Effects of barium stearate-modified wollastonite fibers on processability, mechanical performance and ceramization behavior of EVA composites

Ceramifiable polymer composites can form a dense ceramic layer under fire exposure, which protects the integrity of internal materials and enables equipment to operate normally for a certain period of time. Nevertheless, high loading of ceramic fillers inevitably deteriorates the mechanical and processing properties of the composites. In this study, a flexible and ceramizable EVA composite was prepared via compounding barium stearate-modified wollastonite fibers (BS-WF) with the magnesium hydroxide (MH)/zinc borate (ZB)/barium sulfate (BaSO 4 )/silica-alumina glass powder (SAGP) hybrid system. Adding 30 wt% BS-WF increased the elongation at break and melt flow index of the composites from 31.65% to 0.08 g/10 min to 259.8% and 0.86 g/10 min, respectively. The modified WF dispersion and improved interfacial compatibility significantly enhanced toughness, while the mobile BS layer remarkably boosted processability. Thermogravimetric analysis confirmed the synergistic thermal stability improvement by SAGP and BS-WF. Furthermore, the effects of different SAGP/BS-WF ratios on ceramization behavior were evaluated by analyzing sintered ceramic morphology, shrinkage, self-supporting ability, and flexural strength. The results showed that SAGP and BS-WF cooperatively promoted sintering and ceramization, reduced internal porosity, decreased volume shrinkage, and enhanced self-supporting performance. BS-WF also significantly improved the flexural strength of the ceramized composites. The SAGP/WF 1:3 system exhibited a flexural strength of 24.56 MPa at 950°C, representing a 153.98% increase compared with the system without BS-WF. The ceramization mechanism was clarified by investigating BS-WF effects on microstructure and phase transformations. High-temperature melting of SAGP, ZB and new glass phases formed a fluid glassy liquid that bridged WF whiskers and residues, reducing voids. Eutectic reactions among SAGP, BaSO 4 and WF generated new phases (CaAl 2 Si 2 O 8 , BaCa 2 Si 3 O 9 ), facilitating densification and high-strength ceramic formation. This work provides a scalable strategy for multifunctional ceramizable composites with balanced mechanical properties and structural stability, showing great potential in fire-resistant cables and building materials.