Chengshuang Wang

Thermal, damping, and mechanical properties of thermosetting epoxy-modified asphalts

Epoxy-modified asphalts (epoxy asphalts) have been widely used in the pavements of orthotropic steel bridge deck. In this paper, several effects on the properties of epoxy asphalts have been investigated in detail. First, the addition of asphalts showed no significant effects on the curing reaction and the glass transition temperature of epoxy resin. Second, the damping properties of epoxy asphalts were increased with the addition of asphalt contents. Furthermore, mechanical results showed that the stress at yield, stress at break, and tensile modulus of epoxy asphalts decreased with the increase of asphalt contents, whereas the strain at break increased with the increasing asphalt contents. The morphology of phase separation for epoxy asphalts was also observed.

Thermal, mechanical, and morphological properties of soybean oil-based polyurethane/epoxy resin interpenetrating polymer networks (IPNs)

A series of interpenetrating polymer networks (IPNs) based on epoxy (EP) resin and polyurethane (PU) prepolymer derived from soybean oil-based polyols with different mass ratios were synthesized. The structure, thermal properties, damping properties, tensile properties, and morphology of soybean oil-based PU/EP IPNs were characterized by Fourier-transform infrared spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), universal test machine, and scanning electron microscopy (SEM). DSC and DMA results show that the glass transition temperature of the soybean oil-based PU/EP IPN decreases with the increase of PU prepolymer contents. Soybean oil-based PU/EP IPNs have better damping properties than that of the pure epoxy resin. The tensile strength and modulus of PU/EP IPNs decrease, while elongation at break increases with the increase of PU prepolymer contents. SEM observations reveal that phase separation appears in PU/EP IPNs with higher PU prepolymer contents.

Ladder- and bridge-like polynorbornenes with phosphate linkers: facile one-pot synthesis and excellent properties

A facile one-pot synthesis of a novel bridge-like polymer was accomplished by a sequential ring-opening metathesis polymerization (ROMP) and acyclic diene metathesis (ADMET) polymerization. A telechelic double-stranded poly(norbornene dicarboximide) (PNBI) with two terminal alkenyl groups was first prepared through the third generation Grubbs catalyst-mediated ROMP of a bis(NBI) derivative bearing a phosphate linker, in the presence of a symmetrical multifunctional terminating agent, and was then utilized as a macromonomer in the subsequent ADMET polymerization to yield a bridge-like polymer consisting of a non-conjugated polyolefin backbone and separated double-stranded PNBI. According to the TGA test, the amount of residual carbonaceous mass also increased with the molecular weight of the resultant polymers, indicating excellent thermal stability. The micro-scale combustion calorimetry and limiting oxygen index tests also displayed a superior flame retardant performance.