A quartz-crystal microbalance apparatus for water sorption by polymers

Abstract

A quartz-crystal microbalance (QCM) apparatus has been assembled for studying the water sorbed by polymeric materials from 0.1 to 100 μm thick. The apparatus consists of an UHV system with a turbomolecular pump, valves, low-pressure gauges, a capacitance manometer, a residual gas analyzer, and reservoirs for water vapor and other adsorbate gases. Up to five different polymer coated quartz crystals can be inserted into hangdown tubes using a 20-in.-long, water-cooled, sensor head with appropriate feedthroughs for the electrical connections and thermocouple leads. The QCM controller consists of a power supply, oscillators, frequency meter, and output for obtaining mass change data. The sensitivity of 14 ng/cm2 Hz corresponds to a mass change of about 0.1% for a 100-nm-thick polymer film. Sample temperatures are controlled to better than 0.1 °C by immersing the hangdown tubes in a liquid water bath. The controller is interfaced with computers for data acquisition, storage, manipulation, etc. to output data for sorption isotherms, the rate of sorption and desorption, and comparing the cyclic reproducibility of rate and capacity. Representative sorption data for three polymers are presented.

Polymers as advanced materials for desiccant applications, 1988

“…(1) Advanced Passive Solar Materials Research, (2) Collector Technology Research, (3) Cooling Systems Research, and (4) Systems Analysis and Applications Research.…”

“…each pressure increment or decrement, cyclic stability, and qualitative evaluations of permeation rates (3)(4)(5)~Measurements of the heat of adsorption, pore volume, morphology, etc., for more detailed materials characterization have not been made.…”

“…Designed, purchased, assembled, constructed, installed, and used a quartz crystal microbalance (QCM) for characterizing the sorption performance of organic (polymeric) and inorganic materials (3,4,5) and designed, assembled, and installed a Sartorius microbalance system for use on the project (5,6).…”

“…6a. Measured the sorption performance of more than 23 potential commercially available polymeric ADMs with the QCM (1)(2)(3)(4)(5) and used the criteria in point 2 to narrow the number to seven candidate ADMs (5). The measurements include sorption isotherms, rate of adsorption and desorption at A-3…”

Sorption Characteristics of Organic Powder Sorption Material in Fluidized Bed with a Cooling Pipe

“…One of the suitable materials for solving this problem is an organic sorbent like sorption polymers 7) . A bridged complex of sodium polyacrylate is one of the sorption polymers as an organic sorbent.…”