Degree Of Substitution Values Research Articles

Octenylsuccinated alginate as a delivery agent for encapsulation of bergamot essential oil: Preparation, functional properties and release behavior

This study evaluate the effect of succinylation of sodium alginate (ALG) by octenyl succinic anhydride (OSA) and its effect on the bergamot essential oil (BEO)-loaded ALG beads. The physico-chemical, antioxidant, antibacterial, and in vitro release properties of BEO-loaded ALG beads were assessed. The presence of BEO in alginate beads was assessd using Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) experiments. The higher amount of BEO in modified alginate beads at higher degree of substitution (DS) has been confirmed. Accordingly, it was discovered that the DS has notable effects on encapsulation efficiency (EE), loading capacity (LC) of beads, so that the values of EE and LC were about 31–75 % and 19–45 %, respectively, when the DS value of ALG was 0.00–0.022. Besides, BEO-loaded beads prepared using high DS, exhibited higher total phenolic compound (TPC = 21.101 mg garlic acid/g brad), good antioxidant activity (DPPH radical scavenging activity ≈ 69 %) and antibacterial properties (against E. coli and S. aureus). In vitro release analysis showed the initial fast release followed by a slow-release. OSA modification slowed down the release rate of bergamot essential oil from alginate beads. Also, the release of BEO from the beads followed Fickian diffusion.

Base-free trifluoroacetylation: From methyl glucopyranoside to cellulose nanofibers

Trifluoroacetic anhydride (TFAA) reacts smoothly with low molecular weight carbohydrates and cellulose nanofibers (CNFs) under base-free conditions. Methyl α- and β-d-glucopyranoside were used as model compounds to optimize reaction conditions, which were then applied to lyophilized CNFs for surface modification. ATR-IR spectroscopy and powder X-ray diffraction were employed to characterize the modified CNFs. Trifluoroacetylation for 4 h yields a degree of substitution (DS) of 0.4 acyl groups per anhydroglucose unit while maintaining a crystallinity index near 50 %. DS values were quantified by gravimetry, acid–base titration after saponification, and a novel approach utilizing solution 19F NMR spectroscopy which offers greater accuracy than the other techniques. This study presents an efficient, base-free method for derivatizing carbohydrates as well as surface functionalization of CNFs with trifluoroacetyl groups, potentially expanding their application in fiber-reinforced thermoplastic composites.

Synthesis and characterization of etherified cationic starch flocculant derived from Manihot esculenta peel with varying degrees of substitution

Cationic Manihot esculenta (ME) peel starch was synthesized through etherification method using 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC) as cationizing monomer. The optimization of the main factors influencing the degree of substitution (DS) was conducted using central composite design (CCD) and response surface methodology (RSM). The factors assessed include CHPTAC concentration, catalyst sodium hydroxide (NaOH) concentration, and reaction time. The DS values of the cationic starches were obtained between 0.39 and 0.99. The maximum DS value was up to 0.99 at 0.615 mol/L of CHPTAC, 30 % (w/v) NaOH, and a reaction time of 5 h. The finding based on the optimization using RSM reflected that CHPTAC and NaOH concentrations are the key variables determining the DS value, while reaction time has a negligible impact on the etherification process. Furthermore, the chemical composition, morphology, and structure of the cationic ME peel starch were characterized by scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and nuclear magnetic resonance spectroscopy (1H NMR). It was confirmed that the modifying monomers penetrated the surface layer of the starch granules and attached to the starch backbone.

Polysaccharide‐based H2S donors: Thiol‐ene functionalization of amylopectin with H2S‐releasing N‐thiocarboxyanhydrides

AbstractPolymeric donors of gasotransmitters, gaseous signaling molecules such as hydrogen sulfide, nitric oxide, and carbon monoxide, hold potential for localized and extended delivery of these reactive gases. Examples of gasotransmitter donors based on polysaccharides are limited despite the availability and generally low toxicity of this broad class of polymers. In this work, we sought to create a polysaccharide H2S donor by covalently attaching N‐thiocarboxyanhydrides (NTAs) to amylopectin, the major component of starch. To accomplish this, we added an allyl group to an NTA, which can spontaneously hydrolyze to release carbonyl sulfide and ultimately H2S via the ubiquitous enzyme carbonic anhydrase, and then coupled it to thiol‐functionalized amylopectin of three different molecular weights (MWs) through thiol‐ene “click” photochemistry. We also varied the degree of substitution (DS) of the NTA along the amylopectin backbone. H2S release studies on the six samples, termed amyl‐NTAs, with variable MWs (three) and DS values (two), revealed that lower MW and higher DS led to faster release. Finally, dynamic light scattering experiments suggested that aggregation increased with MW, which may also have affected H2S release rates. Collectively, these studies present a new synthetic method to produce polysaccharide H2S donors for applications in the biomedical field.

Insight into the hydrophobic functionalization of cellulose microfibrils using the Passerini three-component reaction

The aqueous catalyst-free one-pot Passerini 3-component reaction (P-3CR) was employed for the functionalization of dialdehyde cellulose (DAC) derived from the periodate oxidation of microfibrillated cellulose (MFC) with insights provided by 13C and 15N CP-MAS NMR and FTIR analyses. The kinetics of the P-3CR revealed rapid progress within the initial 2 h, reaching a plateau between 6 and 18 h. The reaction achieved a maximum degree of substitution (DS) with only 1 equivalent of carboxylic acid and isocyanide with respect to the number of aldehydes, therefore demonstrating the atom economy character of the P-3CR performed on MFC. Variable DS values (0.08 to 0.37) were achieved by altering the degree of oxidation of DAC (ranging from 0.48 to 1.1) when reacted with heptanoic acid and tert-butyl isocyanide. Additionally, aliphatic chain lengths of carboxylic acids from C4 to C11 were successfully used for the functionalization of DAC with distinct hydrophobic chains. Furthermore, while cosolvents negatively affected the DS when using heptanoic acid, a significant increase was observed in the case of undecanoic acid due to an improved solubility of the reagent. The aqueous medium P-3CR can thus be considered a versatile tool to tailor the functionalization of MFC and provide it with hydrophobicity.

A New Concept for Interpretation of the Viscoelastic Behavior of Aqueous Sodium Carboxymethyl Cellulose Systems.

Viscoelastic behaviors of aqueous systems of commercially available sodium carboxymethyl cellulose (NaCMC) samples with the degrees of substitution (DS) of approximately 0.68 and 1.3, and the weight-average molar masses (Mw) higher than 200 kg mol-1 dissolved in pure water and aqueous sodium chloride solutions were investigated over a wide concentration (c) range of NaCMC samples. The dependencies of the specific viscosity (ηsp), the average relaxation time (τw), and the reciprocal of the steady-state compliance (Je-1) on c were discussed. The relationships ηsp ∝ c3, τw ∝ c2, and Je-1 ∝ c, characteristic of the rod particle suspensions, were clearly observed in a range lower than the c where the critical gel behavior was observed. Thus, a new concept based on the rheology of rod particle suspensions was employed to interpret the viscoelastic behaviors obtained in the c range. In this context, NaCMC polymer molecules are assumed to behave as extended rod particles with length (L) and diameter (d), including effective electrostatic repulsive distances, due to the dissociation of Na+ in aqueous systems. Thus, the number density of polymer molecules is given to be ν = c/Mw, and viscoelastic parameters such as ηsp, τw, and Je-1 are calculated using the theoretical model for rod particle suspensions proposed by Doi and Edwards. This concept reasonably described not only the viscoelastic data obtained in this study but also those from other groups using NaCMC samples with different DS and Mw values.

Extraction and Characterization of Cellulose from Broccoli Stems as a New Biopolymer Source for Producing Carboxymethyl Cellulose Films.

The use of food and agricultural waste-derived carboxymethyl cellulose (CMC) has become of interest due to their biodegradability and cost-effectiveness. In the current research, cellulose was extracted from broccoli stems to produce carboxymethyl cellulose using a carboxymethylation reaction via chloroacetic acid (CAA) and sodium hydroxide (5-10 M). The effects of different synthesis conditions on the degree of substitution (DS) and viscosity of the synthesized CMC powder were investigated. The mechanical properties, water vapor permeability (WVP), and colour of CMC films were also evaluated. The results showed that CMC with the highest DS value (0.60) and the highest viscosity of 0.5 Pa·s could be synthesized from broccoli stems at a concentration of 7.5 M NaOH and a cellulose-to-chloroacetic acid ratio of 1 : 1.2. At CMC concentration of 4 g/100 mL with 0.8 g/100 mL of glycerol, the films had the highest tensile strength (31.91 MPa), whereas with 1.2 g/100 mL glycerol, more flexible films with elongation at break of 27.56% were produced. CMC films with the highest WVP (7.87 × 103 gm2·mmHg-1/day) were made with 6 g/100 mL of CMC and 1.8 g/100 mL of glycerol. This research proposes a new source of cellulose to produce biodegradable packaging materials to initiate a practical basis for food waste reuse.

Preparation and Characterization of Cellulose Derivatives from Agricultural Wastes

Background: Rice straw was pretreated with dilute alkaline and acid solutions to extract cellulose, which was then converted into cellulose acetate with acetic anhydride and phosphotungstic acid (H3PW12O40·6H2O). The concentration of KOH and the duration of immersion in acetic acid solution affected the removal of hemicellulose and lignin, and after pretreatment with 4% KOH and immersion in acetic acid for 5 hours, the treated rice straw contained 83wt.% cellulose. Phosphotungstic acid has been shown to be an excellent catalyst for the acetylation of rice straw cellulose. The degree of substitution (DS) values had a substantial effect on the solubility of cellulose acetate, and acetone-soluble cellulose acetate with DS values about 2.2 can be generated by varying the amount of phosphotungstic acid and acetylation duration. Objectives: The aim of the study was to evaluate the preparation and characterization of cellulose derivatives from agricultural wastes. Methods: This cross-sectional study was carried out in the Department of Communicable Diseases Control, Director General of Health Services, Dhaka, Bangladesh. For this investigation the rice plant straw was collected from Magura district region. The collected straws were then treated with 3 wt% nitric acid and 1.5 wt% NaOH solution separately. Statistical analyses of the results were be obtained by using window-based Microsoft Excel and Statistical Packages for Social Sciences (SPSS-24). Results: This study observed that the rice straw contained about 35.67% cellulose, 5.50% hemicellulose and 30.18 % α-cellulose. And the wheat straw contained about 43.99% cellulose, 7.30% hemicellulose and 36.70% α-cellulose. The degree of acetylation and degree of substitution of the synthesized cellulose acetate from rice straw were 39.046% and 2.413 respectively. On the other hand, the degree of acetylation and degree of substitution of the synthesized cellulose acetate from wheat straw were 40.79% and 2.59 respectively. ....

Acetylation of cotton knitted fabrics for improved quick drying after water absorption

Quick drying after water or sweat absorption is an important function of underwear. In this study, the hydroxy groups of cotton knitted fabrics (CFs) were partially acetylated, maintaining the original fabric structure. The following three heterogeneous acetylation processes were used: Ac-I (Ac2O/H2SO4/toluene), Ac-II (Ac2O/H2SO4/AcOH/water), and Ac-III (Ac2O/AcONa) systems (Ac2O, acetic anhydride; AcOH, acetic acid; AcONa, sodium acetate). Acetylated cotton knitted fabrics (AcCFs) with degree of substitution (DS) ≤ 0.5 and yields of > 80% were prepared. AcCFs prepared with the Ac-III system gave high degree of polymerization (DP) values of > 1500, whereas those prepared with the Ac-II system exhibited low DP values of ≤ 400. The moisture contents of AcCFs at 20 °C and 65% relative humidity decreased from 7.1 to 4.7% with increasing DS value up to 0.46; introducing hydrophobic acetyl groups into the CFs decreased their hydrophilic nature. Quick drying similar to that of a polyester fabric was achieved for some of the AcCFs with DS values of < 0.2. When the acetyl groups in the AcCFs were homogeneously distributed across each fiber width (achieved for AcCFs prepared with the Ac-II system), quick drying was evident in the AcCFs. The crystallinities and crystal widths of cellulose I for the AcCFs with DS values of ≤ 0.28 were almost unchanged compared with those of the original CFs. However, neither the crystallinities nor crystal widths of cellulose I were directly related to quick drying after water absorption. Thermal degradation of the AcCFs varied between the acetylation systems, and depended on the DP values and/or the presence of sulfate ester groups in the AcCFs.Graphical

Synthesis and characterization of polysaccharide carbamates and mixed carbamates with tunable water solubility

Polysaccharide derivatives with two types of functionalities were synthesized; reactive groups for click-chemistry approaches and groups that can tune the water solubility of the products. Xylan phenylcarbonates (XPCs) and cellulose phenylcarbonates (CPCs) with degrees of substitution (DS) ranging from 0.6 to 3.0 were prepared as starting materials. In a modular synthesis approach, these carbonate derivatives were converted with different amines to obtain functional xylan carbamates (XCs) and cellulose carbamates (CCs) with (i) reactive alkynyl- or furfuryl groups and / or (ii) hydrophilic hydroxyalkyl or tertiary amino groups. Both types of functionalities were introduced separately or simultaneously in a convenient one-pot-approach. Mixed polysaccharide carbamates with low, intermediate, and high DS values (0.6 to 2.5) were successfully prepared and characterized. The water solubility of the carbamates and mixed carbamates was tuned by variation of the type and DS of the two hydrophilic substituents. Surprisingly, some of the products showed lower or upper critical solution temperatures (LCSTs, UCSTs). Thus, the thermoreversible phase transition in aqueous solutions was studied. The products obtained in this work are very promising for the preparation of hydrogels through selective covalent crosslinking as well as for the fabrication of thermoresponsive biomaterials.

Effect of Temperatures on Modification of Alginate Hydrophobicity using Dodecenyl Succinic Anhydride

Alginate is a highly hydrophilic polysaccharide as it contains several hydroxyl groups in the main backbone chain. Some applications for example as surfactants, however, require alginate to have higher hydrophobic properties. Hence, attempts are conducted to improve its hydrophobicity. Dodecenyl succinic anhydride (DSA) has a long hydrophobic chain that could substitute the hydroxyl groups of alginate and improve its hydrophobic properties. This study aimed to produce modified alginates with higher hydrophobicity using DSA as a modifier. The alginate modification was conducted at 30-70oC. The result showed that the degree of substitution (DS) increased in short time and low temperature of reaction. The highest DS value (0.1515) was obtained at 30oC for 30 min which gave the highest viscosity (14.74 cps) and the lowest surface tension (94.08 mN/m). The viscosity and surface tension values for the native alginate were 9.53 cps and 162,98 mN/m, respectively. Meanwhile, the viscosity and surface tension of the lowest DS (0.083) were 11.06 cps and 119.63 mN/m, respectively. The attachment of the dodecenyl succinic group was confirmed by the IR spectra as the presence of ester groups in the modified alginate.

Differences in the structural properties of three OSA starches and their effects on the performance of high internal phase Pickering emulsions

The emulsifying properties of emulsions are significantly influenced by the structural properties of octenyl succinic anhydride (OSA) starch. The purpose of this work was to elucidate the effect of the structure of OSA starch on its performance as an emulsifier to stabilize Pickering high-internal-phase emulsions (HIPEs). The degrees of substitution (DS) of the three OSA starches were 0.0137, 0.0177 and 0.0236, and their degrees of branching (DB) were 13.96 %, 14.20 % and 14.32 % measured by 1H NMR, which were sequentially labeled as OSA1, OSA2, and OSA3. The OSA3 starch with higher DS and DB had a lower critical micelle concentration (CMC) (0.11 mg/mL). Its emulsification activity (EAI) and emulsion stability (ES) were 61.8 m2/g and 72.5 min, respectively, which were higher than OSA1 and OSA2 starches. The contact angle of the three OSA starches increased from 45.35° to 80.03° with increasing DS and DB. Therefore, it is hypothesized that OSA3 starches have better emulsification properties. The results of physical stability of HIPEs confirmed the above results. These results indicated that DS and DB have a synergistic effect on emulsion properties, and OSA starch with higher DS and DB values were more conducive to the construction of stable HIPEs systems.

Optimization of preparation conditions of medium and highly substituted carboxymethyl inulin through response surface methodology

This article introduces the synthesis optimization of carboxymethyl inulin using response surface methodology. The important factors affecting the degree of substitution (DS) were determined by Plackett-Burman design, including sodium hydroxide concentration, monochloroacetic concentration, and etherification temperature. Further optimization was conducted using the Box-Behnken response surface design. The coefficient of determination (R2) of the response surface model was 0.9827, and the adjusted R2 value was 0.9516, which proved the significance of the model. The optimized results of the predicted response showed that the molar ratios of sodium hydroxide to monochloroacetic acid and fructose to furan were 3.67 and 2.21, respectively. The maximum DS of 1.67 was obtained at 30 °C alkalization for 30 min and 50.30 °C etherification for 4 h, and the reaction efficiency (RE) reached 76.01 %. Under the optimized conditions, the Experimental DS was 1.68, suggesting that the experimental and predicted values of DS were in good agreement. The characterization results confirmed the synthesis of CMI. In this work, we have provided an effective method for the preparation of moderately to highly substituted CMI in 95 % ethanol.

Structure and properties of sulfopropyl chitins prepared in NaOH/urea aqueous solutions

A series of sulfopropyl chitins (SCs) with the degree of substitution (DS) ranging from 0.11 to 0.40 and high degree of acetylation (DA ≥ 0.82) were homogeneously synthesized by reacting chitin with sodium 3-chloro-2-hydroxypropanesulfonate (SCHPS) in NaOH/urea aqueous solutions under mild conditions. The structure and properties of SCs were characterized with 1H NMR, CP/MAS 13C NMR, FT-IR, XPS, XRD, elemental analysis, GPC, AFM, ζ-potential and rheological measurements. The mild reaction conditions resulted in less N-deacetylation and uniform structures with substitution occurring predominantly at the hydroxyl groups at C6 of the chitin backbone. The DS value for SC soluble in dilute alkali solution is as low as 0.16. SC exhibited good solubility in distilled water when its DS value reached 0.28. Water-soluble SCs self-assembled in water into micelles by the attractive hydrophobic and hydrogen-bonding interactions between polymer chains. The water-insoluble SC-2 with lower DS could thermally form smart hydrogels at body temperature (37 °C) in physiological condition. Moreover, the SCs exhibited good biocompatibility, making them suitable for biomedical applications.

Hydrophobized MFC as Reinforcing Additive in Industrial Silica/SBR Tire Tread Compound.

Silica is used as reinforcing filler in the tire industry. Owing to the intensive process of silica production and its high density, substitution with lightweight bio-based micro fibrillated cellulose (MFC) is expected to provide lightweight, sustainable, and highly reinforced tire composite. MFC was modified with oleoyl chloride, and the degree of substitution (DS) was maintained between 0.2 and 0.9. Subsequently, the morphology and crystallinity of the modified MFC were studied and found to be significantly dependent on the DS. The advantages associated with the use of the modified MFC in synergy with silica for the reinforcement of styrene butadiene rubber (SBR) nanocomposite was investigated in comparison with silica/SBR compound. The structural changes occasioned by the DS values influenced the processability, curing kinetics, modulus-rolling resistance tradeoff, and tensile properties of the resultant rubber compounds. We found that the compound made with modified MFC at a DS of 0.67 (MFC16) resulted to the highest reinforcement, with a 350% increase in storage modulus, 180% increase in Young`s modulus, and 15% increase in tensile strength compared to the referenced silica-filled compounds. Our studies show that MFC in combination with silica can be used to reinforce SBR compound for tire tread applications.

Pickering Emulsions and Hydrophobized Films of Amphiphilic Cellulose Nanofibers Synthesized in Deep Eutectic Solvent.

Herein, a dual-functioning deep eutectic solvent system based on triethylmethylammonium chloride and imidazole was harnessed as a swelling agent and a reaction medium for the esterification of cellulose with n-octyl succinic anhydride (OSA). The modified or amphiphilic cellulose nanofibers (ACNFs), synthesized using three different OSA-to-anhydroglucose unit molar ratios (0.5:1, ACNF-1; 1:1, ACNF-2; and 1.5:1, ACNF-3), were further converted into nanofibers with degree of substitution (DS) values of 0.24-0.66. The ACNFs possessed a lateral dimension of 4.24-9.22 nm and displayed surface activity due to the balance of hydrophobic and hydrophilic characteristics. The ACNFs made stable aqueous dispersions; however, the instability index of ACNF-3 (0.51) was higher than those of ACNF-1 (0.29) and ACNF-2 (0.33), which was attributed to the high DS-induced hydrophobicity, causing the instability in water. The amphiphilic nature of ACNFs promoted their performance as stabilizers in oil-in-water Pickering emulsions with average droplet sizes of 4.85 μm (ACNF-1) and 5.48 μm (ACNF-2). Self-standing films of ACNFs showed high contact angles for all the tested DS variants (97.48-114.12°), while their tensile strength was inversely related to DS values (ACNF-1: 115 MPa and ACNF-3: 49.5 MPa). Aqueous dispersions of ACNFs were also tested for coating fruits to increase their shelf life. Coatings improved their shelf life by decreasing oxygen contact and moisture loss.

Structure and Conformation of Hydroxypropylmethyl Cellulose with a Wide Range of Molar Masses in Aqueous Solution─Effects of Hydroxypropyl Group Addition.

The structure of hydroxypropylmethyl cellulose (HpMC) samples with a wide range of weight average molar masses (Mw) from 23 to 5000 kg mol-1, a controlled degree of substitution (DS) of 1.9 by methyl groups, and a molar substitution number (MS) of 0.25 by hydroxypropyl groups dissolved in aqueous solution was examined using static light scattering (SLS), dynamic light scattering (DLS), small-to-wide angle neutron scattering (S-WANS) techniques, and intrinsic viscosity ([η]) measurements. The determined Mw and the radius of gyration (Rg) showed the relationships Rg ∝ Mw1.0 and [η] ∝ Mw1.7 in a range of Mw < 100 kg mol-1, similar to rigid rod molecules in solution. However, exponents in the relationships decreased gradually with increasing Mw and reached ∼0.5 in a high Mw region, which is a typical value of flexible chain molecules for both Rg and [η]. These observations suggest that the HpMC samples behave as semiflexible rods with a certain persistence length (lp). The ratios of the hydrodynamic radius via DLS measurements to Rg also supported semiflexible rod behavior. Particle form factors and the average lengths (L) resulting from SLS and S-WANS experiments are well described with rigid rod particles in the range of Mw < 100 kg mol-1 and semiflexible rods with lp ∼ 100 nm in Mw > 100 kg mol-1. Because the average contour length (lc) calculated from Mw is approximately twice as long as L in the Mw range < 100 kg mol-1, the formed HpMC particles possess a folded hairpin-like elongated rigid rod structure. However, the lc/L value increases gradually in the range Mw > 200 kg mol-1, where the formed HpMC particles behave as semiflexible rods. The formed particle structure was substantially different from that found in methyl cellulose samples with a similar DS value, which showed rod-like behavior over a wide Mw range. The addition of hydroxypropyl groups only at MS = 0.25 effectively changed the formed particle structure.

Preparation of lauric acid esterified starch by ethanol solvothermal process and its Pickering emulsion

In this paper, the esterification modification of different kinds of starches such as waxy maize, normal maize, high-amylose maize, cassava and potato in high temperature closed system were studied by solvothermal method. The oil-in-water Pickering emulsion were prepared with esterified starches as granule stabilizer. The microscopic state of granules in the emulsion and the physical and oxidation stability of emulsion were studied. The results show that starches are not gelatinized and can be esterified at a temperature (100 °C) much higher than that of gelatinization, and the granule morphology is almost unchanged. DS (degree of substitution) values of esterified starches range from 0.0333 to 0.0512. Pickering emulsion with 50 vol% oil volume fraction prepared with 3.0 wt% granule concentration did not show any instability such as oil-water separation after storage at room temperature for 30 days. Atomic force microscope (AFM) analysis showed that all esterified starch granules had the characteristics of granular cold-water swelling starch (GCWSS). The granules completely swelled into a dense molecular chain in the emulsion, and this three-dimensional network structure improved the stability of emulsion. Therefore, the preparation of esterified starch granules by ethanol solvothermal method is a simple and effective method.

Optimizing Acetic Anhydride Amount for Improved Properties of Acetylated Cellulose Nanofibers from Sisal Fibers Using a High-Speed Blender.

Acetylated cellulose nanofibers (ACNFs) have shown a great potential for strengthening non-polar polymer matrices and better dispersion which can improve composite properties. However, insufficient acetylation may cause inadequate nanofibrillation ACNF during the fibrillation process. The objective of this work was to evaluate the effect of different amounts of acetic anhydride (0, 45, 55, and 65 mL) on the degree of substitution (DS), morphology, crystalline structure, and thermal properties of ACNF obtained from sisal fiber produced using a high-speed blender. The attenuated total reflectance-Fourier transform infrared spectroscopy revealed the success of the acetylation process by the presence of the carbonyl signal around 1724 cm-1. Furthermore, the DS of ACNF was increased with the acetic anhydride amounts. X-ray diffraction analysis revealed that the crystalline structure of ACNF and non-ACNFs were cellulose I, and the crystallinity index of CNF was increased after acetylation treatment. Thermogravimetric analysis showed that the thermal stability of CNF was improved considerably after the acetylation process. The water contact angle of ACNF was higher than that of CNF, indicating that the structural property of CNF altered from hydrophilic to more hydrophobic after acetylation. In addition, the thermal resistance of CNF was improved significantly after acetylation treatment. The optimum amount of acetic anhydride was achieved in 55 mL of acetic anhydride (ACNF-55) which produced ACNF with a DS value of 0.5, a crystallinity index of 77%, a diameter of 87.48 nm, a maximum degradation temperature of 351 °C, and a contact angle of 37.7°. Overall, it was concluded that the obtained ACNF had great potential as reinforcement materials for nanocomposites based on non-polar polymeric matrices.

Optimizing reaction condition of octenyl succinic anhydride on heat-moisture-treated sago starch and its application for biodegradable film

This study presented the impact of pH and octenyl succinic anhydride (OSA) concentration on the esterification reaction of heat-moisture-treated sago starch (HMT-S) using response surface methodology to achieve optimum degree of substitution (DS), reaction efficiency (RE), and water contact angle (CA). The results showed that HMT-OSA sago starch (HMT-OS) starch exhibited an optimum pH of 7.26 and an OSA concentration of 4.53%. The DS value, RE, and water CA of optimized HMT-OS starch were 0.0121, 33.07%, and 90.11°, respectively. Furthermore, the optimized HMT-OS was used to evaluate the effect of starch modification on film characteristics. HMT-OS film has the best moisture-proof and mechanical properties compared to control (NS), HMT-S, and N-OS films, as indicated by lower water vapor permeability (28.69 g H2O.mm/s.m2.Pa × 10-11), water solubility (26.61%), higher CA (104.40°), elongation at break (85.63%), and transparency (3.25% mm-1). According to the scanning electron micrographic images, the absence of cracks or pores was attributed to the waterproof properties and flexibility of the film. Conversely, x-ray diffraction results showed that the crystallinity of HMT-OS film decreased to 36.05%.