Effect of different compatibilizers on environmentally friendly composites from poly(lactic acid) and diatomaceous earth

Abstract

Environmentally friendly composites from poly(lactic acid) (PLA) and diatomaceous earth (DE) were successfully manufactured by extrusion, followed by injection moulding. DE was used as a filler; several compatibilizer/coupling agents, namely (3‐glycidyloxypropyl)trimethoxysilane, epoxy styrene acrylic oligomer and maleinized linseed oil, were used to improve polymer–filler interactions. Mechanical characterization was carried out by standard tensile, impact and hardness tests while morphological characterization of the fractured surfaces was conducted by field emission scanning electron microscopy. The effect of DE was evaluated by differential scanning calorimetry and dynamic mechanical thermal behaviour. The results show that the addition of DE provides an improved tensile modulus and induces more brittle composites due to stress concentration phenomena. The addition of compatibilizers in PLA‐DE positively contributes to improve ductile properties, thus leading to high environmental efficiency materials with balanced mechanical properties. Specifically, the compatibility improvement between the PLA and DE was good with maleinized linseed oil and contributed to improving the impact strength, which is a key factor in PLA‐based composites due to the intrinsic brittleness of neat PLA. © 2019 Society of Chemical Industry

Study of the Influence of the Reprocessing Cycles on the Final Properties of Polylactide Pieces Obtained by Injection Molding

“…Comparative TGA thermograms of the neat PLA piece and the PLA pieces obtained after different reprocessing cycles are displayed in Figure 5. As expected, all samples (from PLA0 to PLA6) showed a one-step degradation process [76], as one can see in Figure 5a. It is worthy to note that several works have suggested that PLA decomposes in a two-step process when the thermogravimetric analysis is carried out under oxygen atmosphere [77], but it does not have any influence on this analysis since this induces thermo-oxidative degradation.…”

Evaluation of Different Compatibilization Strategies to Improve the Performance of Injection-Molded Green Composite Pieces Made of Polylactide Reinforced with Short Flaxseed Fibers

“…This is consistent with the above-reported effect of mechanical reinforcement of PLA by the lignocellulosic fibers. Similar remarkable increases in stiffness for natural filler-reinforced polymer composites have been reported previously [22,48,56]. The reinforcing effect was more pronounced after the glass transition region, in which the G value measured at 75 • C increased from 2.2.…”

“…After this, the silanized FFs were removed from the bath and dried in a stove at 50 • C for 2 days. The concentration of the glycidyl-silane reactive coupling agent was selected based on our previous studies [56][57][58].…”

“…This ductility enhancement can be ascribed to the plasticization of the PLA matrix in which the molecular forces are reduced and the free volume increased [78]. Indeed, MLO has been reported as an effective plasticizer for PLA materials, promoting an additional interfacial adhesion enhancement with both organic and inorganic fillers based on its multi-functionality [22,56,60]. In particular, the MAH groups present in MLO can result in the formation of carboxylic ester bonds by their reaction with the -OH end groups of both the PLA molecules and cellulose, resulting in a cellulose-grafted PLA (cellulose-g-PLA) structure [22].…”

Optimization of the Loading of an Environmentally Friendly Compatibilizer Derived from Linseed Oil in Poly(Lactic Acid)/Diatomaceous Earth Composites

“…Some recent investigations have revealed the interesting plasticization effect of maleinized vegetable oils in some polymers such as poly(lactic acid)—PLA—to increase chain mobility [1,25], but in general, there are few research works on the potential of these biobased materials as additive in plastic formulations. In addition to the plasticization effect of maleinized linseed oil (MLO) on PLA, it has been corroborated the coupling/compatibilizing effect of MLO on PLA composites with diatomaceous earth [26]. For this reason, MLO stands out as an alternative to traditional compatibilizers in the food packaging industry and, in particular, in active packaging, as diatomaceous earth particles are highly porous structures that can be loaded with antioxidants that can be released in a controlled way to increase the shelf life of a product.…”