Coupling Agents

- January 01, 2016 -

Several Dow polymer modifiers can be used as coupling agents in filled plastic compounds. Often, the coupling agent enhances resulting performance properties, while improving production or subsequent melt-processing efficiency by optimizing melt flow. A well chosen coupling resin often improves multiple properties in the filled compound.

Coupling agents from Dow are functional in many compounded resins, delivering benefits described below by resin family:

  • Nylon
  • Polyesters
  • Polyolefins Mixed PE-Based Recycle Stream

Processing and Performance Benefits in Nylon

Dow™ Fusabond® A560 coupling agent in glass-reinforced nylon (PA) 6 and nylon 6,6 improves the adhesion between glass filler and the nylon (PA) matrix. At low concentrations of 3.5% to 7%, Fusabond® A560 increases the Notched Izod impact strength of the glass-reinforced nylon by as much as 30% to 50%.

Compared with other nylon (PA) modifiers, Fusabond® A560 coupling agent also can help reduce compound melt viscosity for improved mold filling and better surface appearance of the glass-filled molded parts. Filled compounds can retain more of their mechanical properties such as tensile strength, modulus, and heat deformation temperature (HDT).

Coupling Agents for Polyesters (PET, PBT and Glass Reinforced PET & PBT)

In polyester resins (PET, PBT, and glass-reinforced PET and PBT), Elvaloy® PTW and Elvaloy® AC can be used for coupling and melt flow optimization.

Elvaloy® PTW is a soft E-nBA-GMA terpolymer that reacts with polyesters, effectively dispersing the modifier in the matrix and bonding the modifier to the polyesters. The terpolymer also has good affinity to glass, helping toughen glass-reinforced PBT.

Elvaloy® AC copolymer moderately improves the toughness of glass-reinforced polyesters. Compared to using the terpolymer, using Elvaloy® AC copolymer offers the benefit of increased melt flow, for faster, easier injection-molding.

Fusabond® Coupling Agent for Polyolefins (PE and PP and inorganic fillers)

For increased flame retardancy and low-temperature flexibility in highly filled polyolefins, a number of very efficient Dow™ Fusabond® coupling agents are available.

Using a Fusabond® coupling agent enhances adhesion between polyolefin matrix and flame-retardant mineral fillers, improving filler dispersibility and filled compound homogeneity. The coupling resin enables higher loadings for improved flame retardancy or higher LOI (Limiting Oxygen Index) while maintaining finished compound tensile strength and elongation-at-break.

Using Fusabond® coupling agent, such as Fusabond® E226 ,can also help protect against unwanted water absorption in finished compounds, and can contribute to the compound’s oil and chemical resistance. Applications include halogen-free, flame-retarded wire and cable jacket formulations.

Coupling Agent for Mixed PE-Based Recycle Stream

Fusabond® M603 coupling agent helps make higher-performing compounds using polyethyelene-based recycle streams.

By improving the properties and processing efficiency of pre- and post-consumer recycled plastics, for example, Fusabond® coupling agent can lower costs for manufacturers of industrial packaging and plastic lumber. Benefits also reach blow molders, injection molders, compounders and others who are feeding into or using higher-value polyethylene- (PE-) based recycle streams.

In wood polymer composites, Fusabond® M603 coupling agent strengthens the composite and reduces moisture absorption into cellulose fibers. This can produce longer service life and better mechanical strength for wood alternative applications, such as outdoor decking.

The costs of sorting and reusing diverse recycle streams can be reduced using a Fusabond® coupling agent to widen the processing window or help compensate for hard-to-eliminate contaminants. Fusabond® M603 helps prevent die buildup problems by incorporating polar components into the polymer matrix.

For technical properties data for any resins named in this summary description, refer to the product information Web pages shown on the right.