Bingli Pan

Wear Performance and Mechanisms of Polyphenylene Sulfide/Polytetrafluoroethylene Wax Composite Coatings Reinforced by Graphene

Polyphenylene sulfide (PPS) composite coatings reinforced by graphene were prepared through a spraying method. Wear performance of the composite coatings were evaluated using a block-on-ring test rig, and the results showed that the wear life of the composite coatings were over seven times higher than that of a pure PPS coating. Wear mechanisms of PPS composite coatings reinforced by graphene are discussed. It was concluded that adhesive wear was the major wear mechanism of the pure PPS coating but the wear form of the composite coatings was dominated by abrasive wear due to the graphene filler that has high mechanical strength. In addition, fatigue wear appeared for composite coatings with higher content of graphene. The formation of a uniform thin transfer film on the counterpart ring and fine wear debris for the composites coatings during abrasion were consistent with the improvement of wear performance. The 3D morphology of the surface of the counterpart ring was also used to discuss the wear mechanism of PPS composite coatings.

Effect of polyethyleneimine modified graphene on the mechanical and water vapor barrier properties of methyl cellulose composite films

A series of novel methyl cellulose (MC) composite films were prepared using polyethyleneimine reduced graphene oxide (PEI-RGO) as an effective filler for water vapor barrier application. The as-prepared PEI-RGO/MC composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, tensile test and scanning electron microscopy. The experimental and theoretical results exhibited that PEI-RGO was uniformly dispersed in the MC matrix without aggregation and formed an aligned dispersion. The addition of PEI-RGO resulted in an enhanced surface hydrophobicity and a tortuous diffusion pathway for water molecules. Water vapor permeability of PEI-RGO/MC with loading of 3.0% of surface modified graphene was as low as 5.98×10-11gmm-2s-1Pa-1. The synergistic effects of enhanced surface hydrophobicity and tortuous diffusion pathway were accounted for the improved water vapor barrier performance of the PEI-RGO/MC composite films.

Reinforcing Effect of Low Polyethylene Wax Content on Polydicyclopentadiene

Polydicyclopentadiene (PDCPD)/polyethylene wax (PEW) blends containing a low content of PEW were prepared by in situ polymerization. The results of mechanical properties showed that the PEW was an effective reinforcing modifier of the PDCPD matrix. Through studying the microstructure of the blends by scanning electron microscopy and dynamic mechanical analysis, the reinforcing mechanisms were discussed. This paper is expected to broaden the selection of reinforcing modifiers of PDCPD and the use of dicyclopentadiene as a healing agent in self-healing applications.

The Adaptive Tribological Investigation of Polycaprolactam/Graphene Nanocomposites

The design and mechanism of adaptive materials in the field of tribology are of particular importance because of the tribological properties greatly depending on the operating conditions and external environment. Polycaprolactam (PCL) adaptive nanocomposites containing porous graphene impregnated with solid paraffin were prepared by in situ polymerization. The tribological results showed that the designed nanocomposites, which displayed adaptive tribological behaviors, had low and stable friction coefficients and the wear rates compared to neat PCL even under high pressure and velocity condition. The proposed adaptive tribological mechanisms are due to the high load-carrying capabilities of graphene nanosheets forming proper surface texture, the lubricating role of molten paraffin produced at sliding interface under friction heating and the mitigated thermal damage caused by lower surface temperature through depleting friction heat. The as-prepared polycaprolactam composites are expected to broaden the application of such polymers in engineering parts, and the design concept can easily apply to other self-adaptive tribological composites.

Graphene Oxide Reinforced Alginate/PVA Double Network Hydrogels for Efficient Dye Removal

Dually crosslinked graphene oxide reinforced alginate/polyvinyl alcohol (PVA) double network (DN) hydrogels were prepared via a facile freeze/thaw method followed by soaking in a Ca2+ solution. The morphology and structure of the hydrogels were systematically examined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The effects of pH, dosage of hydrogel, adsorption time, and temperature on the adsorptive property of DN hydrogels towards methylene blue (MB) were also studied. Results indicated that the hydrogels exhibited typical 3D porous structures and had an efficient adsorption effect towards MB due to strong interactions between DN hydrogels and MB molecules. The adsorption isotherm was found to coincide with the Langmuir model with a monolayer adsorption. The highest adsorption capacity of DN hydrogels for MB was examined as 480.76 mg·g−1.

Silica /polydicyclopentadiene nanocomposites: Preparation, characterization, and mechanical properties

ABSTRACT Silica/poly-dicyclopentadiene (SiO2/poly-DCPD) nanocomposites with improved mechanical properties were successfully prepared by in-situ ring-opening metathesis polymerization (ROMP) using reaction injecting molding (RIM) technique in this work. To improve the interfacial compatibility between SiO2 nanoparticles and poly-DCPD matrix, polystyrene (PS) was chemically modified onto the surface of SiO2 nanoparticles to obtain oil-soluble polystyrene coated silica spheres with core-shell structure (PS@SiO2). The mechanical behaviors of SiO2 /poly-DCPD nanocomposites with different PS@SiO2 content have been investigated in detail. The improved mechanical properties of SiO2 /poly-DCPD nanocomposites were mainly attributed to the well interfacial compatibility between the PS shell layer of PS@SiO2 spheres and poly-DCPD matrix, which resulted from the swelling of DCPD monomer in PS shell before polymerization.

In-situ polymerization of silica/polydicyclopentadiene nanocomposites: Improved tribological properties and evaluation of interfacial compatibility

ABSTRACT Polymer materials concluding polydicyclopentadiene (poly-DCPD) are widely used in engineering fields but have low load-carrying capacities which limit its widely application. SiO2/poly-DCPD nanocomposites were prepared by in situ polymerization in this work. polystyrene (PS), chemically modified onto the surface of SiO2 nanoparticles to obtain oil-soluble polystyrene coated silica spheres with core-shell structure (PS@SiO2), was used to improve the interfacial compatibility between SiO2 nanoparticles and poly-DCPD matrix. Field-emission scanning electron microscope (FESEM) was used to observe and evaluate the interfacial structure of SiO2/poly-DCPD nanocomposites. The tribological behaviors of SiO2 /poly-DCPD nanocomposites with different PS@SiO2 loading have been investigated detailly in this work. The results showed that the addition of PS@SiO2 nanospheres could greatly decrease friction coefficient and wear rate of the SiO2/poly-DCPD nanocomposites, especially when the loading of PS@SiO2 nanospheres arrived to 4 wt%. The well interfacial compatibility between the PS shell layer of PS@SiO2 spheres and poly-DCPD matrix should be resposible for the improved tribological properties of SiO2 /poly-DCPD nanocomposites.

The Tribological and Mechanical Properties of Pdcpd/Pew Composites Prepared by Reaction Injection Moulding

In order to improve mechanical performance and wear resistance of polydicyclopentadiene (PDCPD) by convenient methods and technologies, novel PDCPD/polyethylene wax (PEW) composites were prepared by in-situ polymerization in a simulated reaction injection moulding. Studies on the mechanical and tribological properties of the composites were carried out. The bending strength and hardness of PDCPD/PEW composites significantly improved compared with neat PDCPD. The incorporation of PEW in PDCPD greatly enhanced the wear resistance and reduced the friction coefficients. The wear mass loss and friction coefficients for PDCPD/ PEW composites decreased continuously in the range of our experiments. The SEM micrographs of the worn surface showed the friction and wear mechanism of PDCPD.