b'TECHNICAL & RESEARCH COMMITTEEContinued from page 7spacings. Testing of 1-foot by 1-foot adhered insulation companion specimens each, with single adhesive ribbon, revealed that polymer coated glass fiber faced specimens were 28 percent stronger than those with cellulosic felt facers, with average strengths of 673 psf and 485 psf, respectively. Testing of companion specimens fabricated with full coverage of adhesive over the entire 1 ft square surface had substantially higher strengths of 833 and 896 psf. These comparative test results confirm that when greater amounts of adhesive is present over a given area, larger portions of the facer/Relationship betweeninsulation interfacial zone are mobilized to measured failure loads and adhesive spacing for Polymertransfer loads between adhered boards.coated Glass (Type A-blue color) and Cellulosic FeltTensile bond strengths from 1-foot by 1-foot (Type B-yellow color) facers. companion tests, in general, were higher and not well correlated with the results for full-size, 4-foot square specimens with 12-inch adhesive spacings. Testing using larger (4-foot square) AD HEREspecimens is considered more representative of real-world installations compared to smaller (1 or 2 foot square) specimens size due to the larger included surface area.The tensile bond strength of the foam adhesive only, without the insulation as an assembly component, was tested using 2-inch diameter aluminum pucks attached to threaded rods and pulled apart in a SATEC test machine. Two types of tests were completed in this configuration; testing with a minimal gap between the aluminum pucks, and testing that included a 1/8 inch gap between pucks. The 1/8 inch spacing was achieved by placing the pucks in a custom fabricated jig that controlled the spacing. Polyisocyanurate insulation boards withTesting of the 2-inch diameter pucks with polymer coated glass fiber facers exhibited1/8-inch-thick foam adhesive indicated approximately 9 to 24 percent higher strengthssubstantial tensile strength gains between compared to organic-faced specimens at equaltest ages of two days to five days. Average adhesive spacings using the same adhesivemeasured strengths were 1,355 psf at two type. days and 3,361 psf at five days. As expected Failure of the specimens primarily occurredwith two-part polyurethane-based adhesive, as separations and/or delaminations of thechemical cure and associated strength insulation board facer(s) to the foam bodydevelopment continues well after initial setting, core along the lines of the adhesive ribbons,depending on environment conditions at time of with secondary failures within the body of thedispensing and thereafter.insulation noted in some instances, notably at the specimens with closer adhesive ribbonContinued on page 108 www.mrca.orgMidwest Roofer'