Txoj kev tshem tawm cov npuas npuas los ntawm Polyurethane Prepolymer

1. Siv zeolite molecular sieve rau defoam

Qhov tseem ceeb txoj kab uas hla ntawm cov dej molecules yog 0, 27-0, 32nm, molecular ntev yog 0, 32nm, qhov tseem ceeb diameters ntawm CO₂molecules yog 0,28nm, thiab molecular ntev yog 0,41nm. Hauv kev sib xyaw ntawm prepolymer adhesives (siv PTMG thiab TDI). Ntawm 10 ° C, txheeb ze av noo 40%, thiab molecular sieve cov ntsiab lus mus txog 3%, tsis muaj npuas tshwm nyob rau hauv cov hluavtaws prepolymer nplaum.

Nyob rau hauv defoaming ntawm prepolymer adhesives, 13X activated zeolite molecular sieve yog feem ntau siv, thiab nws ua kom kub yog 200-350 ° C. 13X molecular sieve tuaj yeem tshem tawm cov kab ya raws hauv cov nplaum polyurethane, thiab tuaj yeem nqus cov pa roj carbon dioxide uas tsim los ntawm cov tshuaj tiv thaiv ntawm polyisocyanate thiab dej.

2. Txheej txheem defoaming

Thaum ua ke cov nplaum nplaum prepolymer, feem ntau siv ethyl acetate los yog acetone ua cov kuab tshuaj thaum siv polyester polyol, thiab siv toluene ua cov kuab tshuaj thaum siv polytetracyanofuran. Tom qab ntxiv cov kuab tshuaj, cia nws sawv ntsug rau ib lub sijhawm ua ntej defoaming. Thaum siv cov kuab tshuaj defoaming, qhov nro ntawm cov kuab tshuaj muaj qhov cuam tshuam zoo rau kev tshem tawm npuas. Qhov ntom ntom ntom ntom me me (hauv qab 35 × 10-3N / m), cov npuas tau yooj yim tshem tawm, thiab qhov saum npoo tsis yooj yim ua npuas dej. Thaum xaiv cov kuab tshuaj, xyuam xim rau qhov cuam tshuam ntawm cov kuab tshuaj ntawm cov tshuaj tiv thaiv. Qhov ntau dua qhov polarity ntawm cov kuab tshuaj, qhov yooj yim dua yog los tsim ib lub koom haum hydrogen bond nrog -OH pab pawg, yog li txo cov reactivity ntawm -NCO pawg thiab -OH pawg.