CaCO₃ blowing agent mixing method for biomass composites improved buffer packaging performance

Biodegradable composites with an open-cell structure were developed to replace petroleum-based buffer packaging materials. To overcome the problem of uneven and insufficient foam in the composites, CaCO₃ was used as a nucleating agent to prepare porous composites. At 5 wt% CaCO₃, more uniform and dense composite cells with better cushioning performance were obtained. A further increase in the CaCO₃ content caused the density of the cells and the cushioning properties of the composites to decrease. The addition of CaCO₃ improved the thermal stability and water barrier properties. The moisture absorption was reduced by 15%. X-ray diffraction analysis indicated that the addition of CaCO₃ destroyed the crystalline structure of the starch and produced a new crystalline peak, resulting in a significant reduction in the crystallinity. The decrease in the crystallinity of the starch resulted in the formation of a homogeneous slurry that produced a uniform foam in the composites.