Thermal stability of starch bionanocomposites films: Exploring the role of esterified cellulose nanofibers isolated from crop residue.

Thermal stability and degradation kinetics were studied for glycerol plasticized starch (GPS) nanocomposites reinforced with cellulose nanofibers (CNFs) extracted from wheat straw, a crop residue. To assess the effect of surface modifications on CNFs in improving thermal degradation behavior, three types of CNFs were used viz pristine (p-CNFs), esterified (m-CNFs) and a mixture of pristine and esterified (x-CNFs) in equal ratio. Three kinetics models Ozawa-Flynn, Freidman and Kissinger's were used to evaluate activation energy of thermal degradation for pristine and nanocomposite samples. Properties like morphology, crystallinity and water vapor permeability (WVP) were also evaluated. Morphology of m-CNF/GPS bionanocomposites films was superior as compared to other films with better interfacial bonding. Moreover, m-CNFs also exhibited 81 % reduction WVP as compared to pristine GPS films. Activation energy revealed significant enhancement i.e. as high as 52 % in thermal stability with addition of CNFs. Consequent relation between morphology and thermal stability was also established.

Isolation and characterization of microfibrillated cellulose and nanofibrillated cellulose with "biomechanical hotspots".

Waste biomass of two major milk weeds was separately given combination of chemical-mechanical treatments in order to expose natural cellulosic micro and nano-fibrillated structures (MFCs and NFCs). Compositional and FTIR analysis were initially used to confirm the removal of impurities. WA-XRD and FESEM analysis of MFCs further revealed presence of highly crystalline, fine-shaped materials that resemble carbonaceous structures. HR-TEM analysis further exposed morphology of the two nanofibrils possessing a well entangled network (diameter ≤80 nm) comprising coil shaped fine spots of size up to 80 nm-220 nm. Morphology even got clearer when STEM and EDX mapping of the NFCs assured that observed fine-spots are integral and possibly due to certain biosynthetic process. Presence of calcium elements in two types of NFCs provided important evidence of exposure of nanocellulose-xyloglucan-pectin configuration responsible for coil-shaped fine-spots resembling "biomechanical hot spots".

Simultaneous extraction of lignin and cellulose nanofibrils from waste jute bags using one pot pre-treatment.

Cellulose nanofibrils and lignin were simultaneously isolated from waste jute bags using soda cooking pretreatment method. Soda cooking resulted in reduction of recalcitrance of lignocellulose biomass leading to hydrolysis of hemicellulose into sugars, which was subsequently washed, leaving a residue of cellulose and lignin.The chemical composition, yield of lignin and cellulose were assessed using TAPPI method and ASTM standards, respectively. Yields of lignin and cellulose were 58 and 45%, respectively, calculated separately on the basis of their content in the jute bags. FTIR results confirmed the removal of lignin and hemicellulose from raw jute fibers during soda cooking process. HNMR results depicted the aromatic structure of lignin which was further confirmed by UV results which clearly indicated the presence of phenolic compounds. The thermal stability of cellulose nanofibrils and lignin was higher than raw jute fibers. SEM showed cylindrical cellulose nanofibrils and agglomerates of amorphous and crystalline region of lignin. Size of jute fibers decreased to 12-18nm whereas the crystallinity increased after chemical and mechanical treatments studied using TEM and XRD, respectively. The study confirmed the isolation of cellulose nanofibrils and lignin extraction discarding the hemicellulose using single pot treatment.

Fractionation and physicochemical characterization of lignin from waste jute bags: Effect of process parameters on yield and thermal degradation.

In this work lignin was extracted from waste jute bags using soda cooking method and effect of varying alkali concentration and pH on yield, purity, structure and thermal degradation of lignin were studied. The Lignin yield, chemical composition and purity were assessed using TAPPI method and UV-vis spectroscopy. Yield and purity of lignin ranged from 27 to 58% and 50-94%, respectively for all the samples and was maximum for 8% alkali concentration and at pH 2 giving higher thermal stability. Chemical structure, thermal stability and elementary analysis of lignin were studied using FTIR, HNMR, thermo gravimetric analysis (TGA) and Elemental analyzer. FTIR and HNMR results showed that core structure of lignin starts breaking beyond 10% alkali concentration. S/G ratio shows the dominance of Syringyl unit over guaiacyl unit.

Surface functionalization of nanofibrillated cellulose extracted from wheat straw: Effect of process parameters.

Aggregates of microfibrillated cellulose isolated from wheat straw fibers were subjected to propionylation under different processing conditions of time, temperature and concentration. The treated fibers were then homogenized to obtain surface modified nanofibrillated cellulose. For varying parameters, progress of propionylation and its effects on various characteristics was investigated by FTIR, degree of substitution, elemental analysis, SEM, EDX, TEM, X-ray diffraction, static and dynamic contact angle measurements. Thermal stability of the nanofibrils was also investigated using thermogravimetric technique. FTIR analysis confirmed the propionylation of the hydroxyl groups of the cellulose fibers. The variations in reaction conditions such as time and temperature had shown considerable effect on degree of substitution (DS) and surface contact angle (CA). These characterization results represent the optimizing conditions under which cellulose nanofibrils with hydrophobic characteristics up to contact angle of 120° can be obtained.

Video assessment of supraglottic airway orientation through the perilaryngeal airway in pediatric patients.

The COBRA perilaryngeal airway (PLA) is a new supraglottic airway device available for use in children. We studied the orientation of the larynx as viewed through the PLA using video obtained with a fiberoptic bronchoscope in 45 infants and children. Laryngeal view was scored, and position of the grill bars of the PLA and the epiglottis was assessed. An acceptable airway was obtained in all subjects, but the laryngeal view was nearly or completely obstructed in 76.9% of the patients 10 kg and less, with the epiglottis folded over the glottic opening. This was uncommon in larger children. The grill bars of the PLA were closely opposed to the epiglottis and supraglottic structures in nearly all subjects. We conclude that 1) the PLA provides an acceptable airway in infants and children, but infolding of the epiglottis with obstruction of the view of the glottic opening is common in infants, 2) extra vigilance for airway obstruction in this age group is necessary, and 3) the PLA's close opposition to the supraglottic structures suggests that removal in a deeper plane of anesthesia might minimize laryngeal stimulation.