1.Isakhiwo kunye nomgaqo wokulungiselela we-cellulose ether
Umzobo 1 ubonisa isakhiwo esiqhelekileyo se-cellulose ethers. Iyunithi nganye ye-bD-anhydroglucose (iyunithi ephindaphindiweyo ye-cellulose) ithatha indawo yeqela elinye kwi-C (2), i-C (3) kunye ne-C (6) izikhundla, oko kukuthi, kunokubakho ukuya kumaqela amathathu e-ether. Ngenxa ye-intra-chain kunye ne-inter-chain bonds ye-hydrogen yecellulose macromolecules, kunzima ukunyibilika emanzini kwaye phantse zonke i-solvents eziphilayo. Ukuqaliswa kwamaqela e-ether ngokusebenzisa i-etherification kutshabalalisa i-intramolecular kunye ne-intermolecular hydrogen bonds, iphucula i-hydrophilicity yayo, kwaye iphucula kakhulu ukunyibilika kwayo kwimidiya yamanzi.
Amaqela e-etherified aqhelekileyo ngamaqela anobunzima bemolekyuli ephantsi (1 ukuya kwi-4 yeeathom zekhabhoni) okanye amaqela e-hydroxyalkyl, anokuthi ke athatyathelwe indawo ngamanye amaqela asebenzayo afana ne-carboxyl, i-hydroxyl okanye amaqela e-amino. Amalungu anokuba luhlobo olunye, ezimbini okanye ngaphezulu ezahlukeneyo. Ecaleni kwekhonkco le-cellulose macromolecular, amaqela e-hydroxyl kwi-C (2), C (3) kunye ne-C (6) izithuba zeyunithi nganye ye-glucose zitshintshwa ngokwemilinganiselo eyahlukeneyo. Ukuthetha ngokuthe ngqo, i-cellulose ether ngokubanzi ayinayo ubume bekhemikhali ecacileyo, ngaphandle kwezo mveliso zitshintshwe ngokupheleleyo luhlobo olunye lweqela (onke amaqela amathathu e-hydroxyl afakwe endaweni). Ezi mveliso zingasetyenziselwa kuphela uhlalutyo lwebhubhoratri kunye nophando, kwaye azinalo ixabiso lezorhwebo.
(a) Ulwakhiwo jikelele lweeyunithi ezimbini ze-anhydroglucose zekhonkco lemolekyuli ye-cellulose ether, i-R1~R6=H, okanye i-organic substitute;
(b) Iqhekeza letsheyina lemolekyuli ye-carboxymethyli-hydroxyethyl cellulose, iqondo lokutshintshwa kwe-carboxymethyl yi-0.5, i-degree of substitution ye-hydroxyethyl yi-2.0, kunye ne-degree of substitution of molar yi-3.0. Esi sakhiwo simele umndilili wokutshintshwa kwenqanaba lamaqela etherified, kodwa ama-substituents ngokwenene a random.
Kwi-substitute nganye, isixa sisonke se-etherification sibonakaliswa ngeqondo lokutshintshwa kwexabiso le-DS. Uluhlu lwe-DS yi-0 ~ 3, elilingana nenani eliqhelekileyo lamaqela e-hydroxyl endaweni yawo ngamaqela e-etherification kwiyunithi nganye ye-anhydroglucose.
Kwi-hydroxyalkyl cellulose ethers, i-substitution reaction iya kuqalisa i-etherification evela kumaqela amatsha e-hydroxyl yamahhala, kwaye iqondo lokutshintshwa linokulinganiswa ngexabiso le-MS, oko kukuthi, i-molar degree of substitution. Imele iavareji yenani lee-moles ze-etherifying agent reactant eyongezwe kwiyunithi nganye ye-anhydroglucose. I-reactant eqhelekileyo yi-ethylene oxide kwaye imveliso ine-hydroxyethyl substituent. KuMzobo 1, ixabiso le-MS lemveliso yi-3.0.
Ngokwethiyori, akukho mda uphezulu kwixabiso leMS. Ukuba ixabiso le-DS leqondo lokutshintshela kwiqela ngalinye leringi yeglucose liyaziwa, umndilili wekhonkco lobude betsheyini yecala le-etherAbanye abavelisi nabo bahlala besebenzisa iqhezu lobunzima (wt%) lamaqela ahlukeneyo etherification (afana -OCH3 okanye -OC2H4OH) ukumela inqanaba lokutshintsha kunye nesidanga endaweni ye-DS kunye ne-MS ixabiso. Iqhezu lobunzima beqela ngalinye kunye nexabiso layo le-DS okanye le-MS linokuguqulwa ngokubala okulula.
Uninzi lwe-cellulose ethers ziipolima ezinyibilikayo emanzini, kwaye ezinye zikwanyibilika ngokuyinxenye kwizinyibilikisi zendalo. I-ether ye-cellulose ineempawu zokusebenza okuphezulu, ixabiso eliphantsi, ukucutshungulwa lula, ubuthi obuphantsi kunye neentlobo ezahlukeneyo, kunye nemfuno kunye neendawo zokusetyenziswa zisakhula. Njenge-agent encedisayo, i-cellulose ether inamandla amakhulu okusebenza kwiinkalo ezahlukeneyo zoshishino. inokufunyanwa nguMS/DS.
I-cellulose ethers ihlelwa ngokwesakhiwo sekhemikhali sabathathi-nxaxheba kwi-anionic, i-cationic kunye ne-nonionic ethers. Ii-ether ze-nonionic zinokwahlulwa zibe ziimveliso ezinyibilikayo emanzini kunye ne-oyile.
Iimveliso eziye zaphuhliswa kwimizi-mveliso zidweliswe kwindawo ephezulu yeTheyibhile 1. Inxalenye engezantsi yeThebhile 1 idwelisa amaqela aziwayo etherification, angekabi ziimveliso ezibalulekileyo zorhwebo.
Umyalelo wesifinyezo se-ether exubileyo ethatha indawo inokubizwa ngokwe-alfabhethi okanye inqanaba le-DS (MS), umzekelo, i-2-hydroxyethyl methylcellulose, isifinyezo yi-HEMC, kwaye ingabhalwa njenge-MHEC gxininisa into ebambeleyo yemethyl.
Amaqela e-hydroxyl kwi-cellulose ayifumaneki lula nge-etherification agents, kwaye inkqubo ye-etherification idla ngokuqhutyelwa phantsi kweemeko ze-alkaline, ngokuqhelekileyo isebenzisa i-concentration ethile ye-NaOH isisombululo samanzi. Iselulosi iqale iyilwe ibe yi-alkali cellulose edumbileyo enesisombululo esimanzi se-NaOH, ize emva koko ingene kwi-etherification reaction nge-etherification agent. Ngexesha lokuvelisa kunye nokulungiswa kwee-ethers ezixutywe, iintlobo ezahlukeneyo ze-etherification agents kufuneka zisetyenziswe ngexesha elifanayo, okanye i-etherification kufuneka iqhutywe inyathelo ngesinyathelo ngokutya okuphakathi (ukuba kuyimfuneko). Kukho iintlobo ezine zokusabela kwi-etherification ye-cellulose, ezishwankathelwa ngefomula yokusabela (i-cellulosic ithathelwa indawo yi-Cell-OH) ngolu hlobo lulandelayo:
I-equation (1) ichaza i-Williamson etherification reaction. I-RX yi-ester ye-asidi ye-inorganic, kwaye i-X yi-halogen Br, i-Cl okanye i-ester sulfuric acid. I-Chloride R-Cl isetyenziswa ngokubanzi kwishishini, umzekelo, i-methyl chloride, i-ethyl chloride okanye i-chloroacetic acid. Isixa se-stoichiometric sesiseko sidliwe kwiimpendulo ezinjalo. Iimveliso ze-ether ze-industrialized cellulose i-methyl cellulose, i-ethyl cellulose kunye ne-carboxymethyl cellulose zimveliso ze-Williamson etherification reaction.
I-Reaction formula (2) yimpendulo eyongezelelweyo ye-base-catalyzed epoxides (efana ne-R = H, CH3, okanye i-C2H5) kunye namaqela e-hydroxyl kwii-molecule ze-cellulose ngaphandle kokutya isiseko. Le mpendulo inokuthi iqhubeke njengoko amaqela amatsha e-hydroxyl eveliswa ngexesha lokuphendula, okukhokelela ekubunjweni kwe-oligoalkylethylene oxide side chains: Ukusabela okufanayo kunye ne-1-aziridine (aziridine) iya kwenza i-aminoethyl ether: i-Cell-O-CH2-CH2-NH2 . Iimveliso ezifana ne-hydroxyethyl cellulose, i-hydroxypropyl cellulose kunye ne-hydroxybutyl cellulose zonke ziyimveliso ye-base-catalyzed epoxidation.
I-reaction formula (3) yindlela yokusabela phakathi kwe-Cell-OH kunye ne-organic compounds equkethe i-double bonds esebenzayo kwi-alkaline medium, i-Y liqela lokurhoxisa i-electron, njenge-CN, i-CONH2, okanye i-SO3-Na +. Namhlanje olu hlobo lokusabela alufane lusetyenziswe kwimizi-mveliso.
Ifomula yokusabela (4), i-etherification kunye ne-diazoalkane ayikabikho kushishino okwangoku.
- Iindidi ze-cellulose ethers
I-cellulose ether ingaba yi-monoether okanye i-ether edibeneyo, kwaye iimpawu zayo zihluke. Kukho amaqela asezantsi afakwe endaweni ye-hydrophilic kwi-cellulose macromolecule, njengamaqela e-hydroxyethyl, anokunika imveliso ngeqondo elithile lokunyibilika kwamanzi, ngelixa amaqela e-hydrophobic, anjenge-methyl, i-ethyl, njl., ukutshintshwa okuphakathi kuphela ukunika imveliso ukunyibilika okuthile kwamanzi, kwaye imveliso ephantsi-efakwe endaweni idumba kuphela emanzini okanye inokunyibilika kwisisombululo se-alkali se-dilute. Ngophando olunzulu malunga neempawu ze-cellulose ethers, ii-ether ze-cellulose ezintsha kunye neendawo zabo zokusetyenziswa ziya kuphuhliswa ngokuqhubekayo kwaye ziveliswe, kwaye eyona nto inkulu yokuqhubela phambili yimarike yesicelo esibanzi kwaye eqhubekayo.
Umthetho jikelele weempembelelo zamaqela kwii-ether ezixubeneyo kwiipropati zokunyibilika ngulo:
I-1) Ukwandisa umxholo wamaqela e-hydrophobic kwimveliso yokwandisa i-hydrophobicity ye-ether kunye nokunciphisa i-gel point;
2) Ukwandisa umxholo wamaqela e-hydrophilic (njengamaqela e-hydroxyethyl) ukwandisa i-gel point yayo;
I-3) Iqela le-hydroxypropyl likhethekileyo, kwaye i-hydroxypropylation efanelekileyo inokunciphisa ukushisa kwe-gel yemveliso, kwaye ukushisa kwe-gel yemveliso ephakathi kwe-hydroxypropylated iya kuvuka kwakhona, kodwa inqanaba eliphezulu lokutshintshwa liya kunciphisa i-gel point yayo; Isizathu singenxa yesakhiwo esikhethekileyo se-carbon chain ubude beqela le-hydroxypropyl, i-hydroxypropylation ephantsi, i-hydroxypropylation ephantsi, i-hydrogen bond ebuthathaka ngaphakathi naphakathi kwee-molecule kwi-cellulose macromolecule, kunye namaqela e-hydrophilic hydroxyl kumatyathanga esebe. Amanzi ngawongamele. Ngakolunye uhlangothi, ukuba ukutshintshwa kuphezulu, kuya kubakho i-polymerization kwiqela lecala, umxholo ohambelana neqela le-hydroxyl liya kuncipha, i-hydrophobicity iya kwanda, kwaye i-solubility iya kuncitshiswa endaweni.
Imveliso kunye nophando lwei-cellulose etherinembali ende. Ngo-1905, uSuida waqala wachaza i-etherification ye-cellulose, eyayine-methylated kunye ne-dimethyl sulfate. I-alkyl ethers ye-nonionic yayinelungelo lobunikazi nguLilienfeld (1912), i-Dreyfus (1914) kunye ne-Leuchs (1920) ye-ethers ye-cellulose e-soluble yamanzi okanye i-oil-soluble cellulose, ngokulandelanayo. UBuchler noGomberg bavelisa i-benzyl cellulose kwi-1921, i-carboxymethyl cellulose yaveliswa okokuqala nguJansen ngo-1918, kwaye uHubert wavelisa i-hydroxyethyl cellulose ngo-1920. Ekuqaleni kwe-1920, i-carboxymethylcellulose yayithengiswa eJamani. Ukususela kwi-1937 ukuya kwi-1938, ukuveliswa kwemveliso ye-MC kunye ne-HEC kwaqatshelwa e-United States. ISweden yaqala ukuveliswa kwe-EHEC e-soluble yamanzi kwi-1945. Emva kwe-1945, ukuveliswa kwe-cellulose ether kwanda ngokukhawuleza eNtshona Yurophu, eUnited States naseJapan. Ekupheleni kuka-1957, i-China CMC yaqala ukufakwa kwimveliso kwi-Shanghai Celluloid Factory. Ngo-2004, umthamo wemveliso welizwe lam uya kuba yi-30,000 yeetoni ze-ionic ether kunye ne-10,000 yeetoni ze-ether engeyiyo i-ionic. Ngo-2007, iya kufikelela kwi-100,000 yeetoni ze-ionic ether kunye ne-40,000 yeetoni ze-Nonionic ether. Iinkampani iteknoloji Joint ekhaya nakwamanye amazwe nazo rhoqo zivela, kunye neselulosi yaseTshayina umthamo wemveliso ether kunye nenqanaba lobugcisa rhoqo ukuphucula.
Kwiminyaka yakutshanje, ii-cellulose monoethers ezininzi kunye nee-ethers ezixutywe ngexabiso le-DS ezahlukeneyo, i-viscosities, ubunyulu kunye neempawu ze-rheological ziye zaphuhliswa ngokuqhubekayo. Okwangoku, ugxininiso lophuhliso kwintsimi ye-cellulose ethers kukwamkela iteknoloji yemveliso ephezulu, iteknoloji entsha yokulungiselela, izixhobo ezitsha, iimveliso ezitsha, iimveliso ezikumgangatho ophezulu, kunye neemveliso ezicwangcisiweyo kufuneka ziphandwe ngobugcisa.
Ixesha lokuposa: Apr-28-2024