Fabrication of biodegradable graphene crosslinked polylactic acid nanocomposite with enhanced mechanical strength

Abstract

Intense research interest on development of biodegradable polymers as engineering material is backed by eco-friendliness of bio-based polymers; non-biodegradable nature of petroleum derived polymers; abundant bioavailability of precursor biomolecules in environment; involvement of relatively easy process parameters due to polymeric nature and finally possibility of incorporating multi-functional properties by exploiting advances in nanotechnology. Among synthetic biopolymers, PLA represents itself as a promising candidate to be used in packaging applications where absence of mechanical strength has been a noteworthy limitation. In order to overcome this limitation, incorporation of graphene-based material as filler in PLA has been a wide practice. However, in this experiment GO based 2D chemical crosslinker has been prepared and in situ polycondensation polymerization in presence of GO based 2D-crosslinker led to crosslinked PLA with higher molecular chain. The crosslinker, crosslinked PLA and neat PLA were characterized by XPS, AFM, SEM, TGA-DSC and FTIR. AFM analysis showed more than 10 times of thickness of crosslinked PLA than that of pristine form where an increase of 15 times in mechanical strength is observed. FE-SEM analysis showed that crosslinkers are dispersed homogeneously in PLA matrix without agglomeration and structural features also get improved due to overcoming of crosslinkers loading. Elemental composition and the presence of functional group was studied by FTIR and XPS analysis. Samples were also thermally characterized by TGA and DSC thermograms. The observations found that intelligent optimization in processing parameters pellet formation of GO crosslinked PLA would give high strength PLA with better packaging properties. Our crosslinked PLA exhibited first-rate mechanical properties compared to the neat PLA and pure GO based PLA. A comparison mechanical properties was also studied in different amount of crosslinkers loading.