Foamable systems

The systems are listed In the decreasing ease of formulating foamable systems which will yield foams of the proper stability for foam processing of textiles. While completely non-aqueous foamable systems have been used to apply finishes under laboratory conditions, none have yet been developed that can be handled In a finishing plant environment. Since "100% solids" systems represent the ultimate In energy savings, efforts In this area are continuing. 

Thus foamable systems for printing normally contain, In addition to the foaming agent, an additive to stabilize the foam. 

In order to overcome these drawbacks, novel concepts for enhancing the foamability of such immiscible blends need to be introduced. Using the PPE/SAN 60/40 blend as a reference system, the following concepts appear as most promising (Fig. 14) ... 

As discussed in the previous sections, the blend morphology as well as the processing window of the individual blend components can be identified as key factors for the foamability of multiphase blend systems [47, 84], As a first step, compatibilization via SBM triblock terpolymers was exploited for controlling the blend morphology on a nanoscale, and for reducing the difference in processing window between PPE and SAN. However, in order to exploit the benefits of all blend phases, the properties of each blend phase and the overall microstructure of the blend need to be controlled. 

In the previous sections the foamability of the PPE/SAN blend systems containing elevated contents of the higher viscosity PPE phase were improved by (1) selective blending with PS as well as (2) compatibilization with SBM. 

The excellent foamability of the quaternary blend also relates to the microstructure. All selected quaternary blend systems revealed a PPE/PS matrix phase able to stabilize the formed cells, as a result of the higher glass transition temperature and viscosity compared to the dispersed SAN. 

Foam Volume. The determination of foamability was carried out using the procedure of Hermansson et al. (9.) with modifications. A 1 g sample of the freeze-dried protein fraction was homogenized with 90 ml of citrate-phosphate buffer in a Sorvall Omnimixer at 3000 rpm. The resultant foam and liquid were transferred to a 250 ml graduated cylinder and the mixer cup washed with 10 ml of buffer. The cup was drained for 2 min and the cylinder allowed to stand for 30 min at which time the foam volume was measured. The influence of pH and ionic strength on foam volume was established using the buffer systems previously described. 

Chen WeiZhang, et al. Study on Super Foamability of Solution System of Composite Surfactants[J]. Fine and Specialty Chemicals, 2007, 15 (3/4) 21-27. 

Nemeth et al. [132] also report the effect of polyethoxy-polypropoxy block copolymers (EO .PO .EO , where m = 33 and 2.5 foam behavior of a protein—bovine serum albumin (BSA). These block copolymers reduced both the foamability and stability of the foam of BSA solutions at temperatures below the relevant cloud point where the solution was homogeneous. Filtration of the mixed solutions at the tanperature of these foam experiments produced essentially no enhanconent of foamability or foam stability. However, the filtration was done before foam generation so that the possibility of the decomposition of any putative metastable state during foam generation was not examined. Unlike with the PDMS-EOPO copolymer/Triton X-100 system, the possibility that antifoam effects at temperatnres above a measured cloud point for this EO-PO-EO -i- BSA system, which could be eliminated by removal of the relevant conjugate phase, was not explored. 

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