1. Qaab-dhismeedka iyo mabda'a diyaarinta ee cellulose ether
Jaantuska 1aad wuxuu muujinayaa qaab-dhismeedka caadiga ah ee ethers-ka cellulose. Cutub kasta oo bD-anhydroglucose ah (cutubka soo noqnoqda ee cellulose) wuxuu beddelaa hal koox oo ku yaal boosaska C (2), C (3) iyo C (6), taas oo ah, waxaa jiri kara ilaa saddex kooxood oo ether ah. Sababo la xiriira silsiladda gudaha iyo silsiladda isku xiran ee haydarojiinta.macromolecules-ka cellulose-ka, way adag tahay in lagu milmo biyaha iyo ku dhawaad dhammaan dareerayaasha dabiiciga ah. Soo bandhigida kooxaha ether iyada oo loo marayo etherification waxay burburisaa isku xirnaanta hydrogen-ka gudaha iyo kuwa isku xiran, waxay hagaajisaa hydrophilicity-keeda, waxayna si weyn u wanaajisaa milmideeda biyaha.
Waxyaabaha caadiga ah ee lagu beddelay etherified waa kooxaha alkoxy ee miisaanka yar ee molecular (1 ilaa 4 atamka kaarboon) ama kooxaha hydroxyalkyl, kuwaas oo markaa lagu beddeli karo kooxo kale oo shaqeynaya sida carboxyl, hydroxyl ama kooxaha amino. Waxyaabaha lagu beddelayo waxay noqon karaan hal, laba ama in ka badan oo noocyo kala duwan ah. Silsiladda macromolecular-ka cellulose, kooxaha hydroxyl ee ku jira booska C(2), C(3) iyo C(6) ee cutub kasta oo gulukoos ah ayaa lagu beddelayaa cabbirro kala duwan. Si adag loo hadlo, cellulose ether guud ahaan ma laha qaab-dhismeed kiimiko oo qeexan, marka laga reebo alaabada gebi ahaanba lagu beddelay hal nooc oo koox ah (dhammaan saddexda kooxood ee hydroxyl waa la beddelayaa). Badeecadahan waxaa loo isticmaali karaa oo keliya falanqaynta shaybaarka iyo cilmi-baarista, mana laha qiimo ganacsi.
(a) Qaab-dhismeedka guud ee laba unug oo anhydroglucose ah oo silsiladda molecular ether cellulose ah, R1~R6=H, ama beddel dabiici ah;
(b) Qayb silsilad molekule ah oo carboxymethyl ahcellulose hydroxyethyl, heerka beddelka carboxymethyl waa 0.5, heerka beddelka hydroxyethyl waa 2.0, heerka beddelka gawskana waa 3.0. Qaab-dhismeedkani wuxuu matalaa heerka beddelka celceliska ee kooxaha etherified, laakiin beddelka dhab ahaantii waa kuwo aan kala sooc lahayn.
Beddel kasta, wadarta guud ee etherification waxaa lagu muujiyaa heerka qiimaha DS ee beddelka ah. Kala duwanaanshaha DS waa 0~3, taasoo la mid ah tirada celceliska kooxaha hydroxyl ee lagu beddelay kooxaha etherification ee cutub kasta oo anhydroglucose ah.
Ethers-ka hydroxyalkyl cellulose, falcelinta beddelka ah waxay ka bilaabi doontaa etherification kooxaha cusub ee hydroxyl ee bilaashka ah, heerka beddelkana waxaa lagu qiyaasi karaa qiimaha MS, taas oo ah, heerka molar ee beddelka. Waxay u taagan tahay celceliska tirada moles-ka ee fal-celinta wakiilka etherifying ee lagu daray cutub kasta oo anhydroglucose ah. Fal-celinta caadiga ah waa ethylene oxide badeecaduna waxay leedahay beddel hydroxyethyl ah. Jaantuska 1, qiimaha MS ee badeecaddu waa 3.0.
Aragti ahaan, ma jirto xad sare oo loogu talagalay qiimaha MS. Haddii qiimaha DS ee heerka beddelka ee koox kasta oo giraanta gulukooska ah la yaqaan, celceliska dhererka silsiladda silsiladda dhinaca ether-ka Soo-saareyaasha qaar ayaa sidoo kale badanaa isticmaala jajabka cufka (wt%) ee kooxaha etherification ee kala duwan (sida -OCH3 ama -OC2H4OH) si ay u matalaan heerka iyo heerka beddelka halkii ay ka ahaan lahaayeen qiimayaasha DS iyo MS. Jajabka cufka ee koox kasta iyo qiimaheeda DS ama MS waxaa lagu beddeli karaa xisaab fudud.
Inta badan ether-yada cellulose waa polymers-yo biyaha ku milma, qaarna sidoo kale qayb ahaan waa milmaan dareerayaasha dabiiciga ah. Cellulose ether waxay leedahay astaamo hufnaan sare, qiimo hoose, habayn fudud, sun yar iyo noocyo badan, baahida iyo goobaha codsigana wali way sii kordhayaan. Iyada oo ah wakiil kaaliye ah, cellulose ether waxay leedahay awood codsi oo weyn oo ku saabsan qaybaha kala duwan ee warshadaha. Waxaa laga heli karaa MS/DS.
Ether-yada Cellulose waxaa loo kala saaraa iyadoo loo eegayo qaab-dhismeedka kiimikada ee walxaha beddela, kuwaas oo loo kala saaro ether-yo anionic, cationic iyo nonionic. Ether-yada nonionic waxaa loo qaybin karaa badeecooyin biyo ku milma iyo kuwo saliid ku milma.
Badeecadaha warshadaha laga sameeyay waxaa lagu taxay qaybta sare ee Shaxda 1. Qaybta hoose ee Shaxda 1 waxay taxaysaa kooxo la yaqaan oo loo yaqaan etherification, kuwaas oo aan weli noqon badeecooyin ganacsi oo muhiim ah.
Soo gaabinta kala-soocidda ee walxaha isku dhafan ee ether waxaa loo magacaabi karaa iyadoo loo eegayo nidaamka xarfaha ama heerka DS (MS), tusaale ahaan, 2-hydroxyethyl methylcellulose, soo gaabinta waa HEMC, waxaana sidoo kale loo qori karaa MHEC si loo muujiyo methyl substituent.
Kooxaha hydroxyl ee ku jira cellulose si fudud uma heli karaan wakiilada etherification, habka etherification-kana waxaa badanaa lagu sameeyaa xaalado alkaline ah, guud ahaan iyadoo la adeegsanayo xoogaa gaar ah oo ah xalka biyaha NaOH. Cellulose-ka marka hore waxaa loo sameeyaa cellulose alkali ah oo barara iyadoo la adeegsanayo xalka biyaha NaOH, ka dibna waxaa la mariyaa falcelin etherification ah iyadoo la adeegsanayo wakiilka etherification. Inta lagu jiro soo saarista iyo diyaarinta ethers isku dhafan, noocyada kala duwan ee wakiilada etherification waa in isku mar la isticmaalaa, ama etherification waa in si tallaabo tallaabo ah loo sameeyaa iyadoo la adeegsanayo quudin goos goos ah (haddii loo baahdo). Waxaa jira afar nooc oo falgal ah oo ku jira etherification-ka cellulose, kuwaas oo lagu soo koobay qaacidada falgalka (cellulosic waxaa lagu beddelay Cell-OH) sida soo socota:
Isle'egta (1) waxay qeexaysaa falcelinta etherification-ka Williamson. RX waa ester asiidh aan organic ahayn, X-na waa halogen Br, Cl ama ester asiidh sulfuric ah. Chloride R-Cl guud ahaan waxaa loo isticmaalaa warshadaha, tusaale ahaan, methyl chloride, ethyl chloride ama chloroacetic acid. Qadar saldhig ah oo stoichiometric ah ayaa lagu isticmaalaa falcelinta noocaas ah. Waxyaabaha ether-ka ee ether-ka ee warshadaha leh ee methyl cellulose, ethyl cellulose iyo carboxymethyl cellulose waa wax soo saarka falgalka etherification-ka Williamson.
Qaacidada falcelinta (2) waa falcelinta lagu daro ee epoksaydhyada saldhigga lagu sameeyay (sida R=H, CH3, ama C2H5) iyo kooxaha hydroxyl ee ku jira molecules-ka iyada oo aan la isticmaalin saldhig. Falcelintani waxay u badan tahay inay sii socoto maadaama kooxo hydroxyl cusub la sameeyo inta lagu jiro falgalka, taasoo horseedaysa sameynta silsiladaha dhinaca ee oligoalkyletene oxide: Falcelin la mid ah oo lala sameeyo 1-aziridine (aziridine) waxay samayn doontaa aminoethyl ether: Cell-O-CH2-CH2-NH2. Badeecadaha sida hydroxyethyl cellulose, hydroxypropyl cellulose iyo hydroxybutyl cellulose dhammaantood waa badeecooyin ka yimid epoksaydh salka lagu sameeyay.
Qaacidada falcelinta (3) waa falcelinta u dhaxaysa Cell-OH iyo isku-dhafka dabiiciga ah ee ka kooban xidhmo labanlaab ah oo firfircoon oo ku jira dhexdhexaadka alkaline, Y waa koox elektaroonik ah oo soo saarta, sida CN, CONH2, ama SO3-Na+. Maanta noocan falcelinta ah si dhif ah ayaa loo isticmaalaa warshadaha.
Qaacidada falcelinta (4), etherification oo leh diazoalkane weli lama warshadayn.
- Noocyada ether-ka cellulose
Cellulose ether wuxuu noqon karaa monoether ama ether isku dhafan, sifooyinkiisuna way kala duwan yihiin. Waxaa jira kooxo hydrophilic ah oo hooseeya oo ku jira macromolecule-ka cellulose, sida kooxaha hydroxyethyl, kuwaas oo siin kara badeecada heer gaar ah oo milmi kara biyaha, halka kooxaha hydrophobic, sida methyl, ethyl, iwm., kaliya beddel dhexdhexaad ah Heerka sare wuxuu siin karaa badeecada milmi kara biyaha, badeecada beddelka hooseeyana waxay ku barari kartaa biyaha oo keliya ama waxaa lagu milmi karaa xalka alkali ee khafiifka ah. Iyadoo cilmi-baaris qoto dheer lagu sameeyay sifooyinka ethers cellulose, ethers cellulose cusub iyo goobaha codsigooda si joogto ah ayaa loo horumarin doonaa oo loo soo saari doonaa, xoogga ugu weyn ee wadista ahna waa suuqa codsiga ballaaran oo si joogto ah loo sifeeyay.
Sharciga guud ee saameynta kooxaha ee ku jira ethers isku dhafan ee sifooyinka milmida waa:
1) Kordhi tirada kooxaha hydrophobic ee ku jira badeecada si loo kordhiyo hydrophobicity-ga ether loona yareeyo barta jelka;
2) Kordhi tirada kooxaha hydrophilic (sida kooxaha hydroxyethyl) si loo kordhiyo barta jel-ka;
3) Kooxda hydroxypropyl waa mid gaar ah, hydroxypropylation-ka saxda ah wuxuu hoos u dhigi karaa heerkulka jelka ee badeecada, heerkulka jelka ee badeecada hydroxypropyl ee dhexdhexaadka ah ayaa mar kale kor u kici doona, laakiin heerka sare ee beddelka ayaa yareyn doona barta jelka; Sababtu waxay tahay qaab-dhismeedka dhererka silsiladda kaarboon ee gaarka ah ee kooxda hydroxypropyl, hydroxypropylation heerka hoose, isku xirnaanta haydarojiinta oo daciiftay gudaha iyo inta u dhaxaysa molecules-ka ku jira macromolecule-ka cellulose, iyo kooxaha hydroxyl hydrophilic ee silsiladaha laamaha. Biyuhu waa kuwo badan. Dhanka kale, haddii beddelka uu sarreeyo, waxaa jiri doona polymerization kooxda dhinaca, tirada qaraabada ah ee kooxda hydroxyl way yaraan doontaa, hydrophobicity way kordhi doontaa, milmiduna way yaraan doontaa.
Wax soo saarka iyo cilmi-baaristacellulose etherWaxay leedahay taariikh dheer. Sannadkii 1905, Suida waxay markii ugu horreysay soo sheegtay etherification-ka cellulose, kaas oo lagu dahaadhay dimethyl sulfate. Nonionic alkyl ethers waxaa shati ka qaatay Lilienfeld (1912), Dreyfus (1914) iyo Leuchs (1920) si ay u helaan cellulose ethers-ka biyaha ku milma ama saliidda ku milma, siday u kala horreeyaan. Buchler iyo Gomberg waxay soo saareen benzyl cellulose sannadkii 1921, carboxymethyl cellulose waxaa markii ugu horreysay soo saaray Jansen sannadkii 1918, Hubert-na wuxuu soo saaray hydroxyethyl cellulose sannadkii 1920. Horraantii 1920-meeyadii, carboxymethylcellulose waxaa laga ganacsan jiray Jarmalka. Laga bilaabo 1937 ilaa 1938, wax soo saarka warshadaha ee MC iyo HEC waxaa laga hirgeliyay Mareykanka. Sweden waxay bilowday soo saarista EHEC-ka biyaha ku milma sannadkii 1945. Ka dib 1945, soo saarista cellulose ether ayaa si degdeg ah ugu fiday Galbeedka Yurub, Mareykanka iyo Japan. Dhammaadkii 1957, Shiinaha CMC waxaa markii ugu horreysay laga soo saaray Warshadda Celluloid ee Shanghai. Marka la gaaro 2004, awoodda wax soo saarka dalkaygu waxay noqon doontaa 30,000 oo tan oo ah ether ionic iyo 10,000 oo tan oo ah ether aan ionic ahayn. Marka la gaaro 2007, waxay gaari doontaa 100,000 oo tan oo ether ionic ah iyo 40,000 oo tan oo ether Nonionic ah. Shirkadaha tignoolajiyada wadajirka ah ee gudaha iyo dibadda ayaa sidoo kale si joogto ah u soo baxaya, awoodda wax soo saarka ether cellulose ee Shiinaha iyo heerka farsamo ayaa si joogto ah u soo hagaagaya.
Sannadihii ugu dambeeyay, monoethers cellulose badan iyo ethers isku dhafan oo leh qiimayaal DS oo kala duwan, viscosities, daahirnimo iyo sifooyin rheological ah ayaa si joogto ah loo sameeyay. Waqtigan xaadirka ah, diiradda horumarinta ee ethers cellulose waa in la qaato tignoolajiyada wax soo saarka ee horumarsan, tignoolajiyada diyaarinta cusub, qalabka cusub, Badeecadaha cusub, badeecooyinka tayada sare leh, iyo badeecooyinka nidaamsan waa in si farsamo ahaan loo baaraa.
Waqtiga boostada: Abriil-28-2024