Masters Theses

Date of Award

12-1995

Degree Type

Thesis

Degree Name

Master of Science

Major

Environmental Engineering

Major Professor

Wayne Davis

Committee Members

Terry Miller, Maureen Dever

Abstract

Many commercially available indoor air filters are currently being marketed with topically applied tackifier filter adhesives. The concept is as old as the mucous coated cilia in the human respiratory tract. The idea is that a fibrous filter's capture efficiency may be improved by applying a sticky substance to the individual dry fibers. However, little information is available in the literature concerning the application of tackifiers and their effectiveness on decreasing particle penetration through filters. Therefore, it is of scientific value to investigate the efficacy of such tackifiers over a variety of operating air velocities, especially in light of the increasing concern for indoor air quality. This thesis presents the results of an investigation in which polypropylene melt-blown media were manufactured at a variety of operating conditions, to produce media which might be suitable for use in indoor air quality filters. The objectives of the research were to determine the efficiencies of the media, both as manufactured, and after application of a commercially available tackifier, at velocities ranging from 3 to 375 cm/s and to compare the measured results to filtration theory. The filter media were prepared at the Textiles and Nonwovens Development Center (TANDEC) and tested for filtration efficiency in the Air Quality Laboratory housed in the Department of Civil and Environmental Engineering at the University of Tennessee, Knoxville. Efficiencies were determined using both cold, polydispersed dioctylpthalate (OOP), as well as monodispersed latex particles (0.6 to 3.0 μm) using an ASTM 1215 test method. At the higher velocities, typical of those used in indoor air filters, the experimental efficiencies of the untreated media, using dry particles were significantly less than both the DOP and theoretical efficiencies. This is believed to be due to the kinetic energy of the particles which resulted in particle bounce. Empirical corrections were developed as a function of the kinetic energy to account for the decreased efficiency due to particle bounce and are presented. On the media which were coated with various loadings of tackifier, the results showed that the efficiencies at high velocities were improved. This is believed to be due to the reduction in particle bounce. The efficiencies at low velocities were unchanged even though larger effective fiber diameters resulted from application of the tackifier.

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