AC Foaming Agent – Solving Core Blackening and Enhancing Foam Quality in Polymer Processing

One of the common challenges encountered in polymer and rubber foam manufacturing is the phenomenon of core blackening, where the inner portion of the foamed product appears darker or partially burnt. This issue is typically caused by the uneven decomposition of blowing agents, excessive localized heat, or poor gas dispersion. To address these defects and ensure cleaner, more uniform cell structures, the AC foaming agent (azodicarbonamide, ADC) has become an essential solution due to its stable decomposition behavior, high gas yield, and excellent compatibility with various polymer systems.

AC foaming agent decomposes by releasing large volumes of gases such as nitrogen, carbon monoxide, carbon dioxide, and ammonia, creating the foam’s internal cellular network. Unlike lower-efficiency blowing agents that may decompose unpredictably and contribute to core darkening, AC foaming agent offers a more controlled breakdown process. Its high purity and consistent decomposition kinetics help minimize overheating, ensuring that the inner foam remains bright, uniform, and free from scorching.

The core blackening problem often results from excessive decomposition temperatures, insufficient heat transfer, or incompatible activators. Standard AC foaming agent features a decomposition temperature of around 200–205°C, which can be adjusted using activators such as zinc oxide, urea, or zinc stearate. These activators help reduce the decomposition temperature to better fit polymer processing environments like PVC, PE, PP, EVA, and rubber. By fine-tuning the decomposition range, manufacturers can reduce the risk of localized burning while optimizing the density and uniformity of the foam.

Additionally, AC foaming agent produces higher gas yields—typically 220–240 mL/g—allowing for efficient foaming at lower additive dosages. This reduces thermal stress within the polymer matrix and helps prevent the overheating that leads to core blackening. Its superior dispersibility within polymers ensures even cell nucleation, enhancing surface quality and mechanical properties while minimizing defects such as yellowing, charred spots, or collapsed cells.

In rubber footwear, sealing materials, automotive components, and sports products, AC foaming agent helps achieve smooth, fine cell structures with excellent elasticity. By selecting modified AC grades with lower residue content and cleaner decomposition profiles, manufacturers can further eliminate signs of discoloration in the core region. These cleaner grades contribute to improved product aesthetics and better performance stability.

In plastics processing, including extrusion, injection molding, calendaring, and rotational molding, AC foaming agent enhances structural integrity, reduces raw material consumption, and provides weight reduction benefits. When properly formulated, it also improves thermal insulation, cushioning properties, and dimensional stability. The ability to tailor the decomposition curve makes AC foaming agent adaptable to complex processing environments where thermal gradients or uneven heating might otherwise cause foam discoloration.

From an environmental and safety perspective, modern AC foaming agent technologies have significantly improved decomposition cleanliness, minimizing irritating odors and volatile residues. Manufacturers increasingly use AC foaming agents that meet international standards for consumer product safety and environmental performance. For applications requiring extremely clean surfaces—such as food packaging, children’s products, and medical components—refined grades of AC foaming agent provide reliable solutions without contributing to the central blackening issue.

Quality control remains essential for achieving optimal results. Key parameters include particle size distribution, decomposition temperature, moisture level, gas volume, and compatibility with polymer binders. Proper blending and temperature control during processing are equally important in preventing uneven decomposition. When AC foaming agent is correctly matched with processing conditions, it enables the formation of uniform, bright, and defect-free foam structures.

In summary, AC foaming agent is a highly efficient and versatile blowing agent that effectively addresses foam core blackening while delivering superior performance across a wide range of polymer applications. Its controlled decomposition, high gas output, and excellent compatibility make it a preferred choice for manufacturers seeking improved product quality, reduced defects, and enhanced foam characteristics. As the demand for lightweight, environmentally friendly, and durable materials continues to grow, AC foaming agent will remain an indispensable component in modern polymer foaming technology.