Search Results (18)

Recent studies have shown that using conventional plastics to produce disposable tableware significantly impacts the environment. Alternatively, using cellulosic pulp from harnessing agro-industrial wastes, such as mango, provides a unique opportunity to create eco-friendly and biodegradable disposable tableware, a high-volume single-use item. Cellulosic pulp from the tegument of mango (cultivar Tommy Atkins) was successfully obtained by a semichemical pulping process to manufacture biodegradable plates. Refining times of 0, 5, 10, and 15 min were tested, and it was observed that a refining time of 10 min yielded a notably stronger material of 2.15 km in breaking length. Moreover, when the mango fibers were blended with pine fibers in a 70:30 (mango/pine) ratio, the material’s porosity significantly improved from 0 to 0.60 s/100 cc air. Alkyl ketene dimer at 1.5% was incorporated to impart water-resistant properties, changing the contact angle drop test from 0 to >120°. The biodegradation test indicated that the samples achieved a significant biodegradation level of 62.14 and 67.65 after 182 days of testing. The results demonstrated that the tegument from mango agro-industrial waste has the potential to be a source of cellulosic pulp to produce biodegradable and disposable tableware, contributing to the decrease in the use of conventional plastics. Full article

The need for sustainable, biodegradable materials to address environmental challenges, such as oil-water separation, is growing. Cellulose-based absorbents offer an eco-friendly alternative to synthetic materials. However, their hydrophobicity must be enhanced for efficient application. In this study, cellulose-based sorbents derived from Kraft and half-bleached chemo-thermomechanical pulp (BCTMP) were hydrophobized using silanization and alkyl ketene dimer (AKD) techniques. Hydrophobic properties were successfully imparted using methyltrimethoxysilane (MTMOS), n-octyltriethoxysilane (NTES), and N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane (AATMS), with water contact angles ranging from 120° to 140°. The water sorption capacity was significantly reduced to below 1 g/g, whereas the oil sorption capacity remained high (19–28 g/g). The most substantial reduction in water vapor absorption (3–6%) was observed for the MTMOS- and AATMS-silanized samples. These results demonstrate the potential of hydrophobized cellulose-based sorbents as sustainable alternatives for oil-water separation, contributing to environmentally friendly water treatment solutions. Full article

The growing prevalence of disposable toilet seat covers in public restrooms stems from concerns about personal hygiene, given the direct contact between the seat and various users’ skin. To enable these disposable cover sheets to be flushed down the toilet instead of being discarded in the trash, they must possess specific properties. These include rapid water absorption for quick disintegration, strength to endure user movement or moisture on the toilet seat surface, and a comfortable texture. To address these challenges, the study investigated the disintegration characteristics of flushable cover sheets prepared under different refining conditions. Alkyl ketene dimer (AKD) was also employed to enhance water resistance, while an organic antibacterial agent was used to impart antimicrobial properties. The findings revealed that adding 0.2% AKD and 1% organic antibacterial agent to pulp stock with a freeness of about 650 mL CSF was suitable for manufacturing disposable cover sheets with disintegration characteristics like toilet tissue paper. Full article

Portland cement has a limited shelf life because of the prehydration that can occur during storage. One approach to mitigating strength losses observed for concrete is to pretreat cement with a protective coating to slow the advance of prehydration. This study compared cement pretreatments with alkyl ketene dimer (AKD) wax and a combination of AKD + paraffin wax to a more traditional pretreatment approach using oleic acid. After exposing the treated cements to elevated temperature and humidity conditions, paste and mortar calorimetry tests showed improved resistance to prehydration reactions. The cements aged up to 12 weeks under the accelerated regime showed strength improvement for the mortars made with AKD and AKD + paraffin-treated cements relative to the mortars made with oleic acid-treated cement and mortars made with untreated cement. The wax can be added during clinker milling and additionally functions as a grinding aid. Full article

Livestock dung, discarded crop straws, and residual plastic film are the primary agricultural non-point sources of pollution. For livestock dung and discarded crop straw, the general treatment focuses on compost, animal fodder, industrial raw material, and new energy. The development of degradable mulch film is the main way to solve pollution from residual plastic film. However, an effective way to solve the above three types of pollution simultaneously and use them for ecological circular agriculture has been less studied. In this study, using cow dung and flax straw wastes as raw materials, we prepared natural, fibre-based paper mulch using the rapid-Kothen method and analysed the film-forming mechanism. Based on the Van Soest method, the cow dung and flax straw waste contain abundant cellulose fibres: 36.75% and 54.69%, respectively. The tensile strength and tear strength of fibre paper mulch are 1.87 kN/m and 19.91 N/mm, respectively. To enhance the adaptability of the fibre paper mulch in humid environments, the surface of the mulch was treated with alkyl ketene dimer (AKD). The AKD-coated fibre paper mulch displays hydrophobic properties, indicated by a contact angle of 128° ± 2°. It has a wet tensile strength of 0.64 kN/m and a wet tear strength of 8.23 N/mm. Additionally, it exhibits a dry tensile strength and a tear strength of 2.13 kN/m and 16.43 N/mm, respectively. Notably, the dry tensile strength is increased by 16.31%. In this way, the livestock dung and discarded crop straw can be reused, reducing dung pollution and straw burning in livestock farms, and the final products can alleviate the residual film pollution simultaneously. Full article

The aim of the present study was to investigate highly efficient alkyl ketene dimer (AKD) emulsions to improve the hydrophobicity of cellulose paper. AKD emulsions stabilized by guar gel were obtained; the guar gel was prepared by hydrogen bond cross-linking sodium tetraborate and guar gum. The cross-linking was confirmed by combining FTIR and SEM. The effect of guar gel on the performance of the AKD emulsions was also studied by testing AKD emulsions stabilized by different guar gel concentrations. The results showed that with increasing guar gel concentration, the stability of the AKD emulsions improved, the droplet diameter decreased, and the hydrophobicity and water resistance of the sized packaging paper were gradually enhanced. Through SEM, the guar gel film covering the AKD emulsion droplet surface and the three-dimensional structure in the aqueous dispersion phase were assessed. This study constructed a scientific and efficient preparation method for AKD emulsions and provided a new method for the application of carbohydrate polymer gels which may avoid the adverse effect of surfactant on paper sizing and environmental problems caused by surfactant bioaccumulation. Full article

In this study, a stable alkyl ketene dimer (AKD) Pickering emulsion was obtained using chitosan and titanium dioxide (TiO₂) as effective emulsifiers to disperse AKD. Superhydrophobic filter paper was prepared, using the filter paper as the substrate, by dipping it into AKD Pickering emulsion and then drying the coating papers at different temperature. The contact angle of the treated filter papers dried at 45 °C could reach more than 150°, and these filter papers effectively separated oil–water mixtures with an efficiency of over 93%. It is worth noting that the preparation process of the superhydrophobic material was simple and mild, and all the raw material was green without secondary pollution to the environment, so it has great practical application potential. This experiment could provide a new idea for the preparation of AKD superhydrophobic coatings and broaden their application. Full article

The preparation of biodegradable mulch film to replace non-degradable mulch film is of great significance for reducing the harm of non-degradable agricultural mulch film to the environment. However, there are few studies on the degradation performance and degradation mechanisms of degradable cellulose mulch. Therefore, the wet papermaking process was adopted in this work. Salix fiber and wheat straw fiber were used as raw materials. A Salix/wheat straw fiber degradable film was prepared by adding cationic polyacrylamide, alkyl ketene dimer, and paraffin emulsion. The degradation process of cellulose film was studied using a UV degradation test and an acid-base degradation test system. The results showed that after 40 days of UV degradation, the degradation rate of Salix/wheat straw fiber degradable film could reach 6.66%. The tensile strength could still maintain 2.878 KN/m. The results of the brightness change index ($\Delta$L) and color overall change index ($\mathsf{\Delta }E$) showed that the surface of the Salix/wheat straw fiber degradable film had been successfully partially degraded. After 4 days of alkaline degradation, the degradation rate could reach 11.89%. After 4 days of acid degradation, the degradation rate could reach 14.64%. At the same time, the specific degradation process of Salix/wheat straw fiber degradable film was further studied by infrared spectroscopy and scanning electron microscopy. This work provides a new method for the study of agricultural degradable cellulose mulch, which is of great significance for the future development of agricultural mulch. Full article

This paper analyzes the potential of coatings based on xylan derivatives and chitosan to provide barrier properties and antimicrobial protection for paper food packaging and also to substitute the synthetic materials currently used in the food packaging industry. Colloidal dispersions of xylan derivatives (hydrophobized xylan with alkyl ketene dimers—XyAKD—and acetylated xylan—XyAc) and a chitosan biopolymer (Ch) were applied as coatings in single and two successive layers on a paper substrate using a laboratory automatic film applicator. The assessment of the water and fatty compound barrier properties of coated paper samples showed differences in effectiveness among xylan derivatives and their combination with chitosan. Generally, xylan derivative coatings improved the barrier and antimicrobial features of coated papers compared with native xylan. However, important improvements were obtained by adding to the coating formula a chitosan biopolymer. Thus, the best barrier properties for water, water vapors, oils and greases were obtained for paper coated with the acetylated xylan and chitosan formula in a single layer, where values of 30 g/m².day for the water vapor transmission rate (WVTR), a 92.8° contact angle (CA) and a KIT rating of 8 were achieved. All coated paper samples exhibited the total inhibition of Bacillus sp. both after 24 and 48 h. Based on the obtained results in this study, one can conclude that the area of application of xylan hemicelluloses could be extended. Their utilization in appropriate chemical structures and combinations as coatings for paper can be a sustainable alternative for the food packaging industry. Full article

Here, we first report the 2′-acyloxy-1,3-dicarbonyl compound construction in a three-component oxidative reaction of alkyl ketene dimer with cyclic diacyl peroxide and trimethyl orthoformate. The discovered synthesis allows us to form 2′-functionalized 1,3-dicarbonyl compounds instead of the common 2-functionalized moiety. The reaction between 4-butylidene-3-propyloxetan-2-one and cyclopropyl malonoyl peroxide proceeds in the presence of trifluoroacetic acid and trimethyl orthoformate at 120 °C for 1 h. The synthesized compound was characterized by NMR spectroscopy, mass spectrometry, and IR spectroscopy. Full article

In order to improve the hydrophobicity of xylan hemicellulose, a simple procedure of its chemical modification with alkyl ketene dimer (AKD), a non-toxic, cost-effective, and eco-friendly chemical, was performed. For this purpose, the reaction products of beech wood xylan and different amounts of hydrophobic AKD were used for paper surface treatment. Thus, the coatings of about 4.5 g/m² were applied on both sides of base paper in single and three successive layers. To obtain a complete reaction between AKD and xylan hemicellulose, the coated papers were thermal cured (about 110 °C) and the effects of AKD content on the barrier (water, oil, and water vapours) and mechanical properties were analysed. The structural analyses by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) of coated samples emphasized the presence of β-keto-ester compounds as a result of the reaction between xylan hemicelluloses and AKD. This is confirmed by the improving of barrier properties as the AKD content in coating dispersion is higher. The good barrier performance and improved strength properties were obtained for the coated papers with xylan hemicellulose and 1% AKD applied on paper surface in three successive layers (about 4.5 g/m²). In this case, the water vapours transmission rate (WVTR) was 35% lower than those untreated and the resistance to air passing through coated papers was over 3 times higher compared with base paper. There are no results reported on the chemical reaction of xylan hemicelluloses with AKD as well as its application in coatings for paper packaging. In this context, the obtained results in this study can contribute to expand the applications area of hemicelluloses offering a sustainable strategy for the developing of food packaging papers with appropriate barrier properties using biopolymer coating materials. Full article

The aim of this research was to evaluate the multiple effects of both thermal modification and alkyl ketene dimer (AKD) on the deodar cedar (Cedrus deodara Roxb.) wood surface, before and after an irradiation test. The physical and chemical changes that occurred on the cedar wood samples due to the combined effect of these modifications were evaluated by measuring their wettability and colour and using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The surface analysis by XPS showed the expected variability among the sampled layers for unmodified and thermally modified cedar wood samples and a uniform composition after the AKD coverage, regardless of their pre-treatments. The FTIR spectra before the irradiation test showed that the hydrophobicity of the samples was ensured by the formation of carbonyl groups originating from the reaction between the AKD and hydroxyl groups of cellulose, which is related to the presence of the absorption band between 1700 cm⁻¹ and 1750 cm⁻¹. Markedly, after the irradiation test, a degradation of the amorphous cellulose component occurred, showing that photoisomerisation to the enolic form took place. Overall, although uniform AKD coverage was derived from the surface analysis and wetting test, the combined ATR-FTIR results and colour measurements showed that it could not provide permanent protection to the underlying wood structure due to its own tendency to degrade mainly in colour over time, under the action of UV rays and atmospheric agents. Full article

It has been a persistent challenge to develop eco-friendly packaging cellulose film providing the required multiple barrier properties whilst simultaneously contributing to a circular economy. Typically, a cellulosic film made from nanocellulose materials presents severe limitations, such as poor water/moisture resistance and lacking water vapour barrier properties, related primarily to the hydrophilic and hygroscopic nature of cellulose. In this work, alkyl ketene dimer (AKD) and starch, both eco-friendly, non-toxic, cost-effective materials, were used to achieve barrier properties of novel cellulose–calcium carbonate composite films regenerated from paper components, including paper waste, using ionic liquid as solvent. AKD and starch were applied first into the ionic cellulose solution dope mix, and secondly, AKD alone was coated from hot aqueous suspension onto the film surface using a substrate surface precooling technique. The interactions between the AKD and cellulose film were characterised by Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) showing the formation of a ketone ester structure between AKD and the hydroxyl groups of cellulose. The presence of calcium carbonate particles in the composite was seen to enhance the cellulose crystallinity. The initial high-water vapour and oxygen transmission rates of the untreated base films could be decreased significantly from 2.00 to 0.14 g m⁻² d⁻¹, and 3.85 × 10² to 0.45 × 10² cm³ m⁻² d⁻¹, respectively. In addition, by applying subsequent heat treatment to the AKD coating, the water contact angle was markedly increased to reach levels of superhydrophobicity (>150°, and roll-off angle < 5°). The resistance to water absorption, grease-permeation, and tensile strength properties were ultimately improved by 41.52%, 95.33%, and 127.33%, respectively, compared with those of an untreated pure cellulose film. The resulting regenerated cellulose–calcium carbonate composite-based film and coating formulation can be considered to provide a future bio-based circular economy barrier film, for example, for the packaging, construction and agriculture industries, to complement or replace oil-based plastics. Full article

Thermal stress and moisture absorption can cause a synergetic negative impact on kraft paper. Among various approaches for improving the dielectric properties of kraft paper, nanotechnology has had promising results. However, the hydrophilicity of most metal oxide nanoparticles renders nanomodified kraft paper more vulnerable to thermal stress and moisture, thereby inducing degradation. In nanomodified kraft paper research, the use of TiO₂ nanoparticles has yielded the most promising results. The major shortfall, however, is the hydrophilicity of TiO₂. This work investigated surface modifications of rutile-TiO₂ nanoparticles (NPs) for improved hydrophobicity and thermal stability. Rutile-TiO₂ NPs is a nontoxic metal oxide that can withstand high temperature and is stable in chemical reactions. Two cases of surfactants were used—alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA). The intention was to increase heat resistance and reduce the surface free energy of the rutile-TiO₂ NPs. The impacts of the surface modifiers on the rutile-TiO₂ NPs were characterised using FT-IR, muffle furnace, analytical weight balance, and TGA. It was discovered that new functional groups were formed on the modified NPs examined through FT-IR spectra. This indicates new chemical bonds, introduced through the surface modification. The unmodified rutile-TiO₂ NPs absorbed moisture, increasing their mass by 3.88%, compared with the modified nanoparticles, which released moisture instead. TGA analysis revealed that AKD- and ASA-modified rutile-TiO₂ needed higher temperatures than the unmodified rutile-TiO₂ to markedly decompose. AKD, however, gave better performance than ASA in that regard. As an example, those modified with 5% AKD sustained a 45% higher temperature than the pure TiO₂ nanoparticles. Furthermore, in both cases of the surfactants, the higher the percent of surfactant content was, the more thermally stable the nanoparticles became. This work demonstrates the possibility of fabricating rutile-TiO₂ NPs to give improved hydrophobicity and thermal stability for possible dielectric applications such as in kraft paper for power transformer insulation. Full article

Recently, cellulose nanofibers (CNF) are used as one novel fillers to reinforce poly(lactic acid) (PLA) matrix and form PLA green nanocomposites. In the present work, alkyl ketene dimer (AKD) was used as the sizing of CNF to improve the interfacial compatibility between the hydrophilic CNF and the hydrophobic PLA. The interactions between the AKD and CNF were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), which showed the formation of ketone ester structure between AKD and the hydroxyl groups of CNF. Thermo gravimetric analysis (TGA) showed the little reduced thermal stability of the AKD-CNF/PLA composites. The AKD-CNF/PLA morphology has rough surfaces due to the incorporation of cellulose nanofibers. The mechanical properties of AKD-CNF/PLA were tested by tensile testing, which discovered more AKD-CNF content enhances stress–strain performance. The highest tensile strength of composites was obtained for PLA with 5.0 wt.% AKD-cellulose, which is almost nine times higher than that of the pure PLA. Full article