structure was evident with dose-dependent rates between 10 and 20 kGy/hour. The antioxidant properties of horseshoe crab-derived chitosan were evaluated in vitro. The 20 kGy γ-irradiation applied to chitosan changed the structure and reduced the molecular weight, providing sufficient degradation for an increase in antioxidant activity. Our findings indicate that horseshoe crab chitosan can be employed for both scald-wound healing and long-term food preservation due to its buffer-like and radical ion scavenging ability.
This research paper investigates the electrochemical performance of chitosan (CS): dextran (DX) polymer-blend electrolytes (PBEs), which have been developed successfully with the incorporation of ammonium hexafluorophosphate (NH4PF6). X-ray diffraction (XRD) analysis indicates that the plasticized electrolyte system with the highest value of direct current (DC) ionic conductivity is the most amorphous system. The glycerol addition increased the amorphous phase and improved the ionic dissociation, which contributed to the enhancement of the fabricated device's performance. Transference number analysis (TNM) has shown that the charge transport process is mainly by ions rather than electrons, as tion = 0.957. The CS:DX:NH4PF6 system was found to decompose as the voltage goes beyond 1.5 V. Linear sweep voltammetry (LSV) revealed that the potential window for the most plasticized system is 1.5 V. The fabricated electrochemical double-layer capacitor (EDLC) was analyzed with cyclic voltammetry (CV) and charge-discharge analysis. The results from CV verify that the EDLC in this work holds the characteristics of a capacitor. The imperative parameters of the fabricated EDLC such as specific capacitance and internal resistance were found to be 102.9 F/g and 30 Ω, respectively. The energy stored and power delivered by the EDLC were 11.6 Wh/kg and 2741.2 W/kg, respectively.
This study aimed to investigate the effects of nanohydroxyapatite-silica-glass ionomer cement (nanoHA-silica-GIC) on the differentiation of dental pulp stem cells (DPSCs) into odontogenic lineage. DPSCs were cultured in complete Minimum Essential Medium Eagle-Alpha Modification (α-MEM) with or without nanoHA-silica-GIC extract and conventional glass ionomer cement (cGIC) extract. Odontogenic differentiation of DPSCs was evaluated by real-time reverse transcription polymerase chain reaction (rRT-PCR) for odontogenic markers: dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), osteocalcin (OCN), osteopontin (OPN), alkaline phosphatase (ALP), collagen type I (COL1A1), and runt-related transcription factor 2 (RUNX2) on day 1, 7, 10, 14, and 21, which were normalized to the house keeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Untreated DPSCs were used as a control throughout the study. The expressions of DSPP and DMP1 were higher on days 7 and 10, that of OCN on day 10, those of OPN and ALP on day 14, and that of RUNX2 on day 1; COL1A1 exhibited a time-dependent increase from day 7 to day 14. Despite the above time-dependent variations, the expressions were comparable at a concentration of 6.25 mg/mL between the nanoHA-silica-GIC and cGIC groups. This offers empirical support that nanoHA-silica-GIC plays a role in the odontogenic differentiation of DPSCs.
The scope of additive manufacturing, particularly fused deposition modelling (FDM), can indeed be explored with the fabrication of multi-material composite laminates using this technology. Laminar composite structures made up of two distinct materials, namely acrylonitrile butadiene styrene (ABS) and carbon fiber reinforced polylactic acid (CF-PLA), were produced using the FDM process. The current study analyzes the effect of various printing parameters on the interfacial bond strength (IFBS) of the ABS/CF-PLA laminar composite by employing response surface methodology. The physical examination of the tested specimens revealed two failure modes, where failure mode 1 possessed high IFBS owing to the phenomenon of material patch transfer. Contrarily, failure mode 2 yielded low IFBS, while no patch transfer was observed. The analysis of variance (ANOVA) revealed that printing parameters were highly interactive in nature. After extensive experimentation, it was revealed that good quality of IFBS is attributed to the medium range of printing speed, high infill density, and low layer height. At the same time, a maximum IFBS of 20.5 MPa was achieved. The study presented an empirical relation between printing parameters and IFBS that can help in forecasting IFBS at any given printing parameters. Finally, the optimized printing conditions were also determined with the aim to maximize IFBS.
Diabetic foot ulcer (DFU) is a chronic wound frequently delayed from severe infection. Wound dressing provides an essential barrier between the ulcer and the external environment. This review aimed to analyse the effectiveness of antibacterial collagen-based dressing for DFU treatment in a clinical setting. An electronic search in four databases, namely, Scopus, PubMed, Ovid MEDLINE(R), and ISI Web of Science, was performed to obtain relevant articles published within the last ten years. The published studies were included if they reported evidence of (1) collagen-based antibacterial dressing or (2) wound healing for diabetic ulcers, and (3) were written in English. Both randomised and non-randomised clinical trials were included. The search for relevant clinical studies (n) identified eight related references discussing the effectiveness of collagen-based antibacterial wound dressings for DFU comprising collagen impregnated with polyhexamethylene biguanide (n = 2), gentamicin (n = 3), combined-cellulose and silver (n = 1), gentian violet/methylene blue mixed (n = 1), and silver (n = 1). The clinical data were limited by small sample sizes and multiple aetiologies of chronic wounds. The evidence was not robust enough for a conclusive statement, although most of the studies reported positive outcomes for the use of collagen dressings loaded with antibacterial properties for DFU wound healing. This study emphasises the importance of having standardised clinical trials, larger sample sizes, and accurate reporting for reliable statistical evidence confirming DFU treatment efficiency.
It is necessary to consider the influence of moisture damage on the interlaminar fracture toughness for composite structures that are used for outdoor applications. However, the studies on the progressive variation of the fracture toughness as a function of moisture content M (%) is rather limited. In this regard, this study focuses on the characterization of mode II delamination of carbon/epoxy composites conditioned at 70 °C/85% relative humidity (RH). End-notched flexure test is conducted for specimens aged at various moisture absorption levels. Experimental results reveal that mode II fracture toughness degrades with the moisture content, with a maximum of 23% decrement. A residual property model is used to predict the variation of the fracture toughness with the moisture content. Through numerical simulations, it is found that the approaches used to estimate the lamina and cohesive properties are suitable to obtain reliable simulation results. In addition, the damage initiation is noticed during the early loading stage; however, the complete damage is only observed when the numerical peak load is achieved. Results from the present research could serve as guidelines to predict the residual properties and simulate the mode II delamination behavior under moisture attack.
In this research, the physical, mechanical and morphological properties of oil palm empty fruit bunch (EFB) mat/woven kenaf fabric-reinforced epoxy composites have been investigated. The oil palm EFB/woven kenaf fabrics were varied, with weight ratios of 50/0 (T1), 35/15 (T2), 25/25 (T3), 15/35 (T4) and 0/50 (T5). The composites were fabricated using a simple hand lay-up technique followed by hot pressing. The result obtained shows that an increase in kenaf fiber content exhibited higher tensile and flexural properties. On the other hand, the opposite trend was observed in the impact strength of hybrid composites, where an increase in kenaf fiber content reduced the impact strength. This can be corroborated with the physical properties analysis, where a higher void content, water absorption and thickness swelling were observed for pure oil palm EFB (T1) composites compared to other samples. The scanning electron microscopy analysis results clearly show the different failure modes of the tensile fractured samples. Statistical analysis was performed using one-way ANOVA and shows significant differences between the obtained results.
Polydopamine has been widely used as an additive to enhance membrane fouling resistance. This study reports the effects of two-step dopamine-to-polydopamine modification on the permeation, antifouling, and potential anti-UV properties of polyethersulfone (PES)-based ultrafiltration membranes. The modification was performed through a two-step mechanism: adding the dopamine additive followed by immersion into Tris-HCl solution to allow polymerization of dopamine into polydopamine (PDA). The results reveal that the step of treatment, the concentration of dopamine in the first step, and the duration of dipping in the Tris solution in the second step affect the properties of the resulting membranes. Higher dopamine loadings improve the pure water flux (PWF) by more than threefold (15 vs. 50 L/m2·h). The extended dipping period in the Tris alkaline buffer leads to an overgrowth of the PDA layer that partly covers the surface pores which lowers the PWF. The presence of dopamine or polydopamine enhances the hydrophilicity due to the enrichment of hydrophilic catechol moieties which leads to better anti-fouling. Moreover, the polydopamine film also improves the membrane resistance to UV irradiation by minimizing photodegradation's occurrence.
Various types of activated carbon nanofibers' (ACNFs) composites have been extensively studied and reported recently due to their extraordinary properties and applications. This study reports the fabrication and assessments of ACNFs incorporated with graphene-based materials, known as gACNFs, via simple electrospinning and subsequent physical activation process. TGA analysis proved graphene-derived rice husk ashes (GRHA)/ACNFs possess twice the carbon yield and thermally stable properties compared to other samples. Raman spectra, XRD, and FTIR analyses explained the chemical structures in all resultant gACNFs samples. The SEM and EDX results revealed the average fiber diameters of the gACNFs, ranging from 250 to 400 nm, and the successful incorporation of both GRHA and reduced graphene oxide (rGO) into the ACNFs' structures. The results revealed that ACNFs incorporated with GRHA possesses the highest specific surface area (SSA), of 384 m2/g, with high micropore volume, of 0.1580 cm3/g, which is up to 88% of the total pore volume. The GRHA/ACNF was found to be a better adsorbent for CH4 compared to pristine ACNFs and reduced graphene oxide (rGO/ACNF) as it showed sorption up to 66.40 mmol/g at 25 °C and 12 bar. The sorption capacity of the GRHA/ACNF was impressively higher than earlier reported studies on ACNFs and ACNF composites. Interestingly, the CH4 adsorption of all ACNF samples obeyed the pseudo-second-order kinetic model at low pressure (4 bar), indicating the chemisorption behaviors. However, it obeyed the pseudo-first order at higher pressures (8 and 12 bar), indicating the physisorption behaviors. These results correspond to the textural properties that describe that the high adsorption capacity of CH4 at high pressure is mainly dependent upon the specific surface area (SSA), pore size distribution, and the suitable range of pore size.
Biofouling on the membrane surface leads to performance deficiencies in membrane filtration. In this study, the application of ginger extract as a bio-based additive to enhance membrane antibiofouling properties was investigated. The extract was dispersed in a dimethyl acetamide (DMAc) solvent together with polyvinylidene fluoride (PVDF) to enhance biofouling resistance of the resulting membrane due to its antibiotic property. The concentrations of the ginger extract in the dope solution were varied in the range of 0-0.1 wt %. The antibacterial property of the resulting membranes was assessed using the Kirby Bauer disc diffusion method. The results show an inhibition zone formed around the PVDF/ginger membrane against Escherichia coli and Staphylococcus aureus demonstrating the efficacy of the residual ginger extract in the membrane matrix to impose the antibiofouling property. The addition of the ginger extract also enhanced the hydrophilicity in the membrane surface by lowering the contact angle from 93° to 85°, which was in good agreement with the increase in the pure water flux of up to 62%.
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.
In this paper, sugar palm nanocellulose fibre-reinforced thermoplastic starch (TPS)/poly (lactic acid) (PLA) blend bionanocomposites were prepared using melt blending and compression moulding with different TPS concentrations (20%, 30%, 40%, 60%, and 80%) and constant sugar palm nanocellulose fibres (0.5%). The physical, mechanical, thermal, and water barrier properties were investigated. The SEM images indicated different TPS loading effects with the morphology of the blend bionanocomposites due to their immiscibility. A high content of TPS led to agglomeration, while a lower content resulted in the presence of cracks and voids. The 20% TPS loading reduced the tensile strength from 49.08 to 19.45 MPa and flexural strength from 79.60 to 35.38 MPa. The thermal stability of the blend bionanocomposites was reduced as the TPS loading increased. The thickness swelling, which corresponded to the water absorption, demonstrated an increasing trend with the increased addition of TPS loading.
The refining of the crude palm oil (CPO) generates the palm oil refinery effluent (PORE). The presence of high contents of biochemical oxygen demand (BOD), chemical oxygen demand (COD), turbidity, and suspended solids (SS) in PORE encourages the determination of an effective treatment process to minimize the environmental pollution and preserve aquatic life. In the present study, a biodegradable natural polymer, namely tannin, was utilized as a coagulant to treat PORE. The coagulation experiment was conducted using a jar test apparatus. The tannin coagulation efficiency was evaluated based on the BOD, COD, turbidity, and SS removal from PORE by varying the tannin dose (50-300 mg/L), pH (pH 4-10), treatment time (15-90 min), and sedimentation time (15-90 min). It was found that the maximum removal of BOD, COD, turbidity, and SS was 97.62%, 88.89%, 93.01%, and 90.21%, respectively, at pH 6, a tannin dose of 200 mg/L, 60 min of coagulation time, and 60 min of sedimentation time. Analyses of isotherm models revealed that the Freundlich isotherm model was well fitted with the coagulation study. Kinetics studies show that the pseudo-second-order kinetics model was the well-fitted kinetics model for the BOD, COD, turbidity, and SS removal from PORE using tannin as a polymeric coagulant. The determination of thermodynamics parameters analyses revealed that BOD, COD, turbidity, and SS removal from PORE was spontaneous, exothermic, and chemical in nature. The finding of the present study shows that tannin as a natural polymeric coagulant would be utilized in PORE treatment to avoid toxic sludge generation.
This work reports the use of a ternary composite that integrates p-Toluene sulfonic acid doped polyaniline (PANI), chitosan, and reduced graphene oxide (RGO) as the active sensing layer of a surface plasmon resonance (SPR) sensor. The SPR sensor is intended for application in the non-invasive monitoring and screening of diabetes through the detection of low concentrations of acetone vapour of less than or equal to 5 ppm, which falls within the range of breath acetone concentration in diabetic patients. The ternary composite film was spin-coated on a 50-nm-thick gold layer at 6000 rpm for 30 s. The structure, morphology and chemical composition of the ternary composite samples were characterized by FTIR, UV-VIS, FESEM, EDX, AFM, XPS, and TGA and the response to acetone vapour at different concentrations in the range of 0.5 ppm to 5 ppm was measured at room temperature using SPR technique. The ternary composite-based SPR sensor showed good sensitivity and linearity towards acetone vapour in the range considered. It was determined that the sensor could detect acetone vapour down to 0.88 ppb with a sensitivity of 0.69 degree/ppm with a linearity correlation coefficient of 0.997 in the average SPR angular shift as a function of the acetone vapour concentration in air. The selectivity, repeatability, reversibility, and stability of the sensor were also studied. The acetone response was 87%, 94%, and 99% higher compared to common interfering volatile organic compounds such as propanol, methanol, and ethanol, respectively. The attained lowest detection limit (LOD) of 0.88 ppb confirms the potential for the utilisation of the sensor in the non-invasive monitoring and screening of diabetes.