Yintoni ukuthotywa kwe-thermal ye-hydroxypropyl methylcellulose?

I-Hydroxypropyl methylcellulose (HPMC) yi-ether ye-cellulose engekho i-ionic esetyenziswa ngokubanzi kumayeza, ukutya, ukwakhiwa kunye nezinye iindawo, ngakumbi kwiipilisi ezikhutshwa ngokuqhubekayo kwiziyobisi kunye nezixhobo zokwakha. Uphononongo lokuthotywa kwe-thermal ye-HPMC alubalulekanga nje kuphela ekuqondeni utshintsho lwentsebenzo olunokuthi luhlangatyezwe ngexesha lokulungiswa, kodwa lubaluleke kakhulu ekuphuhliseni izixhobo ezitsha kunye nokuphucula ubomi benkonzo kunye nokhuseleko lweemveliso.

Iimpawu zokuthotywa kobushushu be-HPMC

I-thermal degradation ye-hydroxypropyl methylcellulose ichaphazeleka kakhulu kwisakhiwo sayo se-molecular, ubushushu bokufudumala kunye neemeko zayo zokusingqongileyo (ezifana nomoya, umswakama, njl.). Isakhiwo sayo se-molecular iqulethe inani elikhulu lamaqela e-hydroxyl kunye neebhondi ze-ether, ngoko ke iyakwazi ukuphendulwa kweekhemikhali ezifana ne-oxidation kunye nokubola kwiqondo lokushisa eliphezulu.

Inkqubo yokuthotywa kwe-thermal ye-HPMC idla ngokwahlulwa ngokwezigaba ezininzi. Okokuqala, kumaqondo okushisa aphantsi (malunga ne-50-150 ° C), i-HPMC inokufumana ilahleko enkulu ngenxa yokulahlekelwa kwamanzi akhululekile kunye namanzi adsorbed, kodwa le nkqubo ayibandakanyi ukuphulwa kweebhondi zeekhemikhali, kuphela utshintsho lomzimba. Njengoko iqondo lokushisa likhuphuka ngakumbi (ngaphezu kwe-150 ° C), iibhondi ze-ether kunye namaqela e-hydroxyl kwisakhiwo se-HPMC siqala ukuphuka, okubangelwa ukuphulwa kwekhonkco le-molecular kunye noshintsho kwisakhiwo. Ngokukodwa, xa i-HPMC ishushu malunga ne-200-300 ° C, iqala ukubola, ngelo xesha amaqela e-hydroxyl kunye namatyathanga asecaleni afana ne-methoxy okanye i-hydroxypropyl kwi-molecule ngokuthe ngcembe ibola ukuvelisa iimveliso ezincinci ze-molecular ezifana ne-methanol, i-formic. iasidi kunye nenani elincinci le-hydrocarbons.

Indlela yokuthotywa kwe-thermal

Indlela yokuthotywa kwe-thermal ye-HPMC inzima kwaye ibandakanya amanyathelo amaninzi. Indlela yokuthotywa kwayo inokushwankathelwa ngolu hlobo lulandelayo: njengoko iqondo lobushushu linyuka, iibhondi ze-ether kwi-HPMC zophuka ngokuthe ngcembe ukuze zivelise amaqhekeza amancinane emolekyuli, athi ke abole ngakumbi ukuze akhulule iimveliso zegesi ezifana namanzi, ikharbon diokside, kunye nekhabhon monokside. Iindlela zayo eziphambili zokuthotywa kwe-thermal ziquka la manyathelo alandelayo:

Inkqubo yokuphelelwa ngamanzi emzimbeni: I-HPMC ilahlekelwa ngamanzi adsorbed ngokwasemzimbeni kunye nenani elincinci lamanzi abophekileyo kwiqondo lokushisa eliphantsi, kwaye le nkqubo ayibhubhisi isakhiwo sayo sekhemikhali.

Ukuthotywa kwamaqela e-hydroxyl: Kuluhlu lweqondo lokushisa malunga ne-200-300 ° C, amaqela e-hydroxyl kwi-HPMC ye-molecular chain aqala ukwenza i-pyrolyze, ukuvelisa amanzi kunye ne-hydroxyl radicals. Ngeli xesha, i-methoxy kunye ne-hydroxypropyl amatyathanga asecaleni nawo ayabola ngokuthe ngcembe ukwenza iimolekyuli ezincinci ezifana ne-methanol, i-asidi ye-formic, njl.

Ukuqhekeka kwe-chain chain: Xa ukushisa kunyuka ngakumbi ukuya kwi-300-400 ° C, i-β-1,4-glycosidic bonds ye-cellulose chain chain iya kudlula i-pyrolysis ukuvelisa iimveliso ezincinci kunye neentsalela zekhabhoni.

Ukuqhekeka okungakumbi: Xa iqondo lobushushu linyuka liye ngaphaya kwe-400 ° C, ii-hydrocarbons ezishiyekileyo kunye nezinye iziqwenga zeselulosi ezingathotywanga ziya kutyhutyha ngakumbi ukuvelisa i-CO2, i-CO kunye nezinye izinto ezincinci ze-molecular organic.

Izinto ezichaphazela ukuthotywa kwe-thermal

Ukuthotywa kobushushu beHPMC kuchatshazelwa zizinto ezininzi, ingakumbi ezibandakanya le miba ilandelayo:

Ubushushu: Izinga kunye neqondo lokuthotywa kwe-thermal zihambelana ngokusondeleyo nobushushu. Ngokubanzi, okukhona iqondo lobushushu liphezulu, kokukhona ukusabela kokuthotywa ngokukhawuleza kokukhona kokukhona liphezulu iqondo lokuthotywa. Kwizicelo ezisebenzayo, indlela yokulawula ubushushu bokusebenza ukunqanda ukuthotywa okugqithisileyo kwe-HPMC ngumba ofuna ingqwalasela.

I-atmosphere: Ukuziphatha kokuthotywa kwe-thermal ye-HPMC kwiiatmosphere ezahlukeneyo kwahlukile. Kwimeko yomoya okanye i-oksijini, i-HPMC ilula i-oxidize, ivelisa iimveliso ze-gaseous ngakumbi kunye neentsalela zekhabhoni, ngelixa kwi-atmospheric ye-inert (efana ne-nitrogen), inkqubo yokunciphisa ibonakaliswe ngokukodwa njenge-pyrolysis, ivelisa inani elincinci le-carbon residues.

Ubunzima bemolekyuli: Ubunzima bemolekyuli ye-HPMC buchaphazela nokuziphatha kwayo kokuthotywa kwe-thermal. Ukuphakama kobunzima bemolekyuli, kokukhona ubushushu bokuqala bokwehla kwe-thermal. Oku kungenxa yokuba ubunzima obuphezulu bemolekyuli HPMC inamatyathanga amade eemolekyuli kunye nezakhiwo ezizinzileyo, kwaye ifuna amandla aphezulu ukuba aphule iibhondi zayo zeemolekyuli.

Isiqulatho sokufuma: Isiqulatho sokufuma kwi-HPMC sikwachaphazela ukuhla kobushushu bayo. Ukufuma kunokwehlisa iqondo lobushushu lokubola, ukuvumela ukuthotywa ukuba kwenzeke kumaqondo aphantsi.

Impembelelo yokusetyenziswa kokuthotywa kwe-thermal

Iimpawu zokuthotywa kwe-thermal ye-HPMC zinempembelelo ebalulekileyo kwisicelo sayo esisebenzayo. Umzekelo, kumalungiselelo amayeza, i-HPMC isoloko isetyenziswa njengezinto ezikhutshwa ngokuqhubekayo ukulawula izinga lokukhutshwa kwechiza. Nangona kunjalo, ngexesha lokusetyenzwa kweziyobisi, amaqondo obushushu aphezulu aya kuchaphazela ubume be-HPMC, ngaloo ndlela utshintsha ukukhutshwa kwechiza. Ke ngoko, ukufunda isimilo sokuthotywa kwe-thermal kubaluleke kakhulu ekwandiseni ukusetyenzwa kweziyobisi kunye nokuqinisekisa uzinzo lwechiza.

Kwizinto zokwakha, i-HPMC isetyenziswa ikakhulu kwimveliso yokwakha efana nesamente kunye negypsum ukuze idlale indima ekutyebeni nasekugcineni amanzi. Kuba izinto zokwakha zihlala zifuna amava okusingqongileyo obushushu obuphezulu xa zisetyenziswa, uzinzo lwe-thermal ye-HPMC ikwayingqwalasela ebalulekileyo yokukhethwa kwezinto. Kwiqondo lokushisa eliphezulu, ukuthotywa kwe-thermal ye-HPMC kuya kukhokelela ekunciphiseni kokusebenza kwezinto eziphathekayo, ngoko xa ukhetha kwaye uyisebenzise, ​​​​ukusebenza kwayo kumaqondo okushisa ahlukeneyo ngokuqhelekileyo kuqwalaselwa.

Inkqubo yokuthotywa kwe-thermal ye-hydroxypropyl methylcellulose (HPMC) ibandakanya amanyathelo amaninzi, achaphazeleka kakhulu ngubushushu, umoya, ubunzima bemolekyuli kunye nomxholo womswakama. Indlela yayo yokuthotywa kwe-thermal ibandakanya ukuphelelwa ngamanzi emzimbeni, ukubola kwe-hydroxyl kunye namatyathanga asecaleni, kunye nokuqhawulwa kwekhonkco eliphambili. Iimpawu zokuthotywa kwe-thermal ze-HPMC zinokubaluleka kokubaluleka kokusetyenziswa kwiinkalo zamalungiselelo amayeza, izinto zokwakha, njl. Ngoko ke, ukuqonda okunzulu kokuziphatha kwayo kokuthotywa kwe-thermal kubalulekile ekuphuculeni inkqubo yoyilo kunye nokuphucula ukusebenza kwemveliso. Kuphando lwexesha elizayo, ukuzinza kwe-thermal ye-HPMC kunokuphuculwa ngokuguqulwa, ukongeza i-stabilizers, njl., Ngaloo ndlela ukwandisa intsimi yesicelo sayo.