Foaming behaviors and mechanical properties investigation of high‐strength polyethylene terephthalate/polycarbonate bead foam

Abstract

Due to the low melt strength, PET foam cells easily grow, and due to the low CO2 concentration in PET, generating more nucleation sites during the foaming process is difficult. As a result, PET foam produced using the supercritical CO2 foaming method possesses a large cell size and a low expansion ratio, which leads to poor mechanical performance. In addition, there has not been much research on how to improve CO2 concentration in PET. In this work, the PC with higher melt strength and CO2 absorption capacity was incorporated into the PET matrix to improve the foaming behaviors of the blend. The results showed that the melt strength and CO2 concentration of PET/PC blends are much higher than that of pure PET. For instance, the melt strength and CO2 concentration of the PET/PC10 blend would be more than twice that of pure PET when the PC content is only 10%wt. By studying the foaming behavior, it was found that high melt strength inhibited the cell overgrowth and collapse of PET/PC foam, resulting in the foam with good cell structure was obtained. In addition, the high CO2 concentration in PET/PC blend is conducive to cell nucleation, thereby increasing the foam expansion ratio during the CO2 foaming process. Finally, the PET/PC blend foam with excellent mechanical properties was obtained. To be specific, the expansion ratio of the PET/PC blend foam was about 9.61, and the average cell size was only 40.38 μm. And the PET/PC blend foam possessed an excellent compressive strength of 7.41 MPa due to the strong interfacial bead cohesion, which showed the application prospect in the field of construction engineering.

Microwave-Induced Facile Molding of Lightweight and High-Strength Segregated-CNTs/Polycarbonate Foams

“…For the physical foaming process, the polymer and foaming agent are mixed to form a homogeneous system, and then the cell growth is completed by rapid depressurizing or rapid temperature rising to achieve the foaming expansion . Supercritical CO 2 (scCO 2 ) or supercritical N 2 (scN 2 ) is widely used in physical foaming processes owning to its stability, environmental friendliness, availability, and notably low cost features. − At present, the mainstream polymer foaming technologies include autoclave foaming, injection mold foaming, extrusion foaming, and vapor-based bead foaming. − The autoclave foaming process is characterized by simple operation. The polymer foam material with a significantly high foaming ratio can be achieved by precisely adjusting the foaming parameters such as temperature, pressure, impregnation time, depressurization rate, etc .…”

Phosphorus/Bromine Synergism Improved the Flame Retardancy of Polyethylene Terephthalate Foams

“…It is one of the structural core materials which have been widely used in the wind power field [ 3 ]. In addition, PET foam has low thermal conductivity, low water absorption, no rot, no mildew, easy to process and other characteristics, so it also would have a wide range of applications in automobiles, rail transportation, construction, ships, and other prospects [ 4 , 5 , 6 ]. Therefore, the flame retardancy of PET foams has become more and more critical, which affects its wide application in construction, automobiles and rail, etc.…”

“…Tg analysis data of PET/ZDP/DBDPE composites in an N 2 environment. Temperature at which the sample loses 5 wt% of its weight; 2 temperature at which the sample loses 5 wt% of its weight; 3 temperature at which the maximum rate of thermal decomposition occurs;4 actual mass residuals at 600 • C;5 actual mass residuals at 800 • C; 6 calculated mass residuals at 800 • C.…”