Cov ntaub ntawv raw ntawm polyvinyl cawv
Polyvinyl cawv (PVA) tsis tsim ncaj qha los ntawm polymerization ntawm vinyl cawv; es, nws yog tsim los ntawm ob - cov txheej txheem. Nws cov khoom siv tseem ceeb yog vinyl acetate, cov kua tsis muaj xim ua ke los ntawm cov tshuaj tiv thaiv ntawm ethylene thiab acetic acid. Raws li kev cuam tshuam ntawm cov catalyst, vinyl acetate thawj polymerizes rau hauv polyvinyl acetate-ib qho tseem ceeb hauv kev tsim cov polyvinyl cawv. Interestingly, polyvinyl cawv tsis muaj nyob lawm; nws yog tag nrho cov khoom ntawm cov khoom siv hluavtaws.
Cov txheej txheem Miraculous Hydrolysis
Kev hloov pauv polyvinyl acetate rau hauv polyvinyl cawv cuam tshuam nrog kev hloov tshuaj lom neeg zoo ib yam li khawv koob: cov tshuaj tiv thaiv hydrolysis. Nyob rau hauv alkaline los yog acidic tej yam kev mob, cov acetate pawg nyob rau hauv lub polyvinyl acetate saw yog hloov los ntawm hydroxyl pawg; qhov kev hloov pauv no txiav txim siab cov khoom ntawm cov khoom kawg. Cov qib sib txawv ntawm hydrolysis yields ntau qib ntawm polyvinyl cawv- qee qhov khaws cia ib feem ntawm lawv cov acetate pawg, thaum lwm tus yuav luag ua tiav hydrolysis- yog li tso cai rau txhua tus tswv cuab ntawm tsev neeg polyvinyl cawv nrog nws tus kheej lub zog tshwj xeeb.
Los ntawm chav kuaj mus rau Lub Neej Txhua Hnub
Tom qab ua kom huv thiab ziab, polyvinyl cawv tuaj txog peb nyob rau hauv daim ntawv ntawm cov hmoov dawb los yog granules. Nws cov khoom tshwj xeeb ua rau nws ua lub luag haujlwm tseem ceeb hauv ntau yam kev siv, suav nrog cov khoom siv textile sizing, adhesives, ntim zaj duab xis, thiab txawm tias kev kho mob. Ntawm qhov kev ceeb toom tshwj xeeb yog cov dej solubility zoo heev uas nthuav tawm los ntawm cov dej cawv hydrolyzed polyvinyl tag nrho; Cov yam ntxwv no tso cai rau nws ua lub luag haujlwm tseem ceeb hauv eco-cov ntaub ntawv ntim cov phooj ywg, muab cov kev daws teeb meem tshiab los txo cov pa phem.