He aha ke ano o ka cellulose derivatives?

Hana ʻia nā derivatives cellulose e ka esterification a i ʻole etherification o nā pūʻulu hydroxyl i nā polymers cellulose me nā reagents kemika.Wahi a nā hiʻohiʻona o nā huahana hopena, hiki ke hoʻokaʻawale ʻia nā derivatives cellulose i ʻekolu mau ʻāpana: cellulose ethers, cellulose esters, a me cellulose ether esters.ʻO nā esters cellulose i hoʻohana maoli ʻia i ke kālepa: cellulose nitrate, cellulose acetate, cellulose acetate butyrate a me cellulose xanthate.ʻO ka cellulose ethers ka: methyl cellulose, carboxymethyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose a me hydroxypropyl methyl cellulose.Eia kekahi, aia nā ester ether i hui pū ʻia.

Nā waiwai a me nā hoʻohana Ma o ke koho ʻana i nā reagents a me ka hoʻolālā kaʻina hana, hiki ke hoʻoheheʻe ʻia ka huahana i loko o ka wai, hoʻoheheʻe ʻia ka hopena alkali a i ʻole ka mea hoʻoheheʻe organik, a i ʻole nā ​​​​mea thermoplastic, a hiki ke hoʻohana ʻia e hana i nā fibers kemika, nā kiʻiʻoniʻoni, nā kumu kiʻiʻoniʻoni, plastics, insulating. nā mea, nā uhi, slurry, polymeric dispersant, meaʻai meaʻai a me nā huahana kemika i kēlā me kēia lā.ʻO nā waiwai o ka cellulose derivatives e pili ana i ke ʻano o nā mea pani, ke degere DS o nā pūʻulu hydroxyl ʻekolu ma ka pūʻulu glucose i hoʻololi ʻia, a me ka māhele ʻana o nā mea pani ma ke kaulahao macromolecular.Ma muli o ka randomness o ka hopena, koe wale no ka huahana i hoʻololi like ʻia ke hoʻololi ʻia nā pūʻulu hydroxyl ʻekolu (DS ʻo 3), ma nā hihia ʻē aʻe (ka hopena homogeneous a i ʻole ka hopena heterogeneous), loaʻa nā kūlana hoʻololi like ʻole ʻekolu: Nā huahana i hui pū ʻia me nā pūʻulu glucosyl i hoʻololi ʻole ʻia: ① monosubstituted (DS ʻo 1, C, C a i ʻole ke kūlana C i hoʻololi ʻia, ʻike ʻia ke ʻano o ke ʻano o ka cellulose);② hoʻopau ʻia (DS ʻo 2, C, C, C, C a i ʻole C, ua pani ʻia nā kūlana C);③ pani piha (DS he 3).No laila, ʻokoʻa paha nā waiwai o ka derivative cellulose like me ka waiwai hoʻololi like.No ka laʻana, cellulose diacetate pololei esterified i ka DS o 2 he insoluble i ka acetone, akā, cellulose diacetate i loaʻa ma ka saponification o piha esterified cellulose triacetate hiki ke hoʻopau loa i ka acetone.ʻO kēia heterogeneity o ka hoʻololi e pili ana i nā kānāwai kumu o ka cellulose ester a me nā hopena etherification.

ʻO ke kānāwai kumu o ka esterification cellulose a me ka hopena etherification i loko o ka mole cellulose, ʻokoʻa nā kūlana o nā pūʻulu hydroxyl ʻekolu i ka pūʻulu glucose, a ʻokoʻa hoʻi ka mana o nā mea pani a me nā steric hindrance.ʻO ka ʻakika pili a me ke degere o ka wehe ʻana o nā pūʻulu hydroxyl ʻekolu: C>C>C.Ke hoʻokō ʻia ka hopena etherification i loko o kahi ʻano alkaline, ʻo ka hui C hydroxyl e hana mua, a laila ka pūʻulu C hydroxyl, a ma hope ka hui hydroxyl mua C.Ke hoʻokō ʻia ka hopena esterification i loko o kahi mea ʻawaʻawa, ʻo ka paʻakikī o ka pane ʻana o kēlā me kēia hui hydroxyl e kū'ē i ke kauoha o ka hopena etherification.I ka pane ʻana me kahi reagent hoʻololi nui, he mana koʻikoʻi ka hopena steric hindrance, a ʻoi aku ka maʻalahi o ka hui C hydroxyl me kahi hopena steric hindrance liʻiliʻi ma mua o nā hui hydroxyl C a me C.

ʻO ka cellulose kahi polymer kūlohelohe crystalline.ʻO ka hapa nui o ka esterification a me ka etherification reactions he heterogeneous reactions ke paʻa ka cellulose.Ua kapa ʻia ke kūlana diffusion o nā reagents i loko o ka fiber cellulose ka hiki ke hiki.Hoʻonohonoho paʻa ʻia ka hoʻonohonoho intermolecular o ka ʻāpana crystalline, a hiki i ka reagent ke hoʻolaha wale i ka ʻili crystalline.ʻO ka hoʻonohonoho intermolecular i loko o ka ʻāina amorphous ua wehe, a ʻoi aku ka nui o nā pūʻulu hydroxyl manuahi e maʻalahi e hoʻopili me nā reagents, me ka hiki ke kiʻekiʻe a me ka maʻalahi.ʻO ka maʻamau, ʻaʻole maʻalahi nā mea maka me ka crystallinity kiʻekiʻe a me ka nui aniani nui e like me nā mea maka me ka crystallinity haʻahaʻa a me ka nui aniani liʻiliʻi.Akā ʻaʻole ʻoiaʻiʻo loa kēia, no ka laʻana, ʻoi aku ka haʻahaʻa o ka acetylation rate o nā fiber viscose maloʻo me ka crystallinity haʻahaʻa a me ka crystallinity liʻiliʻi ma mua o ka pulupulu pulupulu me ka crystallinity kiʻekiʻe a me ka crystallinity nui.No ka mea, ua hana ʻia kekahi mau kiko hoʻopaʻa hydrogen ma waena o nā polymers e pili ana i ka wā o ka hoʻomaloʻo ʻana, kahi e pale ai i ka laha ʻana o nā reagents.Inā hoʻololi ʻia ka makū i loko o ka wai cellulose maka i kahi mea hoʻoheheʻe organik nui (e like me ka acetic acid, benzene, pyridine) a laila maloʻo, e hoʻomaikaʻi maikaʻi ʻia kona reactivity, no ka mea ʻaʻole hiki i ka maloʻo ke kipaku loa i ka solvent, a ʻo kekahi. paʻa ʻia nā molekala i loko o nā "puka" o ka cellulose maka mea, hana i kapa ʻia he cellulose.ʻAʻole maʻalahi ka hoʻihoʻi ʻana o ka mamao i hoʻonui ʻia e ka pehu ʻana, ʻo ia ka mea e kōkua ai i ka hoʻopuehu ʻana o nā reagents, a hoʻoikaika i ka wikiwiki o ka hopena a me ke kūlike o ka hopena.No kēia kumu, i ke kaʻina hana o nā ʻano derivatives cellulose, pono e loaʻa ka mālama ʻana i ka pehu.Hoʻohana maʻamau ka wai, ka waikawa a i ʻole kekahi ʻano o ka hopena alkali ma ke ʻano he mea pehu.Eia kekahi, ʻokoʻa loa ka paʻakikī o ka hopena kemika o ka pulp dissolving me nā hōʻailona kino a me nā kemika like ʻole, i kumu ʻia e nā kumu morphological o nā ʻano mea kanu a i ʻole nā ​​​​pūnaewele me nā ʻano biochemical a me nā hana hana i loko o ka mea kanu like.o.ʻO ka paia mua o ka papa o waho o ka fiber mea kanu ke keʻakeʻa nei i ke komo ʻana o nā reagents a hoʻopaneʻe i nā hopena kemika, no laila pono pono e hoʻohana i nā kūlana kūpono i ka hana pulping e luku ai i ka pā mua i mea e loaʻa ai ka dissolving pulp me ka reactivity ʻoi aku ka maikaʻi.No ka laʻana, ʻo ka bagasse pulp kahi mea maka me ka hana maikaʻi ʻole i ka hana ʻana o ka viscose pulp.Ke hoʻomākaukau nei i ka viscose (cellulose xanthate alkali solution), ʻoi aku ka nui o ka carbon disulfide ma mua o ka pulupulu linter pulupulu a me ka pulp lāʻau.ʻOi aku ka haʻahaʻa o ka kānana ma mua o ka viscose i hoʻomākaukau ʻia me nā pulps ʻē aʻe.ʻO kēia no ka mea ʻaʻole i hōʻino maikaʻi ʻia ka pā mua o nā pūnaewele kō i ka wā o ka pulping a me ka hoʻomākaukau ʻana i ka cellulose alkali e nā ʻano maʻamau, e hopena i ka paʻakikī i ka hopena melemele.

Pre-hydrolyzed alkaline bagasse pulp fibers] a me Figure 2 [bagasse pulp fibers after alkali impregnation] he electron microscope scanning kiʻi o ka ʻili o ka bagasse pulp fibers ma hope o ke kaʻina hana alkaline pre-hydrolyzed a me ka impregnation alkaline maʻamau, hiki ke ʻike ʻia ka mua. lua maopopo;i ka hope, ʻoiai nalo nā lua ma muli o ka pehu ʻana o ka solution alkali, ua uhi mau ka pā mua i ka fiber holoʻokoʻa.Inā ʻo ka "impregnation lua" (impregnation maʻamau a ukali ʻia e ka impregnation ʻelua me kahi solution alkali dilute me ka hopena pehu nui) a i ʻole ka dip-grinding (impregnation maʻamau i hui pū ʻia me ka mechanical grinding), hiki ke hele mālie ka hopena melemele, ʻo ka viscose filtration rate. ua hoʻomaikaʻi nui ʻia.ʻO kēia no ka mea hiki i nā ʻano hana ʻelua ma luna ke ʻili i ka pā mua, e hōʻike ana i ka papa o loko o ka ʻano maʻalahi o ka pane ʻana, e kūpono i ke komo ʻana o nā reagents a hoʻomaikaʻi i ka hana pane (Fig. 3 [secondary impregnation of bagasse pulp fiber. ].

I nā makahiki i hala iho nei, ua puka mai nā ʻōnaehana hoʻoheheʻe wai ʻole i hiki ke hoʻopau pololei i ka cellulose.E like me ka dimethylformamide a me NO, dimethyl sulfoxide a me ka paraformaldehyde, a me nā mea hoʻoheheʻe hui ʻia, a me nā mea ʻē aʻe, hiki i ka cellulose ke hana i kahi hopena homogeneous.Eia naʻe, ʻaʻole pili hou kekahi o nā kānāwai i ʻōlelo ʻia ma luna o ka hopena o waho.No ka laʻana, i ka hoʻomākaukau ʻana i ka cellulose diacetate hiki ke hoʻoheheʻe ʻia i ka acetone, ʻaʻole pono e hana i ka hydrolysis o cellulose triacetate, akā hiki ke esterified pololei a hiki i ka DS he 2.