Kinetics of the aeration of ethylene-oxide sterilized plastics.
The aeration of ethylene-oxide (EO) sterilized medical plastic materials is dealth with mathematically, and subsequently the model found is used for calculation of the EO diffusion coefficient in various plastics with the composition and temperature as variables. Absorption and dissolution of EO in various plastic materials are measured at varying concentrations of EO, temperatures and compositions of plastics. The mathematical model is used to evaluate the EO desorption from medical devices under different physico-chemical conditions as well as in vivo. EO analysis methods are evaluated on the basis of the model and are compared with experimental results.
Infrared spectroscopic study of polymers exposed to ethylene oxide.
Fourier transform infrared spectroscopy has been used to study thin polymer films exposed to ethylene oxide (EO). The i.r. technique represents a new way of studying this subject. The polymers studied were poly(vinyl chloride), polyethylene and polystyrene. They were exposed to EO, either in a small commercial EO-sterilizer which uses pure EO and operates at subatmospheric pressure, at a temperature of 37 or 55 degrees C, or under experimental laboratory conditions. The absorption and diffusion of EO in the polymers was studied. Potential reaction products, such as ethylene glycol and ethylene chlorohydrin, were looked for but could not be traced. The detection limit of the method was 1 ppm (microgram/g) EO. Typical spectra of the polymer films, before and after exposure to EO, are shown. Diffusion coefficients for poly(vinyl chloride) and polyethylene have been calculated.
Trends in kiln drives
The heart of the cement plant is the rotary kiln, and continuous quality production of cement clinker depends on the continuous accurate performance of the rotary kiln drive.