Hydroxypropyl methylcellulose (HPMC)wani fili ne mai narkewar ruwa da ake amfani da shi wajen gine-gine, magunguna, abinci da masana'antun sinadarai. Yana da ether wanda ba na ionic cellulose ba wanda aka samu ta hanyar gyare-gyaren sinadarai na cellulose na halitta, tare da kauri mai kyau, emulsification, ƙarfafawa da abubuwan samar da fim. Duk da haka, a ƙarƙashin yanayin zafi mai zafi, HPMC za ta fuskanci lalatawar thermal, wanda ke da tasiri mai mahimmanci akan kwanciyar hankali da aiki a aikace-aikace masu amfani.
Tsarin lalata thermal na HPMC
Lalacewar thermal na HPMC ya ƙunshi canje-canjen jiki da canje-canjen sinadarai. Canje-canje na jiki ana bayyana su ne azaman ƙawancen ruwa, canjin gilashi da raguwar danko, yayin da canje-canjen sinadarai sun haɗa da lalata tsarin kwayoyin halitta, tsagewar ƙungiyar aiki da tsarin carbonization na ƙarshe.
1. Matsayin ƙananan zafin jiki (100-200 ° C): ƙashin ruwa da bazuwar farko
A ƙarƙashin ƙananan yanayin zafi (kimanin 100 ° C), HPMC galibi yana jurewa ruwa da canjin gilashi. Tun da HPMC ya ƙunshi wani adadin ruwan da aka daure, wannan ruwan zai ƙafe sannu a hankali yayin dumama, don haka yana shafar halayen rheological. Bugu da kari, danko na HPMC shima zai ragu tare da karuwar zafin jiki. Canje-canje a cikin wannan matakin galibi canje-canje ne a cikin kaddarorin jiki, yayin da tsarin sinadarai ya kasance baya canzawa.
Lokacin da zafin jiki ya ci gaba da hauhawa zuwa 150-200 ° C, HPMC ya fara fuskantar halayen lalatawar sinadarai na farko. An fi bayyana shi a cikin kawar da hydroxypropyl da ƙungiyoyi masu aiki na methoxy, wanda ke haifar da raguwa a cikin nauyin kwayoyin halitta da canje-canjen tsarin. A wannan mataki, HPMC na iya samar da ƙananan ƙananan ƙananan ƙwayoyin cuta, irin su methanol da propionaldehyde.
2. Matsayin zafin jiki na matsakaici (200-300 ° C): babban lalata sarkar da ƙananan ƙwayoyin ƙwayoyin cuta
Lokacin da aka ƙara yawan zafin jiki zuwa 200-300 ° C, ƙimar lalata na HPMC yana ƙaruwa sosai. Babban hanyoyin lalata sun haɗa da:
Ether bond breakage: Babban sarkar HPMC yana haɗe da raka'o'in zobe na glucose, kuma ether bond ɗin da ke cikinta sannu a hankali yana karyewa a ƙarƙashin matsanancin zafin jiki, yana haifar da sarkar polymer ta rube.
Maganin rashin ruwa: Tsarin zobe na sukari na HPMC na iya fuskantar yanayin rashin ruwa a babban zafin jiki don samar da tsaka-tsaki mara tsayayye, wanda ya kara lalacewa zuwa samfuran maras tabbas.
Sakin ƙananan ƙwayoyin ƙwayoyin cuta: A wannan mataki, HPMC tana fitar da CO, CO₂, H₂O da ƙananan kwayoyin halitta, irin su formaldehyde, acetaldehyde da acrolein.
Wadannan canje-canje za su sa nauyin kwayoyin halitta na HPMC ya ragu sosai, danko ya ragu sosai, kuma kayan zai fara yin rawaya har ma da samar da coking.
3. Babban yanayin zafi (300-500 ° C): carbonization da coking
Lokacin da zafin jiki ya haura sama da 300°C, HPMC ya shiga wani mataki na lalata tashin hankali. A wannan lokacin, ƙarin raguwa na babban sarkar da haɓakar ƙananan ƙwayoyin ƙwayoyin cuta suna haifar da cikakkiyar lalata tsarin kayan aiki, kuma a ƙarshe ya samar da ragowar carbonaceous (coke). Halayen masu zuwa suna faruwa galibi a wannan matakin:
Lalacewar Oxidative: A babban zafin jiki, HPMC yana jurewa yanayin iskar oxygen don samar da CO₂ da CO, kuma a lokaci guda yana samar da ragowar carbonaceous.
Coking dauki: Wani ɓangare na tsarin polymer yana canzawa zuwa samfuran konewa da bai cika ba, kamar baƙar carbon ko ragowar coke.
Kayayyakin da ba su da ƙarfi: Ci gaba da sakin hydrocarbons kamar ethylene, propylene, da methane.
Lokacin zafi a cikin iska, HPMC na iya ƙara ƙonawa, yayin da dumama in babu iskar oxygen galibi ke haifar da ragowar carbonized.
Abubuwan da ke shafar lalatawar thermal na HPMC
Lalacewar thermal na HPMC yana shafar abubuwa da yawa, gami da:
Tsarin sinadarai: Matsayin maye gurbin hydroxypropyl da ƙungiyoyin methoxy a cikin HPMC yana shafar kwanciyar hankali ta thermal. Gabaɗaya magana, HPMC tare da babban abun ciki na hydroxypropyl yana da mafi kyawun kwanciyar hankali na thermal.
Yanayi na yanayi: A cikin iska, HPMC yana da saurin lalacewa, yayin da a cikin yanayin iskar iskar gas (kamar nitrogen), ƙarancin ƙarancin zafinsa yana raguwa.
Yawan dumama: Saurin dumama zai haifar da bazuwar sauri, yayin da jinkirin dumama zai iya taimakawa HPMC don rage carbonize a hankali da kuma rage samar da iskar gas.
Abun ciki na danshi: HPMC yana ƙunshe da ƙayyadaddun adadin ruwan da aka ɗaure. A lokacin aikin dumama, ƙawancen danshi zai shafi yanayin canjin gilashinsa da tsarin lalata.
Tasirin aikace-aikacen aikace-aikace na lalatawar thermal na HPMC
Halayen lalatawar zafi na HPMC suna da mahimmanci a fagen aikace-aikacen sa. Misali:
Masana'antar gine-gine: Ana amfani da HPMC a cikin turmi siminti da samfuran gypsum, kuma dole ne a yi la'akari da kwanciyar hankali yayin gini mai zafi don guje wa lalata da ke shafar aikin haɗin gwiwa.
Masana'antar harhada magunguna: HPMC wakili ne mai sarrafa magunguna, kuma dole ne a guje wa bazuwar yayin samar da yanayin zafi don tabbatar da kwanciyar hankali na miyagun ƙwayoyi.
Masana'antar abinci: HPMC ƙari ne na abinci, kuma halayensa na lalata yanayin zafi sun ƙayyade fa'idar sa a cikin gasa da sarrafa zafin jiki.
The thermal lalata tsari naHPMCza a iya raba shi cikin ƙawancen ruwa da raguwa na farko a cikin ƙananan yanayin zafi, babban sarkar sarkar da ƙananan ƙananan ƙwayoyin cuta a cikin matsakaicin matsakaici, da carbonization da coking a cikin babban yanayin zafi. Tsawon yanayin zafi yana shafar abubuwa kamar tsarin sinadarai, yanayi na yanayi, ƙimar dumama da abun cikin danshi. Fahimtar tsarin lalata yanayin zafi na HPMC yana da babbar fa'ida don haɓaka aikace-aikacen sa da haɓaka kwanciyar hankali na kayan.
Lokacin aikawa: Maris 28-2025