Chongda Wang

• Postdoctoral Researcher at University of Toronto

This work demonstrates the substantially improved thermal radiation blocking capability of polymer foams with the utilization of carbonaceous nanoparticles to overcome the limitation of the nanocellular foam's thermal insulation capability to achieve superinsulation. Without carbon, the radiation heat transfer becomes extremely high through thin an...

The limitations of the traditional low-pressure foam injection molding technique (such as cell nucleation at the gate, coupled growth and filling stages, and active coalescence) often lead to poor morphology and properties. In this work, the critical, but often overlooked, packing/holding stage that decouples the foaming and filling steps in high-p...

Carbon dioxide (CO2) in a supercritical condition is utilized to develop hierarchical cellular structures in injection molding. Polypropylene is used as sample semicrystalline polymer. First, a single-phase CO2-charged melt was produced under pressure. Then, a gradient cell structure was induced onto the polymer melt by pressure reduction and cryst...

Lightweight and open-cell thermoplastic foams have proven superior to common counterparts in terms of functional performances, such as oil absorption, sound and thermal insulation, contributing to energy saving, environmental protection, and sustainable development of the economy and society. Herein, a novel strategy was employed to prepare lightwe...

Although polypropylene (PP) foams fabricated by microcellular injection molding (MIM) have been widely studied and globally applied, it is still a big challenge to achieve lightweight products with high mechanical performance. Herein, the MIM method associated by a fast cooling design was applied to prepare lightweight bimodal nanoporous PP foams w...

This work aims to predict the thermal conductivity of microcellular and nanocellular thermal insulation foams to explore the correlation between the cellular structure and the thermal insulating properties. Closed-cell foam consisting of cell walls and struts was used as the base geometry for modeling. The mathematical correlations to calculate the...

Lightweight plastic foams are of great significance for saving resources and reducing energy consumption. Foam injection molding (FIM) shows a promising future to provide lightweight and shape‐complex plastic components. However, it is still challenging to produce lightweight and strong polypropylene (PP) foams by FIM due to PP's poor foaming abili...

In processes such as foam injection molding, due to the strong dependence of melt viscosity on gas content, the overall viscosity of a polymer melt will increase once the air phase (i.e., the bubbles) is developed in the polymer matrix. The diffusion of gas from the polymer melt into growing bubbles results in a gas concentration-dependent viscosit...

In this study, novel poly(vinylidene fluoride) (PVDF)/multiwalled carbon nanotube (MWCNT) nanocomposite foams with various foaming degrees (void fractions) were prepared using a home-made batch foaming process. The effects of the foaming degree in the range of 45.7% to 84.3% on the electrical conductivity, the dielectric permittivity, and the micro...

Polypropylene (PP) shows wide applications in many industries, especially for automotive. To save resources and energy, lightweight is an essential pursuit for industrial products. Foam injection molding (FIM) is a cost-effective method to manufacture lightweight plastic products, but it is still challenging to fabricate high-performance PP microce...

A novel simulation model has been developed that can predict cell growth tailored to high-pressure foam injection molding (HP-FIM) processes during the entire processing period. This was done together with systematic HP-FIM experiments using a visualization technique. The mathematical model that has been developed is based on the well-known Cell Mo...

Mold filling plays a crucial role in determining the cells’ structural morphology and uniformity in high-pressure foam injection molding. This process affects the formation, deformation, and dissolution of premature cells, which nucleate in the melt/gas mixture during the mold filling. We investigated the mold-filling phenomena and the cell structu...

Correction for ‘Modelling of thermal transport through a nanocellular polymer foam: toward the generation of a new superinsulating material’ by Guilong Wang et al. , Nanoscale , 2017, 9 , 5996–6009.

In this study, we found a simple and effective way to fabricate lightweight poly(vinylidene fluoride) (PVDF) /10wt% graphene nanoplatelet (GnP) nanocomposite foams with excellent EMI shielding effectiveness. To this end, solvent blending, film casting, and hot compression procedures were used. The PVDF/10wt%-GnP nanocomposite foams, which had diffe...

In this study, we used a batch foaming method to prepare closed-cell poly(vinylidene fluoride) (PVDF) foams with tailored microcellular structures. This is a simple, cost-effective, and environmentally-friendly method, and it offers a tunable microcellular structure that is wide ranging. The cell size and porosity volume of PVDF foams can be effect...

Polymer foam has become an important thermal insulation material due to its outstanding features, while its fabrication is still very challenging by foaming injection molding technology. Herein, we reported the successful fabrication of low-density branched polypropylene (BPP) foam with an expansion ratio of up to 25-fold and fine cellular structur...

We adopted an in-situ mold visualization technique and monitored the mold cavity pressure to investigate cell nucleation phenomena in high-pressure foam injection molding with mold opening. The cavity pressure was maintained by using a melt-packing pressure. Visualization results suggest that a proper packing pressure could re-dissolve cells, nucle...

We investigated the solidification behavior and foaming behavior of a grade polypropylene in high-pressure foam injection molding process by means of an in-situ mold visualization technique. We observed that the solidification behavior of polypropylene had a clear influence on the cell nucleation and on the final cellular morphology of the foam inj...

We investigated the cell-nucleation mechanisms in high-pressure foam injection molding for high expansion using the mold-opening technology. A polystyrene/carbon dioxide was used as the foam system. The cellular structure’s entire formation process was monitored using an in-situ mold visualization technique. Although mold opening was used to increa...

Nanocellular polymers have been considered promising multifunctional materials with unique properties. The key challenge is to fabricate nanocellular polymers with adequate cell sizes and densities. Herein, we report a novel method to prepare nanocellular polymethylmethacrylate (PMMA)/ thermoplastic polyurethane (TPU) with tunable structures. The n...

Polypropylene (PP) foams with a thermal conductivity of as low as 36.5 mW m− 1 K− 1 are fabricated by high-pressure foam injection molding followed by mold-opening with CO2 as a blowing agent. Regular PPs are not suitable for foaming due to their poor melt strength. To improve melt strength, the in-situ fibrillated blends of PP/polytetrafluoroethyl...

The superinsulating material plays a pivotal role in achieving the sustainable development of our modern world by improving the energy efficiency, and reducing the energy consumption and CO2 emission. The nanocellular polymer foam has been expected as a promising superinsulating material, but as yet not achieved. The understanding of thermal transp...

In this research, an analytical model was developed to describe the instantaneous location and angle of short fibers as a function of cell growth during foaming of fiber-filled polymer composites. The fibers located at the center line between two cells were considered at first. The final fiber angle as a function of the corresponding cell size and...