Influence of Thermally Reduced Graphene Low-Loadings on the Crystallization Behavior and Morphology of Biodegradable Poly(ethylene succinate)

Abstract

Through a solution and coagulation method, biodegradable poly(ethylene succinate) (PES) and thermally reduced graphene (TRG) nanocomposites were prepared at low TRG loadings. The nonisothermal melt crystallization peak temperature values and overall isothermal melt crystallization rates are greater in the nanocomposites than in neat PES, indicative of a nucleating agent effect of TRG; however, the crystallization mechanism of PES remains unchanged in the nanocomposites, regardless of TRG loading and crystallization temperature. The nonisothermal and melt crystallization processes of the nanocomposites are found to vary with the TRG loading, exhibiting a maximum at 0.25 wt % TRG loading. The incorporation of a small amount of TRG shows little influence on the spherulitic growth rates but obviously affects the spherulites nucleation density values of the nanocomposites. TRG does not modify the crystal structure of PES in the nanocomposites. ■ INTRODUCTIONIn the last two decades, some biodegradable aliphatic polyesters have attracted considerable research interests from both academic and industrial viewpoints, including poly(3-hydroxybutyrate) (PHB), poly(L-lactide) (PLLA), poly(ε-caprolactone) (PCL), and poly(butylene succinate) (PBS). 1−4 Similar to PBS, poly(ethylene succinate) (PES) is also a kind of biodegradable aliphatic polyester. PES has a chemical structure of (OCH 2 CH 2 O 2 CCH 2 CH 2 CO) n , which is similar to that of PBS. The chemical structures of PBS and PES are only different in their numbers of methylene groups between the two ether groups, namely four for the former and two for the latter, respectively. Till now, the crystal structure, crystallization kinetics, multiple melting behavior, spherulitic morphology, and enzymatic degradation of PES have been studied extensively. 5−14 To extend a wider practical application, some methods have been used for the development of PES-based multicomponent materials, including copolymerization, polymer blending, and the fabrication of polymer nanocomposites. 15−26 As the physical properties of host polymer can be improved obviously by a small amount of nanofillers, the fabrication of polymer nanocomposites has recently found more applications to develop PES-based multicomponent materials. 23−26 As a novel two-dimensional material, graphene shows many excellent physical properties. 27 Thermally reduced graphene (TRG) is produced through the exfoliation and reduction process of graphite oxide (GO). 28−30 Similar to other nanofillers, graphene can also improve significantly the physical properties of host polymers even at very low loading. 28−30 Till now, graphene or graphene oxide has been used for the fabrication of polymer nanocomposites for several kinds of biodegradable polymers, including PLLA, PHB, and PCL; moreover, the degree of dispersion or aggregation of graphene or graphene oxide, crystallization kinetics, and many other physical properties of these novel polymer nanocomposites have been investigated in detail. 31−37 In this research note, we ...

Preparation and characterization of biodegradable poly(ϵ-caprolactone) self-reinforced composites and their crystallization behavior

“…The enhancement effect of coalesced PCL on non‐isothermal crystallization of PCL was more pronounced at lower loadings. Similar results have also been reported for polymer/thermally reduced graphene nanocomposites and isotactic polypropylene/carbon nanotube nanocomposites …”

Role of In situ thermal‐reduced graphene oxide on the morphology and properties of biodegradable poly(Lactic acid)/poly(butylene succinate) blends

“…Figure shows the TGA curves of GO and RGO. GO exhibited a significant weight loss (about 60 wt%) from 50 to 300°C, which can be attributed to the removal of the liable oxygen‐containing chemical moieties in the GO lamellas generated from the oxidation treatment, yielding CO, CO 2 , and water vapor . However, the RGO had almost no weight loss at 300°C and less than 10 wt% of weight loss in the whole test temperature range (50–600°C).…”

Effect of graphene oxide and its modification on the microstructure, thermal properties and enzymatic hydrolysis of poly(ethylene succinate) nanocomposites

“…However, the overall crystallinity remained almost unchanged. The same effect was observed when thermally reduced graphene (TRG) was added into PESu matrix [25] or when graphene oxide was grafted by insitu polymerisation with PESu [24].…”

“…In literature several aliphatic polyesters/ graphene nanocomposites have been reported with emphasis to be given in reinforcement and thermal properties effect of graphene in polymer matrices [9,[16][17][18][19][20][21][22]. However, till now, only a few works have appeared on the synthesis and characterization of graphene reinforced PESu [23][24][25]. Almost all of them are dealing with the effect of graphene on crystallization behavior of PESu and on its mechanical properties.…”