Additives

Ingredients to tailor polymer properties

Polymer properties can be manipulated by the use of additives (e.g., plasticizers). In this way, tailor-made plastics for many technical products can successfully be manufactured. When the used additives fail, this will result in the loss of essential properties (e.g. UV stability) and, in the long run, often failure of the plastics. Of course, polymer processors have a keen interest in understanding and avoiding possible future damage. Analytical methods such as ToF-SIMS, FT-IR or XPS (ESCA)   can provide helpful information, as the following example shows:

Plastics

Blooming of polymer additives

Root cause investigation with ToF-SIMS

Discoloration on surfaces is often due to de-mixing of material components with subsequent surface segregation. “Blooming” is the segregation of additives from polymers. It is usually triggered by incompatibility of the additives used in the plastic with the polymer or other additives. Figure 1 shows a micrograph of a crystalline bloom on polypropylene (PP),

which was characterized by ToF-SIMS. To clearly identify the structures that appear as crystals, the chemical composition of the surface was imaged. Figure 2 shows that lithium stearate (blue) is detected on the base polymer (PP (red)) and the stabilizer Ultranox 626 (green) in the region of the crystalline structure. The above figure in the header also shows interferometry data of such a bloom. Clearly, the crystalline needle structure of the additive material is recognizable. On the basis of the associated interferometry data (see also header image) a height of the bloom of up to 8 μm can be determined.

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