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Considering the importance of polylactic acid (PLA) biopolymer in industry, in this research we represent a protocol that benefits from the presence of PA6 phase (30 wt%), using an ester-amide exchange catalyst and GN as nanofiller to enhance PLA mechanical properties. To this purpose, it was decided to fabricate blends and nanocomposites in the presence of cobalt(II) acetylacetonate (Cat) as the catalyst. XRD patterns revealed good compatibility of the polymer moieties by broadening of the PLA characteristic peaks and also good dispersion of the GN nanoparticles within the matrix. In the TEM pictures, the GN nanoparticles size ranged from 20 to 130 nm which confirms its good intercalation and exfoliation. T0 and Tmax, considered as thermal stability, of the samples decreased slightly by reactive blending, however, the values were still comparable with them in pure PLA. DSC thermograms and the curves from DMTA exhibited the lower Tg, Tm and crystallinity values of PLA matrix in the alloys and nanocomposites especially in the presence of Cat. Investigation of tensile properties revealed significantly enhanced elongation at break, from 7 in origin PLA to the maximum of 29% in PLA/PA/Cat, with negligible deficiency in modulus, from 2.85 to a minimum of 1.95 GPa, and tensile strength, from 65 to a minimum of 46 MPa, respectively. MFI test results disclosed higher flow-ability of the alloys and composites in compare with neat PLA and also melt flow ratio in two different testing weighs, shows broad molecular weight distribution of the fabricates due to the occurrence of exchange reactions in the presence of Cat. [ABSTRACT FROM AUTHOR]

To make potential the biodegradable polyethylene glycol (PEGO) toward photocrosslinking, it was cooligomerized with fumaryl chloride by esterification reaction. The obtained viscous liquid injectable macromere, OPEGF, was characterized by FTIR and GPC. In another reaction, nanosilica was treated with acryloyl chloride to obtain silica-AC nanopowder and subsequently dispersed in the OPEGO matrix in 1 and 2 wt.% in the presence of either 1,4-butanediol dimethacrylate (BDM) or 1,12-dodecanediol dimethacrylate (DDM) as reactive diluent. The obtained slurries were photocured by blue light irradiation and the characteristics of prepared nanocomposites as well as crosslinked OPEGF were studied via XRD, TEM, tensile, equilibrium swelling and cell culture tests. XRD patterns revealed amorphous nature of all samples. TEM and Si mapping pictures demonstrated good dispersion of silica-AC at nano level (particle size of 20–30nm) in the fabricated samples. Tensile test disclosed a noticeable improvement in mechanical properties of the nanocomposites by increasing in nanofiller level. Equilibrium swelling study revealed that the presence of nanosilica and reactive diluent improved the crosslinking phenomenon. Finally, cell culture test evidenced higher biocompatibility of the samples containing silica-AC nanofiller and BDM reactive diluent. As the consequence of employed tests, designed nanocomposites can be considered as capable candidates for biomedical applications. [ABSTRACT FROM AUTHOR]

This article presents a general solution scheme for finite horizon optimal control of variable order Caputo dynamic systems with specified initial and final conditions. The main approach of the article is using variable order calculus of variations. After deriving the necessary optimality conditions, as the main contribution of the article, a change of variable is used to rearrange the set of conditions as a set of coupled variable order differential equations. Then, a numerical method is introduced to solve the corresponding equations. Finally, a case study shows the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]