Controllable synthesis of hierarchical nanostructured anhydrous MgCO3 and its effect on mechanical and thermal properties of PVC composites

Anhydrous MgCO3 is a new attractive inorganic filler due to its many excellent properties. However, MgCO3 particles are currently commercially unavailable because of their harsh synthesis conditions. In this study, a novel and efficient hydrothermal carbonization method was developed for synthesizing MgCO3 using ascorbic acid (ASA) as both CO2 source and crystal modifier. Hierarchical nanostructured MgCO3 particles with dumbbell-, hydrangea- and cube-like morphologies were successfully fabricated, and then MgCO3/PVC composites were prepared and their comprehensive properties were investigated. The results show that directly incorporating a low content of MgCO3 into PVC matrix can not only greatly reinforce and toughen PVC matrix, but can also impart PVC composites with enhanced thermal stability. Significantly, the impact strength of PVC composite with only 4 wt% of dumbbell-like MgCO3 reaches 11.5 kJ/m2, with an increment of 117% compared with pure PVC, while the flexural modulus and the initial degradation temperature of PVC composite with 4 wt% of hydrangea-like MgCO3 reach 5771 MPa and 269 °C, with an enhancement of 106% and 12 °C compared with pure PVC, respectively.