Wang Xiaoqun

Manufacturing and Characteristics of Glass Reinforced PTFE

A study on reinforced Polytetrafluoroethylene (PTFE) with chopped glass fiber or glass cloth was described. This study included manufacturing process of fibrous PTFE, the effects of the content of chopped glass fiber or glass cloth on the tensile strength and dielectric properties of the reinforced PTFE and the effect of filling particles on tensile strength and morphology of PTFE composites, etc. Our results showed that about 11% chopped fiber or 37% glass cloth reinforcing PTFE had the highest tensile strength and acceptable dielectric properties. Crystallizing phenomenon of PTFE was readily observed with the adding of particles. Finally, predicting of dielectric properties was discussed.

Molecular dynamics simulations of interfacial adhesion between carbon fibers and various epoxies/hardeners and its calorimetric validation

Separate molecular dynamics simulations are carried out to study interfacial interactions between various monomers of epoxies and their hardeners with T300 and CCF300 carbon fibers. Atomistic models of T300 and CCF300 carbon fibers, both in sized and unsized states, are prepared on the basis of their X-ray Photoelectron Spectroscopy data. Calorimeteric measurement of heat of adsorption is used to validate the simulated values of interfacial interactions. Results demonstrate a ranking of epoxies and hardeners on the basis of their interfacial adhesion with T300 and CCF300 carbon fibers.

Microwave curing process and mechanical properties study of epoxy mortars for repairing concrete pavement rapidly

Polymer mortars are used frequently to repair pavement owing to their excellent properties (mix flexural strength ≥5.75 MPa, compressive strength ≥25 MPa). To repair concrete pavement with polymer mortars rapidly, uniform microwave energy can be used to reduce hardening time of polymer mortars. In this study, the distribution of electromagnetic fields in an industrial microwave facility was optimized, and an area AG with uniform and intensive electric field was obtained. Then microwave curing process of epoxy mortars containing fly ash in the area AG was optimized, and mechanical strengths of the epoxy mortars cured in the optimum process were tested. The results show that, although the distribution of electromagnetic fields in the microwave facility is non-uniform overall, there still are some brush-fire areas, where electric field distribution is relatively uniform. Epoxy mortars added with 10 wt% fly ash can be cured rapidly (approximately 20 min) in the area AG and exhibit outstanding mechanical strengths, which can be used to repair concrete pavement rapidly.

Co-intercalation of Montmorillonite by Poly(oxypropylene) Amine Hydrochlorides with Different Chain Length

In order to improve the performance of polymer/montmorillonite nanocomposite, montmorillo- nite (MMT) must be modified organically so that the hydrophobicity of MMT and the compatibility between polymer and MMT can both be increased. In spite of this, it is also necessary to enlarge the basal spacing of MMT. In this paper, a new method was developed to co-intercalate MMT with two poly(oxypropylene) amine hydrochlorides with different chain length. Therefore, two kinds of co-intercalated MMTs, D400-D2000-MMT and D400-T5000-MMT were prepared. Their basal spacing, organic fraction and ther- mal stability were investigated by XRD and TGA, respectively. In addition, the effect of stirring methods and the number of intercalation times were also investigated. The results show the co-intercalation method can largely increase the basal spacing and organic fraction of MMT modified with D400. T5000 amine hydrochloride is much better than D2000 to increase the basal spacing (6.86 nm) and organic fraction (64.06%) of co-intercalated MMT because of the cage structure comprised of branched chain of T5000 between the layers of MMT co-intercalated.