Introduction
Cellulose is a higher plant cell wall main component, which ensures their strength. Cotton, Linos, hemp and jute are around 99% cellulose. Of these plants produced textile fibers, used in a variety of fabrics, rope and other products manufacture. Wood contains about 50% cellulose and the remainder composed of wood lignin, resins and minerals. It can be assumed that the wool and filter paper is 100% cellulose.
Obtaining pulp from wood, usually used a softer wood. Grind timber and heated with a calcium HYDROGEN or other substances at specified temperatures and pressures. Such a process is dissolved and then are discharged away other wood components and pulp remains in its pure form. Next, it is dried and used as needed.
Cellulose composition and structure
Cellulose is a natural high molecular weight compound which naturally formed by mutual binding of many β-glucose molecules.
Pulp composition as starch composition can be expressed by molecular formula (C6H10O5) n. Cellulose molecules consist of spunbonded, interconnected β-glucose residues. Cellulosic filamentary molecules form long fibers. The degree of polymerisation n is from 300 to 3000. The fiber linked together by hydrogen bonds.
Paper manufacturing
Important pulp processing industry is the paper industry. At the beginning of the paper produced from linen rags. 19th century, the second half began producing paper from pulp, but later - directly from the timber.
In the production of paper from pulp, pulp maceration, saplucina and special mill grind. The mass is bleached. Then, a comminuted pulp is poured into the long, vibrating sieve, which runs through the water, the cellulose fibers create fabric-like layer. Below the roller wet wet layer is removed from the sieve and then press and dried in the hot cylinders. Paper folded in rolls or of finished paper products.
The world produces hundreds of varieties of paper. Making them, in the initial cellulose pulp is added to each paper varieties of the necessary substances.
The paper also produces, the second time in the processing of paper waste - waste paper.
Celuloze ir augstāko augu šūnapvalku galvenā sastāvdaļa, kas nodrošina to stiprību. Kokvilnā, linos, kaņepājos un džutā ir pat līdz 99 % celulozes. No šiem augiem iegūst tekstilšķiedras, ko izmanto dažādu audumu, virvju un citu izstrādājumu izgatavošanai. Koksnes sastāvā ir apmēram 50 % celulozes, bet pārējo koksnes sastāvu veido lignīns, sveķi un minerālvielas. Var uzskatīt, ka vatē un filtrpapīrā ir 100 % celulozes.
Iegūstot celulozi no koksnes, parasti izmanto mīkstāku koksni. Koksni sasmalcina un karsē kopā ar kalcija hidrogēnsulfītu vai citām vielām noteiktā temperatūrā un spiedienā. Šādā procesā izšķīdina un pēc tam aizvada prom citas koksnes sastāvdaļas, bet celuloze paliek tīrā veidā. Tālāk to žāvē un izmanto pēc vajadzības.
Celulozes sastāvs un struktūra
Celuloze ir dabisks lielmolekulārs savienojums, kas dabā veidojies, savstarpēji saistoties daudzām β-glikozes molekulām.
Celulozes sastāvu, tāpat kā cietes sastāvu, var izteikt ar molekulformulu (C6H10O5)n. Celulozes molekulas sastāv no savērptiem, savstarpēji saistītiem β-glikozes atlikumiem. Celulozes pavedienveida molekulas veido garas šķiedras. To polimerizācijas pakāpe n ir no 300 līdz 3000. Šīs šķiedras savā starpā saistītas ar ūdeņraža saitēm.
Papīra ražošana
Svarīga celulozes pārstrādes nozare ir papīrrūpniecība. Papīru sākumā ražoja no linu lupatām. 19. gs otrajā pusē papīru sāka ražot no celulozes, bet vēlāk - tieši no koksnes.
Ražojot papīru no celulozes, celulozi izmērcē, saplucina un speciālās dzirnavās samaļ. Iegūto masu balina. Tad ļoti sasmalcināto papīrmasu lej uz gara, vibrējoša sieta, kuram cauri iztek ūdens, bet celulozes šķiedras izveido audumam līdzīgu slāni. Tālāk veltnis šo slapjo slapjo slāni noņem no sieta, tad to presē un žāvē starp karstiem cilindriem. Papīru satin ruļļos vai no tā gatavo papīra izstrādājumus.
Pasaulē ražo vairākus simtus papīra šķirņu. Izgatavojot katru no tām, sākotnēji celulozes masai pievieno katras papīra šķirnes ražošanai vajadzīgās vielas.
Papīru ražo arī, otro reizi pārstrādājot papīra atkritumus - makulatūru.
Task
Answer the questions by choosing the right answer/variant.
You may use the video below to give more exact answers.
Process
1.Cellulose is a natural high molecular weight compound which formed....
A)....industrially.
B)....naturally.
C)....with the help of people.
2. Which materials have 99% cellulose?
A)....cotton, jute and hemp
B)....cotton, leather and wool.
C)....cotton, silk and denim.
3. In 19th century paper producing was from....
A)....timber.
B)....pulp.
C)....glass.
4.Silicate Industry is industry, which uses a variety of silicon compounds, its main raw materials are....
A)....rocks and glass.
B)....mud and water.
C)...sand and clay.
5.The world produces...
A)... one way of paper
B)...many thousand ways of paper...
C)...hundreds of ways of paper.
6. Glass is produced from...
A)....sodium carbonate, magnesium sulfate and calcium sulfate.
B)....sand, limestone, sodium carbonate and sodium sulphate.
C)....iron disulfate, calcium hydroxide and sodium phosphate.
7.The highest temperature at which the glass mass is heated...
A)....630 degrees.
B) ....1200 degrees.
C).... 1450 degrees.
Evaluation
There was only one right answer for each question.
To make sure that you were answering right, here are the answers :
1.B
2.A
3.B
4.C
5.C
6.B
7.C
Conclusion
This webquest was based on the information that was in Introduction part and on the information in video.