In recent years, there has been considerable interest in the use of natural fibers as potential reinforcing fillers in polymer composites despite their hydrophilicity, which limits their widespread commercial application. The present study explored the fabrication of nanocomposites by melt mixing, using an internal mixer followed by a compression molding technique, and incorporating rice husk (RH) as a renewable natural filler, montmorillonite (MMT) nanoclay as water-resistant reinforcing nanoparticles, and polypropylene-grafted maleic anhydride (PP-g-MAH) as a compatibilizing agent. To correlate the effect of MMT delamination and MMT/RH dispersion in the composites, the mechanical and thermal properties of the composites were studied. XRD analysis revealed delamination of MMT platelets due to an increase in their interlayer spacing, and SEM micrographs indicated improved dispersion of the filler(s) from the use of compatibilizers. The mechanical properties were improved by the incorporation of MMT into the PP/RH system and the reinforcing effect was remarkable as a result of the use of compatibilizing agent. Prolonged water exposure of the prepared samples decreased their tensile and flexural properties. Interestingly, the maximum decrease was observed for PP/RH composites and the minimum was for MMT-reinforced and PP-g-MAH-compatibilized PP/RH composites. DSC results revealed an increase in crystallinity with the addition of filler(s), while the melting and crystallization temperatures remained unaltered. TGA revealed that MMT addition and its delamination in the composite systems improved the thermal stability of the developed nanocomposites. Overall, we conclude that MMT nanoclay is an effective water-resistant reinforcing nanoparticle that enhances the durability, mechanical properties, and thermal stability of composites.
Palm fatty acid distillate (PFAD), is a by-product of the crude palm oil refining process. It comprises mainly of free fatty acids-around 45% palmitic and 33% oleic acids-as the major components. Ultra-violet (UV) curable urethane acrylate (UA) oligomers could be synthesized from PFAD, by the following procedure. A hydroxyl terminated macromer was first prepared by reacting PFAD with a mixture of isophthalic acid, phthalic anhydride, neopentagylcol (NPG), and pentaerythritol. The macromer was then reacted with 2-hydroxylethylacrylate (2HEA) and toluene diisocynate (TDI) to generate a resin, containing acrylate side chains for UV curable application. A series of UA resins were prepared by using 15, 25, 45, 55, and 70% of PFAD, respectively. The UA resin has Mw in the range of 3,200 to 27,000. They could be cured by UV irradiation at an intensity of 225 mW/cm². Glass transition temperature (Tg) of the cured film was measured by differential scanning calorimeter (DSC), and hardness of the film was determined by a pendulum hardness tester, according to American Society for Testing and Materials (ASTM)4366. The resins were used in a wood-coating application. All of the cured films showed good adhesion, hardness, and chemical resistance except for the one using the 70% PFAD, which did not cure properly.
A series of ten 5-arylidene Meldrum’s acid derivatives had been synthesised in excellent yield via Knoevenagel condensation. This method does not require catalyst, or any further purification. Isopropylidene malonate (2,2-dimethyl-1,3-dioxane-4,6-dione), also known as Meldrum’s acid, is utilised as a core skeleton for various kind of reactions. Meldrum’s acid has features of a peculiar ring- opening sequences based on nucleophile-sensitive carbonyl functional groups at C-4 and C-6, which has made it possible for useful synthetic transformations, as well as its high acidity of methylene hydrogen at carbon position C-5. Hence, it allows the compound to be a flexible reagent for further reaction to prepare other derivatives. Therefore, Meldrum’s acid derivatives showed high potential of biological functions, such as antibacterial, antimalarial and antioxidant activities due to the olefinic linkage which played an important role in the enhancement of antimalarial activity. Furthermore, when arylidene Meldrum’s acid transformed to epoxide, the compound showed losses of antimalarial behaviour. Additionally, this compound has unique molecules due to the high acidity of methylene hydrogen at the carbon-5 position to initiate various reactions with different functional groups. In this research, Meldrum’s acid, 3 and ten its 5-arylidene derivatives (4a-e) and (5a-e) were synthesised by using two short and efficient reaction steps. The first step involved the condensation of malonic acid, 1 with acetone, 2 in acetic anhydride and acid via one-pot reaction to give Meldrum’s acid, 3 in 50% overall yield. Having Meldrum’s acid in hand, the reaction was proceeded with the Knoevenagel condensation reaction by using various functional groups, such as aryl aldehydes and aryl amines. All the synthesised compounds were characterised by using 1H and 13C spectroscopy.
The effect of polypropylene maleic anhydride (PPMAH) on tensile properties and morphology of polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr)/ rice husk powder (RHP) composites has been studied. The composites were prepared through melt mixing at 180ºC for 9 minutes using 50 rpm rotor speed. The specimens were analyzed using different techniques, namely tensile test and Scanning Electron Microscopy (SEM). The results obtained showed that the tensile strength and Young’s modulus of the modified composites were increased, while the elongation at break showed the opposite trend as compared with the unmodified composites. The morphology results support the tensile properties and these indicated a better interaction between the filler and matrix with the presence of PPMAH as a compatibilizer.
Recently, research and development in the field of drug delivery systems (DDS) facilitating site-specific therapy has reached significant progression. DDS based on polymer micelles, coated micro- and nanoparticles, and various prodrug systems including water-soluble polymer have been prepared and extensively studied as novel drugs designed for cancer chemotherapy and brain delivery. Since polymers are going to be used in human, this study has the interest of testing two types of polymer, polyimides (PI) and polyphenylenevinylene (PPV) on neuronal cells. The objective of this study was to determine the possible neurotoxicity and potential neuroprotective effects of PI and PPV towards SH-SY5Y neuronal cells challenged by hydrogen peroxide (1120) as an oxidant. Cells were pretreated with either PI or PPV for 1 hour followed by incubation for 24 hour with 100 ,uM of 11201. MTS • assay was used to assess cell viability. Results show that PI and PPV are not harmful within the concentration up to 10 pM and 100 pM, respectively. However, PI and PPV do not protect neuronal cells against toxicity induced by H2O, or further up the cell death.
In this study, the effects of lignin modification on the properties of kenaf core fiber reinforced poly(butylene succinate) biocomposites were examined. A weight percent gain (WPG) value of 30.21% was recorded after the lignin were modified with maleic anhydride. Lower mechanical properties were observed for lignin composites because of incompatible bonding between the hydrophobic matrix and the hydrophilic lignin. Modified lignin (ML) was found to have a better interfacial bonding, since maleic anhydrides remove most of the hydrophilic hydrogen bonding (this was proven by a Fourier-transform infrared (FTIR) spectrometer-a reduction of broadband near 3400 cm-1, corresponding to the -OH stretching vibration of hydroxyl groups for the ML samples). On the other hand, ML was found to have a slightly lower glass transition temperature, Tg, since reactions with maleic anhydride destroy most of the intra- and inter-molecular hydrogen bonds, resulting in a softer structure at elevated temperatures. The addition of kraft lignin was found to increase the thermal stability of the PBS polymer composites, while modified kraft lignin showed higher thermal stability than pure kraft lignin and possessed delayed onset thermal degradation temperature.
In this study, poly(ethylene terephthalate) (PET) wastes bottle was recycled by glycolysis process using ethylene glycol. The unsaturated polyester resin (UPR) was then prepared by reacting the glycolysed product with maleic anhydride. The blend of UPR based on recycled PET wastes with liquid natural rubber (LNR) was carried out by varying the amount of LNR from 0 to 7.5 wt%. Mechanical tests such as tensile and impact were conducted to investigate the effects of LNR on the mechanical properties. Scanning Electron Microscopy (SEM) was used to analyze the morphology of the breaking area resulted from the tensile tests on the UPR and blend samples. From the results, the blend of 2.5 wt% LNR in UPR based recycled PET wastes achieved the highest strength in the mechanical properties and showed a well dispersed of elastomer particles in the sample morphology compared to other blends concentrations. This blend sample was then compared to the optimum blend of LNR with commercial resin through the glass transition temperature value Tg, mechanical strength and morphology properties. The comparison study showed that the Tg for UPR based recycled PET was higher than the value represented from commercial resin due to the degree of crystalinity in the molecular structure of the materials. LNR was found to be an effective impact modifier which gave a greater improvement in UPR from recycled PET wastes structure but not to the commercial one which needs 5% LNR to achieve the optimum properties. Thus, the compatibility between the UP resin based recycled PET and LNR was much better than with the commercial resin.
In this work, the oil palm empty fruit bunch (EFB) fiber was used as a source of lignocellulosic filler to fabricate a novel type of cost effective biodegradable composite, based on the aliphatic aromatic co-polyester poly(butylene adipate-co-terephtalate) PBAT (Ecoflex™), as a fully biodegradable thermoplastic polymer matrix. The aim of this research was to improve the new biocomposites' performance by chemical modification using succinic anhydride (SAH) as a coupling agent in the presence and absence of dicumyl peroxide (DCP) and benzoyl peroxide (BPO) as initiators. For the composite preparation, several blends were prepared with varying ratios of filler and matrix using the melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 (wt %) and characterized. The effects of fiber loading and coupling agent loading on the thermal properties of biodegradable polymer composites were evaluated using thermal gravimetric analysis (TGA). Scanning Electron Microscopy (SEM) was used for morphological studies. The chemical structure of the new biocomposites was also analyzed using the Fourier Transform Infrared (FTIR) spectroscopy technique. The PBAT biocomposite reinforced with 40 (wt %) of EFB fiber showed the best mechanical properties compared to the other PBAT/EFB fiber biocomposites. Biocomposite treatment with 4 (wt %) succinic anhydride (SAH) and 1 (wt %) dicumyl peroxide (DCP) improved both tensile and flexural strength as well as tensile and flexural modulus. The FTIR analyses proved the mechanical test results by presenting the evidence of successful esterification using SAH/DCP in the biocomposites' spectra. The SEM micrograph of the tensile fractured surfaces showed the improvement of fiber-matrix adhesion after using SAH. The TGA results showed that chemical modification using SAH/DCP improved the thermal stability of the PBAT/EFB biocomposite.
The aims of this study were to fabricate cellulose acetate (CA) film from oil palm empty fruit bunch (OP-EPB), as well as to characterize and evaluate their biocompatibility. Several processes were carried out, and these included prehydrolysis-soda method, chlorine free bleaching method, including oxygen, ozone and peroxide, to produce the cellulose pulp. Then, a liquid phase acetylation method was applied through acetic acid-acetic anhydride-sulphuric acid. Triethyl citrate (TEC) ester was used as additive at different percentages of 10, 20, 30 and 40 wt%. The film produced was characterized by FTIR to identify the functional group of the CA film and their tensile properties were further characterized. Biocompatibility of the film was evaluated using cytotoxicity test. Stem cell derived from human deciduous teeth (SHED) was used with MTS assay. The results showed at 30% of TEC, the tensile strength and elongation of CA (OP-EFB) film was at the optimum and is therefore suitable to be used in dental application. The cytotoxicity evaluated showed that the fabricated CA (OP-EFB) films were non-toxic up to the concentration tested, and are thus compatible with SHED.