STP1190: Chemical Stability of Polyester Fibers and Geotextiles Without and Under Stress

    Netravali, AN
    Assistant Professor and research assistant, Cornell University, Ithaca, NY

    Krstic, R
    Assistant Professor and research assistant, Cornell University, Ithaca, NY

    Crouse, JL
    Senior Development Chemist, Firestone Fibers and Textile Company, Hopewell, VA

    Richmond, LE
    Manager, Product Development, Conwed Plastics, Minneapolis, MN

    Pages: 11    Published: Jan 1993


    Abstract

    High tenacity industrial grade polyester fibers were aged up to three months, in various chemicals at different stress levels. The accelerated aging was done at temperatures up to 70°C, which is thought to be the maximum underground temperature for applications such as surface veneers for waste landfills. The chemicals used in the study include trichloroethylene, deionized water, sea water, and 2% solutions of sulfuric acid and sodium hydroxide. The stress values used were 0 MPa, 100 MPa, and 260 MPa. The fibers were tested for their mechanical and thermal properties as a function of aging.

    The results suggest that there are no changes in the fiber strength and glass transition temperature (Tg) after aging in trichloroethylene, sea water, and deionized water under any stress level and test temperatures. However, there is a small increase in the melting temperature indicating the possibility of crystal growth, especially at 70°C, due to the annealing effect.

    Significant degradation in fiber strength is seen after a week of aging in sulfuric acid solution (-1.1 pH) at room temperature and 40°C. Under the severe acidic conditions, at 70°C and higher stress levels, the fibers completely disintegrated after one week.

    In the strong alkaline condition (-13.7 pH), strength decreases of 33% and more than 50% are seen under 0 and 100 MPa stress levels within the first week of aging in NaOH, at RT. All fibers, regardless of stress, did not survive one month in the highly alkaline environment.

    These results suggest that 1) severe hydrolysis occurs in strong alkaline and acidic media 2) no hydrolysis occurs under more normal soil conditions (∼pH 7-8) at temperatures up to 70%C and 3) higher stress levels do not significantly affect the degradation process.

    Keywords:

    polyester, chemical aging, hydrolysis, thermal properties, mechanical properties


    Paper ID: STP24323S

    Committee/Subcommittee: D35.02

    DOI: 10.1520/STP24323S


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