Holding power

Pressure sensitive adhesives normally are rated in terms of shear holding power, ie, time to fail in minutes under a constant load. 

Type Load bearing/holding power (kPa) Peel strength (N/m)... 

Fig. 1. PSA te.sling. (a) 180° Peel test (radius exaggerated), (b) Shear holding power test, front and side view.

The last decade has also seen the advent of commercial SIS polymers with 15-18% styrene content, but with higher diblock content (typically 30-55%). These are available from many of the major suppliers. The higher diblock content makes them ideal for label applications where low modulus PSAs provide easy die cuttabilty in processing, and rapid wet out and bonding to the substrate in the label application. The shear holding power characteristic would be reduced, but this would not be a critical factor for many label applications. 

Fig. 7. Room temperature adhesive holding power as a function of acrylic acid content.

Removal by Gravitational Force. This method simply involves a settling chamber in which the fact that the liquid-solid mixture-solid pore interface has little holding power. Thus, given sufficient time, the solids will settle into the base of the chamber due to gravitational forces. 

Ipatieff, however, remained loyal to Russia, even in its new form. He was also a pragmatist who understood that he must find a way to accommodate the new way of life in Russia, and gain the confidence of those currently holding power if he was to continue his chemical research. 

If a self-threading screw can be substituted, it will not only appreciably decrease mold maintenance and mold cost but most likely, with proper type selection, also give better holding power. A screw that has a thin thread with relatively deep flights can give high holding power. If the screw or plastic is preheated... 

The practice of molding inserts in place is usually employed to provide good holding power for plastic products, but there are drawbacks to this method. It normally takes a pin to support the insert, and since this pin is small in relation to the cored hole for the insert, it is easily bent or sheared under the influence of injection pressure. Should the insert fall out of position, there is danger of mold damage. Also, the hand placement of inserts contributes to cycle variation and with it potentially product quality degradation. Some of these problems can be overcome by higher mold expenditures,... 

Plastic molded clasps are commonly used to secure tops and lids on different type packages. Their holding power can be obtained from simple friction between the joint surfaces or from positive mechanical engagement. Plastic flexing capability is important because the products must flex in order to... 

Patel et al. [70] in a recent publication have explored the adhesive action of the mbber-siUca hybrid nanocomposites on different substrates. The rubber-silica hybrid nanocomposites are synthesized through in situ silica formation from TEOS in strong acidic pH within acryhc copolymer (EA-BA) and terpolymer (EA-BA-AA) matrices. The transparent nanocomposites have been apphed in between the aluminum (Al), wood (W), and biaxially oriented polypropylene (PP) sheets separately and have been tested for peel strength, lap shear strength, and static holding power of the adhesive joints. 

FIGURE 3.28 Static holding power test results of acrylic terpolymer-silica nanocomposite adhesives carried out on Al, W, and PP substrates. (From Patel, S., Bandyopadhyay, A., Ganguly, A., and Bhowmick, A.K., J. Adhes. Sci. TechnoL, 20, 371, 2006. Courtesy of VSP-Brill Academic Publishers.)... 

The holding power, adhesion, and probe tack of selected pressure-sensitive adhesive sheets were evaluated in accordance with JIS Z0237. Testing results are provided in Table 2. 

Entry Holding Power (s) Adhesion (N/25 mm) Probe Tact TGA Weight Loss at 300°C (%)... 

Entry Holding Power 10N (ambient temperature) (min) Shear Adhesive Failure Temperature Bond Strength to Polyethylene (N/cm)... 

As each kernel is heated, the water within each kernel is also heated to the point that it would turn into water vapor. The shell of the kernel, however, is airtight and this keeps the water as a superheated liquid. Eventually, the pressure exerted by the superheated water exceeds the holding power of the kernel and the water bursts out as a vapor, which causes the kernel to pop. These are physical changes. The starches within the kernel, however, ate also cooked by the high temperatures, and this is an example of a chemical change. 

The HDCC can be used to accelerate positive ions. For an ion-loaded HDCC of sufficiently high holding power, the rate of energy gain of the ion in an axial (z) electric field E is... 

Miktoarm stars of the type (PS-b-PI)n(PI)m prepared using DVB as linking agent were employed in adhesive compositions, showing a good balance of tack, peel strength and hold power near room temperature due to their reduced cohesive strength and viscosity without any reduction in the service temperature... 

The flexibility of PVC film makes it ideal for many industrial tape and label applications. Unfortunately, PVC film can be difficult for many adhesives to bond to and transfer failure is common. This can lead to long-term debonding as well as reduced holding power and chemical resistance. An in-depth look at PVC adhesion is provided and a solventbome adhesive with superior anchorage to PVC films as well as improved heat-resistance is described. 4 refs. 

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