Mechanism ntawm Redispersible Emulsion Powder hauv Qhuav Mix Mortar

Redispersible latex hmoov thiab lwm yam inorganic adhesives (xws li cement, slaked txiv qaub, gypsum, av nplaum, thiab lwm yam) thiab ntau yam aggregates, fillers thiab lwm yam additives [xws li hydroxypropyl methylcellulose, polysaccharide ( starch ether), fiber ntau, thiab lwm yam.] nyob rau hauv qhuav-mixed mortar los ntawm lub cev sib tov. Thaum cov hmoov hmoov qhuav ntxiv rau hauv dej thiab nplawm, nyob rau hauv qhov kev txiav txim ntawm hydrophilic tiv thaiv colloid thiab mechanical shear force, latex hmoov hais tau sai sai dispersed rau hauv dej, uas yog txaus rau tag nrho cov redispersible latex hmoov rau hauv ib tug zaj duab xis. Cov khoom xyaw ntawm cov hmoov roj hmab muaj qhov sib txawv ntawm cov khoom siv rheological ntawm mortar thiab ntau yam kev tsim kho: kev sib raug zoo ntawm cov hmoov latex rau dej thaum nws rov ua dua, qhov sib txawv viscosities ntawm cov hmoov latex tom qab dispersion, cuam tshuam rau cov ntsiab lus ntawm huab cua. ntawm cov mortar thiab kev faib tawm ntawm huab cua npuas, Kev sib cuam tshuam ntawm cov roj hmab hmoov thiab lwm yam additives ua rau cov hmoov latex sib txawv muaj qhov cuam tshuam ntawm kev nce fluidity, nce thixotropy, thiab nce viscosity.

Nws yog feem ntau ntseeg hais tias lub mechanism ntawm redispersible latex hmoov los txhim kho lub workability ntawm tshiab mortar yog: lub affinity ntawm latex hmoov, tshwj xeeb tshaj yog cov tiv thaiv colloid, rau dej thaum nws dispersed, tsub kom lub viscosity ntawm slurry, thiab txhim kho cov cohesion. lub tsev mortar.

Tom qab cov tshuaj sib xyaw tshiab uas muaj cov latex hmoov dispersion yog tsim, nrog kev nqus dej los ntawm lub hauv paus nto, kev noj cov tshuaj tiv thaiv hydration, thiab volatilization rau saum huab cua, cov dej yuav maj mam txo, cov resin particles yuav maj mam mus, lub interface. yuav maj mam plooj, thiab cov resins yuav maj mam fuse nrog ib leeg. thaum kawg polymerized rau hauv zaj duab xis. Cov txheej txheem ntawm kev tsim cov yeeb yaj kiab polymer tau muab faib ua peb theem. Nyob rau hauv thawj theem, cov polymer hais txav dawb do nyob rau hauv daim ntawv ntawm Brownian motion nyob rau hauv thawj emulsion. Raws li cov dej evaporates, kev txav ntawm cov khoom yog ib txwm muaj kev txwv ntau dua, thiab qhov sib cuam tshuam ntawm cov dej thiab huab cua ua rau lawv maj mam ua ke. Nyob rau theem thib ob, thaum cov khoom sib cuag nrog ib leeg, cov dej hauv lub network evaporates los ntawm cov hlab ntsha capillary, thiab lub siab capillary nro thov rau saum npoo ntawm cov khoom ua rau cov deformation ntawm cov latex spheres rau fuse lawv ua ke, thiab cov dej uas seem nyob puv lub pores, thiab zaj duab xis yog roughly tsim. Qhov thib peb, theem kawg tso cai rau qhov diffusion (qee zaum hu ua nws tus kheej-adhesion) ntawm cov polymer molecules los ua ib zaj duab xis txuas ntxiv. Thaum lub sij hawm tsim cov yeeb yaj kiab, cov xov tooj ntawm tes latex sib cais sib sau ua ke rau hauv cov yeeb yaj kiab tshiab nrog kev ntxhov siab tensile siab. Pom tseeb, nyob rau hauv thiaj li yuav pab kom cov redispersible polymer hmoov los ua ib zaj yeeb yaj kiab, nws yog ib qho tsim nyog los xyuas kom meej qhov ntsuas kub (Mft) yog qis dua li kev kho tus kheej ntawm lub cug.

Colloids - polyvinyl cawv yuav tsum tau muab cais tawm ntawm cov txheej txheem zaj duab xis polymer. Qhov no tsis yog teeb meem nyob rau hauv alkaline cement mortar system, vim hais tias polyvinyl cawv yuav saponified los ntawm alkali generated los ntawm cov cement hydration, thiab cov adsorption ntawm quartz khoom yuav maj mam cais cov polyvinyl cawv los ntawm lub system, tsis muaj hydrophilic tiv thaiv colloid. , Cov zaj duab xis tsim los ntawm ib zaug dispersion ntawm redispersible latex hmoov, uas nws tus kheej yog insoluble nyob rau hauv dej, muaj peev xwm ua hauj lwm tsis tau tsuas yog nyob rau hauv qhuav tej yam kev mob, tab sis kuj nyob rau hauv lub sij hawm ntev dej immersion tej yam kev mob. Tau kawg, nyob rau hauv cov txheej txheem uas tsis yog-alkaline, xws li gypsum los yog muab tub lim-tsuas yog, vim hais tias polyvinyl cawv tseem muaj qee qhov hauv cov yeeb yaj kiab polymer kawg, uas cuam tshuam rau cov dej tsis kam ntawm cov yeeb yaj kiab, thaum cov tshuab no tsis siv rau cov dej mus ntev. immersion , thiab cov polymer tseem muaj nws cov khoom siv tshwj xeeb, thiab cov hmoov polymer redispersible tseem tuaj yeem siv rau hauv cov tshuab no.

Nrog rau qhov kawg tsim ntawm lub polymer zaj duab xis, ib tug system tsim ntawm inorganic thiab organic binder lug yog tsim nyob rau hauv lub kho mortar, uas yog, ib tug nkig thiab tawv pob txha pob txha tsim los ntawm hydraulic cov ntaub ntawv, thiab redispersible latex hmoov ua ib zaj duab xis ntawm qhov sib txawv thiab cov khoom nto. hloov tau yooj yim network. Lub zog tensile thiab cohesion ntawm polymer resin zaj duab xis tsim los ntawm latex hmoov yog txhim kho. Vim lub elasticity ntawm cov polymer, lub peev xwm deformation yog ntau dua li cov cement pob zeb nruj qauv, qhov deformation kev ua tau zoo ntawm cov mortar yog txhim kho, thiab cov nyhuv ntawm dispersing kev nyuaj siab yog heev txhim kho, yog li txhim kho qhov tawg tsis kam ntawm mortar. .

Nrog rau qhov nce ntawm cov ntsiab lus ntawm redispersible latex hmoov, tag nrho cov txheej txheem tsim los ntawm yas. Nyob rau hauv cov ntaub ntawv ntawm high latex hmoov cov ntsiab lus, lub polymer theem nyob rau hauv lub kho mortar maj mam tshaj lub inorganic hydration khoom theem, thiab lub mortar yuav hloov mus rau qhov zoo thiab ua ib tug elastomer, thaum lub hydration khoom ntawm cement yuav ua ib tug "filler". ". Lub zog tensile, elasticity, saj zawg zog thiab sealability ntawm mortar hloov los ntawm redispersible latex hmoov yog tag nrho cov txhim kho. Kev sib xyaw ntawm cov hmoov latex redispersible tso cai rau cov yeeb yaj kiab polymer (latex film) tsim thiab tsim ib feem ntawm cov phab ntsa pore, yog li sealing cov qauv ntxeem tau ntawm cov tshuaj khib. Lub latex membrane muaj ib tug self-stretching mechanism uas exerts nro qhov twg nws yog anched rau lub mortar. Los ntawm cov zog sab hauv, cov tshuaj khib nyiab yog khaws cia tag nrho, yog li ua kom lub zog cohesive ntawm lub mortar. Lub xub ntiag ntawm cov khoom siv tau yooj yim thiab cov khoom siv elastic zoo txhim kho qhov yooj thiab elasticity ntawm cov tshuaj khib nyiab.

Cov txheej txheem rau kev nce hauv kev ntxhov siab thiab tsis ua haujlwm lub zog yog raws li hauv qab no: thaum siv lub zog, microcracks ncua sij hawm kom txog thaum muaj kev ntxhov siab ntau dua vim kev txhim kho yooj thiab elasticity. Tsis tas li ntawd, cov interwoven polymer domains tseem cuam tshuam cov coalescence ntawm microcracks rau hauv cov kab nrib pleb. Yog li ntawd, cov respersible polymer hmoov txhim kho qhov tsis ua hauj lwm kev nyuaj siab thiab tsis ua hauj lwm strain ntawm cov khoom.

Polymer zaj duab xis nyob rau hauv polymer hloov mortar muaj ib tug tseem ceeb heev nyhuv ntawm hardening mortar. Lub redispersible latex hmoov faib rau ntawm lub interface plays lwm lub luag hauj lwm tseem ceeb tom qab dispersed thiab zaj duab xis-tsim, uas yog ua kom cov adhesion rau cov ntaub ntawv tiv tauj. Nyob rau hauv lub microstructure ntawm cov hmoov polymer hloov cov pobzeb sib txuas mortar thiab cov pobzeb interface, cov yeeb yaj kiab tsim los ntawm cov ntaub ntawv polymer ua tus choj ntawm cov vuas vuas nrog cov dej tsis tshua muaj dej thiab cov cement mortar matrix. Qhov chaw sib cuag ntawm ob cov ntaub ntawv sib txawv yog qhov tshwj xeeb tshaj yog muaj kev pheej hmoo siab rau cov kab nrib pleb shrinkage los tsim thiab ua rau poob ntawm cohesion. Yog li ntawd, lub peev xwm ntawm cov yeeb yaj kiab latex los kho cov kab nrib pleb yog qhov tseem ceeb heev rau cov nplais nplaum.

Nyob rau tib lub sij hawm, cov redispersible latex hmoov uas muaj ethylene muaj zoo heev adhesion rau cov organic substrates, tshwj xeeb tshaj yog cov ntaub ntawv zoo sib xws, xws li polyvinyl chloride thiab polystyrene. Ib qho piv txwv zoo yog thaum nws los rau lub qhov ncauj qhov ntswg.