Lie Shen

A phosphorus-, nitrogen- and carbon-containing polyelectrolyte complex: preparation, characterization and its flame retardant performance on polypropylene

A new polyelectrolyte complex (PEC), containing phosphorus, nitrogen and carbon elements, has been prepared from positively charged polyethylenimine (PEI) and negatively charged phytic acid (PA). The PEC shows good performance in improving the thermo-oxidative stability and flame retardancy of pristine polypropylene (PP). When the content of PEC is 20 wt%, the char residues at 600 °C for the PP/PEC composites (PP/20PEC) are 10 wt% higher than those of pristine PP under an air atmosphere. Meanwhile, the peak heat release rate and total heat release of PP/20PEC are 314 W g−1 and 7.7 kJ g−1 lower than those of pristine PP, respectively. In comparison, PEI or PA is less effective than PEC in improving the thermo-oxidative stability and flame retardancy of pristine PP. Furthermore, the char residues of PP/20PEC are more full and compact, the surfaces of which are covered with a perfect intumescent layer. This work proposes a new guideline for designing and fabricating an intumescent flame retardant system.

Fabrication of superhydrophobic surfaces by smoke deposition and application in oil–water separation

Utilizing the smoke emitted by discarded silicone combustion, a simple method of smoke deposition is presented for fabricating a superhydrophobic surface with outstanding water repellence, which exhibited a water contact angle of 164 ± 0.8° and a sliding angle of lower than 1°. In addition, the as-prepared surface possesses favourable heat, water impact and water immersion stabilities. Oil leakages seriously endanger both the environment and the social economy. By this simple smoke deposition method, a selective-wettability copper mesh has been fabricated to separate oil–water mixtures. The smoke-deposited mesh achieved a high separation efficiency of over 93% for various oils, and showed excellent reusability, maintaining a high separation efficiency over 10 cycles. The water repellence of the used mesh can be refreshed by recoating with silicone and smoke deposition. This work provides a new strategy to utilize discarded silicone to fabricate superhydrophobic surfaces and oil–water separation meshes.

Stable superhydrophobic surface based on silicone combustion product

Discarded silicone products can be recycled to prepare superhydrophobic powder by simply burning and smashing. The powder can be used to fabricate a superhydrophobic surface with mechanical durability such that the superhydrophobicity was kept after 50 abrasion cycles. A robust electroconductive superhydrophobic surface can also be obtained by this simple method.

Rheological technique as a sensitive method to characterize the chain diffusion across the interface between polystyrene and carbon black filled polystyrene

ABSTRACT The mutual diffusion process and interphase development taking place at the interface between disks of polystyrene (PS) and carbon black filled polystyrene (CB-PS) in the molten state were investigated by a small-amplitude, oscillatory shear, rheological technique. The rheological method was employed to probe the thermorheological complexity of these polymer disks. It was found that the dynamic complex shear modulus, G*(t), increased with the time of contact in two time regimes at a fixed frequency. The time of transition between the two regimes was observed to be close to the time needed for the transition from the Rouse mode to the reptation mode. The results showed that the content of the carbon black and the temperature affected the slope of the G*(t) – t curve. Scanning electron microscopy revealed the interface disappeared when the diffusion process was complete.