Unique Additives for Polymer Modification

Dispersants

Poorly dispersed filler gives rise to several problems. Agglomerates act as stress concentration sites which weaken the polymer. This is exacerbated when fine fillers or nano-fillers are used. Dramatic reductions in impact resistance and elongation to break are observed. Flow and throughput are reduced, gloss is decreased and strength may be sacrificed as well.

A well-designed dispersant bonds strongly to the filler or pigment particles and forms a barrier preventing adjacent particles from approaching closely and sticking together. The criteria for effective stabilizer are:
  • Must bond well to the filler and not be displaced at high temperatures or under high shear force
  • Must be of sufficiently high molecular weight to form a thick enough barrier to prevent close particle approach
  • Should be compatible with, i.e. soluble in, the polymer phase so that it expands to form a thick layer around each particle
Cray Valley’s experts have the technology available to tune each of these three factors in order to deliver optimized performance.

Figure 1
Dispersants lower viscosity thereby improving processability and throughput
dispersants-figure-1


Figure 1 demonstrates the efficacy of Ricon® 131MA5 to improve the dispersion of highly filled ATH/EVA systems as manifested by improved ductility and tensile strength. At 60% by weight ATH, the systems inherent properties were deteriorated by the inclusion of filler agglomerates. Pre-treating the ATH with Ricon®131MA5 lessened the propensity for agglomerates, but also provided added structural integrity by entangling with the EVA matrix. Using treated ATH in a highly filled system can either improve the mechanical properties, or facilitate greater loadings of the flame retardant mineral.


Author
Dr. Chris DeArmitt
President of Phantom Plastics
www.PhantomPlastics.com
Cray Valley Hydrocarbon Specialty Chemicals  |  468 Thomas Jones Way, Suite 100  |  Exton PA 19341  |  USA  |  www.CrayValley.com