Extraction of lignin via green methods is a crucial step in promoting the bioconversion of lignocellulosic biomasses. In the present study, utilisation of natural deep eutectic solvent for the pretreatment of kenaf fibres biomass is performed. Furthermore, extracted lignin from natural deep eutectic solvent pretreated kenaf biomass was carried out and its comparative study with commercial lignin was studied. The extracted lignin was characterized and investigated through Infrared Fourier transform spectroscopy, X-ray Diffraction, thermogravimetric analysis, UV-Vis spectroscopy, and scanning electron microscopy. FTIR Spectra shows that all samples have almost same set of absorption bands with slight difference in frequencies. CHNS analysis of natural deep eutectic solvent pretreated kenaf fibre showed a slight increase in carbon % from 42.36 to 43.17% and an increase in nitrogen % from - 0.0939 to - 0.1377%. Morphological analysis of commercial lignin shows irregular/uneven surfaces whereas natural deep eutectic solvent extracted lignin shows smooth and wavy surface. EDX analysis indicated noticeable peaks for oxygen and carbon elements which are present in lignocellulosic biomass. Thermal properties showed that lignin is constant at higher temperatures due to more branching and production of extremely condensed aromatic structures. In UV-VIS spectroscopy, commercial lignin shows slightly broad peak between 300 and 400 nm due to presence of carbonyl bond whereas, natural deep eutectic solvent extracted lignin does not show up any peak in this range. XRD results showed that the crystallinity index percentage for kenaf and natural deep eutectic solvent treated kenaf was 70.33 and 69.5% respectively. Therefore, these innovative solvents will undoubtedly have significant impact on the development of clean, green, and sustainable products for biocatalysts, extraction, electrochemistry, adsorption applications.
Hibiscus , Lignin , Lignin/chemistry , Deep Eutectic Solvents , Biomass , Carbohydrates , Solvents/chemistry , Carbon , Hydrolysis
The utilization of agricultural residues to obtain biocompounds of high-added value has significantly increased in the past decades. The conversion of agro-based residues into valuable products appears to be an economically efficient, environment-friendly, and protracted waste management practice. The implementation of ultrasonic technologies in the conversion of value-added goods from agricultural waste materials through pre-treatment and valorization processes has imparted many advantageous effects including rapid processing, effective process performance, minimization of processing steps, minimal dependency on harmful chemicals, and an increased yield and properties of bio-products. To further enliven the literature and inspire new research investigations, this review covers the comprehensive work including theoretical principles, processes, and potential benefits of ultrasonic treatment technologies to assist the production of bio-products which emphasize the extraction yield and the characteristic of the end-product extracted from agriculture residues. A detailed evaluation of these methods and key aspects impacting their performance as well as the features and shortcomings of each ultrasound-assisted approach is also discussed. This review also addressed some of the challenges associated with using ultrasonic irradiation and proposed several potential techniques to maximize productivity. Understanding the concept of ultrasonication technique allow the academician and industrial practitioners to explore the possibility of applying a greener and sustainable approach of biomass extraction to be translated into higher scale production of commercial products.
Recently, most of the commercial polyols used in the production of rigid polyurethane foams (RPUFs) have been derived from petrochemicals. Therefore, the introduction of modified palm oil derivatives-based polyol as a renewable material into the formulation of RPUFs is the focus of this study. A palm oil derivative-namely, methyl oleate (MO)-was successfully modified through three steps of reactions: epoxidation reaction, ring-opened with glycerol, followed by amidation reaction to produce a bio-based polyol named alkanolamide polyol. Physicochemical properties of the alkanolamide polyol were analyzed. The hydroxyl value of alkanolamide polyol was 313 mg KOH/g, which is suitable for producing RPUFs. Therefore, RPUFs were produced by replacing petrochemical polyol with alkanolamide polyol. The effects of alkanolamide polyol on the physical, mechanical and thermal properties were evaluated. The results showed that the apparent density and compressive strength increased, and cell size decreased, upon introducing alkanolamide polyol. All the RPUFs exhibited low water absorption and excellent dimensional stability. The RPUFs made with increased amounts of alkanolamide polyol showed higher thermal conductivity. Nevertheless, the thermal conductivities of RPUFs made with alkanolamide polyol are still within the range for thermal insulating materials (<0.1 W/m.K). The thermal stability of RPUFs was improved with the addition of alkanolamide polyol into the system. Thus, the RPUFs made from alkanolamide polyol are potential candidates to be used as insulation for refrigerators or freezers.
Lignin is a natural biopolymer with a complex three-dimensional network and it is rich in phenol, making it a good candidate for the production of bio-based polyphenol material. This study attempts to characterize the properties of green phenol-formaldehyde (PF) resins produced through phenol substitution by the phenolated lignin (PL) and bio-oil (BO), extracted from oil palm empty fruit bunch black liquor. Mixtures of PF with varied substitution rates of PL and BO were prepared by heating a mixture of phenol-phenol substitute with 30 wt.% NaOH and 80% formaldehyde solution at 94 °C for 15 min. After that, the temperature was reduced to 80 °C before the remaining 20% formaldehyde solution was added. The reaction was carried out by heating the mixture to 94 °C once more, holding it for 25 min, and then rapidly lowering the temperature to 60 °C, to produce the PL-PF or BO-PF resins. The modified resins were then tested for pH, viscosity, solid content, FTIR, and TGA. Results revealed that the substitution of 5% PL into PF resins is enough to improve its physical properties. The PL-PF resin production process was also deemed environmentally beneficial, as it met 7 of the 8 Green Chemistry Principle evaluation criteria.
This present study optimized the cellulose nanofiber (CNF) loading and melt processing conditions of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) P(HB-co-11% HHx) bionanocomposite fabrication in twin screw extruder by using the response surface methodology (RSM). A face-centered central composite design (CCD) was applied to statistically specify the important parameters, namely CNF loading (1-9 wt.%), rotational speed (20-60 rpm), and temperature (135-175 °C), on the mechanical properties of the P(HB-co-11% HHx) bionanocomposites. The developed model reveals that CNF loading and temperature were the dominating parameters that enhanced the mechanical properties of the P(HB-co-11% HHx)/CNF bionanocomposites. The optimal CNF loading, rotational speed, and temperature for P(HB-co-11% HHx) bionanocomposite fabrication were 1.5 wt.%, 20 rpm, and 160 °C, respectively. The predicted tensile strength, flexural strength, and flexural modulus for these optimum conditions were 22.96 MPa, 33.91 MPa, and 1.02 GPa, respectively, with maximum desirability of 0.929. P(HB-co-11% HHx)/CNF bionanocomposites exhibited improved tensile strength, flexural strength, and modulus by 17, 6, and 20%, respectively, as compared to the neat P(HB-co-11% HHx). While the crystallinity of P(HB-co-11% HHx)/CNF bionanocomposites increased by 17% under the optimal fabrication conditions, the thermal stability of the P(HB-co-11% HHx)/CNF bionanocomposites was not significantly different from neat P(HB-co-11% HHx).
The current production method of nanobiochar (NBC), an emerging, environmentally friendly nanocarbon material, is tedious and lengthy. Therefore, in this study we aimed to improve the productivity of NBC via high-energy ball milling by manipulating the grinding media and processing time. The particle size distribution of the resulting NBC measured using dynamic light scattering showed that grinding media with steel balls of different sizes were more effective at producing NBC than small uniform steel balls, which failed to produce NBC even after 90 min of milling. Average NBC particles of around 95 nm were achieved after only 30 min of ball milling, and the size was further reduced to about 30 nm when the milling was prolonged to 150 min. Further prolonging the milling duration led to agglomeration, which increased the size of the biochar nanoparticles. The thermogravimetric analysis (TGA) data showed that the duration of milling and particle size did not cause noticeable differences in the thermal stability of the NBC. Based on the FTIR analysis, the chemical structure of the NBC was not affected by the ball milling. The results showed that 60 min of high-energy ball milling is sufficient to produce NBC particles of 75 nm, with a large surface area and high thermal stability. This could prove beneficial in a myriad of applications, ranging from agriculture to composite fabrication.
Biochar is conventionally and widely used for soil amendment or as an adsorbent for water treatment. Nevertheless, the need for transition to renewable materials has resulted in an expansion of biochar for use as a filler for polymer composites. The aim is to enhance the physical, chemical, mechanical and rheological properties of the polymer composite. The reinforcement of biochar into a polymer matrix however is still new, and limited reports are focusing on the effects of biochar towards polymer composite properties. Hence, this review highlights the unique properties of biochar and its effect on the crystallization, thermal, flammability, electrical conductivity, and mechanical properties of polymer composites. This review does not solely summarize recent studies on biochar-polymer-based composites, but also offers insights into a new direction of biochar as a renewable and superior polymer filler in the future.
Dried hybrid fillers comprised of silica/CNF were successfully synthesized in ethanol/water mixed solvents at room temperature without the usage of any precursor. The as-prepared fillers were incorporated with polypropylene (PP) as a polymer matrix through a twin-screw extruder. From surface morphology analysis, the agglomeration of the silica/CNF hybrid fillers was prevented in the PP matrix and they exhibited moderate transparency, around 17.9% and 44.6% T at 660 nm. Further, the chemical structures of the polymer composites were identified by Fourier transform infrared (FT-IR) analysis. According to thermogravimetric analysis (TGA), the insertion of silica as a co-filler to the PP matrix resulted in an increase in its degradation onset temperature and also thermal stability. In addition, the mechanical properties of the PP composites also increased after the blending process with the hybrid fillers. Overall, sample PP-SS/CNF exhibited the highest tensile strength, which was 36.8 MPa, or around 73.55% compared to the pristine PP. The improvements in tensile strength were attributed to good dispersion and enhanced efficiency of the stress transfer mechanism between the silica and the cellulose within the PP matrix. However, elongation of the sample was reduced sharply due to the stiffening effect of the filler.
This work investigated the combined effects of CNF nucleation (3 wt.%) and PLA-g-MA compatibilization at different loadings (1-4 wt.%) on the crystallization kinetics and mechanical properties of polylactic acid (PLA). A crystallization kinetics study was done through isothermal and non-isothermal crystallization kinetics using differential scanning calorimetry (DSC) analysis. It was shown that PLA-g-MA had some effect on nucleation as exhibited by the value of crystallization half time and crystallization rate of the PLA/PLA-g-MA, which were increased by 180% and 172%, respectively, as compared to neat PLA when isothermally melt crystallized at 100 °C. Nevertheless, the presence of PLA-g-MA in PLA/PLA-g-MA/CNF3 nanocomposites did not improve the crystallization rate compared to that of uncompatibilized PLA/CNF3. Tensile strength was reduced with the increased amount of PLA-g-MA. Contrarily, Young's modulus values showed drastic increment compared to the neat PLA, showing that the addition of the PLA-g-MA contributed to the rigidity of the PLA nanocomposites. Overall, it can be concluded that PLA/CNF nanocomposite has good performance, whereby the addition of PLA-g-MA in PLA/CNF may not be necessary for improving both the crystallization kinetics and tensile strength. The addition of PLA-g-MA may be needed to produce rigid nanocomposites; nevertheless, in this case, the crystallization rate of the material needs to be compromised.
In this study, Kraft lignin was esterified with phthalic anhydride and was served as reinforcing filler for poly(butylene succinate) (PBS). Composites with different ratios of PBS, lignin (L), modified lignin (ML) and kenaf core fibers (KCF) were fabricated using a compounding method. The fabricated PBS composites and its counterparts were tested for thermal, physical and mechanical properties. Weight percent gain of 4.5% after lignin modification and the FTIR spectra has confirmed the occurrence of an esterification reaction. Better thermo-mechanical properties were observed in the PBS composites reinforced with modified lignin and KCF, as higher storage modulus and loss modulus were recorded using dynamic mechanical analysis. The density of the composites fabricated ranged from 1.26 to 1.43 g/cm3. Water absorption of the composites with the addition of modified lignin is higher than that of composites with unmodified lignin. Pure PBS exhibited the highest tensile strength of 18.62 MPa. Incorporation of lignin and KCF into PBS resulted in different extents of reduction in tensile strength (15.78 to 18.60 MPa). However, PBS composite reinforced with modified lignin exhibited better tensile and flexural strength compared to its unmodified lignin counterpart. PBS composite reinforced with 30 wt% ML and 20 wt% KCF had the highest Izod impact, as fibers could diverge the cracking propagation of the matrix. The thermal conductivity value of the composites ranged from 0.0903 to 0.0983 W/mK, showing great potential as a heat insulator.
Residual hemicellulose could enhance cellulose nanofiber (CNF) processing as it impedes the agglomeration of the nanocellulose fibrils and contributes to complete nanofibrillation within a shorter period of time. Its effect on CNF performance as a reinforcement material is unclear, and hence this study seeks to evaluate the performance of CNF in the presence of amorphous hemicellulose as a reinforcement material in a polypropylene (PP) nanocomposite. Two types of CNF were prepared: SHS-CNF, which contained about 11% hemicellulose, and KOH-CNF, with complete hemicellulose removal. Mechanical properties of the PP/SHS-CNF and PP/KOH-CNF showed an almost similar increment in tensile strength (31% and 32%) and flexural strength (28% and 29%) when 3 wt.% of CNF was incorporated in PP, indicating that hemicellulose in SHS-CNF did not affect the mechanical properties of the PP nanocomposite. The crystallinity of both PP/SHS-CNF and PP/KOH-CNF nanocomposites showed an almost similar value at 55-56%. A slight decrement in thermal stability was seen, whereby the decomposition temperature at 10% weight loss (Td10%) of PP/SHS-CNF was 6 °C lower at 381 °C compared to 387 °C for PP/KOH-CNF, which can be explained by the degradation of thermally unstable hemicellulose. The results from this study showed that the presence of some portion of hemicellulose in CNF did not affect the CNF properties, suggesting that complete hemicellulose removal may not be necessary for the preparation of CNF to be used as a reinforcement material in nanocomposites. This will lead to less harsh pretreatment for CNF preparation and, hence, a more sustainable nanocomposite can be produced.
This study provides insight into the decolorization strategy for crude glycerol obtained from biodiesel production using waste cooking oil as raw material. A sequential procedure that includes physico-chemical treatment and adsorption using activated carbon from oil palm biomass was investigated. The results evidenced decolorization and enrichment of glycerol go hand in hand during the treatment, achieving >89% color removal and > 98% increase in glycerol content, turning the glycerol into a clear (colorless) solution. This is attributed to the complete removal of methanol, free fatty acids, and triglycerides, as well as 85% removal of water, and 93% removal of potassium. Properties of the resultant glycerol met the quality standard of BS 2621:1979. The economic aspects of the proposed methods are examined to fully construct a predesign budgetary estimation according to chemical engineering principles. The starting capital is proportionate to the number of physical assets to acquire where both entail a considerable cost at USD 13,200. Having the benefit of sizeable scale production, it reasonably reduces the operating cost per unit product. As productivity sets at 33 m3 per annum, the annual operating costs amount to USD 79,902 in glycerol decolorization. This is translatable to USD 5.38 per liter glycerol, which is ~69% lower compared to using commercial activated carbon.
Charcoal , Glycerol , Adsorption , Biofuels , Biomass , Palm Oil
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.
The development of bio-polyol from vegetable oil and its derivatives is gaining much interest from polyurethane industries and academia. In view of this, the availability of methyl oleate derived from palm oil, which is aimed at biodiesel production, provides an excellent feedstock to produce bio-polyol for polyurethane applications. In this recent study, response surface methodology (RSM) with a combination of central composite rotatable design (CCRD) was used to optimise the reaction parameters in order to obtain a maximised hydroxyl value (OHV). Three reaction parameters were selected, namely the mole ratio of epoxidised methyl oleate (EMO) to glycerol (1:5-1:10), the amount of catalyst loading (0.15-0.55%) and reaction temperature (90-150 °C) on a response variable as the hydroxyl value (OHV). The analysis of variance (ANOVA) indicated that the quadratic model was significant at 98% confidence level with (p-value > 0.0001) with an insignificant lack of fit and the regression coefficient (R2) was 0.9897. The optimum reaction conditions established by the predicted model were: 1:10 mole ratio of EMO to glycerol, 0.18% of catalyst and 120 °C reaction temperature, giving a hydroxyl value (OHV) of 306.190 mg KOH/g for the experimental value and 301.248 mg KOH/g for the predicted value. This result proves that the RSM model is capable of forecasting the relevant response. FTIR analysis was employed to monitor the changes of functional group for each synthesis and the confirmation of this finding was analysed by NMR analysis. The viscosity and average molecular weight (MW) were 513.48 mPa and 491 Da, respectively.
Epoxy Compounds/chemistry , Palm Oil/chemistry , Polymers/chemistry , Biofuels , Catalysis , Glycerol/chemistry , Polyurethanes/chemistry , Temperature
Polylactic acid (PLA), a potential alternative material for single use plastics, generally portrays a slow crystallization rate during melt-processing. The use of a nanomaterial such as cellulose nanofibers (CNF) may affect the crystallization rate by acting as a nucleating agent. CNF at a certain wt.% has been evidenced as a good reinforcement material for PLA; nevertheless, there is a lack of information on the correlation between the amount of CNF in PLA that promotes its functionality as reinforcement material, and its effect on PLA nucleation for improving the crystallization rate. This work investigated the nucleation effect of PLA incorporated with CNF at different fiber loading (1-6 wt.%) through an isothermal and non-isothermal crystallization kinetics study using differential scanning calorimetry (DSC) analysis. Mechanical properties of the PLA/CNF nanocomposites were also investigated. PLA/CNF3 exhibited the highest crystallization onset temperature and enthalpy among all the PLA/CNF nanocomposites. PLA/CNF3 also had the highest crystallinity of 44.2% with an almost 95% increment compared to neat PLA. The highest crystallization rate of 0.716 min-1 was achieved when PLA/CNF3 was isothermally melt crystallized at 100 °C. The crystallization rate was 65-fold higher as compared to the neat PLA (0.011 min-1). At CNF content higher than 3 wt.%, the crystallization rate decreased, suggesting the occurrence of agglomeration at higher CNF loading as evidenced by the FESEM micrographs. In contrast to the tensile properties, the highest tensile strength and Young's modulus were recorded by PLA/CNF4 at 76.1 MPa and 3.3 GPa, respectively. These values were, however, not much different compared to PLA/CNF3 (74.1 MPa and 3.3 GPa), suggesting that CNF at 3 wt.% can be used to improve both the crystallization rate and the mechanical properties. Results obtained from this study revealed the dual function of CNF in PLA nanocomposite, namely as nucleating agent and reinforcement material. Being an organic and biodegradable material, CNF has an increased advantage for use in PLA as compared to non-biodegradable material and is foreseen to enhance the potential use of PLA in single use plastics applications.
Incorporation of nanocellulose could improve wear resistance of ultra-high molecular weight polyethylene (UHMWPE) for an artificial joint application. Yet, the extremely high melt viscosity of the polymer may constrict the mixing, leading to fillers agglomeration and poor mechanical properties. This study optimized the processing condition of UHMWPE/cellulose nanofiber (CNF) bionanocomposite fabrication in triple screw kneading extruder by using response surface methodology (RSM). The effect of the process parameters-temperature (150-190 °C), rotational speed (30-60 rpm), and mixing time (30-45 min)-on mechanical properties of the bionanocomposites was investigated. Homogenous filler distribution, as confirmed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, was obtained through the optimal processing condition of 150 °C, 60 rpm, and 45 min. The UHMWPE/CNF bionanocomposites exhibited improved mechanical properties in terms of Young's and flexural modulus by 11% and 19%, respectively, as compared to neat UHMWPE. An insignificant effect was observed when maleic anhydride-grafted-polyethylene (MAPE) was added as compatibilizer. The obtained results proved that homogenous compounding of high melt viscosity UHMWPE with CNF was feasible by optimizing the melt blending processing condition in triple screw kneading extruder, which resulted in improved stiffness, a contributing factor for wear resistance.
Cellulose/chemistry , Nanocomposites/chemistry , Nanofibers/chemistry , Polyethylenes/chemistry , Analysis of Variance , Elastic Modulus , Maleic Anhydrides/chemistry , Nanocomposites/ultrastructure , Nanofibers/ultrastructure , Polyethylene/chemistry , Temperature , Tensile Strength
Mechanical strength, thermal conductivity and electrical breakdown of polypropylene/lignin/kenaf core fiber (PP/L/KCF) composite were studied. PP/L, PP/KCF and PP/L/KCF composites with different fiber and lignin loading was prepared using a compounding process. Pure PP was served as control. The results revealed that tensile and flexural properties of the PP/L/KCF was retained after addition of lignin and kenaf core fibers. Thermal stability of the PP composites improved compared to pure PP polymer. As for thermal conductivity, no significant difference was observed between PP composites and pure PP. However, PP/L/KCF composite has higher thermal diffusivity. All the PP composites produced are good insulating materials that are suitable for building. All PP composites passed withstand voltage test in air and oil state as stipulated in IEC 60641-3 except PP/L in oil state. SEM micrograph showed that better interaction and adhesion between polymer matrix, lignin and kenaf core fibers was observed and reflected on the better tensile strength recorded in PP/L/KCF composite. This study has successfully filled the gap of knowledge on using lignin and kenaf fibers as PP insulator composite materials. Therefore, it can be concluded that PP/Lignin/KCF has high potential as an insulating material.
This research investigated the effect of synthesis temperature on the size and shape of zinc oxide (ZnO) nanoparticles (NPs) synthesized using pineapple peel waste and antibacterial activity of ZnO NPs in starch films. Zinc oxide NPs synthesized at different temperatures were characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Micrographs of ZnO NPs synthesized at 28 and 60 °C showed that synthesis temperature affected the sizes and shapes of ZnO NPs. The non-heated (28 °C) condition resulted in NPs with diameters in the range of 8-45 nm with a mixture of spherical and rod shapes, whereas the heated (60 °C) condition led to NPs with diameters in the range of 73-123 nm with flower rod shapes. The ZnO-starch nanocomposite films incorporated with 1, 3, and 5 wt.% ZnO NPs were prepared via a film casting method. The antibacterial activity of the films against Gram-positive and Gram-negative bacteria was investigated using the disc diffusion method. The results showed an increase in the inhibition zone for Gram-positive bacteria, particularly Bacillus subtilis, when the concentration of ZnO NPs incorporated in the film was increased from 1 to 5 wt.%.
Two different liquid assisted processing methods: internal melt-blending (IMB) and twin-screw extrusion (TWS) were performed to fabricate polyethylene (PE)/cellulose nanofiber (CNF) nanocomposites. The nanocomposites consisted maleic anhydride-grafted PE (PEgMA) as a compatibilizer, with PE/PEgMA/CNF ratio of 97/3/0.5-5 (wt./wt./wt.), respectively. Morphological analysis exhibited that CNF was well-dispersed in nanocomposites prepared by liquid-assisted TWS. Meanwhile, a randomly oriented and agglomerated CNF was observed in the nanocomposites prepared by liquid-assisted IMB. The nanocomposites obtained from liquid-assisted TWS exhibited the best mechanical properties at 3 wt.% CNF addition with an increment in flexural strength by almost 139%, higher than that of liquid-assisted IMB. Results from this study indicated that liquid feeding of CNF assisted the homogenous dispersion of CNF in PE matrix, and the mechanical properties of the nanocomposites were affected by compounding method due to the CNF dispersion and alignment.
The aim was to isolate cellulose nanocrystals (CNC) from commercialized oil palm empty fruit bunch cellulose nanofibre (CNF) through sulphuric acid hydrolysis and explore its safeness as a potential nanocarrier. Successful extraction of CNC was confirmed through a field emission scanning electron microscope (FESEM) and attenuated total reflection Fourier transmission infrared (ATR-FTIR) spectrometry analysis. For subsequent cellular uptake study, the spherical CNC was covalently tagged with fluorescein isothiocyanate (FITC), resulting in negative charged FITC-CNC nanospheres with a dispersity (Ð) of 0.371. MTT assay revealed low degree cytotoxicity for both CNC and FITC-CNC against C6 rat glioma and NIH3T3 normal fibroblasts up to 50 µg/mL. FITC conjugation had no contribution to the particle's toxicity. Through confocal laser scanning microscope (CLSM), synthesized FITC-CNC manifested negligible cellular accumulation, indicating a poor non-selective adsorptive endocytosis into studied cells. Overall, an untargeted CNC-based nanosphere with less cytotoxicity that posed poor selectivity against normal and cancerous cells was successfully synthesized. It can be considered safe and suitable to be developed into targeted nanocarrier.
