Rau PFA (Perfluoroalkoxy) Cov Cuab Yeej Siv los tuav 120℃hauv 50% Lithium Bromide Absorption Chiller Solution, Lithium Bromide Concentration (50% vs. 60}%) Yuav Ua Li Cas Hloov Qhov Equilibrium Moisture Absorption hauv Polymer thiab Risk ntawm Hydrolyticre Degradation?

PFA absorbs 0.2-0.4% noo noo nyob rau hauv 50% lithium bromide ntawm 120℃nrog me ntsis o. Hauv 60% LiBr (cov dej qis dua, cov ntsev ntau dua) qhov nqus dej noo yog 0.1-0.2 feem pua. Cov ntsiab lus dej qis txo qhov kev pheej hmoo ntawm hydrolytic degradation ntawm PFA kawg pawg. Txawm li cas los xij, PFA tsis cuam tshuam nrog LiBr nws tus kheej. Lub ntsiab deterioration txaus ntshai yog vim dej ntawm qhov kub thiab txias. Qhov kev ruaj ntseg hydrolytic ntawm PFA no zoo heev ntawm 120℃thiab tsis muaj qhov degradation tseem ceeb hauv qab 200 degree.

Degradation Mechanism ntawm PFA ntawm Hydrolysis

The PFA contains trace carboxyl end groups (-COOH) from the polymerization process. These can be hydrolysed at very high temperatures (>200 C) nyob rau hauv lub xub ntiag ntawm dej. Hydrolysis ntawm 120℃tshwm sim ntawm tus nqi tsawg. LiBr tsis catalyze hydrolysis. Qhov sib npaug ntawm qhov nqus dej yog tswj hwm los ntawm cov dej ua haujlwm ntawm cov tshuaj thiab txo qis nrog nce LiBr concentration.

Quantitative Moisture Uptake ua haujlwm ntawm LiBr Concentration

Cov hauv qab no yog tsim los rau PFA los ntawm kev tswj xyuas hauv LiBr kev daws teeb meem ntawm 120℃rau 1,000 teev. Kev nqus dej noo ntawm 40% LiBr yog 0.3-0.5% thiab tsis muaj deterioration tshwm sim. Kev nqus dej los ntawm LiBr yog 0.2-0.4% ntawm 50% thiab tsis muaj kev puas tsuaj tshwm sim. Absorption ntawm noo noo 0.1-0.2% Tsis muaj deterioration pom 60% LiBr. Moisture uptake yog 0.05-0.10% ntawm 70% LiBr, thiab tsis muaj deterioration. Ntawm tag nrho cov concentrations, 95-100% ntawm lub zog tensile yog khaws cia tom qab 1,000 teev.

Cov nyhuv ntawm LiBr concentration ntawm PFA

LiBr Concentration (%) Moisture Absorption (%) Degradation Pom Pom Zoo Tsis Muaj 50 0.2-0.4 Tsis Yog 60 0.1-0.2 Tsis Yog Yog 70 0.05-0.10 Tsis Yog
Tsim ib lub suab Specification

Ob leeg 50% thiab 60% LiBr tau txais rau PFA rhaub hauv LiBr nqus chiller kev pabcuam ntawm 120 degree. Hydrolytic tawg tsis tau pom ntawm qhov kub no. Tus kws ua haujlwm paub tseeb tias ntev -lub sijhawm ruaj khov hauv LiBr kev pabcuam nrog PFA.