Surface Modification of Cellulose Microcrystalline with Aluminate Coupling Agent and Its Effects on Flame Retardant and Mechanical Properties of Epoxy Resin

Cellulose microcrystalline (CMC), a linear polysaccharide with glucosidic bond, was successfully extracted from bamboo powder and modified by aluminate coupling agent (ACA) to prepare ACA-CMC. The chemical structure of as-designed ACA-CMC was characterized by scanning electron microscopy and Fourier transform infrared spectra. ACA-CMC, in association with ammonium polyphosphate (APP), was introduced into epoxy resin (EP) by casting process to obtain flame-resistant composites. The fire performance evaluation indicated that the presence of 10 phr APP and 5 phr ACA-CMC in EP achieved the maximal LOI value of 29.0 %, passed the UL-94 V-0 rating, and significantly decreased the peak heat release rate from 1055 kW · m⁻² of neat EP to 294 kW · m⁻². The introduction of ACA-CMC could also improve the mechanical properties of EP composites due to the strengthening effect of CMC and better interfacial compatibility after modification with ACA. Moreover, the relative mechanisms were also proposed.