IHydroxypropyl methylcellulose (HPMC)yikhompawundi yepolymer enyibilikayo emanzini esetyenziswa kakhulu kulwakhiwo, amayeza, ukutya kunye namashishini amachiza. I-ether ye-cellulose engeyona i-ionic efunyenwe ngokuguqulwa kweekhemikhali ze-cellulose yendalo, kunye nokuqina okulungileyo, i-emulsification, ukuzinzisa kunye neempawu zefilimu. Nangona kunjalo, phantsi kweemeko eziphezulu zokushisa, i-HPMC iya kuthotywa kwe-thermal, enempembelelo ebalulekileyo ekuzinzeni nasekusebenzeni kwayo kwizicelo eziphathekayo.
Inkqubo yokuthotywa kwe-Thermal ye-HPMC
Ukuthotywa kwe-thermal ye-HPMC kubandakanya kakhulu utshintsho lomzimba kunye nokutshintsha kweekhemikhali. Utshintsho olwenzekayo lubonakaliswa ngokubonakalayo njengokuphuma kwamanzi, ukuguqulwa kweglasi kunye nokunciphisa i-viscosity, ngelixa utshintsho lweekhemikhali lubandakanya ukutshatyalaliswa kwesakhiwo se-molecular, i-cleavage yeqela elisebenzayo kunye nenkqubo yokugqibela ye-carbonization.
1. Inqanaba lobushushu eliphantsi (100-200 ° C): ukuguquka kwamanzi kunye nokubola kokuqala
Ngaphantsi kweemeko eziphantsi zobushushu (malunga ne-100 ° C), i-HPMC idlula kakhulu i-evaporation yamanzi kunye nokuguqulwa kweglasi. Ekubeni HPMC iqulathe umlinganiselo othile wamanzi ebotshiweyo, la manzi ngokuthe ngcembe aya kuba ngumphunga ngexesha lokufudumeza, ngaloo ndlela echaphazela iimpawu zayo rheological. Ukongeza, i-viscosity ye-HPMC nayo iya kuncipha ngokunyuka kwamaqondo obushushu. Utshintsho kweli nqanaba lutshintsha kakhulu kwiimpawu ezibonakalayo, ngelixa isakhiwo sekhemikhali sihlala singatshintshi.
Xa iqondo lobushushu liqhubeka nokunyuka ukuya kwi-150-200 ° C, i-HPMC iqalisa ukufumana iimpendulo zokuqala zokuthotywa kweekhemikhali. Ibonakaliswa ikakhulu ekususweni kwe-hydroxypropyl kunye namaqela asebenzayo e-methoxy, okubangela ukuncipha kwesisindo se-molecular kunye noshintsho lwesakhiwo. Kweli nqanaba, i-HPMC inokuvelisa inani elincinci leemolekyuli ezincinci eziguquguqukayo, ezinjenge-methanol kunye nepropionaldehyde.
2. Inqanaba lobushushu eliphakathi (200-300 ° C): ukuthotywa kwekhonkco eliphambili kunye nokuveliswa kwemolekyuli encinci
Xa izinga lokushisa linyuka ngakumbi ukuya kwi-200-300 ° C, izinga lokubola kwe-HPMC likhawuleza kakhulu. Ezona ndlela zokwehlisa umgangatho ziquka:
Ukuqhekeka kwebhondi ye-Etere: Ikhonkco eliphambili le-HPMC lidityaniswe ngamayunithi eringi ye-glucose, kunye neebhondi ze-ether kuyo ngokuthe ngcembe ziqhekeka phantsi kobushushu obuphezulu, okubangela ukuba ikhonkco lepolymer libole.
Ukusabela kokuphelelwa ngamanzi emzimbeni: Ulwakhiwo lweringi yeswekile ye-HPMC lunokuthi lungene kwi-reaction yokuphelelwa ngamanzi emzimbeni kwiqondo lobushushu eliphezulu ukwenza i-intermediate engazinzanga, ephinda iboliswe ibe yimveliso eguquguqukayo.
Ukukhutshwa kwezinto ezincinci ze-molecule: Ngeli nqanaba, i-HPMC ikhupha i-CO, i-CO₂, i-H₂O kunye ne-molecule encinci yezinto eziphilayo, ezifana ne-formaldehyde, i-acetaldehyde kunye ne-acrolein.
Olu tshintsho luya kubangela ukuba ubunzima bemolekyuli ye-HPMC yehle kakhulu, i-viscosity yehle kakhulu, kwaye izinto ziya kuqala ukujika zityheli kwaye zivelise i-coking.
3. Inqanaba eliphezulu lokushisa (300-500 ° C): i-carbonization kunye ne-coking
Xa ubushushu buphakama ngaphezu kwe-300 ° C, i-HPMC ingena kwinqanaba lokuthotywa kobundlobongela. Ngeli xesha, ukuphulwa okuqhubekayo kwekhonkco eliphambili kunye nokuguqulwa kwezinto ezincinci ze-molecule zikhokelela ekutshatyalalisweni ngokupheleleyo kwesakhiwo sezinto eziphathekayo, kwaye ekugqibeleni zenze iintsalela ze-carbonaceous (coke). Oku kusabela kulandelayo kwenzeka ikakhulu kwesi sigaba:
Ukutshatyalaliswa kwe-oxidative: Kwiqondo lokushisa eliphezulu, i-HPMC ifumana i-oxidation reaction ukuze ivelise i-CO₂ kunye ne-CO, kwaye ngexesha elifanayo yenze iintsalela ze-carbonaceous.
I-Coking reaction: Inxalenye yesakhiwo se-polymer iguqulwa ibe yimveliso engaphelelanga yokutsha, efana ne-carbon black okanye i-coke residues.
Iimveliso eziguquguqukayo: Qhubeka nokukhupha iihydrocarbons ezifana ne-ethylene, ipropylene, kunye nemethane.
Xa ishushu emoyeni, i-HPMC inokutshisa ngakumbi, ngelixa ukufudumeza ngokungabikho kwe-oksijini kukwenza iintsalela ze-carbonized.
Izinto ezichaphazela ukuthotywa kwe-thermal ye-HPMC
Ukuthotywa kwe-thermal ye-HPMC kuchatshazelwa zizinto ezininzi, ezibandakanya:
Ubume beMichiza: Iqondo lokutshintshwa kwe-hydroxypropyl kunye namaqela e-methoxy kwi-HPMC ichaphazela ukuzinza kwayo kwe-thermal. Ngokubanzi, i-HPMC enomxholo ophezulu we-hydroxypropyl inozinzo olungcono lwe-thermal.
I-Ambient atmosphere: Emoyeni, i-HPMC ithanda ukonakaliswa yi-oxidative, ngelixa ikwimo engqongileyo yerhasi engasebenziyo (efana nenitrogen), izinga layo lokuthotywa kwe-thermal liyacotha.
Izinga lokufudumeza: Ukufudumeza okukhawulezayo kuya kukhokelela ekuboleni ngokukhawuleza, ngelixa ukufudumeza okucothayo kunokunceda i-HPMC ukuba kancinci kancinci ikharbhoze kwaye inciphise ukuveliswa kweemveliso eziguqukayo zegesi.
Umxholo wokufuma: I-HPMC iqulethe isixa esithile samanzi abophekileyo. Ngethuba lenkqubo yokufudumala, i-evaporation yomswakama iya kuchaphazela ukushisa kwayo kweglasi kunye nenkqubo yokuthotywa.
Impembelelo yesicelo esisebenzayo sokuthotywa kwe-thermal ye-HPMC
Iimpawu zokuthotywa kwe-thermal ye-HPMC zibaluleke kakhulu kwindawo yesicelo sayo. Umzekelo:
Ishishini lokwakha: I-HPMC isetyenziselwa udaka lwesamente kunye neemveliso zegypsum, kwaye ukuzinza kwayo ngexesha lokwakhiwa kobushushu obuphezulu kufuneka kuqwalaselwe ukuphepha ukuthotywa okuchaphazela ukusebenza kwebhondi.
Umzi-mveliso wamachiza: I-HPMC yi-arhente yokukhululwa elawulwa ngamachiza, kwaye ukubola kufuneka kuphetshwe ngexesha lemveliso yobushushu obuphezulu ukuqinisekisa ukuzinza kwechiza.
Umzi-mveliso wokutya: I-HPMC sisongezo sokutya, kwaye iimpawu zayo zokuthotywa kwe-thermal zimisela ukusebenza kwayo ekubhakeni nasekuqhubeni ubushushu obuphezulu.
Inkqubo yokuthotywa kwe-thermalHPMCinokwahlulwa ibe ngumphunga wamanzi kunye nokuthotywa kwangaphambili kwinqanaba lobushushu obuphantsi, i-chain chain cleavage kunye ne-molecule encinci ye-volatilization kwinqanaba lobushushu obuphakathi, kunye ne-carbonization kunye ne-coking kwinqanaba eliphezulu lobushushu. Ukuzinza kwayo kwe-thermal kuchatshazelwa yizinto ezifana nokwakhiwa kweekhemikhali, i-ambient atmosphere, izinga lokushisa kunye nomxholo womswakama. Ukuqonda indlela yokuthotywa kwe-thermal ye-HPMC kunexabiso elikhulu ukwandisa ukusetyenziswa kwayo kunye nokuphucula ukuzinza kwezinto.
Ixesha lokuposa: Mar-28-2025