Polyethylene nanocomposites with silica, alumino-silicate and thermally reduced graphene were generated by adding pro-oxidant additive. Additive resulted in early degradation of pure polymer, however, the degradation was delayed in the presence of fillers. Graphene resulted in maximum extent of enhancement of peak degradation temperature (13–14 °C depending on the additive content) followed by silicate and silica. Additive also resulted in enhancement of polymer crystallinity, which was further aided by the filler, though no change in peak melting and crystallization temperatures was observed. The graphene and silicate particles were also observed to be uniformly dispersed in polymer matrix, whereas some aggregates were present in silica based composites. In graphene composite with 2.5 wt% additive content, the tensile modulus was increased by 1.95 times that of pure polymer. Increasing the additive content was also observed to enhance the mechanical performance. For instance, graphene nanocomposite with 1 % additive content had 40 % and 33 % increment in storage modulus at 50 °C and 70 °C respectively as compared to pure PE. The thick plaques of composites exhibited oxo-degradation in the presence of pro-oxidant with silica and silicate composites with 2.5 wt% additive having 100 % degree of embrittlement in 15–16 months at 30 °C. Graphene composites also exhibited ∼50 % embrittlement for the same conditions. The filler particles were observed to delay the time needed to attain embrittlement due to reduction in oxygen permeation in the matrix as well as UV absorption, however, these materials confirmed that degradation of the materials could be successfully tuned without sacrificing the mechanical, thermal and rheological properties of the nanocomposites.

Melt processed bio-nanocomposites of poly(butylene succinate) (PBS)-chitosan (CS) generated with varying amounts of silica, alumina-silicate, and thermally reduced graphene were analyzed for their biodegradation behavior. The nanocomposite samples were embedded in soil under natural environment for varying periods of time and the weight loss analysis was complemented with changes in surface morphology, crystallinity, and thermal degradation. Both the type and amount of filler were observed to affect the extent of biodegradation, though no change in biodegradation mechanism occurred. Nanocomposites had in general lower extent of weight loss than the pure blend, but the extensive surface roughness and cracks were observed for all systems indicating the initiation of biodegradation. Silica and silicate nanocomposites exhibited higher extent of biodegradation in comparison with graphene nanocomposites possibly because of the obstructive pathways to microbes in the presence of high aspect ratio graphene platelets. The crystallinity in the pure blend and nanocomposites was observed to increase as a function of embedding time because of degradation of the random amorphous material in the initial degradation phase. Subsequently, the increase levelled off because of attack of microbes on more organized crystalline content, which was also supported by the reduction in overall weight loss. Increase in melting point of PBS with embedding time as well as depletion of CS flakes from the crosssection of the composites in AFM confirmed that CS was degraded earlier than PBS. Thermal analysis also indicated faster onset of degradation of CS with soil burial time. The degradation studied through TGA-MS also revealed that degradation was accompanied by evolution of H 2 O, CO 2 , and NH 3

The objective of the study was to generate degradable polypropylene nanocomposites by incorporation of prooxidant and different fillers like silica, silicate, and thermally reduced graphene. Graphene-based composites exhibited higher crystallinity attributed to better dispersion and high aspect ratio platelets. Graphene composites with 2.5% additive content significantly enhanced the peak degradation temperature to 4648C as compared to 4488C for pure polymer. The processing conditions used for the nanocomposite generation were optimum as a uniform distribution of filler particles (or platelets) was observed in the PP matrix. The tensile modulus of the graphene composite with 2.5% additive content was 80% higher than pure PP, as compared to 60 and 30% for silicate and silica composites, respectively. Similarly, the storage modulus of the graphene nanocomposite with 1% additive content had 30% increment at 408C as compared to pure PP. PP-additive blends as well as PP nanocomposites with silica and silicate were observed to attain 100% degree of embrittlement within 6 months of UV exposure at 308C. Graphene composites, though, had delayed photo-degradation due to UV absorption by the platelets and high aspect ratio platelets acting as oxygen barrier for PP matrix, but the pro-oxidant was successful in attaining controlled degradation. POLYM. ENG. SCI., 00:000-000,

Summary: Mechanical, rheological and thermal properties of melt processes bionanocomposites of poly(butylene succinate) (PBS) and chitosan blends with 0-dimensional and 2-dimensional nanofillers were studied. The weight ratio of PBS and chitosan in the blend was optimized based on ease of processing, mixing quality and mechanical performance. The chitosan phase was observed to be dispersed as noncontinuous phase in PBS and enhanced it mechanical properties markedly. The fillers had different degrees of improvement in the mechanical performance with graphene exhibiting a maximum increase of > 225% in the Young's modulus at 10% filler content. The IR characterization also signaled toward chemical interactions between the polymer and graphene phases. Increasing the filler content had overall reduction in crystallinity.