Cellulose Crystallinity Index Research Articles

Precise high-throughput online near-infrared spectroscopy assay to determine key cell wall features associated with sugarcane bagasse digestibility

BackgroundSugarcane is one of the most crucial energy crops that produces high yields of sugar and lignocellulose. The cellulose crystallinity index (CrI) and lignin are the two kinds of key cell wall features that account for lignocellulose saccharification. Therefore, high-throughput screening of sugarcane germplasm with excellent cell wall features is considered a promising strategy to enhance bagasse digestibility. Recently, there has been research to explore near-infrared spectroscopy (NIRS) assays for the characterization of the corresponding wall features. However, due to the technical barriers of the offline strategy, it is difficult to apply for high-throughput real-time analyses. This study was therefore initiated to develop a high-throughput online NIRS assay to rapidly detect cellulose crystallinity, lignin content, and their related proportions in sugarcane, aiming to provide an efficient and feasible method for sugarcane cell wall feature evaluation.ResultsA total of 838 different sugarcane genotypes were collected at different growth stages during 2018 and 2019. A continuous variation distribution of the near-infrared spectrum was observed among these collections. Due to the very large diversity of CrI and lignin contents detected in the collected sugarcane samples, seven high-quality calibration models were developed through online NIRS calibration. All of the generated equations displayed coefficient of determination (R2) values greater than 0.8 and high ratio performance deviation (RPD) values of over 2.0 in calibration, internal cross-validation, and external validation. Remarkably, the equations for CrI and total lignin content exhibited RPD values as high as 2.56 and 2.55, respectively, indicating their excellent prediction capacity. An offline NIRS assay was also performed. Comparable calibration was observed between the offline and online NIRS analyses, suggesting that both strategies would be applicable to estimate cell wall characteristics. Nevertheless, as online NIRS assays offer tremendous advantages for large-scale real-time screening applications, it could be implied that they are a better option for high-throughput cell wall feature prediction.ConclusionsThis study, as an initial attempt, explored an online NIRS assay for the high-throughput assessment of key cell wall features in terms of CrI, lignin content, and their proportion in sugarcane. Consistent and precise calibration results were obtained with NIRS modeling, insinuating this strategy as a reliable approach for the large-scale screening of promising sugarcane germplasm for cell wall structure improvement and beyond.

Characterization of natural cellulosic fibers from Yucca aloifolia L. leaf as potential reinforcement of polymer composites

In this work lignocellulosic fibers were obtained from Yucca aloifolia L. leaves and their chemical, morphological, thermal and mechanical properties were studied. The fibers were pullout from the leaves and characterized by infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), chemical characterization, thermogravimetric analysis (TGA), single fiber tensile tests and scanning electron microscopy (SEM). The cellulose crystallinity index found was 69.43%. The fibers presented a high cellulose content, ~ 52.5%, and they are thermally stable until 193.4 °C. The tensile test for single fibers showed average results for the tensile strength of 800 MPa, Young's modulus of 39 GPa, and 2% strain at failure. Morphological analysis indicated the presence of a large number of parenchymal cells and not cellulosic constituents in fiber surface. These results indicated that Yucca aloifolia L. fibers have potential to application in polymeric matrices as fibrous reinforcement material.

High yield synthesis of hexitols and ethylene glycol through one-pot hydrolytic hydrogenation of cellulose

Catalytic valorization of biomass has gained a significant global attention in recent years. Cellulose is an interesting bio-renewable feedstock, which can be utilized to replace the fossil fuel derived chemicals to attain a sustainable bio-based economy. Our research shows a one-pot conversion of cellulose through hydrolytic hydrogenation using heteropolyacid (HPA)/zirconia and Ru/C catalyst. The developed catalytic system was found to be highly active towards selective production of hexitols and ethylene glycol. A significant improvement in the catalytic performance towards cellulose conversion was observed when the cellulose was pre-treated using ball-milling (900 rpm, 8 h), as the ball-milling significantly reduced the crystallinity index of cellulose, which decreased the recalcitrance of the cellulose structure. Almost complete conversion (100%) of cellulose was observed when the reaction was performed at 220 °C for 5 h giving hexitols and ethylene glycol yields of 26.2 and 40%, respectively. Based on a series of experiments, a possible reaction pathway was proposed which suggested heteropolyacid/zirconia catalyzed hydrolysis and retro-aldol condensation reactions, accompanying by hydrogenation with Ru/C. Interestingly, HPA immobilized on the composite catalyst shows enhanced stability and recyclability, demonstrating the utilization of a heterogeneous system for tandem conversions of biomass to renewable fuels and feedstocks.

The effects of chemical and structural factors on the enzymatic saccharification of Eucalyptus sp. samples pre-treated by various technologies

Lignocellulosic biomass is an important renewable resource to produce biofuels, due to its abundance and high polysaccharide content. Bioconversion is generally achieved in two stages: (i) pre-treatment, to reduce biomass recalcitrance, and (ii) enzymatic cellulose hydrolysis into fermentable sugars. However, the key structural and chemical features of biomass which hinder enzymatic hydrolysis remains challenging to evaluate. In this study, we explored the effect of eight different pre-treatments on the enzymatic hydrolysis of a Eucalyptus sp. – a potential feedstock for biofuel production. The analytical data collected covered the mass fractions of cellulose, hemicellulose and lignin, the syringyl: guaiacyl (S/G) ratio of lignin, functional group determination, crystallinity index (CrI) and accessibility of cellulose. Enzymatic hydrolysis was then performed using an in-house optimised cellulolytic enzyme cocktail (either alone or supplemented with xylanase or laccase) to elucidate the key factors of biomass recalcitrance which influence its enzymatic hydrolysis. Enzymatic saccharification was improved by changes in Eucalyptus induced by steam explosion pre-treatment, such as substantial removal of hemicelluloses, increased cellulose accessibility, and disruption of cell wall architecture and exposure of fibres. Partial removal of lignin, increased S/G lignin subunit ratio and lowered cellulose crystallinity exhibited no significant positive effects on biomass enzymatic hydrolyzability. Thus, this study provides insight into important chemical and structural features related to biomass recalcitrance arising from various pre-treatment methods, which can ultimately be used as a platform for the development of more efficient conversion technologies for novel and competitive bio-refineries.

Hydroxypropyl cellulose loaded with ZnO nanoparticles for enhancing the mechanical properties of papyrus (Cyperus papyrus L.) strips

Unfortunately, papyrus has not been sufficiently studied regarding improvement of the mechanical or optical properties, which degrade under the impact of aging factors over time. The aims of this research were studying the effects of hydroxypropylcellulose (HPC) loaded with 0.25% of ZnO nanoparticles (NP) at different concentrations (1% and 2%) on papyrus sheet properties before and after aging. Various analyses were used, such as visual assessment by a universal serial bus (USB) digital microscope, mechanical properties, Fourier-transform infrared (FTIR) analysis, color change, and pH measurement. A dramatic increase in mechanical properties was observed after treatment. Besides, FTIR illustrated increasing of CH2 and OH stretching, which contribute to increasing the cellulose crystallinity index. There was no significant change in pH values after treatment or ageing. Slight changes of optical characteristics were observed for treated samples, after the artificial aging of the treated samples, the mechanical measurements showed that the values of tensile strength and elongation were close to the values of the standard sample, which may contribute to preventive protection of ZnO NP for treated samples from the artificial ageing.

An analytical study on the relationship between the fungal degradation and multi-component nature of paper manuscripts

PurposeThis paper aims to identify the most common fungal species that grow on paper manuscripts and cause bio-deterioration. It also detects the impact of additive materials on fungal degrading and builds a wide database. Thus, it helps conservators understand this phenomenon.Design/methodology/approachIn total, 15 samples were collected from different paper manuscripts suffering from fungi. The achievement of the study objectives depends on using a variety of analyzes, such as a microbiological study, which indicated that three main fungi grew on the paper samples. Then, a digital microscope and an environmental scanning electron microscope were used to detect the effect of fungi on paper fibers. Fourier transform infrared microscopy was used to identify the binding medium and the X-ray diffraction method was used to measure the crystallinity index of cellulose of the paper samples.FindingsArabic gum was used as a binder medium with the samples. Aspergillus Niger, Aspergillus Fumigatus and Aspergillus Clavatus were the most common fungal species that grew on the Qur’an papers under investigation. They also caused much common damage to the paper samples. The results of the analyzes also showed that the highest crystallinity index of cellulose was in the samples that contained the lowest rate of fungal growth.Originality/valueThis paper highlights the relationship between fungal degradation and the multi-component nature of paper manuscripts. It builds a wide database that correlates the composition and the degradation of the Qur’an papers.

Separation and characterization of cellulose from sugarcane tops and its saccharification by recombinant cellulolytic enzymes

In the present study, the cellulose from sugarcane tops (SCT) was separated and characterized for its purity. Approximately, 85% (w/w) of total cellulose present in raw SCT was recovered by using alkaline method. The monosaccharide analysis of SCT cellulose by HPLC showed 91% D-glucose, 7.5% D-xylose and 1.5% D-arabinose residues. Surface morphology study of dried cellulosic fibers by FESEM exhibited the fibrous structure. The FTIR analysis of separated cellulose displayed the peaks corresponding to the peaks obtained from commercial cellulose, confirming its purity. The crystallinity index (CrI) of separated cellulose increased to 49% after delignification and xylan extraction from 36% of raw SCT. The typical TGA curve of separated SCT cellulose showed decomposition and mass reduction at 327 °C resulting in single decomposition peak in TGA analysis, confirming its purity. CHNS analysis supported the purity of separated cellulose by confirming absence of nitrogen and sulfur. The separated cellulose was hydrolyzed by recombinant endo-β-1,4-glucanase (CtCel8A), cellobiohydrolase (CtCBH5A) from Clostridium themocellum and β-1,4-glucosidase (HtBgl) from Hungateiclostridium thermocellum at pH 5.8, 50 °C for 24 h, resulting in the production of 188 mg/g of total reducing sugar (TRS). The separated cellulose from SCT can be utilized as an alternative substrate for commercialization and for bioethanol production.

Effect of magnesium oxide pretreatment on the delignification and enzymatic hydrolysis of corncob

Pretreatment process is a critical technological step in the bioconversion of lignocellulose. In the present work, magnesium oxide (MgO) was applied in corncob pretreatment for improving the lignin removal and subsequently enhancing the sugar yield via enzymatic hydrolysis. Results showed that a lignin removal of 19.18 % was achieved when the corncob was pretreated with 0.1 mol/L MgO at a solid to liquid ratio of 1:10 and 190 °C for 50 min. Compared to raw material, the pretreated corncob exhibited looser surface, higher crystallinity index and higher content of cellulose. Under the optimal pretreatment conditions, glucose yield of 68.13 %, xylose yield of 25.93 %, and total sugar yield of 49.68 % were obtained via enzymatic hydrolysis of corncob. This work would be helpful in updating the corncob pretreatment process and promoting the valorization of corncob.

Deacidification of Microalgal Oil with Alkaline Microcrystalline Cellulose.

Microalgal oil is considered a promising candidate for edible oils. However, investigation of the refining processes of microalgal oil has been limited, especially deacidification. In this work, microcrystalline cellulose (MCC) was pretreated using different methods and utilized for the first time in the deacidification of microalgal oil. Detection results from FTIR and XRD indicated alkali pretreatment had a significant effect on the structure of MCC. Some inter- and intramolecular hydrogen bonds in AMCC (alkali-pretreated MCC) were destroyed, and crystallinity index of cellulose decreased, which increased its adsorption capacity and the reaction of OH groups with free fatty acids. Some NaOH was adsorbed into AMCC through cellulose swelling, which also contributed to deacidification. The interaction with oil was also improved with many cracks and voids on the surface of AMCC. AMCC could reduce the acid value to about 2mgKOH/g. Comparatively, original MCC and MCC pretreated with microwave or ultrasound did not exhibit the ability to deacidify. Furthermore, the conditions of alkali treatment were optimized. Treatment with 20% NaOH for 20min was optimal. Compared with other adsorbents, such as sodium silicate and chitosan treated with alkali and resin, only AMCC could effectively reduce acid value while maintaining high lipid recovery. Therefore, AMCC was considered a better adsorbent for the deacidification of microalgal oil.

Solid state NMR investigation of the roman Acqualadroni rostrum: tenth year assessment of the consolidation treatment of the wooden part

This work follows a previous one dealing with the state of conservation study of the wooden part of the roman Acqualadroni rostrum soon after its finding in the seabed of Acqualadroni (Messina, Italy). The archaeological survey and recovery were particularly relevant since this artefact is one of the two rostrums, nowadays known, found together with its wooden part. Following the recovery, it was consolidated by immersion in a melamine-formaldehyde resin (Kauramin) aqueous solution for eight months at the “Centro di Restauro del Legno Bagnato” (Pisa, Italy). The present investigation is aimed to determine at microscopic scale the wood state of conservation and to highlight interactions of the consolidant with wood components, by using solid-state NMR spectroscopy ten years after the consolidation treatment. Sampling by coring was exceptionally authorized, and the wood core was divided into seven aliquots as a function of depth. 13C cross-polarization magic angle spinning (13C{1H} CP-MAS NMR) spectra and variable contact time (VCT) experiments have been carried out to determine the cellulose crystallinity index, the lignin condensation degree and the holocellulose-lignin ratio. The interactions between the resin and the wood components were highlighted by T1ρH relaxation times determination and two-dimensional 13C–1H correlation (FSLG CP HETCOR) NMR experiments. Findings revealed specific interactions between the aromatic part of the resin and the lignin, as well as a network of hydrogen bonds involving all components of the system.

Enzymatic extract of Aspergillus fumigatus CCT 7873 for hydrolysis of sugarcane bagasse and generation of cellulose nanocrystals (CNC)

In this study, cellulose nanocrystals (CNC) were produced from untreated and pretreated sugarcane fibers through enzymatic hydrolysis using a crude cellulolytic extract produced by the fungus Aspergillus fumigatus CCT 7873 using semi-solid fermentation (SSF). The fibers were characterized in terms of cellulose, hemicellulose, and lignin contents and crystallinity index. The CNC generated during the enzymatic hydrolysis using a sugarcane fiber pretreated with 4% NaOH and an enzymatic loading of 7.5 FPU g−1 of bagasse were characterized by atomic force microscopy (AFM). The results showed that after the hydrolysis time of 48 h, spherical-like particles with a good size distribution and a mean diameter of 61 nm were obtained. In this study, we produced cellulose nanocrystals (CNC) from untreated and pretreated sugarcane fibers through enzymatic hydrolysis using a crude cellulolytic extract produced by the fungus Aspergillus fumigatus CCT 7873 using semi-solid fermentation (SSF). In fact, the main novelty of this manuscript is the fact that it accompanies the formation of CNC, by means of atomic force microscopy (AFM). It is noteworthy that there are few manuscripts with this approach in the literature. In addition, this was performed during the cultivation of a fermentation broth containing cellulases produced by an enzymatic extract of the fungus Aspergillus fumigatus CCT 7873 using SSF. Thus, CNC, a highly added value product, can be obtained from lignocellulosic residues, which is a renewable and low-cost source. The results showed that, during the cultivation, there is a variation in the size distribution of the CNC and that, for the hydrolysis time of 48 h, a good size distribution was obtained for the CNC with about 61 nm in diameter, presenting a spherical shape.

Characterization of lignocellulose of Opuntia (Cactaceae) species using FTIR spectroscopy: possible candidates for renewable raw material

Opuntia is mainly cultivated for its fruit and cladodes, but the chemical composition of lignocellulose in this genus is unknown. The aims of this study were to quantify the extracts in different organic solvents and water, to quantify the lignocellulosic compounds, to compare the syringyl/guaiacyl ratio of lignin, and to calculate the crystallinity index of cellulose. The mature cladodes of three Opuntia species were dehydrated and milled; with the powder, sequential solvent extractions were performed based on TAPPI T-222 om-02 standard. Lignin Klason, cellulose, and hemicellulose were quantified. Fourier transform infrared spectra were obtained from cellulose and lignin samples to calculate the syringyl/guaiacyl ratio and the crystalline cellulose index. The percentages of water ranged from 89 to 92%; the Kruskal-Wallis analysis showed significant differences (p < 0.05) in the extracts with ethanol/benzene, cellulose, and hemicelluloses. Opuntia ficus-indica had the highest amount of cellulose (32.6%) and hemicelluloses (9.8%). The syringyl/guaiacyl ratio was 1.59 to 2.12, due to the presence of 60% of syringyl. The crystallinity index revealed percentages higher than 60% of crystalline cellulose. The lignocellulosic percentages and the chemical composition of lignin and cellulose allow Opuntia species to be used in the production of cellulose nanofibers and biofuels.

Properties of Natural Luffa Vine as potential reinforcement for biomass composites

The exploration of luffa vine (LV) in the polymer composites field can contribute to the development of lightweight composites and expand their use in new wide scale applications. In this study, the physical and chemical properties and the microstructure of the LV fibers were investigated by various techniques. The results of LV density and microscopic characteristics indicated that this crop is a lightweight (with density mainly concentrated in 0.30–0.45 g cm−3) natural fiber with a porous structure (the ratio of wall to lumen: 0.2–0.3). Transmission electron microscopy and nanoindentation analyses showed that the secondary wall of the LV sclerenchyma cell is made up of two layers with spiral thickening and exhibiting a high nanoindentation modulus (7.8–10.4 GPa) and a high nanoindentation hardness (0.40–0.58 GPa). The chemical composition and X-ray diffraction analysis indicated that the LV has high lignin content (20–25%) and a relatively high relative crystallinity index of cellulose, which are conducive to increase the hardness of the LV fiber. Moreover, microscopic characteristics analysis also revealed that the LV fiber cells have a relatively high aspect ratio (30.3), there are pit pairs on the LV fiber cell walls, and the core fiber cells of the LV have relatively high flexibility coefficient (0.8), which are beneficial to increase the processability of composite materials with the LV fibers as reinforcement.

Physico Chemical Characterization of Fiber from Melia Azedarach Barks as an Effective Reinforcement in Polymer Matrices

ABSTRACT The present study aimed to investigate the physico-chemical properties of new cellulosic fiber obtained from the bark of Melia Azedarach tree. The investigation outcomes revealed that, the cellulose content, crystallinity index and density of Melia Azedarach Fiber (MAF) were determined as 66.5 wt.%, 45.45% and 950 Kg/m3, respectively. The MAF had thermal stability up to 220θC which is evidenced from the thermo gravimetric analysis. The Fourier Transform Infra Red test clearly specified the existence of cellulosic and non-cellulosic substance in MAF. The morphological analysis showed that MAF contains smooth surfaces and its diameter is measured as 48.2 ± 2 µm. The results of this investigation on MAF were evident that it can be used as future reinforcement material to develop the green composite for potential applications.

The production of hydrogen–deuterium exchanged cellulose fibers with exchange-resistant deuterium incorporation

Production of deuterated cellulose is important from both theoretical and practical perspectives. In this study, cellulose fibers of cotton and Tencel fibers with exchange-resistant deuterium incorporation were prepared by hydrogen–deuterium exchange treatment. The effect of the micro-structure of cellulose crystallinity index as well as the reaction conditions including catalyst, reaction time, and temperature on the exchange-resistant deuterium incorporation process are reported. The ability of deuterated cellulose fibers to resist protium-exchange during H2O washing was also explored. The results found that higher crystallinity index is beneficial to stabilize the deuteration of cellulose fibers. Furthermore, alkaline catalysts such as sodium hydroxide or potassium carbonate and higher exchange temperature as well as longer reaction time contribute significantly to the stabilization of deuterium incorporation in the deuterated cellulose fibers. These observations revealed that the hydrogen–deuterium exchange treatment is effective to obtain exchange-resistant deuterium incorporated cellulose fibers. In addition, cotton fibers with several deuteration levels were produced and could be considered for the study of deuterium effect on cellulose properties.

Profiling of Chemical and Structural Composition of Lignocellulosic Biomasses in Tetraploid Rice Straw.

The improvement of the saccharification of rice straw is one of the strategies to reduce the sophisticated pretreatment that results in high cost and is unfriendly to the environment. We explored the cell wall features in tetraploid rice and highlighted the enhanced saccharification of tetraploid with large biomass. Results showed that lignin content and S/G ratio reduced to 17.09% and 0.37, respectively, in tetraploid straw by the determination of the pyGC-MS method. After the pretreatment, the cellulose crystallinity index decreased from 63.22% to 57.65% in tetraploid straw, which is lower than that of pretreated diploid straw. Surface topological analysis of SEM images indicated that tetraploid straw was more susceptible to the pretreatment. Tetraploid straw showed a strong advantage in the process of enzymatic hydrolysis. The enzyme efficiency reached the highest value of 77.60%, and the rate of enzyme reaction was improved to make the reaction saturated earlier than conventional rice. We concluded that the high saccharification has resulted from the alteration of lignin and cellulose in tetraploid rice. Our research provides an improved green feedstock for bioenergy, and the tetraploid rice straw shows the potential utilization value in bioethanol production.

Tensile strength and elongation analysis on nano cellulose Film Isolated from Sugarcane Bagasse

Nano cellulose was successfully isolated from sugarcane bagasse through sulphuric acid hydrolysis of sugarcane bagasse cellulose. Physically, Nano cellulose was transparent and broken white. The crystallinity index of sugarcane bagasse nano cellulose was 80.72%. The particle size of sugarcane bagasse nano cellulose was 225 nm. Delignification process in isolation was successfully showed by releasing peaks in 1239.3 and 1507.7. It show C-O-C vibration of aryl group in lignin and C=C aromatic ring in lignin respectively. Sugarcane bagasse cellulose shows peaks at 1720.2 that represent COOH and hemicellulose carboxylic groups, while the others were not found. The crystallinity index of Nano cellulose was 42.65%. Nano cellulose film prepared in several concentrations (3%, 6%, and 9%). Nano cellulose film also prepared with adding HPMC 2%. Nano cellulose film prepared in 9% concentration was too strict and broken easily. The tensile strength and elongation of Nano cellulose film that prepared in 3% + HPMC 2% and 6% + HPMC 2% were 3.177 Mpa, 10.93% and 3.315 Mpa dan 3.7% respectively.

Brassinosteroid overproduction improves lignocellulose quantity and quality to maximize bioethanol yield under green-like biomass process in transgenic poplar

BackgroundAs a leading biomass feedstock, poplar plants provide enormous lignocellulose resource convertible for biofuels and bio-chemicals. However, lignocellulose recalcitrance particularly in wood plants, basically causes a costly bioethanol production unacceptable for commercial marketing with potential secondary pollution to the environment. Therefore, it becomes important to reduce lignocellulose recalcitrance by genetic modification of plant cell walls, and meanwhile to establish advanced biomass process technology in woody plants. Brassinosteroids, plant-specific steroid hormones, are considered to participate in plant growth and development for biomass production, but little has been reported about brassinosteroids roles in plant cell wall assembly and modification. In this study, we generated transgenic poplar plant that overexpressed DEETIOLATED2 gene for brassinosteroids overproduction. We then detected cell wall feature alteration and examined biomass enzymatic saccharification for bioethanol production under various chemical pretreatments.ResultsCompared with wild type, the PtoDET2 overexpressed transgenic plants contained much higher brassinosteroids levels. The transgenic poplar also exhibited significantly enhanced plant growth rate and biomass yield by increasing xylem development and cell wall polymer deposition. Meanwhile, the transgenic plants showed significantly improved lignocellulose features such as reduced cellulose crystalline index and degree of polymerization values and decreased hemicellulose xylose/arabinose ratio for raised biomass porosity and accessibility, which led to integrated enhancement on biomass enzymatic saccharification and bioethanol yield under various chemical pretreatments. In contrast, the CRISPR/Cas9-generated mutation of PtoDET2 showed significantly lower brassinosteroids level for reduced biomass saccharification and bioethanol yield, compared to the wild type. Notably, the optimal green-like pretreatment could even achieve the highest bioethanol yield by effective lignin extraction in the transgenic plant. Hence, this study proposed a mechanistic model elucidating how brassinosteroid regulates cell wall modification for reduced lignocellulose recalcitrance and increased biomass porosity and accessibility for high bioethanol production.ConclusionsThis study has demonstrated a powerful strategy to enhance cellulosic bioethanol production by regulating brassinosteroid biosynthesis for reducing lignocellulose recalcitrance in the transgenic poplar plants. It has also provided a green-like process for biomass pretreatment and enzymatic saccharification in poplar and beyond.

Chemical Structure and Mechanical Properties of Wood Cell Walls Treated with Acid and Alkali Solution

The mechanical properties of individual fibers are related to the production and performance of papers and fiberboards. This paper examines the behavior of the microstructure constituents of wood subjected to acid and alkali treatments. The chemical structure and mechanical properties of wood cell walls with different acid or alkali treatments was analyzed. The results show that, compared with acid treatment, the crystal size and crystallinity index of cellulose increased after alkali treatment, resulting in an increase in the cell wall elastic modulus. The mechanical properties of the wood cell wall S2 region were higher than those of the compound middle lamella (CML) region. There was a topochemical effect between the CML and the S2 region in acid and alkali-treated samples, which provided a major threshold that facilitates the production/separation of wood fibers for better strength fiber properties.

Physico-Chemical and Thermal Characterization of Some Lignocellulosic Fibres: &amp;lt;i&amp;gt;Ananas comosus&amp;lt;/i&amp;gt; (AC), &amp;lt;i&amp;gt;Neuropeltis acuminatas&amp;lt;/i&amp;gt; (NA) and &amp;lt;i&amp;gt;Rhecktophyllum camerunense&amp;lt;/i&amp;gt; (RC)

This paper focuses on the study of the physical, biochemical, structural, and thermal properties of plant fibres of Rhecktophyllum camerunense (RC), Neuropeltis acuminatas (NA) and Ananas comosus (AC) from the equatorial region of Cameroon. The traditional use of these fibres inspired researchers to investigated their properties. This study aims at improving the state of knowledge with a view to diversifying applications. The fibres are extracted by retting. Then, their apparent density was measured following the ASTM D792 standard and their water moisture absorption and moisture content were also evaluated. Their molecular structure was studied by ATR-FTIR spectroscopy. A quantitative analysis of the biochemical composition was performed according to the analytical technique for the pulp and paper industry (TAPPI). A TGA/DSC analysis was also performed. The results reveal that the AC, NA and RC fibres have densities of 1.26 ± 1.06, 0.846 ± 0.13 and 0.757 ± 0.08 g·cm-3 respectively. They are also hydrophilic with a water absorption rate of 188.64 ± 11.94%, 276.16% ± 8.07% and 198.17% ± 20%. They have a moisture content of 12.21%, 10.36% and 9.37%. The studied fibres exhibit functional groups that are related to the presence of hemicellulose, pectin, lignin and cellulose. The cellulose crystallinity index was found to be 67.99%, 46.5% and 59.72% respectively. The fibres under study have the following chemical composition: an extractive content of 3.07%, 14.77% and 8.74%; a pectin content of 4.15%, 7.69% and 3.45%; a hemicellulose content of 4.90%, 15.33% and 7.42%; a cellulose content of 68.11%, 36.08% and 65.15%; a lignin content of 12.01%, 25.15% and 16.2%; and an ash content of 0.27%, 1.53% and 0.47% respectively. The thermal transitions observed on the thermograms correlate with the TAPPI chemical composition. It is observed that these fibres are thermally stable up to temperatures of 200°C, 220°C and 285°C. These results make it possible to envisage uses similar to those of sisal, hemp and flax fibres.