Facile dispersion of exfoliated graphene/PLA nanocomposites via in situ polycondensation with a melt extrusion process and its rheological studies

Abstract

This work attempted to improve the dispersion of graphene by coating poly(lactic acid) pellets with a masterbatch before melt processing. An in situ polycondensation reaction of lactic acid oligomer was utilized to prepare the masterbatch (MB) of exfoliated graphene (GR). MB dispersed composites of poly(lactic acid) (PLA) were fabricated by melt extrusion of MB‐coated PLA. One normal coated composite without MB coating (PLA‐M‐0.2GR) was fabricated for comparing properties. X‐ray diffraction, Raman spectroscopy, and morphological studies revealed better compatibility, dispersion, and interaction of GR for the diluted‐MB composite compared to the normal coated composite. The thermal stability, crystallization properties, and mechanical properties of the composites were examined, and the effect of short PLA chains in diluted‐MB composites was observed. The melt rheology nature of the composites was examined. Cole–Cole plots and Han plots suggested a uniform distribution of graphene. The sample PLA‐MB‐0.05GR showed improved modulus and elongation at break. It also showed better dispersion of GR, comparable thermal stability, good miscibility, good chain mobility, and high activation energy. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46476.

Biocomposites of poly(lactic acid) and lactic acid oligomer‐grafted bacterial cellulose: It's preparation and characterization

“…The surface wetting characteristics of the PLA/OLLA‐ g ‐BC and bionanocomposite films was studied using the sessile drop contact angle measurements as shown in Figure (a). The contact angle measured for PLA was around 83.5 ± 0.8° which was found to be matching with the values reported elsewhere . Due to the in situ polymerization, condensation polymerization, the grafting process occurred where the polar (OH) groups on BC backbone were replaced by hydrophobic ester groups of OLLA .…”

“…The OLLA‐ g ‐BC shows the formation of PLA chains during the in situ melt polycondensation due to the presence of strong band at 1755 cm −1 which ascribes to the carbonyl stretching (CO) . Peaks at 1456, 1188, and 1092 cm −1 are observed which represent the stretching, rocking, and assymetric vibrations, respectively, of the CCH 3 in polylactide . It is noteworthy to mention that the peaks present in the region 3400–3500 cm −1 which ascribe to OH groups of bacterial cellulose are now missing in the OLLA‐ g ‐BC.…”

“…Superiority of filler reinforced polymer bionanocomposites is dictated by dispersion and interfacial adhesion. Therefore, dispersion of filler particles inside the polymer matrix becomes a key factor for nanocomposite properties . The filler dispersion can be improved by numerous techniques such as grafting, sonication, compounding, in situ polymerization .…”

“…Therefore, dispersion of filler particles inside the polymer matrix becomes a key factor for nanocomposite properties . The filler dispersion can be improved by numerous techniques such as grafting, sonication, compounding, in situ polymerization . In situ polymerization approach has been widely used for dispersion of fillers such as chitosan, gum, clay, and so on into the PLA matrix to prepare “green biocomposites” with potential to become future fabrication materials …”

Extrusion of Polymer Nanocomposites with Graphene and Graphene Derivative Nanofillers: An Overview of Recent Developments

“…Therefore, the recent interest in the development of biodegradable materials has attracted increasing attention towards PLA nanocomposites [100]. Table 4 summarizes the very last PLA-graphenic composites prepared by means of melt blending [101][102][103][104][105][106][107][108][109][110][111] and other biodegradable and biocompatible polymers [112][113][114][115][116][117].…”