Compounding World Expo 2021 - Highly Effective Additive Combination for Biodegradable Plastics

WACKER’s applications engineers who carried out the screening chose the biopolyesters polylactic acid and polybutylene succinate as representatives of biodegradable plastics. While biopolyesters are, in principle, considered alternatives to conventional thermoplastics, they are difficult to process and require suitable additives to achieve the property profile customary of thermoplastics. The additives examined were VINNEX® 2504, VINNEX® 2525, GENIOPLAST® Pellet S and GENIOPLAST® Pellet P plus.

The key finding of the screening is the observation that VINNEX® and GENIOPLAST® complement each other in their effects – in both filled and unfilled bioplastic systems. When used together, the processing and performance properties of bioplastics can be optimally adapted to the specific requirements. But there is also another advantage: both additives are more effective when they are used in combination than when they are used separately. Depending on the grade used, VINNEX® either has a particularly positive influence on the polymer melt or the mechanical properties. The additive ensures that bioplastics can be processed without difficulty. Mixed in with VINNEX®, GENIOPLAST® primarily affects the surface properties of the plastic item, especially in filled systems.

In the bioplastic samples that were tested, GENIOPLAST® acts as a booster and enhances the effects achieved with the VINNEX® additive which had been previously added. In several cases, the silicone additive also improves properties that VINNEX® has no influence on. It is the addition of GENIOPLAST®, for instance, that reduces surface friction, thus increasing the bioplastics’ scratch and abrasion resistance. This was verified by examination of the depth and roughness of scratches with a confocal microscope.

The unique additive combination furthermore improves the mechanical properties of the final good. Used together, VINNEX® and GENIOPLAST® boost the flexibility and impact strength of bioplastics and, in filled systems, increase elongation at break without impairing thermostability. Plastics modified in this way are thus suitable for applications previously reserved for conventional thermoplastics.

When added in the usual amounts and depending on the individual system, VINNEX® and GENIOPLAST® additives do not hamper the degradability of biopolyesters such as polybutylene succinate, polylactid acid or thermoplastic starch and combinations of these biodegradable polymers.