T-peel

Peel tests are accompHshed using many different geometries. In the simplest peel test, the T-peel test, the adherends are identical in size, shape, and thickness. Adherends are attached at thek ends to a tensile testing machine and then separated in a "T" fashion. The temperature of the test, as well as the rate of adherend separation, is specified. The force requked to open the adhesive bond is measured and the results are reported in terms of newtons per meter (pounds per inch, ppi). There are many other peel test configurations, each dependent upon the adhesive appHcation. Such tests are well described in the ASTM hterature. 

Fig. 25. Evolution of the tack of polychloroprene-aromatic hydrocarbon resin blends as a function of the resin content. Tack was obtained as the immediate T-peel strength of joints produced with 0.6 mm thick styrene-butadiene rubber strips placed in contact without application of pressure. Peeling rate = 10 cm/min.

The chemical nature of the tackifier also affects the compatibility of resin-elastomer blends. For polychloroprene (a polar elastomer) higher tack is obtained with a polar resin (PF blend in Fig. 27) than with a non-polar resin (PA blend in Fig. 27). Further, the adhesion of resin-elastomer blends also decreases by increasing the aromatic content of the resin [29]. Fig. 28 shows a decrease in T-peel strength of styrene-butadiene rubber/polychloroprene-hydrocarbon resin blends by increasing the MMAP cloud point. Because the higher the MMAP... 

Flexibilized epoxy resins are important structural adhesives [69]. Liquid functionally terminated nitrile rubbers are excellent flexibilizing agents for epoxy resins. This liquid nitrile rubber can be reacted into the epoxy matrix if it contains carboxylated terminated functionalities or by adding an amine terminated rubber. The main effects produced by addition of liquid nitrile rubber in epoxy formulations is the increase in T-peel strength and in low-temperature lap shear strength, without reducing the elevated temperature lap shear. 

St. Clair et. al. investigated a series of maleimide and nadimide terminated polyimides and developed LARC-13 [8,9]. Changing the terminal group from maleimide to nadimide, the value of the lap shear strength of a titanium lap shear joint increased from 7 to 19 MPa [9]. They also added an elastomeric component to the adhesive formulation. The introduction of 15 wt% of a rubbery component, ATBN (amine terminated butadiene nitrile polymer) and ADMS (aniline terminated polydimethyl siloxane) enhanced the adhesive properties as follows 19 MPa to 25 MPa (ATBN) titanium T-peel strength 0.2 kN/m to 1.4... 

Abrieb, m. rubbings, grindings, dust, fines, abrinden, v.t. peel, strip, scale, bark, decorticate. Abriss, m. outline, sketch, design. 

An immersion time less than 1 min, the neutralization with ammonium hydroxide (it extracts the hydrogen from the sulfonic acid and leaves stabilized S03 NH4 ion pair), and the high concentration of the sulfuric acid (95 wt%) are essential to produce adequate effectiveness of the treatment. H2SO4 treatment increases the T-peel strength of treated TR or SBR-polyurethane adhesive joints (Figure 27.2). 

FIGURE 27.2 T-peel sfrength values of sulfuric acid-treated styrene-butadiene rubber (SBR)/polyurethane adhesive joints as a function of the immersion time in sulfuric acid. A = adhesion failure R = cohesion failure in the rubber. (From Cepeda-Jimenez, C.M., Pastor-Bias, M.M., Ferrandiz-Gomez, T.P., and Martm-Martmez, J.M., J. Adhes., 73, 135, 2000.)... 

FIGURE 27.9 T-peel strength values of styrene-butadiene rubber (SBS) treated with chloramine T aqueous solutions with different pH/waterbome polyurethane adhesive/roughened leather joints, as a function of the pH value of the chloramine T aqueous solutions. A adhesion failure to the rubber, M cohesive failure in tbe rubber. (From Navarro-Banon, M.V., Pastor-Bias, M.M., and Martm-Martinez, J.M., Proceedings of the 27th Adhesion Society, Wilmington, NC.)... 

T-Peel strengths qfEPDM bonded with adhesive containing ZA or silane... 

T-peel strengths or EPDM bonded with zircoaluminate or silane-containing adhesive"... 

Thus, in alkyd, polyester, and epoxy coatings applied to CRS, phosphatized steel, and aluminum, the use of ZAs APG (aminofunctional) and CPG (carboxy-functional) has allowed for the virtual elimination of blister formation and corrosion after 300 h of salt fog exposure. The use of multifunctional ZAs in a Kraton base adhesive has allowed for a 52% increase in T-peel strength on EPDM rubber when compared with the same adhesive containing aminofunctional silane. Incorporation of mercaptofunctional ZA into crosslinkable elastomers has... 

The Standard Test Method for Strength Properties of Tissue Adhesive in T-Peel by Tension Loading, ASTM F 2256-03, was not employed for testing barrier dressings only porcine tissue was available in 15 cm strips that possessed thick hair on the epidermis side and a thick fat layer on the underside that was not conducive to testing. Removal of the fat layer to isolate the dermis will be necessary before testing by the T-Peel method. 

ASTM F 2256 - 03, Standard Test Method for Strength Properties of Tissue Adhesives in T-Peel by Tension Loading, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959. 

Hybrid adhesive Tensile shear strength, psi T-peel strength, lb/in... 

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