Lead University: Lehigh University
PI: H. Daniel Ou-Yang
Co-PIs: Eric S. Daniels; Willie Lau (Oriental Yuhong America)
Polymer-modified, self-adhesive waterproofing membranes are one of the major products of Oriental Yuhong America, LLC., with 200,000,000 m2 manufactured each year in China, and has been increasing 40% each year. The membrane can be applied at low temperatures (ca. 5 oC) without needing any heating (representing significant energy savings) and adheres directly to wet cement. However, there have been important losses in the adhesive properties for this product, and the goal of this PITA grant would be to understand the underlying reason for the decrease in properties of the self-adhesive membranes, to utilize applicable test methods to understand the loss of adhesion and residual odor in the membrane and to develop solutions to solve these issues.
Polymer-modified, self-adhesive waterproofing membranes are one of the major products of Oriental Yuhong America, LLC., with 200,000,000 m2 manufactured each year. This product is prepared with asphalt, styrene-butadiene-styrene (SBS triblock copolymer), styrene-butadiene rubber copolymer (SBR), along with mineral spirits and tackifying resin alomg with several other components. The membrane can be applied at low temperatures (ca. 5 oC) without needing any heating and adheres diectly to wet cement. This will help to ensure better environmental stewardship, since this product is self-adhesive and no heat (energy) would be used to adhere the membrane to costruction materials that are used in high volume. The market share of all water-proof membranes has been increasing at a rate of 25 %/year for all industry working in this application area and 40%/year for Oriental Yuhong itself because of the ease of application of the membranes,
Self-adhesive membranes should be stored below 45℃ in a protected environment to avoid temperature-related damage as well as damage from exposure to rain (moisture) in order to meet the one year quality guarantee period offered by Oriental Yuhong. However, it is difficult for the self-adhesive membrane produced in China to meet industry standards during their quality guarantee period. In particular, the peel strength of the adhesive membrane decreased significantly in construction applications where storage conditions can't be met to satisfy the standards requirements. If the product is applied after the membranes have laid on the ground for two or three hours, the products will exhibit no adhesive properties. However, comparable products manufactured by our competitors don’t exhibit this phenomenon. In addition, if the membranes remain unprotected prior to installaton, there are odor issues, the cause of which are not known, that need to be resolved.
For the measurement of the adhesive properties of the membranes, we use a viscosity meter to measure the initial viscosity of the system, and use industry-standard peel strength test methods to analyze the initial moisture and peel strength under exposure to different environmental conditions, in order to judge the performance of the product. The results of these tests are shown in Figures 1 to 4 (included in a separate attachment). In addition, we plan to utilize other test methods and instrumentation to address surface aging concerns of the asphalt memberanes, and enhance our understanding of their microstructure. Analytic equipment in various labs at Lehigh will be used in this study, such as ESCA (for surface characterization of "fresh" and "aged" membranes), atomic force spectroscopy (AFM), optical microscopy, electron microscopy, dynamic mechanical analysis, rheology, and adhesive tack testing to measure debonding of the adhesive, among other tests.
The reasons that adhesion may be lost may include the following factors: due to cost pressures, the raw materials used in the manufacturing of the membranes may not be as good as foreign supplies; the itype of insulating membrane can affect the adhesion; and no additives such as antioxidants or UV absorber additives are included in the formulation which could influence adhesion.
In addition, the properties of thick latex films, which are an integral component of the waterproof technoligy used to mnufacture these emberanes, will be studied as well.