This work reports the enhancement of the properties of poly(butylene succinate) (PBS) composites containing 30 wt% almond shell flour (ASF) by using different compatibilizer families: epoxy, maleic anhydride and acrylic. With regard to the epoxy compatibilizers, epoxidized linseed oil (ELO) and epoxidized soybean oil (ESBO) were used. Two maleic anhydride-derived compatibilizers, namely, maleinized linseed oil (MLO) and dodecenyl succinic anhydride (DDSA) were used. Finally, two acrylic monomers, namely methyl methacrylate (MMA) and acrylic acid (AA) were employed. Uncompatibilized and compatibilized PBS/ASF composites were characterized in terms of their mechanical properties, morphology, thermal behaviour and thermomechanical performance. The obtained results suggest that all three vegetable oil-derived compatibilizers (ELO, ESBO and MLO) give a remarkable increase in ductile properties while poor compatibilization is obtained with the acrylic monomers. These vegetable-oil derived compatibilizers could represents an interesting environmentally friendly solution to compatibilizing polyester-type polymers and their composites with lignocellulosic materials.

In this work poly(butylene succinate) (PBS) composites with varying loads of almond shell flour (ASF) in the 10–50 wt % were manufactured by extrusion and subsequent injection molding thus showing the feasibility of these combined manufacturing processes for composites up to 50 wt % ASF. A vegetable oil-derived compatibilizer, maleinized linseed oil (MLO), was used in PBS/ASF composites with a constant ASF to MLO (wt/wt) ratio of 10.0:1.5. Mechanical properties of PBS/ASF/MLO composites were obtained by standard tensile, hardness, and impact tests. The morphology of these composites was studied by field emission scanning electron microscopy—FESEM) and the main thermal properties were obtained by differential scanning calorimetry (DSC), dynamical mechanical-thermal analysis (DMTA), thermomechanical analysis (TMA), and thermogravimetry (TGA). As the ASF loading increased, a decrease in maximum tensile strength could be detected due to the presence of ASF filler and a plasticization effect provided by MLO which also provided a compatibilization effect due to the interaction of succinic anhydride polar groups contained in MLO with hydroxyl groups in both PBS (hydroxyl terminal groups) and ASF (hydroxyl groups in cellulose). FESEM study reveals a positive contribution of MLO to embed ASF particles into the PBS matrix, thus leading to balanced mechanical properties. Varying ASF loading on PBS composites represents an environmentally-friendly solution to broaden PBS uses at the industrial level while the use of MLO contributes to overcome or minimize the lack of interaction between the hydrophobic PBS matrix and the highly hydrophilic ASF filler.

Green composites of poly(butylene succinate) (PBS) were manufactured with almond shell flour (ASF) by reactive compatibilization with maleinized linseed oil *MLO) by extrusion and subsequent injection molding. ASF was kept constant at 30 wt %, while the effect of different MLO loading on mechanical, thermal, thermomechanical, and morphology properties was studied. Uncompatibilized PBS/ASF composites show a remarkable decrease in mechanical properties due to the nonexistent polymer‒filler interaction, as evidenced by field emission scanning electron microscopy (FESEM). MLO provides a plasticization effect on PBS/ASF composites but, in addition, acts as a compatibilizer agent since the maleic anhydride groups contained in MLO are likely to react with hydroxyl groups in both PBS end chains and ASF particles. This compatibilizing effect is observed by FESEM with a reduction of the gap between the filler particles and the surrounding PBS matrix. In addition, the Tg of PBS increases from −28 °C to −12 °C with an MLO content of 10 wt %, thus indicating compatibilization. MLO has been validated as an environmentally friendly additive to PBS/ASF composites to give materials with high environmental efficiency.