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The purpose of this work was to monitor the uptake and identify the location of a poly-aminoamide (PAE) wet-strength additive on a series of laboratory-prepared tissue papers using a combination of surface analytical methods. XPS and ToFSIMS were used to characterise the degree of uptake of the PAE on the tissue surface. A quantitative comparison of three PAE loadings, monitored by ToFSIMS, is shown below compared with a treated commercial paper.
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The presence of the PAE on the paper surface is established by the detection of N in the XPS spectrum and CN- using ToFSIMS. However the exact location of the wet-strength additive, with respect to the paper structure, can only be obtained by Imaging SIMS analysis. Prior to this analysis the theoretical studies had predicted that wet-strength additives act by accumulating at cross-over points in the tissue structure - thereby aiding adhesion between paper fibres. The SIMS image overlay below shows the CN- (from PAE) in red and the paper fibre structure, monitored as C2H-, in cyan.
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It is evident that the PAE accumulates in regions between fibres (cross-over points) providing clear confirmation of the theory of wet-strength additive location.
Further analysis by Retrospective SIMS Profiling of discrete areas of the fibre structure, marked as F1, F2, Cr1 and Cr2 below, confirmed that there is a three-fold increase in wet-strength additive concentration in cross-over point areas. |
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Summary
The combined use of SIMS mass spectral, imaging and depth profiling techniques, often in conjunction with XPS analyses, provides clear resolution of production problems, competitor analysis and cost-effective support to R+D.
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