Efficacy of natural products as antifungal agents in carpet and investigation of ethylcellulose polymer as an extender
Abstract
Health problems caused by indoor fungi have become an important issue in recent years and carpets are known to be suitable substrates for fungal growth. The purpose of this research was to identify some natural products of relatively low human toxicity that can act as substitutes for potentially hazardous antifungal agents currently applied to carpets, and to investigate the efficacy of ethylcellulose as an extender of these unstable products in carpets. Tea tree oil, garlic oil, benzoate, sorbate, propionate, thymol, star-anise, eugenol, and cinnamaldehyde were each introduced into Potato Dextrose Agar (PDA) plates inoculated with Aspergillus versicolor or Penicillium chrysogenum. The plates were then incubated at 25°C, and the zones of inhibition were measured. Of nine agents tested, thymol, benzoate, and sorbate were chosen for their higher inhibitory effects. Next, solutions of thymol, benzoate, and sorbate, individually and in various combinations were applied to carpet square samples, which were then inoculated with A. versicolor and P. chrysogenum and incubated at 25°C with 97% relative humidity (RH). Spore counting was conducted, and carpet treated with the mixture of thymol (3.3μg/mm 2), benzoate (16.5μg/mm2), and sorbate (16.5μg/mm 2) (TBS-carpet) showed inhibitory effects at the low concentrations tested. Ethylcellulose was then added to the TBS mixture as a coating polymer (TBSC-carpet). TBSC- and TBS-carpet were compared and results indicated that the addition of the cellulose maintained the antifungal properties of TBS even in carpet samples stored for up to 12 months. These comparison tests were repeated under extreme conditions of high humidity (99%RH for 168 hours) or immersion in water (for 24 hours followed by a 10 minute rinse). HPLC determination for the amounts of remaining thymol, benzoate, and sorbate in carpets indicated that all were greater in the TBSC-carpet than in the TBS-carpet. Spore counting also was performed. However, spore counting indicated TBS-carpet still had inhibitory effects that were only slightly less than TBSC-carpet.
Degree
Ph.D.
Advisors
Zimmerman, Purdue University.
Subject Area
Occupational safety|Textile research
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.