Soosaarayaasha cellulose waxaa lagu soo saaraa esterification ama etherification ee kooxaha hydroxyl ee polymers cellulose leh reagents kiimikaad. Marka loo eego sifooyinka qaab dhismeedka alaabada falcelinta, derivatives cellulose waxaa loo qaybin karaa saddex qaybood: ethers cellulose, esters cellulose, iyo esters cellulose. Esters cellulose ee dhab ahaantii ganacsi ahaan loo isticmaalo waa: cellulose nitrate, cellulose acetate, cellulose acetate butyrate iyo cellulose xanthate. Ethers Cellulose waxaa ka mid ah: methyl cellulose, carboxymethyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose iyo hydroxypropyl methyl cellulose. Intaa waxaa dheer, waxaa jira ester ether derivatives isku dhafan.
Guryaha iyo isticmaalka Iyada oo la dooranayo reagents beddelka iyo naqshadaynta habka, badeecada waxaa lagu milmi karaa biyaha, xalalka alkali ah ama dareeraha organic, ama waxay leeyihiin sifooyin heerkulbeeg ah, waxaana loo isticmaali karaa in lagu soo saaro fiilooyinka kiimikada, filimada, saldhigyada filimada, balaastikada, daboolka. agabka, dahaarka, slurry, polymeric dispersant, cuntada lagu daro iyo alaabta maalinlaha ah ee kiimikaad. Astaamaha soosaarayaasha cellulose waxay la xiriiraan dabeecadda beddelka, heerka DS ee saddexda kooxood ee hydroxyl ee kooxda gulukooska oo la beddelayo, iyo qaybinta beddelka ee silsiladda macromolecular. Sababtoo ah kala-soocida falcelinta, marka laga reebo badeecada si isku mid ah loo beddelay marka dhammaan saddexda kooxood ee hydroxyl la beddelo (DS waa 3), xaalado kale (falcelin isku mid ah ama falcelin kala duwan), saddexda boos ee beddelka ee soo socda ayaa la helayaa: Alaabooyin isku dhafan oo leh Kooxaha glucosyl ee aan la bedelin: ① monosubstituted (DS waa 1, C, C ama booska C waa la bedelay, qaabka qaabdhismeedka eeg cellulose); ② waa la bedelay (DS waa 2, C, C, C, C ama C, boosaska C waa la bedelay); ③ Beddel buuxa (DS waa 3). Sidaa darteed, sifooyinka soo saara cellulose-ka ee leh qiimaha beddelka ee isku midka ah ayaa sidoo kale laga yaabaa inay aad uga duwan yihiin. Tusaale ahaan, diacetate cellulose si toos ah loogu dhejiyay DS of 2 waa mid aan milmi karin acetone, laakiin diacetate cellulose ee lagu helo saponification ee triacetate cellulose si buuxda loo nadiifiyey ayaa si buuxda loogu milmi karaa acetone. Kala duwanaanshahan beddelka ahi wuxuu la xiriiraa sharciyada aasaasiga ah ee ester cellulose iyo falcelinta etherification.
Sharciga aasaasiga ah ee esterification cellulose iyo falcelinta etherification ee molecule cellulose, boosaska saddexda kooxood ee hydroxyl ee kooxda gulukooska way kala duwan yihiin, iyo saameynta beddelka ku xiga iyo caqabada stric ayaa sidoo kale ka duwan. Aashitada qaraabada ah iyo heerka kala qaybsanaanta saddexda kooxood ee hydroxyl waa: C>C>C. Marka falcelinta etherification lagu sameeyo dhexdhexaad ah alkaline, kooxda C hydroxyl ka falcelin marka hore, ka dibna kooxda C hydroxyl, iyo ugu dambeyntii kooxda C aasaasiga ah hydroxyl. Marka falcelinta esterification lagu sameeyo dhexdhexaad acidic ah, dhibka falcelinta koox kasta hydroxyl ayaa ka soo horjeeda nidaamka falcelinta etherification. Marka aad ka falcelinayso reagent beddelka weyn, saamaynta xannibaadda stericku waxay leedahay saamayn muhiim ah, iyo kooxda C hydroxyl oo leh saameyn yar oo xannibaad ah ayaa ka fudud inay ka falceliyaan kooxaha C iyo C hydroxyl.
Cellulose waa polymer dabiici ah oo crystalline ah. Inta badan falcelinta esterification iyo etherification waa falcelinno kala duwan marka cellulose uu sii ahaado mid adag. Xaaladda fidinta falcelinta falcelinta ee faybarka cellulose waxaa loo yaqaannaa gaadhista. Habaynta intermolecular ee gobolka crystalline si adag ayaa loo habeeyey, reagent-ku wuxuu kaliya ku faafi karaa dusha sare ee crystalline. Habka intermolecular ee gobolka amorphous waa dabacsan, waxaana jira kooxo badan oo hydroxyl ah oo bilaash ah kuwaas oo ay fududahay in lala xiriiro reagen, oo leh helitaan sare iyo falcelin sahlan. Guud ahaan, alaabta ceeriin ee leh crystallinity sare iyo cabbir weyn oo crystallinity ma fududa in laga falceliyo sida alaabta ceeriin leh crystallinity hoose iyo cabbir yar oo crystal. Laakiin tani maahan wax run ah oo dhan, tusaale ahaan, heerka acetylation ee fiilooyinka viscose qalalan ee leh crystallinity hoose iyo crystallinity yar ayaa aad uga hooseeya kan suufka leh crystallinity sare iyo crystallinity ka weyn. Tani waa sababta oo ah qaar ka mid ah dhibcaha isku xidhka hydrogen ayaa ka dhex abuurma polymers-ka xiga inta lagu jiro habka qalajinta, taas oo caqabad ku ah faafinta reagents. Haddii qoyaanka ku jira alaabta ceeriin ee qoyan lagu beddelo dareeraha organic ka weyn (sida acetic acid, benzene, pyridine) ka dibna la qalajiyo, falcelintiisa si weyn ayaa loo wanaajin doonaa, sababtoo ah qalajinta si buuxda uma saari karto dareeraha, iyo qaar ka weyn molecules waxay ku xayiran yihiin "godadka" alaabta ceeriin ee cellulose, samaynta waxa loogu yeero cellulose. Fogaanta lagu balaariyay bararka ma fududa in laga soo kabsado, taas oo u sahlaysa faafinta reagents, waxayna kor u qaadaa heerka falcelinta iyo isku midnimada falcelinta. Sababtan awgeed, habka wax soo saarka ee noocyada kala duwan ee cellulose, waa in ay jiraan daaweyn barar u dhiganta. Caadi ahaan biyo, aashito ama qayb gaar ah oo xalalka alkali ah ayaa loo isticmaalaa sidii wakiilka bararka. Intaa waxaa dheer, dhibka falcelinta kiimikaad ee saxarka milanka leh isla tilmaamayaasha kiimikaad iyo kiimikaad inta badan aad bay u kala duwan yihiin, taas oo ay sababto arrimaha qaab-dhismeedka ee noocyada kala duwan ee dhirta ama unugyada kala duwan ee biochemical iyo hawlaha qaabdhismeed ee isla geedka. ee Darbiga aasaasiga ah ee lakabka sare ee fiber dhirta ayaa caqabad ku ah dhexgalka reagents iyo dib u dhigista falcelinta kiimikada, sidaas darteed inta badan waa lagama maarmaan in la isticmaalo xaaladaha u dhigma ee habka pulping si loo burburiyo derbiga asaasiga ah si loo helo saxarka kala dirida oo leh falcelin wanaagsan. Tusaale ahaan, saxarka bagaashka waa walxo ceeriin ah oo leh falcelin liidata soo saarista saxarka viscose-ka. Marka la diyaarinayo viscose (cellulose xanthate alkali xal), kaarboon disulfide ka badan ayaa la cunaa marka loo eego saxarka suufka iyo saxarka alwaax. Heerka sifaynta ayaa ka hooseeya kan viscose ee lagu diyaariyey saxarada kale. Tani waa sababta oo ah gidaarka aasaasiga ah ee unugyada fiber-sonkorowga si fiican uma dhaawacmin inta lagu jiro pulping iyo diyaarinta alkali cellulose hababka caadiga ah, taasoo keentay in ay ku adkaato falcelinta jaalaha ah.
Fiilooyinka saxarka alkal ee pre-hydrolyzed iyo Jaantuska 2 [Bagasse saxarka saxarka ka dib markii alkali impregnation] waa sawiro mikroskoob elektaroonik ah oogada fiilooyinka bagasse ka dib habka alkaline pre-hydrolyzed iyo impregnation caadiga ah alkaline siday u kala horreeyaan, hore weli waa la arki karaa godadka cad; dambaysta, in kasta oo godadku baaba'aan sababtoo ah bararka xalalka alkali, derbiga aasaasiga ah ayaa weli daboolaya dhammaan fiber-ka. Haddii "impregnation-ka labaad" (imregnation caadi ah oo ay ku xigto impregnation labaad oo leh xal alkali ah oo la milo leh oo leh saameyn barar weyn) ama shiidid-shiidid (imregnation caadi ah oo ay weheliso qashinka farsamada), falcelinta jaalaha ah waxay u socon kartaa si habsami leh, heerka shaandhaynta viscose si weyn ayaa loo hagaajiyay. Tani waa sababta oo ah labada hab ee kor ku xusan waxay ka saari karaan derbiga asaasiga ah, iyagoo soo bandhigaya lakabka gudaha ee falcelinta fudud, taas oo u sahlaysa gelitaanka reagents waxayna hagaajinaysaa waxqabadka falcelinta (Jaantus. 3 ], Jaantuska. Shiididda Xabadaha Bagasse ee Dhuxusha]).
Sannadihii ugu dambeeyay, hababka dareeraha aan biyaha lahayn ee si toos ah u milmi kara cellulose ayaa soo baxay. Sida dimethylformamide iyo NO, dimethyl sulfoxide iyo paraformaldehyde, iyo dareerayaasha kale ee isku dhafan, iwm. Si kastaba ha ahaatee, qaar ka mid ah sharciyada kor ku xusan ee falcelinta ka baxsan marxaladda hadda ma shaqeeyaan. Tusaale ahaan, marka la diyaarinayo diacetate cellulose ee ku milma acetone, looma baahna in la maro hydrolysis of triacetate cellulose, laakiin si toos ah ayaa loo nadiifin karaa ilaa DS uu yahay 2.
Waqtiga boostada: Febraayo-27-2023