New environmentally friendly plasticized poly(lactic acid) (PLA) kenaf biocomposites were obtained through a melt blending process from a combination of epoxidized jatropha oil, a type of nonedible vegetable oil material, and renewable plasticizer. The main objective of this study is to investigate the effect of the incorporation of epoxidized jatropha oil (EJO) as a plasticizer and alkaline treatment of kenaf fiber on the thermal properties of PLA/Kenaf/EJO biocomposites. Kenaf fiber was treated with 6% sodium hydroxide (NaOH) solution for 4 h. The thermal properties of the biocomposites were analyzed using a differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It must be highlighted that the addition of EJO resulted in a decrease of glass transition temperature which aided PLA chain mobility in the blend as predicted. TGA demonstrated that the presence of treated kenaf fiber together with EJO in the blends reduced the rate of decomposition of PLA and enhanced the thermal stability of the blend. The treatment showed a rougher surface fiber in scanning electron microscopy (SEM) micrographs and had a greater mechanical locking with matrix, and this was further supported with Fourier-transform infrared spectroscopy (FTIR) analysis. Overall, the increasing content of EJO as a plasticizer has improved the thermal properties of PLA/Kenaf/EJO biocomposites.
Crude jatropha oil (JO) was modified to form jatropha oil-based polyol (JOL) via two steps in a chemical reaction known as epoxidation and hydroxylation. JOL was then reacted with isocyanates to produce JO-based polyurethane resin. In this study, two types of isocyanates, 2,4-toluene diisocyanate (2,4-TDI) and isophorone diisocyanate (IPDI) were introduced to produce JPUA-TDI and JPUA-IPDI respectively. 2,4-TDI is categorised as an aromatic isocyanate whilst IPDI is known as a cycloaliphatic isocyanate. Both JPUA-TDI and JPUA-IPDI were then end-capped by the acrylate functional group of 2-hydroxyethyl methacrylate (HEMA). The effects of that isocyanate structure were investigated for their physico, chemical and thermal properties. The changes of the functional groups during each synthesis step were monitored by FTIR analysis. The appearance of urethane peaks was observed at 1532 cm-1, 1718 cm-1 and 3369 cm-1 while acrylate peaks were detected at 815 cm-1 and 1663 cm-1 indicating that JPUA was successfully synthesised. It was found that the molar mass of JPUA-TDI was doubled compared to JPUA-IPDI. Each resin showed a similar degradation pattern analysed by thermal gravimetric analysis (TGA). For the mechanical properties, the JPUA-IPDI-based coating formulation exhibited a higher hardness value but poor adhesion compared to the JPUA-TDI-based coating formulation. Both types of jatropha-based polyurethane acrylate may potentially be used in an ultraviolet (UV) curing system specifically for clear coat surface applications to replace dependency on petroleum-based chemicals.
This paper focuses on the synthesis and mechanism of carbon nanospheres (CNS) coated with few- and multi-layered graphene (FLG, MLG). The graphitic carbon encapsulates the core/shell structure of the Ni/NiO nanoparticles via the chemical vapor deposition (CVD) method. The application of the resulting CNS and hybrids of CNS-FLG and CNS-MLG as reinforcement nanofillers in a polypropylene (PP) matrix were studied from the aspects of mechanical and thermal characteristics. In this research, to synthesize carbon nanostructures, nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) and acetylene (C₂H₂) were used as the catalyst source and carbon source, respectively. Besides, the morphology, structure and graphitization of the resulting carbon nanostructures were investigated. On the other hand, the mechanisms of CNS growth and the synthesis of graphene sheets on the CNS surface were studied. Finally, the mechanical and thermal properties of the CNS/PP, CNS-FLG/PP, and CNS-MLG/PP composites were analyzed by applying tensile test and thermogravimetric analysis (TGA), respectively.
A new sensing area for a sensor based on surface plasmon resonance (SPR) was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI) conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU) were obtained for PPy-CHI film due to a specific binding of chitosan with Pb(2+) and Hg(2+) ions. The Pb(2+) ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb(2+) compared to Hg(2+). The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.
Jatropha oil-based polyol (JOL) was prepared from crude Jatropha oil via an epoxidation and hydroxylation reaction. During the isocyanation step, two different types of diisocyanates; 2,4-toluene diisocyanate (2,4-TDI) and isophorone diisocyanate (IPDI), were introduced to produce Jatropha oil-based polyurethane acrylates (JPUA). The products were named JPUA-TDI and JPUA-IPDI, respectively. The success of the stepwise reactions of the resins was confirmed using 1H nuclear magnetic resonance (NMR) spectroscopy to support the Fourier-transform infrared (FTIR) spectroscopy analysis that was reported in the previous study. For JPUA-TDI, the presence of a signal at 7.94 ppm evidenced the possible side reactions between urethane linkages with secondary amine that resulted in an aryl-urea group (Ar-NH-COO-). Meanwhile, the peak of 2.89 ppm was assigned to the α-position of methylene to the carbamate (-CH2NHCOO) group in the JPUA-IPDI. From the rheological study, JO and JPUA-IPDI in pure form were classified as Newtonian fluids, while JPUA-TDI showed non-Newtonian behaviour with pseudoplastic or shear thinning behaviour at room temperature. At elevated temperatures, the JO, JPUA-IPDI mixture and JPUA-TDI mixture exhibited reductions in viscosity and shear stress as the shear rate increased. The JO and JPUA-IPDI mixture maintained Newtonian fluid behaviour at all temperature ranges. Meanwhile, the JPUA-TDI mixture showed shear thickening at 25 °C and shear thinning at 40 °C, 60 °C and 80 °C. The master curve graph based on the shear rate for the JO, JPUA-TDI mixture and JPUA-IPDI mixture at 25 °C, 40 °C, 60 °C and 80 °C was developed as a fluid behaviour reference for future storage and processing conditions during the encapsulation process. The encapsulation process can be conducted to fabricate a self-healing coating based on a microcapsule triggered either by air or ultra-violet (UV) radiation.
In the present study, a sequence of experiments was performed to assess the influence of the key process parameters on the formation of a carbon nanofiber-coated monolith (CNFCM), using a four-level factorial design in response surface methodology (RSM). The effect of reaction temperature, hydrocarbon flow rate, catalyst and catalyst promoter were examined using RSM to enhance the formation yield of CNFs on a monolith substrate. To calculate carbon yield, a quadratic polynomial model was modified through multiple regression analysis and the best possible reaction conditions were found as follows: a reaction temperature of 800 °C, furfuryl alcohol flow of 0.08525 mL/min, ferrocene catalyst concentration of 2.21 g. According to the characterization study, the synthesized CNFs showed a high graphitization which were uniformly distributed on a monolith substrate. Besides this, the feasibility of carbon dioxide (CO2) adsorption from the gaseous mixture (N2/CO2) under a range of experimental conditions was investigated at monolithic column. To get the most out of the CO2 capture, an as-prepared sample was post-modified using ammonia. Furthermore, a deactivation model (DM) was introduced for the purpose of studying the breakthrough curves. The CO2 adsorption onto CNFCM was experimentally examined under following operating conditions: a temperature of 30-50 °C, pressure of 1-2 bar, flow rate of 50-90 mL/min, and CO2 feed amount of 10-40 vol.%. A lower adsorption capacity and shorter breakthrough time were detected by escalating the temperature. On the other hand, the capacity for CO2 adsorption increased by raising the CO2 feed amount, feed flow rate, and operating pressure. The comparative evaluation of CO2 uptake over unmodified and modified CNFCM adsorbents confirmed that the introduced modification procedure caused a substantial improvement in CO2 adsorption.
The method of pre-irradiation grafting was used with the aid of electron beam (EB) accelerator to accomplish the grafting of polyamide 6 fibers (PA6) with glycidyl methacrylate (GMA). The extent to which GMA was grafted on PA6 was found to be markedly influenced by the absorbed dose of radiation and the reaction time of grafting. Trimethylamine (TMA) was afterwards employed for the functionalization of GMA-grafted fibers (PA6-g-GMA). A range of analyses (e.g., FTIR, FESEM, XRD, BET, and pHpzc) were carried out to determine the physiochemical and morphological properties of the fibrous adsorbent. p-Nitrophenol (PNP) adsorption from aqueous solution was conducted with the resulting TMA-(PA6-g-GMA) adsorbent. The adsorption behaviour of PNP on the fibrous adsorbent was clarified by investigating the adsorption kinetics and isotherm. According to the results, the adsorption of PNP on TMA-(PA6-g-GMA) reflected the pseudo-second order model. Meanwhile, the isotherm analysis revealed that the best description of the equilibrium data was provided by Redlich-Peterson model, followed closely by Langmuir isotherm model. The achieved adsorption capacity was highest at 176.036 mg/g. Moreover, the adsorption was indicated by the thermodynamic analysis to be spontaneous and exothermic. Regeneration and recycling of the adsorbent was possible for a minimum of five cycles with no reduction in adsorption capacity. It was concluded that the fibrous adsorbent could have applications for the removal of PNP at industrial pilot scale.
Iron and steel industries are among the contributors of CO2 emission in large volume into the atmosphere, causing detrimental effects to the environment and the ecosystem at large scale. These industries also generate solid wastes in the form of electric arc furnace (EAF) slag during operations which result in about 10-15% slag wastes per ton of steel produced. In this study, the EAF slags from an iron and steel-making factory in Klang, Malaysia was utilized for CO2 sequestration through direct aqueous mineral carbonation. According to the surface area analysis, the fresh EAF slag has a mesoporous structure, its elemental composition shows the presence of 20.91 wt.% of CaO that was used for the sequestration of CO2 through carbonation. The sequestration capacity was found to be 58.36 g CO2/kg of slag at ambient temperature in 3 h, with the liquid/solid (L/S) ratio of 5:1 and using <63μm particle size. Moreover, the shrinking core model (SCM) was used to analyze the solid-fluid reaction in a heterogeneous phase and the CO2 sequestration shows to be controlled by the product layer phase. The EAF slag is demonstrated to have the potential of CO2 sequestration at ambient temperature.