High recycle content requires good stabilization for high speed processing
Stabilization protects sheet sag properties and reduces sheet thinning
Uniform polymer flow is required for surge prevention
Well stabilized polymer reduces gels, bubble breaks, and gauge variation
Additives for Recycled Polymers
Polymers are designed by their manufacturers with specific molecular structures to have physical properties for specific applications. Every time a polymer is heated, sheared or stressed its original molecular structure can change. Chemical stabilizers can stop or minimize these changes. Melt index is a gross measurement of a polymers molecular structure. Any change in this measurement indicates a significant change to the polymers structure and properties. Stabilizers and other additives preserve a polymers structure by inhibiting the oxidative process or acting as sacrificial oxidation targets.
Oxidation Induction Time (OIT) is a good measurement of how much active stabilizer remains in a polymer. Therefore OIT is good indicator of the polymers resistance to melt shift as well as its long term in service stability. OIT is a good indicator of the polymers resistance to future oxidative degradation and therefore the stability of its rheological properties. OIT is also a key indicator of polymer parts long term stability. Residual stabilization prevents polymer breakdown in the solid state.
Consistent, in specification production requires polymer properties to remain in a narrow band of flow characteristics. Well stabilized polymers retain their flow properties. Recycled polymer that has minimal stabilization consumes stabilizers in the prime resin it is blended with, thus limiting its percentage use. A polymer part with little or no residual stabilization can degrade in the solid state, affecting the physical properties of the part.
Baerlocher’s Special Additives Division offers services in form-giving and the development of customer-specific additive blends. These products and services are used in sophisticated polymer applications for both virgin and recycled polymers.