Focus on Cellulose ethers

Qalabka kiimikada iyo isku dhafka hydroxypropyl methylcellulose (HMPC)

Hydroxypropyl methylcellulose (HPMC) waa polymer synthetic oo laga soo qaatay cellulose waxaana caadi ahaan loo isticmaalaa dhumuc weyn, emulsifier, iyo xasiliye warshado kala duwan sida cuntada, dawooyinka, iyo waxyaalaha la isku qurxiyo. HMPC waa hydroxypropylated derivative of methylcellulose (MC), eter nonionic cellulose biyo-milmi kara oo ka kooban methoxylated iyo hydroxypropylated unug cellulose. HMPC waxaa si weyn loogu isticmaalaa dawooyinka dawooyinka loo sameeyo iyadoo ay ugu wacan tahay sun la'aanteeda, biocompatibility, iyo biodegradability.

HMPC sifooyinka kiimikada:

Sifooyinka kiimikaad ee HMPC waxaa loo aaneynayaa joogitaanka kooxaha hydroxyl iyo ether ee qaab dhismeedka molecular. Kooxaha hydroxyl ee cellulose waxaa lagu shaqeyn karaa iyada oo loo marayo falcelin kiimikaad oo kala duwan, sida etherification, esterification, iyo oksaydhation, si loo soo bandhigo kooxo kala duwan oo shaqeynaya laf-dhabarka polymer. HMPC waxay ka kooban tahay kooxaha methoxy (-OCH3) iyo hydroxypropyl (-OCH2CHOHCH3), kuwaas oo lagu xakameyn karo si loo bixiyo sifooyin kala duwan sida milanka, viscosity iyo gelation.

HMPC aad bay ugu milmay biyaha, samaynta xalal cad, oo viscous ah oo aad u hooseeya. Viscosity ee xalalka HMPC waxaa lagu beddeli karaa iyadoo la hagaajinayo heerka beddelka (DS) ee kooxaha hydroxypropyl, taas oo go'aamisa tirada goobaha hydroxyl ee la bedelay unugga gulukoosta. Mar kasta oo DS-ku uu sarreeyo, hoos u dhaca milanka iyo kor u kaca viscosity ee xalka HMPC. Hantidan waxaa loo isticmaali karaa in lagu xakameeyo sii daynta maaddooyinka firfircoon ee ka samaysan daawooyinka.

HMPC waxay sidoo kale muujisaa dabeecada pseudoplastic, taasoo la micno ah in viscosity-ku hoos u dhaco iyadoo la kordhinayo heerka dhogorta. Hantidaani waxay ka dhigaysa mid ku haboon sida dhumuc ahaan u samaynta dareeraha ee u baahan inay u adkaysato xoogaga dhogorta inta lagu jiro habaynta ama codsiyada.

HMPC heerkul ahaan waa mid deggan ilaa heerkul gaar ah, kaas oo ka sarreeya kaas oo uu bilaabo inuu hoos u dhaco. Heerkulka hoos u dhaca ee HMPC wuxuu ku xiran yahay DS-ka iyo xoojinta polymerka ee xalka. Heerkulka heerkulka hoos u dhaca ee HMPC ayaa lagu soo waramayaa inuu yahay 190-330 ° C.

Isku dhafka HMPC:

HMPC waxaa lagu farsameeyay falcelinta etherification ee cellulose oo leh propylene oxide iyo methylethylene oxide iyadoo ay jirto joogitaanka kicinta alkaline. Dareen-celinta waxay ku socotaa laba tallaabo: marka hore, kooxaha methyl ee cellulose waxaa lagu beddelaa propylene oxide, ka dibna kooxaha hydroxyl waxaa lagu sii bedelayaa methyl ethylene oxide. DS ee HMPC waxaa lagu xakameyn karaa iyadoo la hagaajinayo saamiga molar ee propylene oxide ilaa cellulose inta lagu jiro habka isku-dhafka.

Dareen-celinta waxaa inta badan lagu fuliyaa dhexdhexaad aqueous heerkulka sare iyo cadaadiska. Dareenka aasaasiga ah ayaa badanaa ah sodium ama potassium hydroxide, kaas oo kor u qaadaya falcelinta kooxaha cellulose hydroxyl ee ku wajahan giraanta epoxide ee propylene oxide iyo methylethylene oxide. Alaabta falcelinta ka dib waa la dhexdhexaadin, la dhaqay oo la qalajiyey si loo helo badeecada ugu dambeysa ee HMPC.

HMPC sidoo kale waxaa lagu soo saari karaa iyadoo lagu falcelinayo cellulose leh propylene oxide iyo epichlorohydrin iyadoo ay joogaan kiciyayaal acid. Habkan, oo loo yaqaan habka epichlorohydrin, ayaa loo isticmaalaa in lagu soo saaro cationic cellulose derivatives, kuwaas oo si togan loo dallaco sababtoo ah joogitaanka kooxaha ammonium quaternary.

Gabagabadii:

HMPC waa polymer multifunctional leh sifooyin kiimiko oo aad u wanaagsan oo ku habboon codsiyada kala duwan ee warshadaha kala duwan. Isku-dubarid HMPC waxay ku lug leedahay falcelinta etherification ee cellulose leh propylene oxide iyo methylethylene oxide iyadoo ay jirto joogitaanka kicinta alkaline ama kicinta acidic. Sifooyinka HMPC waxaa lagu hagaajin karaa iyada oo la xakameynayo DS iyo xoojinta polymerka. Badbaadada iyo la jaanqaadka noole ee HMPC ayaa ka dhigaya doorasho ku habboon habaynta dawooyinka.


Waqtiga boostada: Seb-18-2023
WhatsApp Online chat!