•Following structure change by FTIR, the aging characteristics of ABS/PC blend under UV-irradiation in air were studied.•The photo-oxidation-aging of the ABS/PC blend takes place predominantly at the ABS component.•The ABS/PC blend behaves higher photo-oxidation-stability than ABS has.Fourier Transform Infrared Spectroscopy (FTIR) is adopted to study the aging characteristics of poly(acrylonitrile–butadiene–styrene)/polycarbonate (ABS/PC) blend under UV-irradiation in air by analyzing the variation of the three main absorbance at about 967 cm− 1, 1720 cm− 1 and 3420 cm− 1 associated with carbon-hydrogen bonds belonging to 1,4 butadiene, carbonyl and hydroxyl groups, respectively. Results indicate that, under UV-irradiation in air, the photo-oxidation of the blend is not a simple combination of the photo-oxidation of corresponding ABS and PC themselves and takes place predominantly at the ABS component. Due to the interaction between the two components and the Fries rearrangement taken place in the PC component during the UV-irradiation in air, the ABS/PC blends behave higher photo-stability than ABS has.Download high-res image (313KB)Download full-size image

In this paper a series of di-block copolymers of L-lactide and (meth)acrylate [(M)A, representing methyl methacrylate, tert-butyl acrylate and 2-ethylhexyl acrylate] were synthesized by varying the molecular weight of the polylactide (PLLA) macroinitiator and the structure of the (meth)acrylate monomers. The glass transition temperature, crystallinity and thermal stability of copolymers with different poly(meth)acrylate [P(M)A] blocks were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results indicated that the glass transition temperature of the copolymers could be tuned by changing the chain structure and chain length of the P(M)A blocks. Besides, the crystallization of the copolymers was inhibited by the introduction of P(M)A blocks, and the toughness of the copolymers could be tuned. It is noted that the thermal stability of the copolymers depended on the type of P(M)A blocks and the PLLA/P(M)A blocks ratio. Furthermore, the microphase separation of copolymers in thin films was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the results showed that the composition of copolymers significantly affected the surface morphology of the block copolymer thin films.

La and Pr modified ceria–zirconia solid solution materials CeO2–ZrO2–La2O3–Pr6O11 (CZLP) were synthesized through a co-precipitation method, in which the influence of surface tension during the drying process on the textural/structural properties, reduction behavior and oxygen storage capacity of the materials was investigated. The difference in catalytic performance of the supported Pd-only thee-way catalysts was further studied. The results revealed that CZLP3 obtained through a supercritical ethanol drying method which eliminated the surface tension in the drying process exhibited a texture with a larger pore size and wider pore size distribution. Such texture is crucial to improve the thermal stability and anti-aging ability of materials. After calcining at 1000 °C, the specific surface area, cumulative pore volume and average pore radius of CZLP3-a were 52 m2 g−1, 0.52 cm3 g−1 and 20.3 nm, respectively. The XRD and Raman results revealed that a more homogeneous solid solution of Ce, Zr, La and Pr was formed, and the aging-treatment-induced segregation of phases was inhibited for CZLP3. Besides, the slightest grain growth after the aging treatment shown in TEM images indicated the superior anti-aging ability of CZLP3. The Raman and XPS analysis demonstrated the highest concentration of oxygen vacancies and surface Ce3+ species for CZLP3 both before and after the aging treatment, which contributed to the enhancement of its reduction properties and oxygen storage capacity. Consequently, Pd/CZLP3 exhibited outstanding three-way catalytic activity compared with the others both before and after the thermal aging treatment, indicating its tremendous potential possibilities.

Acrylamide (AAm) modified polyvinyl alcohol (PVA) with enhanced water solubility and tunable tacticity and crystallinity was prepared by alcoholysis of vinyl acetate (VAc) and acrylamide copolymers. The chemical structures and performance of VAc–AAm copolymers and AAm-modified PVA were measured by FTIR, UV-vis, XRD, elemental analysis as well as rheometry. FTIR and XRD analysis reveals that AAm units in PVA chain can reduce the stereoregularity effectively, and suppress the crystallinity. And a decreasing linear relationship between crystallinity and AAm mole fractions is observed. Furthermore, the influence of AAm modification on the water solubility of PVA was studied, and a significant enhancement either at low temperature (30 °C) or at high temperature (70 °C) was achieved through AAm modification. Moreover, the rheological investigation suggested that the relative strength of the hydrogen bonding interactions existing between PVA chains was weakened, while those between PVA chains and water molecules, to some extent, were enhanced after AAm modification. The method presented is an easy but promising way to prepare PVA that can have good water solubility even at low temperature while exhibiting high degrees of alcoholysis.

•Reactive PEG epoxide was synthesized and successfully grafted onto CNCs.•CNCs grafted with PEG (CNC-g-PEG) showed enhanced dispersion in PLA matrix.•CNC-g-PEG decreased glass transition and cold crystallization temperature of PLA.•CNC-g-PEG effectively improved the tensile strength of PLA composite nanofibers.•PLA/CNC-g-PEG (5%) scaffold showed improved biocompatibility with hMSCs.Poly(ethylene glycol) (PEG)-grafted cellulose nanocrystals (CNCs) were successfully synthesized and incorporated into poly(lactic acid) (PLA) as a reinforcing filler to produce nanocomposite scaffolds consisting of CNC-g-PEG and PLA using an electrospinning technique. Morphological, thermal, mechanical, and wettability properties as well as preliminary biocompatibility using human mesenchymal stem cells (hMSCs) of PLA/CNC and PLA/CNC-g-PEG nanocomposite scaffolds were characterized and compared. The average diameter of the electrospun nanofibers decreased with increased filler loading level, due to the increased conductivity of the electrospun solutions. DSC results showed that both the glass transition temperature and cold crystallization temperature decreased progressively with higher CNC-g-PEG loading level, suggesting that improved interfacial adhesion between CNCs and PLA was achieved by grafting PEG onto the CNCs. Wettability of the electrospun nanofibers was not affected with the addition of CNCs or CNC-g-PEG and indicating that the fillers tended to stay inside of the fiber matrix under electrical field. The tensile strength of the composite fiber mats was effectively improved by the addition of up to 5% CNC-g-PEG up to 5 wt.%. In addition, the cell culture results showed that PLA/CNC-g-PEG composite nanofibers exhibited improved biocompatibility to hMSCs, which revealed the potential application of this nanocomposite as the scaffolds in bone tissue engineering.