Lightweight Polypropylene/Polylactic Acid Composite Foams with Controllable Hollow Radially Gradient Porous Structures for Oil/Water Separation

Abstract

The structural characteristics of the polymer composite foams play an important role in their properties. Herein, the polypropylene/polylactic acid (PP/PLA) composite foams with the controllable hollow radially gradient porous structures are designed and prepared by the supercritical CO 2assisted foam extrusion coupled with postdrawing auxiliary technology. The above structures consist of the dense skin layer, hollow-core, closed-cell, and open-cell. Under the constant extrusion foaming temperature and pressure, the outer diameter of the as-prepared foams can be adjusted from about 9.8 mm to 5.7 mm, while the inner diameter changes from about 5.5 mm to 1.7 mm, by adding the PLA to regulate the viscoelasticity and thermodynamic differences of the polymeric melt. Besides, the formation mechanism of the hollow radially gradient porous structures is theoretically analyzed. The as-prepared PP/PLA composite foams exhibit outstanding oil/water separation performance, which show potential application in wastewater treatment.

Mechanically Robust Foamed Polypropylene/Bamboo Powder Composite Basketworks by CO2 Extrusion Foaming

“…As shown in Figures 1a and 3, the foams were obtained at the fixed foaming temperature of 160 °C and processing pressure of 6.4 MPa but their calendering gaps were changed (see g 1 −g 4 , g 1 > g 2 > g 3 > g 4 ). From the results of SEM images and expansion ratio, and in the analysis in our previous work, polymers were foamed in a molten state during the extrusion foaming process and the center temperature of foams was higher than their edges, 35,38 which was beneficial to the design of the central cellular structures. Moreover, to investigate the effect of the calendering molding process on foaming behavior, the DSC curves are shown in Figure S7a and melting temperature and crystallinity are summarized in Table S1.…”

“…Specifically, Zhou et al investigated the effect of maleic anhydride-grafted PP for PP/bamboo (33 phr) composite foams, indicating that the interfacial compatibility of PP and BP was improved distinctly and demonstrating improved mechanical properties (like modulus) . Moreover, our previous studies found that high melt strength PP with tensile strain hardening characteristics has outstanding foaming behavior under external stress field and can obtain the gradient porous structures. , …”

Highly Hydrophobic All-Biomass Aerogels with Advanced Oil Absorption and Recyclability

“…Aerogels have a significant advantage in removing high-density oily liquids. 5,40 The results indicate that the properties of the oily liquids themselves also affect the adsorption capacity of the oil-absorbing material. Oils with low densities and particularly high viscosities are detrimental to occupying all available space within the aerogel.…”

“…Environmental protection has received tremendous attention over the past years since water environments have been seriously polluted due to the leakage of petroleum and chemicals, which are extremely harmful to water resources and pose a long-term threat to human health, aquatic organisms, and the ecological environment. , With the vigorous development of the petroleum industry and the marine transportation industry, similar water pollution accidents occur frequently in many countries. There are several types of methods to deal with oil spills on the sea surface, such as physical methods, , chemical methods, and biological methods. , At present, the most commonly used one is the physical adsorption method. ,, The physical adsorption method relies on the use of oil-absorbing materials to achieve the adsorption of oil and is the most effective and cost-effective method for tackling oil pollution. Therefore, seeking an efficient and environmentally friendly oil absorption material with better performance has become urgent.…”

“…There are several types of methods to deal with oil spills on the sea surface, such as physical methods, 3,4 chemical methods, and biological methods. 5,6 At present, the most commonly used one is the physical adsorption method. 4,7,8 The physical adsorption method relies on the use of oil-absorbing materials to achieve the adsorption of oil and is the most effective and cost-effective method for tackling oil pollution.…”