Poly(lactic acid) (PLA), as a biodegradable semicrystalline thermoplastic, is usually blended with degradable poly(butylene-adipate-co-terephthalate) (PBAT) to improve toughness for the sake of environmental concerns. To obtain controllable properties of PLA/PBAT composites, the use of nanoparticles is increasing from a technical point of view, thus making the blends more widely used in the final products. In this study, immiscible blends of PLA and PBAT (70/30 wt%) and PLA/PBAT with different carbon nanotube (CNT) contents (0.5, 1, and 2 wt%) were prepared using a twin-screw extruder followed by injection molding. The preferential distribution of CNTs in the PBAT phase was characterized by SEM and thermodynamic analysis, and reason for selective localization is discussed. The morphology of the PLA/PBAT composite showed PBAT particles dispersed within the PLA matrix with an average diameter of 0.38 μm. For the nanocomposites, the CNTs in the minor PBAT phase produced larger elongated PBAT domains with a maximum average diameter of 1.3 μm. The elongation at break of binary PLA/PBAT blends was 160.9%, while the maximum elongation at break of the nanocomposite was 294.3%. Additionally, the influence of CNTs on the crystallization behavior and rheological and mechanical properties of PLA/PBAT/CNT blends was systematically investigated.carbon nanotubes, nanocomposites, PLA/PBAT blends, rheological, thermal and mechanical properties | INTRODUCTIONPolylactic acid (PLA), as one of the most promising biodegradable and recyclable polymers, has been extensively studied. [1][2][3] Recently, PLA products have been promoted to replace conventional petroleum-based plastics, such as polyethylene (PE), polypropylene (PP), and polystyrene (PS), due to their sustainability, eco-efficiency and high stiffness. [4,5] However, the ductility and toughness of PLA are far from satisfactory from the technological view of producing more widely used final products. Blending PLA with elastomers and/or softer polymers is deemed an economically viable way to modulate the properties. [6][7][8] Considering environmental friendliness, biobased or degradable materials are preferred, such as poly(butylene adipate-co-Zhihua Xiao and Guili Li contributed equally to this work and are considered as co-first authors.

Poly (lactic acid) (PLA) is a biodegradable and environmentally friendly material.And the spent coffee grounds (SCG) are huge waste all over the world. Therefore, the issue that how to convert the low-value wastes SCG into more valuable products is attracting more research attention. In this work, we compounded PLA with SCG.Firstly, the efficiency of oil extraction from SCG was compared by different methods and solvents. Then, the biocomposites specimens of different SCG contents (0, 5, 10, and 15 wt%) were prepared by extrusion and injection molding. The effects of SCG particle size and content on the thermal and mechanical properties were investigated. Next, the effect of coupling agent (4,4-methylene diphenyl diisocyanate [MDI]) on the biocomposites properties at 10 wt% SCG was examined by Field emission-scanning electron microscope and Fourier transform infrared spectroscopy. The results show that the tensile strength and elongation at break of the PLA composites with the optimal contents are increased by about 50% and 120%, respectively, compared with untreated SCG.