Search

A series of long-chain branched polylactide (LCB PLA)/poly(D-lactic acid) (PDLA) blends with different low amounts of PDLA were prepared by a solution blending method. The formation of stereocomple...

A supertoughened ternary polylactide (PLA) blend with high heat deflection temperature was reported in this study. The ternary blend was composed of two major biocompatible and biodegradable polyme...

Conversion of carbon dioxide (CO2) to fuels and chemicals with the help of renewable hydrogen (H2) is a very attractive approach to reduce CO2 emissions and replace dwindling fossil fuels. However,...

Bisphenol A polycarbonate (PC) is difficult to crystallize. In this study, it was found that PC could rapidly accomplish melt crystallization only within 8 min by laying poly(ethylene glycol) (PEG) film on it. Polarized optical microscope (POM) was applied to trace the growth of spherulites of PC in PEG/PC double-layer films during isothermal crystallization in a wide range of temperatures, which were above the melting temperature for PEG. The dependence of spherulitic growth rate (G) on isothermal crystallization temperature (Tc) followed a “bell-shape” curve, just like some other semicrystalline polymers did. A PEG film was laid on a PC film at 250 °C for 5 min to obtain a PEG/PC double-layer film, which was subsequently quenched to different Tc’s for observation on its crystallization process by using POM. It was surprising to observe that the spherulitic growth rate of PC was significantly improved and the crystallization time was obviously shortened. The miscibility for PEG/PC blends was evaluated by...

The effects of flowing preformed spherulites on shear-induced melt crystallization behaviors of isotactic polypropylene (iPP) had been investigated by using a Linkam shearing cell coupled with an optical microscope, atomic force microscope, and rheometer. By quenching iPP melt to 130 °C for a short time, preformed spherulites were intentionally obtained. While iPP films were heated up to temperatures below the nominal melting point of iPP (164 °C), various shear conditions were applied, and then the crystalline morphologies during crystallization at the isothermal crystallization temperature of 135 °C were traced by alternately using phase contrast optical microscopy and polarized optical microscopy modes. Two distinct highly orientated thread- and cylinder-like crystalline morphologies were induced by shearing with preformed spherulites present, which were dependent on the applied shear rate and temperature. The distinct crystalline morphologies were attributed to relative movements between shear flowing...

Through thermal annealing above the glass transition temperature, a supertoughened binary blend with the highest notched Izod impact strength of 98 KJ/m2 was achieved, which was about 52 times of that of neat polylactide (PLA; 1.9 KJ/m2). The binary blend was composed of biocompatible and biodegradable PLA and ethylene–acrylic ester–glycidyl methacrylate terpolymer (EGMA) elastomer at the composition of 80/20 PLA/EGMA. For one toughened binary blend with the notched Izod impact strength of 94 KJ/m2, its tensile elongation at break was kept above 120%. Moreover, this supertoughened binary blend also displayed a much higher heat deflection temperature for application. Thermal annealing induced crystallization of the PLA matrix in the blend, and a linear correlation between the notched Izod impact strength and crystallinity was revealed. The possible toughening mechanism for the PLA/EGMA 80/20 blend with thermal annealing was analyzed from the viewpoint of negative pressure effects, as imposed on EGMA elasto...

The fate of alkoxy radicals formed in the atmospheric oxidation of benzene initiated by OH radical is investigated by using quantum chemistry and kinetics calculations. The two alkoxy radicals (R2 and R3), formed from the commonly accepted bicyclic radical intermediates, are found to undergo ring-closure preferentially, in addition to the ring-breakage, as suggested in previous studies. The ratio between the ring-closure and ring-breakage is ∼2:1. The ring-closure route will lead to equal amounts of glyoxal and 2,3-epoxybutandial, while the ring-breakage route leads to glyoxal and butenedial. Overall, the new mechanism suggests the yield of glyoxal to be three times that of butenedial, consistent with the previous experimental measurements. The new mechanism calls for the search of the newly proposed product 2,3-epoxybutandial.

Although nanocarbon-based nanofillers have been widely used to improve the energy-storing and sensing functions of porous materials, the comparison of the effects of different nanocarbon-based fillers on the capacitive and flexible sensing properties of nanocarbon-based porous sponge composite supercapacitor electrodes by combining a carbon nanotube, graphene, and graphene oxide with porous sponge is incomplete. The specific capacitance of carbon nanotube-based electrodes is 20.1 F/g. The specific capacitance of graphene-based electrodes is 26.7 F/g. The specific capacitance of graphene oxide-based electrodes is 78.1 F/g, and the capacity retention rate is 92.99% under 20 000 charge-discharge cycles. Under a bending load of 180 degrees, the capacitance retention rate of graphene oxide sponge composite electrodes is 67.46%, which indicates that the prepared electrodes of supercapacitor have the advantages of high capacitance and good flexibility at the same time. To demonstrate their performance, an array of three graphene oxide supercapacitors in series was constructed, which could light up a red light-emitting diode (LED). The tensile strength of carbon nanotube sponge composite electrodes is 0.267 MPa, and the tensile linearity is 0.0169. The experimental results show that graphene oxide-based sponge composite supercapacitor electrodes have the best capacitance performance and carbon nanotube sponge composites have the most potential as a flexible sensor. Refereed/Peer-reviewed