Lub hauv paus ntsiab lus tshuaj ntawm cov ntawv sau thaum ub yog qhov tseem ceeb hauv kev hloov tshuaj lom neeg uas tshwm sim thaum lub sijhawm tsim khoom, suav nrog cov khoom siv raw, ua noj, pulping, papermaking, thiab ziab.
Nyob rau hauv cov txheej txheem ntawm raw khoom, papermaking raw cov ntaub ntawv yog feem ntau cog fibers, xws li hemp, bark, thiab xyoob. Cov ntaub ntawv raw yog soaked nyob rau hauv alkaline txiv qaub dej, uas reacts tshuaj nrog impurities nyob rau hauv cov nroj tsuag fibers. Lignin, muaj nyob rau hauv cov nroj tsuag fibers, undergoes hydrolysis nyob rau hauv lub cawv ntawm txiv qaub dej, nws cov qauv raug puas tsuaj, thiab nws cais los ntawm cov fiber. Ib txhij, cov dej txiv qaub kuj decomposes pectin, tshem tawm impurities los ntawm fiber ntau thiab ua kom nws purer.
Nyob rau hauv lub caij ua noj, cov khoom noj uas ntub dej yog muab tso rau hauv lub lauj kaub rau ua noj. Nyob rau hauv kub thiab alkaline tej yam kev mob, cov tshuaj muaj pes tsawg leeg ntawm cov fibers hloov ntxiv. Cellulose ua rau ib nrab degradation, nws cov qauv molecular hloov, nws℃ntawm polymerization txo, thiab molecular chains luv. Qhov no txhim kho cov fiber ntau yooj yooj yim thiab plasticity, tsim cov xwm txheej rau cov ntawv tom ntej.
Cov txheej txheem pulping aims ntxiv refine thiab disperse cov fibers, ib tug txheej txheem uas ua rau cov tshuaj tiv thaiv. Cov fibers raug rau cov neeg kho tshuab quab yuam, ua rau muaj kev hloov pauv hauv pawg ua haujlwm saum npoo av. Piv txwv li, cov pab pawg hydroxyl nyob rau ntawm qhov chaw fiber ntau tau txais cov tshuaj tiv thaiv oxidation qeeb nrog cov pa oxygen hauv huab cua, tsim cov pa oxygen tshiab - muaj cov pab pawg ua haujlwm. Cov pab pawg ua haujlwm tshiab no ua rau muaj zog hydrogen bonding ntawm fibers, muab cov ntawv zoo dua lub zog thiab toughness.
Nyob rau hauv cov txheej txheem papermaking, pulp yog kis rau ntawm lub xyoob tshuaj ntsuam los yog pwm, thiab cov dej yog drained rau daim ntawv. Raws li cov dej evaporates, qhov kev ncua deb ntawm cov fibers txo, thiab kev sib cuam tshuam quab yuam nce. Nyob rau tib lub sijhawm, cov molecules me me ntawm qhov chaw fiber ntau mloog zoo nrog cov evaporation ntawm dej, tsim cov tshuaj sib txuas ntawm cov fibers thiab txhim kho cov qauv kev ruaj ntseg ntawm daim ntawv.