Clay–starch composites and their application in papermaking

Clay–starch composites with different aggregate sizes and starch to clay ratios were prepared by a simple precipitation method. The aggregates of the composites were used as fillers to improve the paper properties. The experimental results showed that the paper strengths increased more than 100% for starch‐modified clay compared to untreated clay at 20–30% clay loading. The increase in paper strengths of clay–starch composite‐filled handsheets was mainly due to two reasons, i.e., the relatively large aggregate size and the improved internal bonding. The optical properties compared at same mechanical strength were also improved. The water solubility of starch in the clay–starch composite was less than 3% at 50°C for 30 min, and it could be further reduced by adding crosslinker. Bonding sites between composite and fiber were investigated by scanning electron microscope. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1032–1038, 2006