PSA Performance

The presence of these low molecular weight tackifiers and plasticizers may also have other negative effects on the PSA performance. For example, the reduced entanglement of the polymer typically reduces the cohesive strength of the PSA, although crosslinking may be used to compensate for this loss in property. Plasticizers and tackifiers may also be susceptible to migration and/or oxidation, both... 

The demands on the PSA performance for these types of applications can be very high, especially in the areas of creep, shear resistance and long-term durability. For these reasons, crosslinked acrylics and stabilized block copolymer adhesives have become the main PSA material choices. 

As discussed earlier in this chapter, PSA performance is very much dependent on temperature, speed of application or removal, and surface contamination. 

To design and develop PSA process, detailed analysis of the fixed-bed dynamics must be preceded, because the key step to developing an optimum PSA process lies in the design and operation of the adsorption step. Also, on the condition that the theoretical models of the adsorption breakthrough can predict its experimental results well, it can be used to investigate the breakthrough dynamics in a bed and predict PSA performance without any specific experiment. 

Figure 10.14. Effect of volume fraction of microporosity of activated carbon on PSA performance.

Varions terms characterize PSA performance. Chief among them are prodnct parity, product recovery, adsorbent productivity, and energy requirements. The parity and recovery normally refer to the light prodnct or sometimes the heavy product. Purity is expressed in terms of the number of nines, e.g., five nines would be 99.999% contaminant free. Freqnently, only specific contaminants are considered in the remainder, leading to delnsions of absolnte parity. Recovery is expressed... 

In view of the many properties and parameters that affect PSA performance, it is possible to characterize the adsorbates and adsorbent for a prospective system in either very simple or very complex terms. The simplest version requires only information regarding the adsorption isotherms and adsorbent void fraction. In the case of linear isotherms, the properties can be combined as in Equation (14.6),... 

The objective of this study was to prepare a UV-crosshnkable acrylic PSA that is able to cure at low UV doses and to elucidate the effect of crosslinking on PSA performances at varying UV doses. The PSAs used in this study were synthesized by solution polymerization method using 2-ethylhexyl acrylate (2-... 

EHA), vinyl acetate (VAc) and acrylic acid (AA), and with varying contents of 2-hydroxyefhyl methacrylate (2-HEMA) and an unsaturated benzophenone derivative (P-36). The UV-crosslinking behavior of the PSAs was monitored by FTIR-ATR and PSA performance was evaluated by probe tack, peel strength, and shear adhesion failure temperature (SAFT) after exposure to various UV doses. 

In the frame of the Fire PSA performed for the German BWR the above mentioned uncertainties have up to now only partly been quantitatively considered in the results (cf. von Linden et al. 2005, Turschmann et al. 20005 and Rowekamp 2008). At the time being, a complete uncertainty and sensitivity analysis is to be performed as a pilot study in the frame of the enlarged... 

Glotfelter, C.A., Valuable properties Tg-Region Breadth is critical to UV-curable PSA performance. Adhesives Age, 2000, 2, 24-30. 

The S parameter has been defined for Langmuir systems, that is, the isotherms for both components are Langmuirian. For non-Langmuirian systems, a 2 probably should be replaced by jades, as given by the AFM, because this ratio was empirically determined. It seems that the a during the adsorption step is more important than during the desorption step in determining the PSA performance. 

Table 10.1. Sorbent selection parameter (S a Aq /Aqo,) for VSA/PSA performance for air separation, comparing LiX and CaX (Si/AI = 1.25 for both)...

The feed pressure was taken arbitrarily at 7 atm in me above simulation. The available pressures in me refinery gas streams and me purge streams from polyolefin reactors are higher man 7 atm. At higher feed pressures, me PSA performance wim AgN03/Si02 will continue to improve because more olefin will be adsorbed, whereas mat wim AIPO4-I4 will not improve because its capacity is already saturated. 

The PSA performance is determined in terms of the specific product and yield at a certain nitrogen product purity. The specific product is defined as the product flow rate per unit adsorbent volume, while the yield is the ratio between the net flow rate of nitrogen produced and the flowrate of nitrogen fed to the system. The specific feed, in turn, is defined as the feed flow rate per unit of adsorbent volume. 

Nitrogen PSA performance has improved considerably in the last 20 years. Since 1980, the power consumption has dropped to a half and the productivity doubled, resulting in both smaller air compressors, and a reduction in the size of the units. These advances, which have allowed to commercialize pure pressure swing adsorption systems supplying nitrogen with purities higher than 99.999%, arise from two different areas molecular sieve developments and process improvements [24]. 

FIGURE 9. PSA performance of Piccolyte A85/natural rubber aqueous vs. solvent systems. 

The PSA performances of NR, SBR, and Kraton blends with tackifying resins shown in this paper were obtained using the following procedures. 

RELATION BETWEEN THE DYNAMIC MECHANICAL PROPERTIES AND PSA PERFORMANCE... 

FIGURE 34. PSA performance of Piccotac 95BHT/natural rubber solvent-based adhesives. 

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