Properties of Composites Based on Recycled Polypropylene and Silico-Aluminous Industrial Waste

Abstract

There is an ever-growing interest in recovering and recycling waste materials due to their hazardous nature to the environment and human health. Recently, especially since the beginning of the COVID-19 pandemic, disposable medical face masks have been a major source of pollution, hence the rise in studies being conducted on how to recover and recycle this waste. At the same time, fly ash, an aluminosilicate waste, is being repurposed in various studies. The general approach to recycling these materials is to process and transform them into novel composites with potential applications in various industries. This work aims to investigate the properties of composites based on silico-aluminous industrial waste (ashes) and recycled polypropylene from disposable medical face masks and to create usefulness for these materials. Polypropylene/ash composites were prepared through melt processing methods, and samples were analyzed to get a general overview of the properties of these composites. Results showed that the polypropylene recycled from face masks used together with silico-aluminous ash can be processed through industrial melt processing methods and that the addition of only 5 wt% ash with a particle size of less than 90 µm, increases the thermal stability and the stiffness of the polypropylene matrix while maintaining its mechanical strength. Further investigations are needed to find specific applications in some industrial fields.

The Effect of Thermoplastic Elastomer and Fly Ash on the Properties of Polypropylene Composites with Long Glass Fibers

“…In the case of composites containing elastomer, PP-25G-E and PP-25G-C-E, a slight shift of these peaks to the left is observed, proof of the interaction between PP and the ethylene-propylene blocks in the elastomer. New FTIR bands at 1578 and 1541 cm −1 were observed in Figure 2 for PP-25G-C and at 1570 and 1543 cm −1 for PP-25G-C-E, being specific to the addition of the treated ash additive, more specifically from the dispersion agent used for the fly ash surface treatment [12], and can be associated with the -COO − antisymmetric stretching vibration group [37][38][39].…”

“…The preparation of fly ash as a reinforcing filler in polymer composites and its treatment with a dispersion agent was discussed in detail in a previous article by Teodorescu et al [12]. In that study, the ash powder was dried, milled and sieved to achieve particle sizes <90 µm and moisture content <0.1%.…”

“…The oxidic chemical composition determination for this fly ash revealed two major components: SiO 2 (56.24%) and Al 2 O 3 (22.44%). The surface of fly ash was treated with poly(propylene glycol adipate) and the modified ash powder, marked with C, was characterized by SEM, EDX, X-ray diffraction and FTIR analysis [12]. The treated ash powder and the glass fiber, compatibilizing agent, and thermoplastic elastomer were dispersed and mixed within the polypropylene matrix (marked with PP) using a Leistritz LSM 30.34 co-rotating twin screw extruder (Leistritz Extrusionstechnik GmbH, Nürnberg, Bayern, Germany) at a temperature of 180-205 • C (ranging from hopper to die), 220 rpm screw rotation speed and 450 rpm feeding rate.…”

“…In a study performed by Kutchko and Kim [11], it is pointed out that smaller-particle-size fly ash leads to better mechanical properties as long as the particles are well dispersed in the polymer matrix. In a previous investigation by Teodorescu et al [12], the characteristics of composites obtained from silico-aluminous industrial waste, similar in composition to fly ash, and recycled polypropylene were studied. Results showed improved thermal and mechanical properties as well as good adhesion between the small particles of ash and the polymer matrix due to the presence of compatibilizing and dispersion agents.…”

Mehaničko recikliranje jednokratnih zaštitnih maski

“…Various studies conducted between 2020 and the present have proposed methods for recycling and reusing DPMs. [2][3][4][5][6][7][8][9][10][11][12][13][14] The primary goal is to reduce, reuse, and recycle. Four potential recycling methods have been identified: 13 primary recycling (re-extrusion) an easy process capable of converting plastic waste into quality products; secondary recycling where the plastic waste is transformed into a new product by mechanical recycling involving segregation, purification, shredding, chopping, and granulation; tertiary recycling as a chemical process that converts a large macromolecule into a smaller molecule by depolymerisation employing heat, chemical agents, and catalysts; and quaternary recycling where energy is recovered from the waste plastic by incineration.…”