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Poly(lactic acid) (PLA) as a bio-based polymer with biodegradability and biocompatibility has attracted much attention. To manipulate its properties for different applications, regulation of crystal structure and crystalline morphology becomes an attractive research topic. In this work, the structure evolution of layered samples containing an amorphous poly(D-lactide) (PDLA) layer and a crystalline poly(L-lactide) (PLLA) layer with highly oriented edge-on α lamellar crystals after annealing at 150 °C or/and after melt-recrystallization has been studied by AFM, FTIR, and TEM combined with electron diffraction. The results demonstrate that melt recrystallization of the as-prepared sample leads to the formation of abundant randomly oriented PLA stereo-complex (PLA SC) crystals. Annealing at 150 °C results in the formation of a small amount of oriented PLA SC crystals at the interface. These PLA SC crystals show great impact on the recrystallization behavior of sample after melting at 190 °C and then crystallizing at 90 °C. First, they impede the mutual diffusion of the overlying PDLA and underlying PLLA, and thus reduce their stereocomplexation ability as manifested by the decreased amount of PLA SC crystals. Second, they act as substrate to initiate the epitaxial crystallization of the overlying PDLA and underlying PLLA, which ensures the production of a highly oriented structure of PDLA and PLLA after melt recrystallization again. [ABSTRACT FROM AUTHOR]

Eryngiolide A (1), the first member of C20 diterpenoids with the skeleton deriving from a cyclododecane core fused with two γ-lactone units, was isolated from the solid culture of the edible mushroom Pleurotus eryngii. The structure of 1was elucidated by extensive analysis of NMR spectra. Compound 1exhibited moderate cytotoxicity against two human cancer lines in vitro. [ABSTRACT FROM AUTHOR]

The effect of freezing layer on the crystallization kinetics of poly(ε-caprolactone) (PCL) thin and ultrathin films was investigated by monitor the growth process of it on oriented polyethylene (PE) and CaF2 with and without freezing layer, respectively. It was found that the PCL films with similar thicknesses crystallize much faster on oriented PE than on CaF2 substrate. For example, the crystallization rate constant of a 102 nm thick PCL film decreases tremendously by 3 orders of magnitude from 1.1×10−1 on PE substrate at 50 °C to 7×10−4 on CaF2 surface at 40 °C. Moreover, the crystallization of PCL accelerates on CaF2 surface while slows down at PE surface with increasing film thickness. The ultrathin films of PCL with thickness less than 14 nm exhibits the fastest crystallization rate on oriented PE with a rate constant of about 3.5×10−1, which is 3 times higher than that of a ca. 50 nm thick film. This illustrates the great influence of freezing layer on the crystallization process of PCL. The freezing layer thickness of PCL on PE is estimated to be in the range of 14–17 nm. Taking the radius of gyration (Rg ∼ 15.6 nm) of the used PCL material into account, the obtained results may imply the existence of a correlation between the Rg of PCL and its freezing layer thickness at PE substrate. [ABSTRACT FROM AUTHOR]

Despite growing interest in nano-sized fillers, micro-sized fillers with desired compatibility are still used for reinforcing rubbers, owing to their lower production cost and easier processing relative to nano-sized fillers. Especially, the abundant and eco-friendly clay minerals are recognized as the materials of the twenty-first century. Herein, illite, a naturally occurring clay having dimension in micrometric scale, has been selected as filler to reinforce the SBR. To improve the compatibility of illite with SBR, the illite was modified by either bis[3-(triethoxysilyl)propyl] tetrasulfide (Si69-illite) or 3-mercaptopropyltriethoxysilane (KH580-illite). The interfacial interactions of SBR composites filled with pristine illite (illite/SBR) and Si69-illite (Si69-illite/SBR), or KH580-illite (KH580-illite/SBR) were characterized by bound rubber content and Payne effect measurements, while dynamic hysteresis losses of these uncured and cured composites were also analyzed under various strain amplitudes. It was found that the filler-rubber interactions were greatly improved for Si69-illite/SBR and KH580-illite/SBR systems compared to the illite/SBR composite. This leads to an increment of modulus at 300% strain of the composites from 3.46 MPa for illite/SBR to 7.70 MPa for Si69-illite/SBR and 12.96 MPa for KH580-illite/SBR. Moreover, lower rolling resistance and better wear resistance without compromising wet traction of Si69-illite/SBR and KH580-illite/SBR have been achieved. This demonstrates the high possibility of Si69 and KH580 modified illites as promising alternative fillers for reinforcing rubbers. [ABSTRACT FROM AUTHOR]