Hydroxypropyl Methylcellulose (HPMC)ndi ether ya cellulose yosakhala ionic yomwe imagwiritsidwa ntchito kwambiri popanga zinthu zopangidwa ndi simenti monga matope omangira, guluu wa matailosi, matope odziyimira pawokha, ndi pulasitala wa simenti. Ntchito yake yayikulu ndikukonza kugwirira ntchito bwino, kusunga madzi, komanso kukhazikika kwa chisakanizocho. Komabe, monga chowonjezera chachilengedwe cholemera kwambiri, HPMC imakhudzanso kwambiri zochita zakuthupi ndi zamankhwala panthawi ya madzi a simenti.
1. Kapangidwe ka HPMC mu Fizikiki
HPMC ndi polima wosungunuka m'madzi wopangidwa kuchokera ku cellulose yachilengedwe kudzera mu etherification reaction yomwe imayambitsa magulu a methoxy ndi hydroxypropoxy. Kapangidwe kake ka molekyulu kali ndi ma hydroxyl ndi ether bonds ambiri, zomwe zimapangitsa kuti ipange netiweki yokhazikika ya hydrogen bond ndi mamolekyu amadzi, zomwe zimapangitsa kuti madzi azisungidwa bwino komanso kuti apange filimu. Madzi ake amadzi amasonyeza makhalidwe a pseudoplastic fluid, zomwe zikutanthauza kuti kukhuthala kwake kumachepa pansi pa shear, zomwe zimathandiza pa ntchito zomanga. Chifukwa cha makhalidwe ake osakhala a ionic, HPMC imagwirizana pang'ono ndi zigawo za ionic mu simenti. Komabe, kudzera mu kulowetsedwa kwa thupi ndi zotsatira zoletsa steric, imakhudzabe njira yothira madzi ya tinthu ta simenti.
2. Mphamvu ya HPMC pa Gawo Loyamba la Kuthira Simenti
Poyamba simenti ikayamba kusungunuka, mamolekyu a HPMC amatha kulowa pamwamba pa tinthu ta simenti, ndikupanga filimu ya polymeric. Filimuyi imalepheretsa kulowa kwa madzi mu tinthu ta simenti, zomwe zimachedwetsa kusungunuka kwa C₃S (triccalcium silicate) ndi C₃A (triccalcium aluminate). Kafukufuku wasonyeza kuti kuwonjezera kwa HPMC kumachedwetsa kwambiri nthawi yoyambitsa simenti, zomwe zimapangitsa kuti chiwongolero cha exothermic cha dongosolocho chichepe pambuyo pake, zomwe zimapangitsa kuti chiwongolero cha madzi chichepe.
Kuchedwetsa kumeneku kumachokera makamaka ku mbali ziwiri:
Cholepheretsa chakuthupi: Filimu ya HPMC imaletsa kufalikira kwa madzi ndi kusinthana kwa ma ion, kuchepetsa kupangika kwa ma nuclei oyambira hydration.
Mpikisano woyamwa madzi: HPMC ili ndi mphamvu yoyamwa madzi kwambiri, ikupikisana ndi simenti kuti ipeze madzi omasuka m'dongosolo, zomwe zimapangitsa kuti chiŵerengero cha madzi ndi simenti chikhale chochepa, motero kuchepetsa kuchuluka kwa madzi m'thupi.
Chifukwa chake, mu makina a matope okhala ndi HPMC, nthawi zonse zoyambira komanso zomaliza nthawi zambiri zimakhala zotalikirapo, koma izi ndizothandiza pakukweza magwiridwe antchito.
3. Mphamvu ya HPMC pa Zinthu Zothira Madzi a Simenti
Ngakhale kuti poyamba HPMC imaletsa kuyamwa kwa madzi, mphamvu yake yochedwetsa siiwononga kuchuluka komaliza kwa kuyamwa kwa simenti. Pakapita nthawi, HPMC imasungunuka pang'onopang'ono kapena kufalikira m'malo okhala ndi alkaline, zomwe zimasokoneza chophimbacho ndikulola kuyamwa kwa simenti kupitirira.
Pambuyo pake, kapangidwe ka zinthu monga calcium silicate yosungunuka (CSH gel) ndi calcium hydroxide (CH) zomwe zimapangidwa m'dongosololi zimakhala zokhuthala, ndipo porosity imachepa. Mphamvu yosunga madzi ya HPMC imatsimikizira kuti hydration ikupitilizabe m'malo ouma, motero imalimbikitsa hydration reaction yonse ndikuchepetsa mapangidwe a ming'alu youma. Kafukufuku wina akuwonetsanso kuti HPMC ikhoza kulimbikitsa mapangidwe ofanana a CSH mwa kuwongolera kusamuka kwa ma ion ndi pH yakomweko, motero kuwonjezera kuchuluka kwa interfacial layer.
4. Zotsatira za HPMC pa Kapangidwe Kakang'ono ndi Kapangidwe ka Makina
Kupezeka kwa HPMC kumasintha kwambiri kapangidwe kake ka simenti. Netiweki yake ya polima ya magawo atatu imathandiza kusunga chinyezi panthawi yolimba, zomwe zimapangitsa kuti zinthu zothira madzi zizifalikira mofanana komanso kuti zikhale ndi ma pore abwino. Kuwona kwa scanning electron microscopy (SEM) kukuwonetsa kuti simenti yokhala ndi HPMC yowonjezera ili ndi ma pore ochepa pamwamba komanso kufalikira kwa CSH gel kolimba.
Komabe, mphamvu za HPMC zachilengedwe zingafooketsenso mphamvu yoyambirira ya thupi lolimba mpaka pamlingo winawake. Izi zili choncho chifukwa poyamba, madera ena samakhala ndi madzi okwanira, ndipo kuchedwa kukhazikitsa kumachepetsa mphamvu yopangira mphamvu. Komabe, pamene madzi akupitirira, mphamvu imabwerera m'mbuyo ndipo imakula pang'ono pambuyo pake. Kachitidwe ka "kuletsa koyambirira, kukulitsa pambuyo pake" kameneka kamawonekera makamaka m'machitidwe a HPMC otsika (<0.5%).
5. Kulinganiza Mlingo ndi Zotsatira za HPMC
Mlingo wa HPMC ndi chinthu chofunikira kwambiri chomwe chimakhudza kugwira ntchito kwake. Nthawi zambiri, pamene mlingo wa HPMC uli 0.1%–0.5% ya simenti, ukhoza kusintha kwambiri kusunga madzi ndi kugwira ntchito popanda kulepheretsa kwambiri njira yothira madzi. Mlingo wochuluka ungayambitse kuchedwa kwa nthawi yayitali mu kayendedwe ka madzi, kuwonjezeka kwa ma porosity a simenti, ndipo pamapeto pake, kusokoneza kwambiri mphamvu za makina.
Mlingo wa kusintha (DS), kuchuluka kwa kukhuthala, ndi kulemera kwa mamolekyu a HPMC zimakhudzanso khalidwe la kukhuthala. HPMC yokhala ndi kukhuthala kwakukulu komanso kusinthasintha kwakukulu imakhala ndi zotsatira zamphamvu zoyamwa ndi zotchinga, zomwe zimapangitsa kuti kukhuthala kuchedwe kwambiri; pomwe kukhuthala kochepa kwa HPMC kumatha kulinganiza magwiridwe antchito ndi kuuma.
HPMC imagwira ntchito ziwiri pakupanga madzi m'zinthu zopangidwa ndi simenti:
Gawo loyambirira: Limachedwetsa kusungunuka kwa madzi m'zidutswa za simenti kudzera mu kulowetsedwa, kupangidwa kwa filimu, ndi kuyamwa madzi, zomwe zimapangitsa kuti nthawi yokhazikika ichepe.
Gawo la pakati mpaka kumapeto: Limalimbikitsa madzi ochulukirapo nthawi zonse kudzera mu kusunga madzi ndikuwongolera momwe zinthu zilili, kukonza kuchuluka kwa kapangidwe kake komanso kukhazikika kwa voliyumu.
Mlingo woyenera ndi kapangidwe koyenera ka mamolekyulu aHPMCSikuti kungowonjezera kugwira ntchito bwino komanso kukweza kapangidwe kake ka simenti ndi magwiridwe antchito a nthawi yayitali pamlingo winawake. Chifukwa chake, mu uinjiniya womanga, kuwongolera mwasayansi mtundu ndi mlingo wa HPMC ndiye chinsinsi chokwaniritsa bwino komanso kukonza magwiridwe antchito a zinthu zopangidwa ndi simenti.
Nthawi yotumizira: Novembala-06-2025