Synergistic Deformation in Co-continuous Polylactic Acid/Cellulose Acetate Butyrate (PLA/CAB) Blends Enables Integrated Strength, Toughness, and Heat Resistance

It is highly challenging to achieve polylactic acid (PLA)-based bioplastics with integrated mechanical properties through a melt-blending modification method. This work effectively combined the complementary advantages of PLA and cellulose acetate butyrate (CAB) by constructing a co-continuous structure guided by the phase inversion point. The co-continuous PLA/CAB (50/50, w/w; denoted as 5P5C) blend exhibits a high elongation at break of 98.6% (approximately 19-fold higher than that of neat PLA), while maintaining a high tensile strength of 79.1 MPa (87.8 MPa for neat PLA). Structure-property relationship analysis indicates that this advantage arises from the synergistic deformation of the interpenetrating PLA/CAB networks in 5P5C under tensile loading. Additionally, the co-continuous 5P5C exhibits favorable heat resistance, with a Vicat softening temperature (VST) of 132.3 °C, which is much higher than that of neat PLA (VST = 59.8 °C). This work provides a viable strategy for developing high-performance PLA-based materials, and the resulting co-continuous PLA/CAB blend shows strong potential for agricultural and packaging applications.