Increase In Crystallinity Index Research Articles

The Effect of Paddy Straw Content on Properties of Regenerated Cellulose Biocomposite Films

Regenerated cellulose (RC)/paddy straw (PS) biocomposite films was prepared by addition of PS powder in partially dissolving microcrystalline cellulose into an 8% lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) solution. The effect of paddy straw on tensile properties and crystallinity index (CrI) of RC/PS biocomposite films were studied. The results obtained revealed that the tensile strength and modulus of elasticity of RC/PS biocomposite films compared with pure regenerated cellulose was significantly improved at 5 wt% PS loading but decrease with the increment of PS. The increase in crystallinity index at 5 wt% proved the enhancement affected by the incorporation of PS.

Exploring the gut of Helicoverpa armigera for cellulose degrading bacteria and evaluation of a potential strain for lignocellulosic biomass deconstruction

Abstract The present study demonstrates the enrichment, isolation and identification of cellulose degrading bacteria from the gut of cotton bollworm, Helicoverpa armigera. The isolate MD21 was identified as Klebsiella sp. MD21 (MG367463) based on 16S rRNA gene sequencing. The isolated bacterium, Klebsiella sp. MD21 secreted many hydrolytic enzymes particularly xylanase and β-glucosidase with highest activities of 276.71 ± 0.98 and 78.45 ± 0.10 IU/ml extract respectively. Scanning electron microscopy of treated filter paper and saw dust revealed structural alterations caused by Klebsiella sp. MD21 leading to hydrolysis of cellulosic waste into reducing sugars (2256 μmol ml−1 min-1) which could be used for the growth of bacteria. X-ray diffraction (XRD) pattern showed an increase in crystallinity index from 58.78% in native biomass to 60.10% of the treated biomass due to hydrolysis of amorphous regions present in the saw dust. Similarly, fourier transform infra-red (FTIR) spectroscopic study of the hydrolyzed saw dust indicated elimination of bands at wave numbers 718, 933 and 1533 cm-1 which also represent the cellulose content. The present study demonstrates utility of H. armigera as a source for isolation of cellulolytic bacteria for use in biorefinery and pulp industries.

Feasibility Study of Chemical Treatments on Sorghum Fibres for Compatibility Enhancement in Polypropylene Composites

Polypropylene (PP) is one of the biggest petro-polymers, which is used in very wide application nowadays. The environment problem due to materials such as plastics having very long time degradability, and critical petroleum sources have promoted some studies to empowerment of natural resources such as natural fibres for substituting or at least modifying petro-polymers. Because of biodegradability obtained from natural source, sorghum fibers are interesting to be used as filler in PP composites, despite of weak compatibility between them. Surface modification on the sorghum fibers through alkalinization prior to acetylation was aimed to improve the fiber compatibility to PP. The treatments were expected to substitute hydroxyl group in the sorghum fibers, into acetic ester group in order to increase their hydrophobicity as the fillers. Moreover, the treatments were able to unbundle single fibers into micro-fibrillated cellulose (MFC) fibres with increase in crystallinity index. Usage of this MFC fiber as filler in PP leads to improvement of the composite performances such as thermal properties. In this study, Fourier Transformation Infra-Red (FTIR) Spectroscopy, X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Field-Emission Scanning Electron Microscope (FE-SEM) were used to evaluate the performances of the Sorghum fibers after the treatments and as the filler in the Sorghum fibers/PP composites. The experimental results showed the MFC fibers as the smallest sizes in 5.0 microns and the highest crystallinity index up to 79.1 %, obtained from alkalinization with 2.5 M NaOH prior to acetylation with 17.4 M CH3COOH and the glacial (CH3CO2)2. Compatibility study of the treated Sorghum fibers on PP shows an improvement indicated by a strong interaction between the fibers and PP on morphology observation, increase in melting point of PP from 163.4°C (using virgin Shorgum fibers) into 163.6°C (using treated Sorghum fibers) in DSC measurements.

The effect of liquid hot water pretreatment on the chemical\u2013structural alteration and the reduced recalcitrance in poplar

BackgroundHydrothermal pretreatment using liquid hot water (LHW) is capable of substantially reducing the cell wall recalcitrance of lignocellulosic biomass. It enhances the saccharification of polysaccharides, particularly cellulose, into glucose with relatively low capital required. Due to the close association with biomass recalcitrance, the structural change of the components of lignocellulosic materials during the pretreatment is crucial to understand pretreatment chemistry and advance the bio-economy. Although the LHW pretreatment has been extensively applied and studied, the molecular structural alteration during pretreatment and its significance to reduced recalcitrance have not been well understood.ResultsWe investigated the effects of LHW pretreatment with different severity factors (log R0) on the structural changes of fast-grown poplar (Populus trichocarpa). With the severity factor ranging from 3.6 to 4.2, LHW pretreatment resulted in a substantial xylan solubilization by 50–77% (w/w, dry matter). The molecular weights of the remained hemicellulose in pretreated solids also have been significantly reduced by 63–75% corresponding to LHW severity factor from 3.6 to 4.2. In addition, LHW had a considerable impact on the cellulose structure. The cellulose crystallinity increased 6–9%, whereas its degree of polymerization decreased 35–65% after pretreatment. We found that the pretreatment severity had an empirical linear correlation with the xylan solubilization (R2 = 0.98, r = + 0.99), hemicellulose molecular weight reduction (R2 = 0.97, r = − 0.96 and R2 = 0.93, r = − 0.98 for number-average and weight-average degree of polymerization, respectively), and cellulose crystallinity index increase (R2 = 0.98, r = + 0.99). The LHW pretreatment also resulted in small changes in lignin structure such as decrease of β-O-4′ ether linkages and removal of cinnamyl alcohol end group and acetyl group, while the S/G ratio of lignin in LHW pretreated poplar residue remained no significant change compared with the untreated poplar.ConclusionsThis study revealed that the solubilization of xylan, the reduction of hemicellulose molecular weights and cellulose degree of polymerization, and the cleavage of alkyl–aryl ether bonds in lignin resulted from LHW pretreatment are critical factors associated with reduced cell wall recalcitrance. The chemical–structural changes of the three major components, cellulose, lignin, and hemicellulose, during LHW pretreatment provide useful and fundamental information of factors governing feedstock recalcitrance during hydrothermal pretreatment.

Dry-Spun Neat Cellulose Nanofibril Filaments: Influence of Drying Temperature and Nanofibril Structure on Filament Properties

Cellulose nanofibrils (CNF) were spun into filaments directly from suspension without the aid of solvents. The influence of starting material properties and drying temperature on the properties of filaments produced from three different CNF suspensions was studied. Refiner-produced CNF was ground using a microgrinder at grinding times of 50 and 100 minutes. Filament spinning was performed using a syringe pump-heat gun setting at three drying temperatures of 210 °C, 320 °C and 430 °C. The structure of starting CNF materials was first evaluated using a combination of optical and atomic force microscopy (AFM) techniques. Surface free energy analysis and attenuated total reflectance—Fourier transform infrared spectroscopy (ATR–FTIR) were used to study changes in hydrophobicity due to grinding. Morphology of the filaments was studied using SEM micrographs. The influence of different drying temperatures and grinding times on mechanical properties of the CNF filaments were further investigated through tensile tests and results were compared using statistical analysis .It was observed that drying temperature did not significantly influence the tensile properties of the filaments while cellulose nanofiber suspension type (grinding time) had a significant influence and improved mechanical properties. FTIR results confirmed an increase in crystallinity index and decrease in hydroxyl group availability due to grinding.

Study the effect of gamma radiation pretreatment of sugarcane bagasse on its physcio-chemical morphological and structural properties

Sugarcane bagasse was exposed to gamma radiation at different doses i.e. 100, 500, 1000 and 2000kGy at a dose rate of 2.5kGy/h and characterized for physical, chemical, morphological and structural properties. Results showed that on exposure of sugarcane bagasse, hemicellulose content reduced from 31% to 12.4% at 2000kGy dose. The cellulose content of bagasse did not get affected much upto 1000kGy exposure; however at 2000kGy dose it decreased considerably. XRD study shows an initial increase in crystallinity index of bagasse at a dose level of 100kGy while on further increase in radiation dose from 100kGy to 2000kGy the crystallinity index of bagasse decreases. Pores in the SEM photograph were observed on the surface of irradiated bagasse. UV–Vis spectra of bagasse showed a red shift indicating internal changes caused by radiation exposure. Study shows that the irradiation of bagasse results in disrupton of the lignocellulosic structure of Bagasse which opens up for easy accessibility of acids and hydrolytic enzymes for cellulosic hydrolysis resulting into fermentable sugars.

Novel Isolation of Empty Fruit Bunch Lignocellulose Nanofibers Using Different Vibration Milling Times-Assisted Multimechanical Stages

A novel isolation of oil palm empty fruit bunch lignocellulose nanofibers (LCNFs) was successfully applied using multimechanical stages assisted with different vibration milling times. Morphology, physical, chemical, and thermal properties of LCNFs were studied. All LCNF samples were agglomerated due to hornification process during the drying of its suspension. The external surface of the nanofibers was irregular, uneven, folding, and unsmooth with approximate nanofibers diameter of above 100 nm. The optimal size of oil palm empty bunch LCNFs was in the range of 53.72–446.80 nm. Bio-oil was suspended in all LCNF samples after analysis with GC–MS in which the most dominant extractives were aromatic and oxygenated compounds. The increase in milling time could lead to the decrease in silica and oxygen elemental compositions. IR analysis revealed that there were no pronounced changes of transmittance peaks during vibration milling processes. The increase in milling time induced the decrease in atomic crystal size of LCNFs but the increase in crystallinity index from 7 to 17 milling times. A pretreatment of 7 vibration milling times to LCNFs brought about the lowest thermal stability.

THERMAL BEHAVIORS OF OIL PALM EMPTY FRUIT BUNCH FIBER UPON EXPOSURE TO ACID-BASE AQUEOUS SOLUTIONS

The effect of chemical treatment on the chemical composition, functional group, crystallinity and thermal stability of palm oil empty fruit bunch (EFB) fiber were investigated. Chemical treatment was conducted by treating EFB with 10% sodium hydroxide aqueous solution and 2% hydrogen peroxide aqueous solution separately. The results indicated that chemical treatment managed to affect chemical composition of the fiber. FTIR analysis proved the removing of hemicellulose and lignin during the treatment based on the peak disappearance around 1700 cm and 1600 cm. The XRD diffractogram showed an increase in crystallinity index of the fiber especially for NaOH treatment. Removal the amorphous component of the fiber influences the thermal degradation of the fiber.

Lignin and Cellulose Changes of Betung Bamboo (Dendrocalamus asper) pretreated Microwave Heating

This study highlighted the effect of microwave pretreatment on betung bamboo on the chemical structural and morphological changes. The hydrothermal condition was performed in varying power loading (330, 550, and 770 W) and microwave irradition time (5-12.5 min). FTIR spectroscopy, X-Ray diffraction and SEM-EDS analysis were utilized to confirm the characteristic changes after pretreatment. The results showed that the severe pretreatment condition tended to increase the carbohydrate losses. From FTIR spectra, microwave pretreatment tended to decrease absorbancy of functional group bands. After microwave pretreatment for 12.5 min (770 W), the band around 1736 cm -1 (C=O in xylan) disappeared in the samples. The syringil propane unit was lower than that of guaiacyl lignin under microwave pretreatment. The disruption of the structure of the cell wall increased the accessibility of cellulase to lignocellulose. Except microwaving for 5 min (330 W), the microwave heating caused carbon and oxygen increasing compared to untreated samples. The increase in crystallinity index of pretreated bamboo suggested the selective degradation of amorphous components.

Dyeing performances of ramie fabrics modified with an amino-terminated aliphatic hyperbranched polymer

An amino-terminated aliphatic hyperbranched polymer (HBP-NH2) was used to modify ramie fabric. The molecular weight of HBP-NH2 was established by GPC. HBP-NH2 structure might represent as BA4BA3BA3 (third generation). The total amine value, secondary amine value and primary amine value of HBP-NH2 were 291.59, 210.14 and 81.45 mg/g respectively with hydrochloric acid—ethanol titration method. The unmodified and modified ramie fabrics were characterized by XRD and FE-SEM. XRD results showed a transformation of crystalline structure from ramie cellulose I to cellulose II allomorph during mercerization and epichlorohydrin modification, and the crystalline structure of cellulose II maintained with obvious crystallinity index increase after HBP-NH2 modification. Nitrogen content of HBP-NH2 modified fabrics were 1.25–2.61 %. Cationization degree (DC) of HBP-NH2 modified ramie fabrics were 4.41–9.40 %. C.I. Reactive Red 2 was applied to study the dyeing performance of modified fabrics. The modification parameters were optimized as 50 °C for 5 h when the concentration of HBP-NH2 was 8 g/L. K/S value and dye uptake of modified fabric was 23.64 and 85.6 % respectively under optimal modification conditions. The washing, rubbing and light fastness of modified ramie fabrics were acceptable. The tensile strength and tear strength of HBP-NH2 modified ramie fabrics were lower than those of unmodified fabrics. The warp, weft of tensile and tear strength retention of modified fabrics were between 85.23 and 87.50 %. The HBP-NH2 modification mechanism and dyeing mechanism on ramie fabric were suggested.

Salt-free dyeing of ramie fabric with an amino-terminated hyperbranched polymer

A new amino-terminated hyperbranched polymer (at-HBP) was synthesized, and its salt-free dyeing property on ramie fabric was studied. The structure and molecular weight of at-HBP were established by Fourier transform infrared spectrometer, H nuclear magnetic resonance and gel permeation chromatography. The untreated ramie fabric and modified ramie fabrics were characterized by an X-ray diffraction (XRD) and field emission scanning electron micrograph (FE-SEM). XRD results showed a transformation of the crystalline structure from ramie cellulose I to cellulose II allomorph during mercerization and epichlorohydrin modification, and the crystalline structure of cellulose II was maintained with an obvious crystallinity index increase after at-HBP modification. FE-SEM results confirmed that at-HBP was successfully grafted onto the fabric surface. Dyed with reactive dye C.I. reactive Blue 4, the color strength of the at-HBP-modified fabric was enhanced, even when dyeing was carried out without the electrolyte. The washing and rubbing fastness of the salt-free dyeing of fabrics was also good compared with those obtained by conventional dyeing. The adsorption isotherm of C.I. reactive Blue 4 on modified fabric was examined and found to follow a Langmuir-type adsorption model. The at-HBP modification mechanism of ramie fabric and dyeing mechanism with reactive dye were suggested.

Autohydrolysis of Tropical Agricultural Residues by Compressed Liquid Hot Water Pretreatment

Pretreatment is an essential step in biorefineries for improving digestibility of recalcitrant agricultural feedstocks prior to enzymatic hydrolysis to composite sugars, which can be further converted to fuels and chemicals. In this study, autohydrolysis by compressed liquid hot water (LHW) pretreatment of various tropical agricultural residues including sugarcane bagasse (BG), rice straw (RS), corn stover (CS), and empty palm fruit bunch (EPFB) was investigated. It was found that LHW pretreatment at 200 °C for 5-20 min resulted in high levels of hemicellulose solubilization into the liquid phase and marked improvement on enzymatic digestibility of the solid cellulose-enriched residues. The maximal yields of glucose and pentose were 409.8-482.7 mg/g and 81.1-174.0 mg/g of pretreated substrates, respectively. Comparative analysis based on severity factor showed varying susceptibility of biomass to LHW in the order of BG> RS> CS> EPFB. Structural analysis revealed surface modification of the pretreated biomass along with an increase in crystallinity index. Overall, 75.7-82.3 % yield of glucose and 27.4-42.4 % yield of pentose from the dried native biomass was recovered in the pretreated solid residues, while 18.3-29.7 % of pentoses were recovered in the liquid phase with dehydration by-product concentration under the threshold for ethanologens. The results suggest the potential of LHW as an efficient pretreatment strategy for implementation in biorefineries operated using various seasonal agricultural feedstocks.

Effect of Ionic Liquids/water Pre-Treatment of Luffa fibres on the Structural Properties

Recently, the use of lignocellulosic fibres to reinforcing composite has received an increased attention. However, lack of good interfacial adhesion makes important the treatment of raw materials. In this study, the raw material Luffa fibres were treated by ionic liquids/water mixture and this treatment proved to be useful by elimination of gummy and waxy substances. The effect of the treatments on the structure of fibres was showed using SEM and XRD (X-Ray Diffraction) analysis. The SEM results revealed that the treatment resulted in a removal of lignin, pectin and hemicellulose substances, and change the characteristics of the surface topography. The XRD analysis shows the increase of crystallinity index.

Effect of enzymatic depolymerization on physicochemical and rheological properties of guar gum

Depolymerization of guar gum using enzymatic hydrolysis was performed to obtain depolymerized guar gum having functional application as soluble dietary fiber. Enzymatic hydrolysis of guar gum significantly affected the physicochemical and rheological characteristics of guar gum. The depolymerized guar gum showed a significant increase in crystallinity index from 3.86% to 13.2% and flow behavior index from 0.31 to 1.7 as compared to native guar gum. Remarkable decrease in intrinsic viscosity and consistency index was also observed from 9 to 0.28 and 4.04 to 0.07, respectively. Results revealed that enzymatic hydrolysis of guar gum resulted in a polysaccharide with low degree of polymerization, viscosity and consistency which could make it useful for incorporation in food products as dietary fiber without affecting the rheology, consistency and texture of the products.

Structure and properties of tempo-oxidized cotton fibers

In this paper, the influence of the catalytic oxidation using water soluble and stable nitroxyl radical 2,2?,6,6?-tetramethylpiperidine-1-oxyl (TEMPO) on structure and properties of cotton fibers was studied. In particular, the selective TEMPO-mediated oxidation has become very interesting way for introduction of functional groups into cellulose fibers with the aim to obtain oxycellulose fibers with specific properties. Unmodified and modified fibers were characterized in terms of weight loss values, introduced functional groups and crystallinity index. Also, oxidized fibers were characterized in terms of the sorption, morphological, and physico-mechanical properties. The TEMPO-oxidized cotton fibers show a minimum increase of fineness (from 1.32 to 1.28 dtex) and increase of crystallinity index (up to 91.9%), while the tensile strength of fibers decreases (up to 10.82 cN/tex). By the TEMPO-mediated oxidation of cotton fibers significant amount of carboxyl groups (up to 0.795 mmol/g cell) can be introduced into cellulose fibers. Introduced hydrophilic carboxyl groups increases the sorption properties of oxidized fibers, that can be used directly or for further chemical modification.

Effect of solvents on cyanoethylation of cotton cellulose and its properties

AbstractThe cyanoethylation of cotton fabric was carried out using aqueous sodium hydroxide with acrylonitrile in presence of solvents like acetone and ethanol in different concentrations. The modified cellulose was investigated with vertical wicking test, X‐ray diffraction (XRD), thermogravimetry‐differential thermal analysis (TG/DTA), and atomic force microscopy (AFM). The wicking height was increased for the modified cellulose. Modified cellulose had increase in crystallinity index with reduction of crystallite size. The thermal stability of the modified cellulose was also increased. The images produced using AFM technique revealed that there is appreciable difference in the surface roughness between scoured, mercerized, cyanoethylated and solvent treated samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Solid-state NMR characterization of switchgrass cellulose after dilute acid pretreatment

Background: Switchgrass (Panicum virgatum L.) is being considered as a potential feedstock for bioethanol production and extensive research is ongoing to establish the optimum pretreatment conditions for switchgrass. Cellulose comprises the most abundant biopolymer in the biosphere and its crystalline/ultrastructure is considered to be related to biomass recalcitrance. This study investigates the effects of dilute acid pretreatment on ultrastructural features of switchgrass cellulose. Results: In this study, switchgrass was pretreated in a pilot-scale reactor at 190°C (0.05 g sulfuric acid per gram of dry switchgrass) with 25% total solid loading and a reactor residence of 1 min. Cellulose was isolated from the pretreated and untreated switchgrass. The impact of pretreatment on the ultrastructure of cellulose was determined by solid-state cross polarization/magic angle spinning 13C NMR spectroscopy. Switchgrass demonstrated a preferable degradation of amorphous cellulose regions during dilute acid pretreatment. The pretreated switchgrass cellulose showed an 18% increase in crystallinity index when compared with the untreated switchgrass. Line-fitting analysis of the C-4 region of 13C NMR spectra revealed that the relative proportion of crystalline and paracrystalline celluloses in switchgrass was observed to increase after dilute acid pretreatment, accompanied with a concurrent decrease of the relative abundance of fibril surface cellulose. Conclusion: After dilute acid pretreatment, most of the hemicellulose in switchgrass was removed. The amorphous cellulose regions in switchgrass were degraded preferably during dilute acid pretreatment and the cellulose crystallinity index of pretreated switchgrass increased. Pretreated switchgrass had an increase in relative proportion of crystalline and paracrystalline cellulose in comparison to the starting material.

Effect of Palm Oil Mill Sterilization Process on the Physicochemical Characteristics and Enzymatic Hydrolysis of Empty Fruit Bunch

Sterilization process of oil palm fruits by-product can be satisfactorily used as alternative degradation method in production of value-added products from Empty Fruit Bunch (EFB). It could be considered as an auto hydrolysis technique in the regular pre-treatment methods. Other studies on lignocelluloses showed that they increase the pore volume of the wood which increases the available surface area for the enzyme. Changes in structure and properties of the EFB cellulose caused by sterilization were investigated by x-ray diffractometry and enzymatic hydrolysis of cellulosic biomass for fermentable sugar production (glucose). The enzymatic hydrolysis results showed that the highest hydrolysis of 53.77±1.38% (g/g biomass) conversion was obtained in EFB after 72 h incubation with glucose production, (Yp/x) of 12.55±0.33 g L-1. The increase in Crystallinity Index (CrI) of sterilized biomass increased the yield of glucose (g L-1) up to 44.55% compared to Fresh Fruit Bunches (FFB) as a control. Results obtained appear to be commercial significance showing the potential of sterilization process in a palm oil mill as a zero cost pre-treatment for the effective utilization of empty fruit bunch biomass for value added production from the palm oil industry.

Effect of pre-treatment of Luffa fibres on the structural properties

Recently, the use of lignocellulosic fibres to reinforcing composite has received an increased attention. However, lack of good interfacial adhesion makes important the treatment of raw materials. Chemical treatment prepared the raw material to be useful by elimination of gummy and waxy substances. In this study, the Luffa fibres were treated by tow methods: alkali treatment and mixed treatment (sodium hydroxide and hydrogen peroxide). The effect of these treatments on the structure of fibres was showed using SEM and XRD (X-Ray Diffraction) analysis. The SEM results revealed that both treatments resulted in a removal of lignin, pectin and hemicellulose substances, and change the characteristics of the surface topography. The XRD analysis shows the increase of crystallinity index by many treatment conditions. We find that the alkali treatment (120 °C; 3 h; 4% NaOH) shows a good cleaning and the higher crystallinity index of treated fibres. It is also interesting to note that mixed treatment can change the Luffa fibres from mat structure to fibrils structure.

Correlation between long-term stability of solid lipid nanoparticles (SLN™) and crystallinity of the lipid phase

Aqueous dispersions of solid lipid nanoparticles (SLN™) are usually physically stable for more than 3 years. However, in some systems gelation occurred leading to solid gels due to an unknown mechanism. To elucidate this mechanism, Compritol® SLN were stored at different temperatures, varying light exposure, in different packing materials and stressed by shear forces in short-term tests and a long-term study of 3 years. The SLN were analyzed by differential scanning calorimetry and sizing techniques. After production by hot homogenization of the melted lipid, the Compritol® SLN crystallize in a mixture of stable β′ with unstable polymorphs ( α, sub α). The destabilizing factors light, temperature and shear forces cause a distinct increase in the recrystallization index by transformation of the lipid to the β′ modification being accompanied by gel formation. Physically stable SLN remain as a mixture of modifications, increase in crystallinity index during storage is slow and crystallization occurs mainly in unstable modifications. From this, stabilization of physically critical SLN dispersions seems possible by inhibition of the transformation of the lipid to the stable modification.