cellulose crystals
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Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3105
Author(s):  
Hui Chen ◽  
Mahafooj Alee ◽  
Ying Chen ◽  
Yinglin Zhou ◽  
Mao Yang ◽  
...  

Edible starch-based film was developed for packaging seasoning applied in instant noodles. The edible film can quickly dissolve into hot water so that the seasoning bag can mix in the soup of instant noodles during preparation. To meet the specific requirements of the packaging, such as reasonable high tensile properties, ductility under arid conditions, and low gas permeability, hydroxypropyl cornstarch with various edible additives from food-grade ingredients were applied to enhance the functionality of starch film. In this work, xylose was used as a plasticizer, cellulose crystals were used as a reinforcing agent, and laver was used to decrease gas permeability. The microstructures, interface, and compatibility of various components and film performance were investigated using an optical microscope under polarized light, scanning electron microscope, gas permeability, and tensile testing. The relationship was established between processing methodologies, microstructures, and performances. The results showed that the developed starch-based film have a modulus of 960 MPa, tensile strength of 36 Mpa with 14% elongation, and water vapor permeability less than 5.8 g/m2.h under 20% RH condition at room temperature (25 °C), which meets the general requirements of the flavor bag packaging used in instant noodles.


2021 ◽  
Author(s):  
◽  
Stefan James Hill

<p>The mechanical properties of wood allow it to be used for numerous purposes. For most purposes, drying of the wood material from the green state, sawn from the log, is first required. This drying step significantly improves the strength properties of wood. It is therefore clear that moisture in wood plays an important role in determining the bulk mechanical properties. Over the last century, many studies have been carried out to investigate the way in which the water content wood affects the bulk mechanical properties. More recent studies have focused to the individual chemical components that make up wood to understand the observed changes in bulk mechanical properties. Models of the nanostructure of wood contained; cellulose, hemicellulose, and lignin, and the arrangement and location of these components in terms of their mechanical properties was interpreted through what was described as the 'slip-stick' mechanism, by which wood, in its green state, maintained its molecular and mechanical properties under external stresses. This model, while insightful, failed to account for the presence and the role of water in the nanostructure of wood. In this work, synchrotron based X-ray diffraction and NMR studies, have been used to develop a new model, in which water plays a vital role in the determination of the mechanical properties of wood in its green, part-dried, and rewet states. X-ray diffraction showed that changes occur to the molecular packing of cellulose crystallites with change in moisture content, and that these changes begin to occur under mild drying conditions, i.e. drying in air at ambient temperatures. These changes depend on the severity of drying, whether ambient or forced oven drying, and are to some extent reversible. A spin-diffusion model was constructed using dimensions obtained from Xray diffraction, comparisons between predictions and experimental data from an NMR study showed that the location of water was dependent on the moisture history of wood. In the green state, at least some of the water in the wood cell wall forms a layer, between the cellulose crystals and the hemicellulose and lignin matrix. If dried and then rewet, this water associated with the cellulose crystals was not present to the same degree as in the green state, allowing a closer association of the hemicellulose with the cellulose. The effect of this change in water distribution in the wood cell wall on the bulk mechanical wood properties was shown in mechanical testing. The nanostructure of the wood cell wall therefore should be considered to contain cellulose, hemicellulose, lignin and water, where each component contributes, according to its molecular properties, dynamic mechanical properties which are reflected in the bulk material properties.</p>


2021 ◽  
Author(s):  
◽  
Stefan James Hill

<p>The mechanical properties of wood allow it to be used for numerous purposes. For most purposes, drying of the wood material from the green state, sawn from the log, is first required. This drying step significantly improves the strength properties of wood. It is therefore clear that moisture in wood plays an important role in determining the bulk mechanical properties. Over the last century, many studies have been carried out to investigate the way in which the water content wood affects the bulk mechanical properties. More recent studies have focused to the individual chemical components that make up wood to understand the observed changes in bulk mechanical properties. Models of the nanostructure of wood contained; cellulose, hemicellulose, and lignin, and the arrangement and location of these components in terms of their mechanical properties was interpreted through what was described as the 'slip-stick' mechanism, by which wood, in its green state, maintained its molecular and mechanical properties under external stresses. This model, while insightful, failed to account for the presence and the role of water in the nanostructure of wood. In this work, synchrotron based X-ray diffraction and NMR studies, have been used to develop a new model, in which water plays a vital role in the determination of the mechanical properties of wood in its green, part-dried, and rewet states. X-ray diffraction showed that changes occur to the molecular packing of cellulose crystallites with change in moisture content, and that these changes begin to occur under mild drying conditions, i.e. drying in air at ambient temperatures. These changes depend on the severity of drying, whether ambient or forced oven drying, and are to some extent reversible. A spin-diffusion model was constructed using dimensions obtained from Xray diffraction, comparisons between predictions and experimental data from an NMR study showed that the location of water was dependent on the moisture history of wood. In the green state, at least some of the water in the wood cell wall forms a layer, between the cellulose crystals and the hemicellulose and lignin matrix. If dried and then rewet, this water associated with the cellulose crystals was not present to the same degree as in the green state, allowing a closer association of the hemicellulose with the cellulose. The effect of this change in water distribution in the wood cell wall on the bulk mechanical wood properties was shown in mechanical testing. The nanostructure of the wood cell wall therefore should be considered to contain cellulose, hemicellulose, lignin and water, where each component contributes, according to its molecular properties, dynamic mechanical properties which are reflected in the bulk material properties.</p>


Cellulose ◽  
2021 ◽  
Author(s):  
Lennart Salmén ◽  
Jasna S. Stevanic ◽  
Claes Holmqvist ◽  
Shun Yu

Abstract Moisture absorption in the cell wall structure of wood is well known to induce considerable swelling of the wood exerting high expansion forces. This swelling is mainly induced by the sorptive action of the hydroxyl groups of the carbohydrate wood polymers; cellulose and hemicelluloses. On the ultrastructural level, there are, however, still questions with regard to the detailed deformations induced by this moisture absorption. Here, FTIR spectroscopy and synchrotron-radiation-based X-ray diffraction were used on paper samples to study the deformation of the cellulose crystals as a consequence of moisture absorption and desorption. Both techniques revealed that the moisture absorption resulted in a transverse contraction of the cellulose crystals accompanied by a somewhat smaller elongation in the cellulose chain direction. The deformations were found to be a direct response to the increased moisture content and were also found to be reversible during moisture desorption. It is hypothesised that these deformations are a consequence of the swelling forces created by the combined longitudinal and lateral expansions of the non-crystalline cellulose molecules and the glucomannan hemicellulose aligned along the cellulose crystals. These forces will impose a lateral contraction of the cellulose crystals, as well as a longitudinal extension of it. Graphic abstract


Cellulose ◽  
2021 ◽  
Author(s):  
Anders Thygesen ◽  
Dinesh Fernando ◽  
Kenny Ståhl ◽  
Geoffrey Daniel ◽  
Moses Mensah ◽  
...  
Keyword(s):  

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Dan Ye ◽  
Sintu Rongpipi ◽  
Sarah N. Kiemle ◽  
William J. Barnes ◽  
Arielle M. Chaves ◽  
...  

Abstract Cellulose, the most abundant biopolymer on earth, is a versatile, energy rich material found in the cell walls of plants, bacteria, algae, and tunicates. It is well established that cellulose is crystalline, although the orientational order of cellulose crystallites normal to the plane of the cell wall has not been characterized. A preferred orientational alignment of cellulose crystals could be an important determinant of the mechanical properties of the cell wall and of cellulose-cellulose and cellulose-matrix interactions. Here, the crystalline structures of cellulose in primary cell walls of onion (Allium cepa), the model eudicot Arabidopsis (Arabidopsis thaliana), and moss (Physcomitrella patens) were examined through grazing incidence wide angle X-ray scattering (GIWAXS). We find that GIWAXS can decouple diffraction from cellulose and epicuticular wax crystals in cell walls. Pole figures constructed from a combination of GIWAXS and X-ray rocking scans reveal that cellulose crystals have a preferred crystallographic orientation with the (200) and (110)/($$1\bar 10$$ 1 1 ¯ 0 ) planes preferentially stacked parallel to the cell wall. This orientational ordering of cellulose crystals, termed texturing in materials science, represents a previously unreported measure of cellulose organization and contradicts the predominant hypothesis of twisting of microfibrils in plant primary cell walls.


2020 ◽  
Vol 1000 ◽  
pp. 272-277
Author(s):  
Marcelinus Christwardana ◽  
Aniek Sri Handayani ◽  
Shirley Savetlana ◽  
Riana Herlina Lumingkewas ◽  
Muchamad Chalid

Micro-fibrillated celluloses (MFCs) are made from oil palm empty fruit bunches (EFB). EFB is processed through several stages of the process, including washing, alkalization, and bleaching to remove impurities, lignin, and hemicellulose. Each treatment stage was characterized by differential scanning calorimeter (DSC) and thermogravimetric (TGA) analysis. Morphological analysis was characterized using Scanning Electron Microscope (SEM). The process results show that MFC has an average length and thickness of 450 and 80 microns for coarse fibers respectively, averaging 50 and 5 microns for fine fibers, respectively. Fibrillation fibers appear on the surface of fibers which are treated using alkalization and bleaching processes. The TGA results showed a decrease in weight occurred at a temperature of 40 to 109 °C for the first stage of the heating process and at a temperature of 247 to 382 °C for the second stage. The decrease in fiber weight is caused by evaporation of water content and degradation of cellulose compounds at each stage. The glass transition temperature of MFC was obtained at 236 °C. The thermal stability of cellulose from fibers treated using alkalization and bleaching processes proved the formation of cellulose crystals. Removal of lignin and hemicellulose is shown by the absorption of O-H and C-C bonds in FTIR spectroscopy. From these results, it is stated that micro-fibrillation cellulose is formed well through a series of processes given.


2020 ◽  
Vol 147 ◽  
pp. 569-575 ◽  
Author(s):  
Stacy A. Love ◽  
Elizabeth Popov ◽  
Karleena Rybacki ◽  
Xiao Hu ◽  
David Salas-de la Cruz

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