Cov khoom ntawm polyvinyl cawv (PVA) yog txiav txim los ntawm nws cov℃ntawm polymerization (DP- feem ntau sib haum rau molecular hnyav) thiab nws qib ntawm hydrolysis (DH- qhia raws li molar feem pua). Cov qib kev lag luam PVA feem ntau raug xaiv los ntawm kev sib xyaw ntawm ob qhov kev txwv no; Piv txwv li, "PVA 17-88" qhia qhov nruab nrab ntawm polymerization ntawm kwv yees li 1,700 thiab qib ntawm hydrolysis ntawm 88%.
1. Cov qauv thiab kev faib tawm
Qib ntawm Polymerization (DP): Muab faib ua ntau qib: qis (20,000–35,000), nruab nrab (120,000–150,000), siab (170,000–220,000), thiab ultra{12}} siab (250,000–300,000). Raws li qib ntawm polymerization nce, cov tshuaj viscosity, zaj duab xis- ua kom muaj zog, thiab hnyav kuj txhim kho, thaum solubility txo.
Qib ntawm Hydrolysis (DH): Cov lus qhia tshwj xeeb suav nrog peb theem tseem ceeb: 78%, 88%, thiab 98%. Qib nrog qib hydrolysis ntawm 78% thiab 89% yog hu ua "ib nrab hydrolyzed" thiab soluble hauv dej txias; Cov qib siab tshaj 98% yog suav tias yog "tag nrho hydrolyzed" thiab yuav tsum tau cua sov kom sov siab tshaj 85℃kom yaj. Qib ntawm hydrolysis yog qhov tseem ceeb cuam tshuam rau kev ua haujlwm ntawm PVA; Piv txwv li, high-hydrolysis PVA yog nquag siv hauv kev tsim cov yeeb yaj kiab thiab fibers.
2. Lub cev muaj zog
Thermal Properties: Lub melting point yog kwv yees li 230 degree. Tshaj li 100 degree, PVA maj mam hloov xim thiab embrittlement; ntawm 160℃thiab 170 degree, lub cev qhuav dej thiab etherification tshwm sim, ua rau poob dej solubility; decomposition pib ntawm 200 degree; thiab siab dua 250 degree, cov polymers uas muaj ob daim ntawv cog lus yog tsim. Cov kev tshawb fawb tsis ntev los no kuj tau tshawb xyuas qhov cuam tshuam ntawm microwave irradiation thiab kub ntawm cov yam ntxwv ntawm PVA.
Optical thiab Hluav Taws Xob Properties: Qhov ntsuas qhov taw qhia ntawm qhov ntsuas ntawm 1.49 txog 1.52. PVA nthuav tawm cov hluav taws xob tiv thaiv siab, feem ntau ntog hauv thaj tsam ntawm (3.1–3.8) × 10⁷ Ω·cm. Los ntawm kev koom ua ke nanocomposites los ntawm doping, optical bandgap nrog rau cov kab thiab nonlinear kho qhov muag ntawm PVA tuaj yeem hloov kho, ua rau nws haum rau ntau yam kev siv optoelectronic.
Cov yam ntxwv daws teeb meem: Cov khoom ntawm aqueous PVA cov kev daws teeb meem raug cuam tshuam los ntawm cov qib tshwj xeeb siv. Cov kev daws teeb meem ntawm qib siab -hydrolysis qib (piv txwv li, PVA 17-99) yog nquag gelation ntawm qhov kub thiab txias. Tsis tas li ntawd, PVA cov kev daws teeb meem yog qhov nkag siab zoo rau qhov muaj borax thiab boric acid; Txawm tias muaj pes tsawg tus ntawm cov tshuaj no tuaj yeem ua rau irreversible gelation.
3. Cov Khoom Siv Tshuaj
Cov saw hlau molecular ntawm polyvinyl cawv yog nplua nuj nyob rau hauv hydroxyl pawg, nthuav tawm cov kev cuam tshuam ntawm polyols; Yog li, lawv tuaj yeem raug kev cuam tshuam xws li esterification, etherification, thiab acetalization (xws li, kev npaj ntawm polyvinyl butyral [PVB] thiab polyvinyl formal [PVFM]). Piv txwv li, kev npaj ntawm carboxyl- hloov PVA cuam tshuam nrog cov copolymerization ntawm vinyl acetate nrog acrylic acid, ua raws li alcoholysis, kom tawm los ntawm PVA cov khoom uas muaj qib siab ntawm alcoholysis, tseem tsis tshua muaj crystallinity thiab dej solubility siab. PVA muaj lub teeb pom kev zoo thiab tsis yooj yim rau kev laus. Nws yog combustible thiab emits ib tug txawv tsw thaum hlawv.