Synthesis and characterization of polyene from polyvinylchloride (PVC) and its coating properties with epoxidised oil resin / Mohd Nurazzi Norizan

Synthesis of polyene for development of conductive coating involves new research area. Hence, this study was aimed to produce the polyene itself from polyvinylchloride (PVC) and disperse into a sustainable oil matrix as coating. Effect of dechlorination of PVC employing different reaction time and conditions were studied. Synthesized polyene formed upon dechlorination process via chemical method was characterized before the polyene powders were dispersed in epoxidised oil (EO) which acts as binder for coating on glass substrate. All polyene powders were then doped with 5% percent of potassium iodide (KI) and the highest value of conductivity was selected to be doped with 10%, 20% and 30% of KI. Thermal characterization via thermal gravimetry analysis and differential scanning calorimetry analysis were also performed to determine the properties of polyene after the dechlorination. For the polyene coated film, conductivity test, UV/Visible and energy band gap determination and wettability study were characterized. Wettability properties of polyene coated layer onto glass slide were determined by performing contact angle test. Based on the elemental analysis by energydispersive x-ray spectroscopy (EDS), it is shown that a maximum about 95% of chlorine was eliminated after 2 hours reaction time of dechlorination process. Existence of conjugated bond and effect of doping onto polyene were proven through fourier transform infrared (FTIR) and polyene index. As for polyene powder/ modified EO coated film, sample with 2 hours reaction time showed optimum value of conductivity before and after doped with 5% KI with the value of 1.92 x 10¯³ Scm¯¹ and 3.37 x 10¯³ Scm¯¹ respectively. Hence, in the second stage of analysis, the 2 hours sample was chosen to be doped with 10%, 20% and 30% of KI for analysis of doping effect on conductivity. Based on UV/Vis analysis, the wavelength of maximum absorbance was found to have various absorption peaks due to the different existence of chain conjugation phenomena. UV wavelength absorbance peak values give energy band gap relation and can thus be calculated. Wettability properties of polyene coated layer onto glass slide were also performed to determine the contact angle of film

The effects of alkali treatment on the mechanical and chemical properties of banana fibre and adhesion to epoxy resin

The main focus of this study was to obtain the optimum alkaline treatment for banana fibre and the its effect on the mechanical and chemical properties of banana fibre, its surface topography, its heat resistivity, as well as its interfacial bonding with epoxy matrix. Banana fibre was treated with sodium hydroxide (NaOH) under various treatment conditions. The treated fibres were characterised using FTIR spectroscopy. The morphology of a single fibre observed under a Digital Image Analyser indicated slight reduction in fibre diameter with increasing NaOH concentration. The Scanning Electron Microscope (SEM) results showed the deteriorating effect of alkali, which can be seen from the removal of impurities and increment in surface roughness. The mechanical analysis indicates that 6% NaOH treatment with a two-hour immersion time gave the highest tensile strength. The adhesion between single fibre and epoxy resin was analysed through the micro-droplet test. It was found that 6% NaOH treatment with a two-hour immersion yielded the highest interfacial shear stress of 3.96 MPa. The TGA analysis implies that alkaline treatment improved the thermal and heat resistivity of the fibre

A review: fibres, polymer matrices and composites

The growing interest, environmental consciousness and high performance demands on engineering have led to extensive research and development of new and improved materials. Among the most commonly used natural fibres are kenaf, oil palm, sugar palm, pineapple leaf fibre, flax, hemp, sisal, coir and jute. These fibres are used to reinforce thermoplastic polymer matrices such as polystyrene (PS), polypropylene (PP), polyethylene (PE) and polyvinyl chloride (PVC). Meanwhile, phenolic, unsaturated polyester vinyl ester and epoxy resin are for thermosetting polymer matrices. The objective of this paper is to solicit works that cover major class of natural fibres, thermosetting polymers matrices, which detail about unsaturated polyester resin and hybrid biocomposites industry

Mechanical properties of sugar palm yarn/woven glass fiber reinforced unsaturated polyester composites: effect of fiber loadings and alkaline treatment

In this paper, hybrid sugar palm yarn and glass fiber reinforced unsaturated polyester composites were investigated in relation to the effects of fiber loadings and alkaline treatment on the composite mechanical properties, such as tensile, flexural, impact and compression strength. The composites were fabricated at a weight ratio of matrix to reinforcement of 70 : 30 and 60 : 40, respectively, while the ratio of sugar palm yarn fiber to glass fiber was selected at 70 : 30, 60 : 40 and 50 : 50, respectively. The results revealed that the mechanical properties of the hybrid composites were increased with an increase of glass fiber loading for both 30 wt % and 40 wt % reinforcement content. The alkaline treatment of the sugar palm fibers have advantageous effect on the hybrid composite performance. The overall results indicated that the developed hybrid composites can be used as an alternative material for glass fiber reinforced polymer composites for various structural applications

Characterizations of MWCNTs nanofluids on the effect of surface oxidative treatments

In this study, multi-walled carbon nanotubes (MWCNTs) were chemically modified using three acid treatment methods to introduce the surface oxygen functional group (SOFG). The presence of SOFG on the MWCNTs has been characterized by Fourier Transform Infrared (FTIR) spectroscopy. Morphology, structural and thermal properties were performed using Field Emission Scanning Electron Microscopy (FESEM), Raman spectroscopy, and Thermogravimetric analysis (TGA), respectively. The result shows that the modification with acid treatment significantly affects the degree of defects and surface group functionality of surface oxidized MWCNTs from method B. The preparation of nanofluids using MWCNTs produced from method B (MWCNT-MB) was prepared using two different parameters: with and without polyvinylpyrrolidone (PVP) as surfactant. The experiment was conducted by setting variable carbon particle concentration from 0.1 wt.% to 1.0 wt.%, and the amount of PVP is 10% of carbon particles at different temperatures (6 ◦C, 25 ◦C, 40 ◦C). Based on visual observation, the dispersion of carbon particles was enhanced by the presence of PVP as the stabilizing agent. The thermal conductivity performance of nanofluids revealed that the surface oxidized MWCNTs with PVP show enhanced thermal conductivity compared to the nanofluid containing MWCNTs without PVP. The improvement contributes to this in terms of stability and homogenization of nanoparticles. Hence the improved distribution of MWCNTs in water-based media improves thermal conductivity. These promising properties of MWCNTs in water-based fluids would enable the nanofluids to be used in heat transfer fluid and cooling applications

Effect of reaction time on the structure and optical properties of P3HT/MWCNT-OH nanocomposites

In the present study, regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) coated hydroxylated multi-walled carbon nanotubes (MWCNT-OH) nanocomposites were prepared over different reaction times of non-covalent functionalization. The reaction time was set as 24, 48, 72, 96, and 120 hours. The structure and optical characteristics of nanocomposites were analyzed using Fourier-transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy, respectively. Reaction time affected prepared nanocomposites by decreasing the intensity of the P3HT/MWCNT-OH peaks gradually with increasing of the reaction time. Comparing with the pure P3HT and MWCNT-OH, the calculated energy band gap and the Urbach energy of the nanocomposites were reduced proportionally as the reaction time reached 120 hours and achieved 2.60 and 0.329 eV, respectively

Surface-oxidised carbon nanofibre-based nanofluids: Structural, morphological, stability and thermal properties

The reputation of nanofluids as a convenient heat transfer media has grown in recent years. The synthesis of nanofluids is often challenging, particularly carbon-based nanofluids, due to the rapid agglomeration of the nanoparticles and the instability of the nanofluids. In this regard, surface modification and surfactant addition are potential approaches to improve the physical and thermal properties of carbon-based nanofluids that have been studied and the structural, morpho-logical, and thermal characteristics of surface-oxidised carbon nanofibre (CNF)-based nanofluids has been characterised. Commercial CNF was first subjected to three different acid treatments to introduce surface oxygen functional groups on the CNF surface. Following the physical and thermal characterisation of the three surface-oxidised CNFs (CNF-MA, CNF-MB, and CNF-MC), including Raman spectroscopy, Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM), the CNF-MB was selected as the best method to synthesise the surface-oxidised CNF-based nanofluid. A total of 40 mL of ultrapure water was used as a pure base fluid and mixed with the surface-oxidised CNF at a concentration range of 0.1– 1.0 wt.%, with a fixed of 10 wt.% amount of polyvinylpyrrolidone (PVP). The thermal conductivity of CNF-based nanofluid was then characterised at different temperatures (6, 25, and 40 °C). Based on the results, surface oxidation via Method B significantly affected the extent of surface defects and effectively enhanced the group functionality on the CNF surface. Aside from the partially defective and rough surface of CNF-MB surfaces from the FESEM analysis, the presence of surface oxygen functional groups on the CNF wall was confirmed via the Raman analysis, TGA curve, and FTIR analysis. The visual sedimentation observation also showed that the surface-oxidised CNF particles remained dispersed in the nanofluid due to the weakened van der Waals interaction. The dispersion of CNF particles was improved by the presence of PVP, which further stabilised the CNF-based nanofluids. Ultimately, the thermal conductivity of the surface-oxidised CNF-based nanofluid with PVP was significantly improved with the highest enhancement percentage of 18.50, 16.84, and 19.83% at 6, 25, and 40 °C, respectively, at an optimum CNF concentration of 0.7 wt.%

Heterojunctions of rGO/metal oxide nanocomposites as promising gas-sensing materials—A review

Monitoring environmental hazards and pollution control is vital for the detection of harmful toxic gases from industrial activities and natural processes in the environment, such as nitrogen dioxide (NO2), ammonia (NH3), hydrogen (H2), hydrogen sulfide (H2S), carbon dioxide (CO2), and sulfur dioxide (SO2). This is to ensure the preservation of public health and promote workplace safety. Graphene and its derivatives, especially reduced graphene oxide (rGO), have been designated as ideal materials in gas-sensing devices as their electronic properties highly influence the potential to adsorb specified toxic gas molecules. Despite its exceptional sensitivity at low gas concentrations, the sensor selectivity of pristine graphene is relatively weak, which limits its utility in many practical gas sensor applications. In view of this, the hybridization technique through heterojunction configurations of rGO with metal oxides has been explored, which showed promising improvement and a synergistic effect on the gas-sensing capacity, particularly at room temperature sensitivity and selectivity, even at low concentrations of the target gas. The unique features of graphene as a preferential gas sensor material are first highlighted, followed by a brief discussion on the basic working mechanism, fabrication, and performance of hybridized rGO/metal oxide-based gas sensors for various toxic gases, including NO2, NH3, H2, H2S, CO2, and SO2. The challenges and prospects of the graphene/metal oxide-based based gas sensors are presented at the end of the review

Effect of fibre length and sea water treatment on mechanical properties of sugar palm fibre reinforced unsaturated polyester composites

This study presented the effect of different fibre length and seawater treatment on mechanical properties of the fabricated composites. The composite was reinforced with fixed 30wt.% of fibre loading. Sugar palm was treated using sea water for 30 days and have been cut into three different lengths by 5cm, 10cm and 15cm. The mechanical properties of the untreated and treated fibre with different fibre length composites were characterised includes tensile test and flexural test. Treated sugar palm fibre composites with 15cm fibre length exhibited higher tensile strength at 18.33 MPa. However, it shows the lowest value for the tensile modulus at 4251.96MPa. The flexural strength shows an increasing trend as the fibre length increased up to 15cm and the maximum flexural strength was exhibited by treated sugar palm fibre with 5 cm at 80.80MPa

Effect of fiber orientation and fiber loading on the mechanical and thermal properties of sugar palm yarn fiber reinforced unsaturated polyester resin composites

Sugar palm [Arenga pinnata (Wurmb.) Merr] fiber reinforced unsaturated polyester resin composites with 0°, 45°, and 90° fiber different orientations were prepared and tested. The composites were characterized for tensile, flexural, impact and compression properties using ASTM D3039, ASTM D790, ASTM D250, and ASTM D3410 standards, respectively. For the thermal characterization, dynamic mechanical analysis (DMA) was conducted to characterize the on storage modulus (E’), loss modulus (E’’) and damping behavior (tan δ) of the composites. The highest mechanical performance of composites was achieved at 0° of fiber orientation composites followed by 45° and 90° fiber orientations. The fiber loading was insignificant for the 90° fiber orientation as the properties were inconsistent. The theoretical value of modulus from the tensile test was calculated using rules of mixture (ROM) and compared with the experimental values for all composites specimens. This research showed that the optimum properties occurred at 30 wt % fiber loading as reflected by the superior tensile and flexural strengths. The optimum properties of compression, impact, storage modulus and better damping properties were achieved at 40 wt % fiber loading