Interference of Biodegradable Plastics in the Polypropylene Recycling Process

Abstract

Recycling polymers is common due to the need to reduce the environmental impact of these materials. Polypropylene (PP) is one of the polymers called ‘commodities polymers’ and it is commonly used in a wide variety of short-term applications such as food packaging and agricultural products. That is why a large amount of PP residues that can be recycled are generated every year. However, the current increasing introduction of biodegradable polymers in the food packaging industry can negatively affect the properties of recycled PP if those kinds of plastics are disposed with traditional plastics. For this reason, the influence that generates small amounts of biodegradable polymers such as polylactic acid (PLA), polyhydroxybutyrate (PHB) and thermoplastic starch (TPS) in the recycled PP were analyzed in this work. Thus, recycled PP was blended with biodegradables polymers by melt extrusion followed by injection moulding process to simulate the industrial conditions. Then, the obtained materials were evaluated by studding the changes on the thermal and mechanical performance. The results revealed that the vicat softening temperature is negatively affected by the presence of biodegradable polymers in recycled PP. Meanwhile, the melt flow index was negatively affected for PLA and PHB added blends. The mechanical properties were affected when more than 5 wt.% of biodegradable polymers were present. Moreover, structural changes were detected when biodegradable polymers were added to the recycled PP by means of FTIR, because of the characteristic bands of the carbonyl group (between the band 1700–1800 cm−1) appeared due to the presence of PLA, PHB or TPS. Thus, low amounts (lower than 5 wt.%) of biodegradable polymers can be introduced in the recycled PP process without affecting the overall performance of the final material intended for several applications, such as food packaging, agricultural films for farming and crop protection.

Effect of pine resin derivatives on the structural, thermal, and mechanical properties of Mater‐Bi type bioplastic

“…The test specimens were standard rectangular specimens (80 × 10 × 4 mm 3 ) and standard tensile specimens “1BA” (length ≥ 75 mm, width of 10 mm, and thickness ≥ 2 mm) according to UNE‐EN ISO 527 . Starchy materials are water sensitive and it has been observed that TPS‐based materials performances are influenced by the humidity (i.e., mechanical and thermal properties). Therefore, all samples were conditioned 24 h at 25 ± 1 °C and 50 ± 5% HR previous to be characterized.…”

Enhancing the Thermal Stability of Polypropylene by Blending with Low Amounts of Natural Antioxidants

“…Thus, PP is widely used for the production of short‐term applications, which generate a huge amount of plastic waste over years which can be recovered in the form of energy or material. Fortunately, more than 70% of plastic wastes are recovered in the form of materials using industrial recycling (31% of plastic waste) and in the form of energy (41.6% of plastic waste), closing the loop of the circular economy . That means that around 8.5 million tonnes of plastics are recycled every year .…”

Analysis of Thermomechanical Properties of Selected Class of Recycled Thermoplastic Materials Based on Their Applications

“…Scientists prefer polymer thermoplastics more than thermosets because of their low production cycle, lower processing costs, and high thermoplastic reparability [1,2]. Global polymer production has increased enormously to more than 330 million tons over the last five decades because polymers are widely used in industry [3][4][5][6]. In 2015, there were around 322 million tons produced worldwide, which was about 90 times higher than polymers produced in 1960.…”

“…In 2015, there were around 322 million tons produced worldwide, which was about 90 times higher than polymers produced in 1960. It was also reported that in the European Union, 58 million tons of polymers were produced and utilized, and only around 30% were recycled [3,4]. As a result of the growth in polymer production and utilization, large quantities of polymer waste are generated [7,8].…”

“…Also, as a side effect to consider, contamination by residues such as inorganic, organic, or biological residues cause deterioration of the polymers during recycling. Besides, the mechanical recycling of polymers introduces further problems owing to the complexity of the morphological structures that occur between the polymeric components [3,[31][32][33]. Based on the various mechanisms involved in the life cycle of polymers, the changes significantly alter the mechanisms of stabilization, mechanical, thermal, and rheological properties of recycled polymers [14,33,34].…”