Castor Oil Research Articles

Sustainable polyurethane biocomposite foams by improved microstructure, acoustic characteristics, thermoregulation performance and reduced CO2 emission through phase change material integration

In this research, phase change material (PCM) comprised of energy storage biocomposite materials were improved with raw materials obtained from renewable resources. Modified raw material was synthesized by epoxy castor oil (ECO). After mixing the obtained modified castor oil (MCO) and polyether polyol, PCM of capric acid (CA) was supplemented. To initiate the chemical reaction, a certain amount of methylene diphenyl diisocyanate (MDI) was added to the mixture to provide cross-linking. The physical and chemical properties of the resulting biocomposite foams (BCF) were characterized. According to the results obtained, mixing MCO into polyether raw material increased the number of closed pores in BCF resulting in more CA stored in BCF cells produced. The use of MCO in BCF materials increased the CA integration ratio to 68 wt%. The melting enthalpy value of the novel BCF-PCM composites has been determined as 121.43 J/g. In a warm environment, the PCM additive creates a temperature difference exceeding 6 °C, while in a cold environment, it provides a cooling effect close to 6 °C. A more than 50 % improvement in thermal conductivity was achieved with 68 wt% PCM addition compared to pure BCF. The addition of PCM caused a reduction in tensile stress and strain values to an acceptable level. BCFs with PCM additives exhibit a sound absorption coefficient of 0.9 in narrow frequency ranges, whereas, in broad frequency ranges, this value was more than 0.7. In cold weather conditions, employing BCF-PCM material instead of traditional EPS material with a thickness of 0.1 m has led to at least a 30 % drop in CO2 emissions, no matter the type of fuel used for heating. When opting for BCF-PCM materials, the necessary heat demand was approximately 33 % less compared to using the same thickness of EPS in cold climates.

Recyclable polyurethane from castor oil based on dynamic disulfide bonds and multiple hydrogen bonds as adhesive and photothermal conversion materials

As an important polymer material, polyurethane brings convenience to daily life but also causes environmental problems, and the manufacturing of bio-based repairable, re-processable and sturdy materials can effectively reduce environmental pressure. Herein a low temperature recyclable polyurethane (PU) was developed with castor oil (CO) by combining isophorone diisocyanate (IPDI), dynamic disulfide bonds and hydrogen bonds. The castor oil-based PU showed impressive tensile strength (16.1MPa) remarkable elongation at break (1055.8%), and high bonding power (up to ~6MPa) with bonding wood chips. The dynamic disulfide bonds and hydrogen bonds imparted the bio-based PU with outstanding elastic recovery, impressive self-healing capability (up to ~90%), short relaxation time (5~6min at 180°C), favorable shape memory behavior, and multiple recyclability. By mixing different proportions of carbon nanotubes (CNTs), recyclable and stretchable conductive composites are realized. In addition, an integrated system of high-efficiency bio-based solar photovoltaic generator is demonstrated for simulating the ambient sunlight-heat-electricity conversion, which provides some guidance for the efficient use of solar energy.

Use of Electrospun Cellulose Acetate/Silica Composites as Multifunctional Ingredients in Eco‐Friendly Semisolid Lubricant Formulations

ABSTRACTCellulose acetate/silica (CA/SIL) nanocomposites are prepared by electrospinning and investigated as multifunctional ingredients in eco‐friendly semisolid lubricant formulations. The structuring ability of these electrospun composites in castor oil and the antifriction and antiwear properties are examined through rheological and tribological experiments. The multifunctionality of CA/SIL composites arises from a balance between the silica content and the formation of nanofiber‐dominated structures. The linear viscoelasticity functions in the oleo‐dispersions increase by several orders of magnitude with both the spinning solution concentration and the CA:SIL ratio. However, the rheological response primarily depends on the morphology of the nanofiber mat obtained, specifically nanofiber diameter and the presence of beads. In contrast, the silica content significantly impacts the tribological performance of the oleo‐dispersions regardless of nanofiber morphology. For similar nanoarchitectures and rheological responses, the friction coefficient is reduced from 0.227 to 0.108 by incorporating silica in a 10:1 CA:SIL ratio, compared with the SIL‐free electrospun CA nanofibers, while wear is completely prevented. Increasing the composite concentration from 5 to 12.5 wt. % enhances wear protection and the gel strength of oleo‐dispersions, for example, the plateau modulus rises from 800 to 42,000 Pa using a composite with a 10:1 CA:SIL ratio.

Thermal behavior of polymers and copolymers based on plant oils with differing saturated and monounsaturated content

AbstractPlant oil‐based acrylic monomers from hydrogenated sunflower (HFM), palm (PMM) and castor (CSM) oils were polymerized to investigate the effect of chemical composition on polymer phase transitions at temperatures relevant to physiological range. While HFM and PMM possess a highly differing content of saturated palmitic and stearic acids combined with unsaturated fatty acids, CSM contains primarily fragments based on monounsaturated ricinoleic hydroxy acid (up to 90%). Differential scanning calorimetry (DSC) measurements indicate that polymers from PMM and HFM are both semicrystalline (with Tm = −6 and −13 °C, respectively), while poly(CSM) appears to be amorphous (Tg = −49 °C). Considering the similarity in polymers' molar mass (Mn = 16 000–20 000 g mol−1), the observed thermal transitions can be explained by the formation of ordered morphological domains due to the presence of saturated palmitic and stearic acid fractions in poly(PMM) and poly(HFM). For copolymers of CSM, PMM and HFM (80 wt% of monomer feed) with styrene, DSC data show two transitions corresponding to the mobility of long alkyl fatty acid side fragments and the macromolecular backbone. For copolymers of PMM and HFM, comparable values (−52.8 and −55.5 °C, respectively) were obtained, while the second transition for poly(CSM‐co‐styrene) appears at 35 °C. We attribute this higher value to the presence of hydroxyl groups in ricinoleic acid fragments of CSM serving as additional chain transfer sites and the formation of macromolecular fractions enriched with polystyrene fragments. We expect that the temperature transitions obtained can be relevant to the future use of these polymers for biomedical applications, including the synthesis of polymer brushes. © 2024 Society of Chemical Industry.

Esterification and Transesterification Optimization Processes of Nonedible (Castor and Neem) Oils for the Production of Biodiesel

In current times, the diminishing reserves of petroleum, increased energy consumption across various sectors, and their consequential environmental impact have become apparent. Consequently, it is necessary to develop sustainable and eco-friendly energy sources to meet growing demands. The article aimed to blend castor and neem oils (in a 50:50 ratio) to rectify the drawbacks present in castor biodiesel such as elevated kinematic viscosity and density. Response surface methodology was used to study the optimization of the two-step biodiesel production process through the use of a central composite design (CCD). For the esterification step, a methanol-to-oil molar ratio of 7.5:1, 1.75 wt.% of H2SO4, and a temperature of 55 °C were optimal. In the transesterification step, optimized conditions included a methanol-to-oil molar ratio of 9:1, 2.50 wt.% of calcium oxide, a temperature of 55 °C, and a stirring speed of 900 rpm, resulting in a 93% yield of methyl ester. Different properties of produced biodiesel were examined using the standard values provided by EN 14214 and ASTM D6751. The production of biodiesel from a mixture of castor and neem oils did not have any adverse impacts on food security.

Evaluating Biodiesel Properties from Waste Cooking Oil for Sustainable Energy Applications

Biodiesel was synthesized from used vegetable oils collected from local restaurants in Minna, Niger State, Nigeria, using a base-catalyzed transesterification process with methanol and potassium methoxide as the catalyst. The physicochemical properties of the produced biodiesel, such as density, kinematic viscosity, flash point, pour point, cetane number, and calorific value, were evaluated and compared against conventional diesel fuels and biodiesel from other sources like Jatropha, Neem, and Castor oils. Gas chromatography (GC) was used to analyze the fatty acid methyl esters (FAMEs) composition, identifying methyl oleate, methyl linoleate, methyl palmitate, and methyl stearate as the primary components. The produced biodiesel exhibited favourable properties, including a cetane number and flash point within recommended ASTM standards, indicating efficient ignition and safe storage characteristics. Additionally, the calorific value and kinematic viscosity of the biodiesel were found to be comparable to conventional diesel, making it a viable blend for diesel engine applications.

Determinant analysis of oil agglomeration of coal fines using multiple regression and neural network models

ABSTRACT Oil agglomeration has gained importance owing to its simplicity and efficiency in beneficiating coal fines. In this study, high ash coal samples taken from six mines in India were put through an oil agglomeration process to investigate the usage of castor oil or blend of castor and turpentine for recovery of coal fines from coal-water slurry. The performance of the process has been evaluated based on ash rejection [AR (%)] and yield (%). Various Statistical analyses were carried out to investigate the role of various process parameters, such as PD, OD, AT, and oil-type on AR (%) and yield (%). Step-wise regression was performed for development of prediction model for AR (%) and yield (%). Determinant analysis was performed using general linear model (GLM). Our findings indicate that pulp density was the strongest determinant for AR (%), followed by oil dosage and agitation time. Similarly, oil dosage was the primary determinant for yield (%), followed by pulp density and agitation time. Sensitivity analysis was also carried out using artificial neural network (ANN) and the results in respect AR (%) revealed that agitation time was the most important predictor followed by pulp density and oil dosage.

Pengaruh Penambahan Minyak Nabati pada Media Tumbuh terhadap Pertumbuhan Cendawan Entomopatogen Lecanicillium lecanii

Pest attacks are one of the challenges frequently encountered in rice cultivation. Effective and environmentally friendly control can be achieved with the entomopathogenic fungus Lecanicillium lecanii. The addition of vegetable oils such as peanut oil and castor oil can enhance the growth and development of the entomopathogenic fungus. This study aims to find the corn growth medium with the addition of vegetable oils that provides the best effect for the growth of the entomopathogenic fungus L. lecanii. The method used is a Completely Randomized Design (CRD) with a single factor consisting of 7 treatments with 4 replications: Control (Corn Medium); T1 (Corn + Peanut Oil 2 ml); T2 (Corn + Peanut Oil 5 ml); T3 (Corn + Peanut Oil 10 ml); J1 (Corn + Castor Oil 2 ml); J2 (Corn + Castor Oil 5 ml); J3 (Corn + Castor Oil 10 ml). The results of this study indicate that the addition of vegetable oils to the corn growth medium has a significant effect on the growth of the entomopathogenic fungus L. lecanii. The most effective growth medium for L. lecanii is corn medium + 10 ml peanut oil, providing an incubation period of 1 days and a colony diameter of 8.00 cm.

Formulation-dependent differences in paclitaxel distribution to anatomical sites relevant to chemotherapy-induced peripheral neuropathy

IntroductionChemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting adverse event observed in patients receiving paclitaxel, associated with initial pathological changes in the peripheral nervous system, i.e., distal nerves and dorsal root ganglia (DRG). The prevalence of CIPN in patients receiving paclitaxel formulated i) in polyethylated castor oil with ethanol (CreEL-PTX), ii) as albumin-bound (nab-PTX), and iii) in XR17 micelles (micellar-PTX), is unexpectedly varying. We hypothesize that the discrepancy in CIPN prevalence could be governed by differences in the extent of paclitaxel distribution across blood-to-tissue barriers at the CIPN-sites, caused by the specific formulation.MethodsThe recently developed Combinatory Mapping Approach for CIPN was used to determine the unbound tissue-to-plasma concentration ratio Kp,uu,tissue, after a 4-h infusion of 4 mg/kg CreEL-PTX, 4 mg/kg nab-PTX or 1 mg/kg micellar-PTX in male and female Sprague Dawley rats. Kp,uu,tissue was determined in conventional (DRG, sciatic nerve) and non-conventional (brain, spinal cord, skeletal muscle) CIPN-sites.ResultsBased on our data, the Cremophor-free paclitaxel formulations were associated with a higher distribution of paclitaxel to CIPN-sites than CreEL-PTX, e.g., Kp,uu,DRG of 0.70 and 0.60 for nab-PTX and micellar-PTX, respectively, in comparison to 0.27 for CreEL-PTX (p < 0.01). In addition, the fraction of unbound paclitaxel in plasma was on average 1.6-fold higher in nab- and micellar PTX arms and equal to 0.061 and 0.065, respectively, compared to 0.039 for the CreEL-PTX treatment arm (p < 0.0001).DiscussionIn the case of similar unbound paclitaxel concentration in the plasma of patients and assumed species-independent extent of paclitaxel transport across the barriers, nab- and micellar-PTX formulations can lead to higher paclitaxel exposure at CIPN-sites in comparison to CreEL-PTX.

Vanillin-Based Polyol Combined with Castor Oil to Fabricate Water-Borne Polyurethane with Recyclability and Self-Healing Properties for Fluorescent Ink and Flexible Sensor Applications

Vanillin-Based Polyol Combined with Castor Oil to Fabricate Water-Borne Polyurethane with Recyclability and Self-Healing Properties for Fluorescent Ink and Flexible Sensor Applications

Modified castor oil-based UV/thermal dual-curing polyurethane acrylate coatings with outstanding comprehensive properties

Due to the fact that single UV-cured coatings frequently fail to fulfill the requirements in terms of depth and chroma, and do not reach the ideal state in terms of comprehensive performance. In order to solve these pain-points more effectively, the sulfhydryl-modified castor oil (COME) was successfully synthesized by introducing β-mercaptoethanol onto the plant-based material castor oil (CO) through the thiol-ene clink reaction. Subsequently, the synthesized polyurethane acrylate prepolymer (COPUA), monomer, photoinitiator and thermocuring agent were used as A component, and COME was used as B component. The two were mixed evenly according to a certain proportion, and the modified castor oil based polyurethane acrylate (COMEPUA) coatings were fabricated by UV/thermal dual-curing technology. Based on a series of performance test outcomes, the coating demonstrates excellent comprehensive properties, encompassing mechanical properties (where the shear strength, tensile strength, elongation at break, and hardness can respectively reach 5.26MPa, 9.92MPa, 132.55%, and 47.77 Shore D), coating properties (where the absorption rates after 72h immersion in water, ethanol, 10wt% HCl, and 10wt% NaOH solvents are respectively 0.66, 17.98, 1.89, and 0.71%, and the volume resistivity and breakdown voltage are respectively 1.74×1016 Ω·cm and 10 KV) and curing properties (where the curing depth can reach 9.82mm, which is significantly higher than 3.51mm of single UV curing, and the colored curing is complete). It can exert protective functions such as anti-corrosion, anti-fouling, and insulation on circuit boards, electronic packaging, and device surfaces, and holds great potential in the application of coating materials.

Nationwide multicenter prospective study on the usefulness, safety, and acceptability of colon capsule endoscopy in Japan

We determined the factors influencing total capsule colonoscopy, adequate cleansing, and detectability of second-generation colon capsule endoscopy (CCE) for colorectal polyps or tumors (CRTs), adverse events, and acceptability. Among 44 Japanese hospitals, 1,006 patients with suspected or documented colorectal diseases who underwent CCE were enrolled prospectively. The total capsule colonoscopy rate was 86.1%. Age younger than 63 years (adjusted odds ratio [aOR], 1.525), male sex (aOR, 1.496), inflammatory bowel disease (aOR, 1.889), lavage intake on Day -1 (aOR, 1.625), ≥1800 mL lavage intake on Day 0 (aOR, 0.595), prokinetics on Day 0 (aOR, 0.608), and ≥30 mL castor oil booster on Day 0 (aOR, 1.734) were significant independent predictors. The overall adequate cleansing rate was 65.5%. Constipation (aOR, 0.527), lavage intake on Day -1 (aOR, 1.822), laxative intake on Day -1 (aOR, 2.616), and ≥1900 mL lavage intake on Day 0 (aOR, 1.449) were significant independent predictors. The detection rates (95% confidence intervals) for patients with CRTs ≥6 mm and ≥10 mm were 92 (84-97) % and 89 (78-96) %, respectively. Inadequate cleansing in the ascending colon (aOR, 0.184), ≥6 mm CRT in the transverse colon (aOR, 4.703), and ≥6 mm CRT in the left-sided colon (aOR, 32.013) were significant independent predictors. CCE retention occurred in two patients (0.20%) requiring endoscopic and surgical interventions. In total, 63% of patients desired CCE for their next colonoscopy. CCE was relatively safe, well tolerated, and useful for detecting colorectal lesions when adequate bowel preparation was made.

Moisture ageing effects on the mechanical performance of eco-friendly sandwich panels made of aluminium skins, bamboo ring core and bio-based adhesives

Recent research has been focused on developing high-performance sandwich structures using renewable resources. The adoption of bamboo rings as a core material and bio-based adhesives has emerged as a promising sustainable design solution for panel construction. It is therefore critical to conduct accelerated ageing tests on these materials to evaluate the impact of environmental humidity on their degradation and durability. This study assessed the effects of moisture ageing on the physic-mechanical properties of eco-friendly sandwich panels and their constituents (aluminium skins, bamboo ring core and castor oil bio-adhesive). Mechanical evaluations of sandwich panels with compacted and spaced bamboo ring cores were performed under varying humidity conditions. Bamboo rings exhibited variable bulk density due to swelling and loss of organic material over time. They also demonstrated increased compressive properties after 2 years of natural ageing but reduced performance after 30 days at 100% relative humidity. The mechanical properties of the bio-based polymer were enhanced through water-ageing exposure. Sandwich panels constructed with compacted bamboo ring cores exhibited higher bending properties than those with spaced ring core architecture, with the latter showing failures characterised by a wrinkling effect on both skins followed by debonding.

DIVERSITE SPECIFIQUE DES PHLEBOTOMES DU NIGER ET DE SES PAYS LIMITROPHES

Introduction: Cutaneous leishmaniasis is an endemic parasitosis in Niger and some of its neighbouring countries. The vectors of this disease are sandflies, which are unfortunately little known in Niger and some of its neighbouring countries. The aim of this study is to inventory the species of sandfly present in Niger and its neighbouring countries. Methodology: This study is conducted in two parts. The first is a systematic review and meta-analysis of articles published on sandflies in Niger and its neighboring countries between the period 2012 to 2022 through Ajol, Pubmed and Science direct. The second is based on a prospective collection of sandflies carried out in the town of Zinder, using castor oil and CDC light traps and morphologically identified. Results: All the sandflies recorded in the systematic review belong to the genera Phlebotomus and Sergentomyia, with a species richness of 43. Phlebotomusperniciosus predominates (28%) on the Maghreb pole. However, on the sub-Saharan pole, Sergentomyiaclydei predominated with 53%. A strong association between the Maghreb pole and the Phlebotomus genus was observed (p-value<0.05). The prospective study carried out in Zinder provided six species with Phlebotomuspapatasi (6%), Phlebotomusduboscqi (6%), Phlebotomussergenti (25%), Sergentomyiaschwetzi (6%), Sergentomyiaafricana (38%) and Sergentomyiaantennata (19%). Conclusion: Niger and its surroundings contain a wide variety of sandflies, with a dominance of species of the Phlebotomus genus, which are the main vectors of leishmaniasis. This study also reports the presence of six species in Zinder, including P. papatasi and S. schwetzi, newly captured in Niger.

Formulation of Microemulsion-Based Gels for Enhanced Topical Administration of Nonsteroidal Anti-Inflammatory Drugs.

Nonsteroidal anti-inflammatory drugs are commonly administered orally to manage pain and inflammation, but they can have negative gastrointestinal side effects. Topical delivery is an alternative, and microemulsions (μEs) have been shown to be effective in facilitating, but they suffer from a liquid nature and low long-term retention on the skin. Hence, microemulsified gels (μEGs) have been developed, and in this study, we explored certain μEGs with diclofenac sodium (DF-Na) and naproxen sodium (NP-Na) with the hypothesis to ensure a slower and more sustained delivery of NSAIDs through the skin. The μEGs comprised castor oil (∼8%), water (∼12%), Tween-20 (∼72%), Span-20 (∼8%), poloxamer 407, and DF-Na or NP-Na. Optical microscopy was used to study the microstructures in the μEs and μEGs, and phase transitions from water-in-oil (w/o) to oil-in-water (o/w) with continuous networks were observed. Based on studies with dynamic light scattering and analyses of electron micrographs, it was observed that the μEs and μEGs loaded with DF-Na and NP-Na comprised monomodal nanodroplets. The average sizes of the droplets were (∼35 nm) and (∼60 nm) for the μEGs, without and with drugs. Fluorescence spectroscopy was used to ensure that the drugs were more likely to be present in the hydrophobic microenvironment of the formulations. Moreover, ex vivo permeation studies were conducted at pH values of 5.5 and 7.4 across rabbit skin. The release rates of DF-Na (>99 ± 1.5%, P < 0.07) and NP-Na (>89 ± 1.1%, P < 0.01) were slower for the μEGs within 8-10 h than for the μEs at the low pH, which is of relevance to the optimal pH of the skin. It was observed that μEGs with high viscosities are effective and may have potential for use in topical drug delivery applications.

Green carbon nanospheres for integrated photo-supercapacitors device with improved efficiency

Achieving a low-cost, high-yield, and environmentally acceptable synthesis of graphene is a significant problem in nanomaterials research. Hence, carbon nanospheres are receiving an increased attention. We have developed a unique and cost-effective method of producing carbon nanospheres from carbon soot. Carbon nanospheres were created using castor oil and virgin green leaf (Anisomeles Malabarica) and then thoroughly examined. When applied to dye-sensitised solar cells and the integrated photo-supercapacitor, the produced soot exhibited the same behavior as reduced graphene oxide. Photoconversion efficiency was 8.47 % in the dye-sensitised solar cells application and in the symmetric supercapacitor device application, it exhibited 11.83 mWh/cm2 of energy density and 0.3 mW/cm2 of power density which illuminated an LED bulb up to 60 s. The capacitive retention of 85.2 % was achieved after 3000 cycles. Finally, the integrated photo-supercapacitor performed about 3.3 % of the overall efficiency and 38 % of the storage efficiency.

Optimization of Microwave‐Assisted Extraction of Curcuma zedoaria Rhizome: A Comparative Study of Castor Oil and Sesame Oil

ABSTRACTCurcuma zedoaria (Christm.) Roscoe is a curcuminoid‐rich plant with potential applications in cosmetic products. This study aimed to optimize the microwave‐assisted extraction (MAE) conditions for C. zedoaria rhizomes using castor oil and sesame oil as solvents. A full factorial design was employed, investigating microwave power levels of 600 and 800 W, and microwave times of 30 and 90 s. The results showed that microwave time significantly affected extraction yield, and individual and total curcuminoid content while microwave power did not. The optimal conditions for maximizing extraction yield and total curcuminoid content were 600 W for 90 s with castor oil, and 600 W for 80 s with sesame oil. Stability testing revealed that curcuminoids were more stable in castor oil than in sesame oil when stored at 4°C, 30°C/75% relative humidity (RH), and 40°C/75% RH over 3 months. In conclusion, this study demonstrates that MAE is an effective method for extracting curcuminoids from C. zedoaria, with castor oil showing superior preservation of curcuminoid content. These findings suggest that castor oil could be a preferable solvent for the extraction and stabilization of curcuminoids in C. zedoaria for cosmetic applications.

Novel Preparation and Characterization of Zinc Ricinoleate Through Alkali Catalysis.

The enhanced thermal and chemical stability of Zinc oxide-based materials make them excellent candidates for the removal of odor-producing pollutants and compounds. The zinc salt of ricinoleic acid, commonly known as zinc ricinoleate, is viewed as the top performer. This article describes an innovative two-step synthesis of zinc ricinoleate, where the first step consists of the preparation of an intermediate compound, methyl ricinoleate, which is synthesized via transesterification of castor oil with methanol and catalyzed by sodium hydroxide. The second step comprises the preparation of zinc ricinoleate through the saponification of methyl ricinoleate in the presence of zinc oxide particles. XRD, FTIR, and NMR spectroscopies confirmed the synthesis of methyl ricinoleate and zinc ricinoleate. HR-SEM and AFM images showed the formation of larger particles, while the thermal stability of the materials was confirmed by TGA.

Quartz crystal microbalance analysis of effects of surfactants on dissolution kinetics of poly(4-hydroxystyrene) partially protected with t-butoxycarbonyl group

Abstract Surfactants comprise water-repellent and water-attracting moieties and have been used to improve the lithographic performance of resist materials. However, the effects of surfactants on the dissolution kinetics of these materials are still unclear. In this study, the effects of surfactants on the dissolution kinetics of partially-protected poly(4-hydroxystyrene) (PHS) in 0.26 N tetramethylammonium hydroxide aqueous solution was investigated using a quartz crystal microbalance method. Anionic (sodium n-octanonate, sodium 1-hexanesulfonate, n-dodecylbenzenesulfonic acid, and sodium n-dodecyl sulfate), cationic (methylamine hydrochloride, dodecyltrimethylammonium chloride, and 30% ammonium lauryl sulfate solution), nonionic (sorbitan monooleate, polyoxyethylene(23)lauryl ether, and polyoxyethylene(10)hydrogenated castor oil), and amphoteric (35% lauryl dimethylaminoacetic acid solution) surfactants were examined. The surfactant significantly affected the dissolution kinetics of the PHS films. The surfactant effects were significantly reduced by protecting the hydroxyl groups of PHS. The effect of the surfactant on the dissolution kinetics depended on the surfactant rather than on the surfactant type.

Optimization of a Solvent Exchange Method Enabling the Use of Dehydrated Cellulose Nanofibers as the Thickener in Lubricating Oleogels

A method that enabled the formulation of lubricating oleogels using dried cellulose nanofibers (CNFs) as an eco-friendly thickener in castor oil was studied. In their dehydrated state, strong hydrogen bonding between nanofibers and high hydrophilicity are the main obstacles to their dispersion in oil. Hence, clusters of dried CNFs had to be previously detached by their dispersion in water. The resulting hydrogels were then subjected to methanol washes to displace the water from the nanofibers. After centrifugation, the methanol-wetted precipitate was readily dispersed in castor oil, forming an oleogel once the methanol was removed. Optimization was conducted in terms of the following variables: (a) hydrogel processing method; (b) hydrogel pH; (c) methanol/hydrogel ratio; (d) number of washes; and (e) oleogel CNF concentration. Their effect on the oleogel linear viscoelastic behavior was analyzed. In general, they demonstrated a prevailing elastic behavior denoted by a well-developed plateau region. The CNF concentration was found to have a more remarkable impact on the oleogels’ rheological behavior than any other variable studied. Hence, substantial differences were observed between 1 and 2 wt.%. The CNFs exhibited a very remarkable thickening capacity in castor oil, achieving a plateau modulus of ca. 700 Pa with just 2 wt.%. Moreover, the resulting oleogels maintained a uniform texture even after one year of storage. This indicates that the oleogels were both homogeneous and storage stable, effectively overcoming the stability issues associated with direct dispersion of dried CNFs in castor oil.