Hydroxypropylmethylcellulose (HPMC) ndi mankhwala omwe akhala chinthu chofunikira kwambiri m'mafakitale ambiri chifukwa cha ntchito zake zambiri. Amagwiritsidwa ntchito kwambiri ngati chowonjezera pazakudya, chokhuthala mu zodzoladzola, komanso ngati chosakaniza chamankhwala m'mankhwala ambiri. Katundu wapadera wa HPMC ndi khalidwe lake la thixotropic, lomwe limalola kuti lisinthe mawonekedwe a kukhuthala ndi kuyenda kwa madzi pansi pa mikhalidwe ina. Kuphatikiza apo, HPMC yokhala ndi kukhuthala kwakukulu komanso kukhuthala kochepa ili ndi kalembedwe kameneka, komwe kamasonyeza thixotropy ngakhale kutentha kwa gel kutsika.
Thixotropy imachitika mu HPMC pamene yankho limakhala lochepa kwambiri pamene kupanikizika kukugwiritsidwa ntchito kapena kusunthidwa, zomwe zimapangitsa kuti kukhuthala kuchepe. Khalidweli lingathenso kusinthidwa; pamene kupsinjika kwachotsedwa ndipo yankholo lasiyidwa kuti lipumule, kukhuthala pang'onopang'ono kumabwerera ku mkhalidwe wake wapamwamba. Kapangidwe kapadera kameneka kamapangitsa HPMC kukhala gawo lofunika kwambiri m'mafakitale ambiri chifukwa limalola kugwiritsa ntchito bwino komanso kukonza mosavuta.
Monga hydrocolloid yosagwiritsa ntchito ma ionic, HPMC imatupa m'madzi kuti ipange gel. Mlingo wa kutupa ndi gelling umadalira kulemera kwa mamolekyulu ndi kuchuluka kwa polima, pH ndi kutentha kwa yankho. Kukhuthala kwakukulu HPMC nthawi zambiri imakhala ndi kulemera kwakukulu kwa mamolekyulu ndipo imapanga gel yokhuthala kwambiri, pomwe kukhuthala kochepa HPMC imakhala ndi kulemera kochepa kwa mamolekyulu ndipo imapanga gel yokhuthala pang'ono. Komabe, ngakhale kusiyana kumeneku pakugwira ntchito, mitundu yonse ya HPMC imawonetsa thixotropy chifukwa cha kusintha kwa kapangidwe komwe kumachitika pamlingo wa mamolekyulu.
Khalidwe la thixotropic la HPMC ndi chifukwa cha kulinganiza kwa unyolo wa polima chifukwa cha kupsinjika kwa shear. Pamene kupsinjika kwa shear kukugwiritsidwa ntchito ku HPMC, unyolo wa polima umalumikizana ndi kupsinjika komwe kukugwiritsidwa ntchito, zomwe zimapangitsa kuti kapangidwe ka netiweki ya magawo atatu kawonongeke popanda kupsinjika. Kusokonezeka kwa netiweki kumapangitsa kuti kukhuthala kwa yankho kuchepe. Kupsinjika kukachotsedwa, unyolo wa polima umakonzedwanso motsatira momwe unalili poyamba, ndikumanganso netiweki ndikubwezeretsa kukhuthala.
HPMC imawonetsanso thixotropy pansi pa kutentha kwa gelling. Kutentha kwa gel ndi kutentha komwe ma polymer amalumikizana kuti apange netiweki ya magawo atatu, ndikupanga gel. Zimatengera kuchuluka, kulemera kwa mamolekyulu ndi pH ya yankho la polima. Gel yomwe imachokera imakhala ndi kukhuthala kwakukulu ndipo sisintha mwachangu ikapanikizika. Komabe, pansi pa kutentha kwa gelation, yankho la HPMC linakhalabe lamadzimadzi, koma likuwonetsabe khalidwe la thixotropic chifukwa cha kukhalapo kwa kapangidwe ka netiweki kopangidwa pang'ono. Netiweki yopangidwa ndi zigawozi imasweka ikapanikizika, zomwe zimapangitsa kuti kukhuthala kuchepe. Khalidweli ndi lothandiza pa ntchito zambiri pomwe mayankho amafunika kuyenda mosavuta akamasunthidwa.
HPMC ndi mankhwala ogwiritsidwa ntchito mosiyanasiyana okhala ndi zinthu zingapo zapadera, chimodzi mwa izo ndi khalidwe lake la thixotropic. Ma HPMC onse okhala ndi kukhuthala kwakukulu komanso kukhuthala kochepa ali ndi khalidweli, ndipo amasonyeza thixotropy ngakhale kutentha kwa gel kutsika. Khalidweli limapangitsa HPMC kukhala gawo lofunika kwambiri m'mafakitale ambiri omwe amafunikira mayankho omwe amagwira ntchito mosavuta kuti atsimikizire kuti akugwiritsidwa ntchito bwino. Ngakhale kusiyana kwa makhalidwe pakati pa ma HPMC okhala ndi kukhuthala kwakukulu ndi kukhuthala kochepa, khalidwe lawo la thixotropic limachitika chifukwa cha kuyanjana ndi kusokonezeka kwa kapangidwe ka netiweki komwe kamapangidwa pang'ono. Chifukwa cha makhalidwe ake apadera, ofufuza nthawi zonse amafufuza ntchito zosiyanasiyana za HPMC, akuyembekeza kupanga zinthu zatsopano ndikupereka mayankho abwino kwa ogula padziko lonse lapansi.
Nthawi yotumizira: Ogasiti-23-2023