Search results
Results from the WOW.Com Content Network
Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants.It is an organic material – a natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin that resists compression.
An example of this is that secondary wall in wood contains polysaccharides called xylan, whereas the primary wall contains the polysaccharide xyloglucan. The cells fraction in secondary walls is also higher. [7] Pectins may also be absent from the secondary wall, and unlike primary walls, no structural proteins or enzymes have been identified. [4]
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
The composition of lignin varies from species to species. An example of composition from an aspen [ 8 ] sample is 63.4% carbon, 5.9% hydrogen, 0.7% ash (mineral components), and 30% oxygen (by difference), [ 9 ] corresponding approximately to the formula (C 31 H 34 O 11 ) n .
Wood chemistry, whose primary focus is the analysis of the chemical constituents comprising wood, with specific emphasis on cellulose, lignin, hemicelluloses, and extractives, as well as on the various products derived from these components. It is also explores potential uses for pulp and paper production, the utilization of wood and wood waste ...
Xylan (/ ˈ z aɪ l æ n /; [3] / ˈ z aɪ l ən / [4]) (CAS number: 9014-63-5) is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. [5]
In hardwoods the main hemicellulose extract is glucuronoxlyan (acetylated xylans), while galactoglucomannan is found in softwoods. [20] [21] Prior to extraction the wood typically must be milled into wood chips of various sizes depending on the reactor used. Following this, a hot water extraction process, also known as autohydrolysis or ...
Plant-derived cellulose is usually found in a mixture with hemicellulose, lignin, pectin and other substances, while bacterial cellulose is quite pure, has a much higher water content and higher tensile strength due to higher chain lengths. [6]: 3384 Cellulose consists of fibrils with crystalline and amorphous regions. [22]