AbstractThe effect of bamboo and hybrid bamboo-precipitated calcium carbonate (PCC) fillers on thermal expansion behavior of filled plastic composites was investigated. The linear coefficient of thermal expansion (LCTE) of the filled composites decreased with increased PCC and bamboo filler loading levels. The composite system with refined bamboo fibers (RBFs) had smaller LCTE values compared with those from the systems with ground bamboo particles (GBPs). The use of silane treatment on bamboo fiber/particle surface helped enhance its bonding to the plastic matrix, leading to a further reduction of LCTE values for both GBP and RBF composite systems. The observed behavior of reduced LCTE is attributed to a small filler LCTE value, reduced overall plastic volume, and enhanced interfacial bonding with treated bamboo materials. Thus, hybrid bamboo and PCC fillers are suitable materials for reducing the thermal expansion of the composites caused by temperature changes.