Abstract:

Molecular dynamics simulations were conducted to investigate the compatibility and mechanical properties of PBS-TME/PLA composites. On this basis, seven PBS-TME/PLA composites with different mixing ratios were prepared. The structural morphology of the composites was characterized by using XRD and XPS methods, and their mechanical properties, hydrophilicity, water vapor transmission rate（WVTR）, degradation rate, and plant growth were investigated. The results of molecular dynamics simulations indicated that PBS-TME exhibited good compatibility with PLA. When PLA was blended with PBS-TME, the crystallization ability of PBS-TME was weakened. Therefore, the crystallization ability of PBS-TME/PLA composite materials was decreased and the degradation rate was increased. When the mass ratio of PBS-TME to PLA was 8∶2, the compatibility of the material was the best, the crystallinity was 25.39%, and the comprehensive mechanical properties were the best（with tensile strength of 15.78 MPa and elongation at break of 19.56%）. With the increase of PBS-TME content, the hydrogen bonding between molecules made water molecules easier to enter the interior of the material, and at the mass ratio of PBS-TME∶PLA of 8∶2, the water contact angle was the smallest（72.6°）and the permeability of water molecules was the largest（WVTR was 63.12 g/（m²·d））. Moreover, at the mass ratio of PBS-TME∶PLA of 8∶2, the material exhibited the highest degradation both in soil supernatant and by enzymatic degradation. This composite material allowed sufficient supply of carbon sources and water molecules for plant growth, resulting in the increased chlorophyll content, soluble protein content, peroxidase activity, and vitamin C content in green vegetables. This work might expand the application of biodegradable materials in practical fields.

Key words: PBS-TME/PLA, molecular simulation, degradation percentage, compatibility