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This study presents the preparation of post‐consumer polypropylene (r‐PP) composites filled with 30 wt% yerba mate (YM) stick particles. To improve the fiber–matrix adhesion, three surface treatments were performed: alkaline treatment with sodium hydroxide (NaOH) and use of 3‐aminopropyltriethoxysilane (APTS) and maleic anhydride graft polypropylene copolymer (PP‐g‐MA) as coupling agents. Mechanical properties including tensile, flexural, and impact resistance were determined, and chemical (Fourier transform infrared spectroscopy [FTIR]), physical (water absorption), and morphological analyses were performed. The main findings show that the treatments were efficient in improving the mechanical properties of the composites, with emphasis on the r‐PP/YM30/APTS and r‐PP/YM30/PP‐g‐MA composites, which proved to be superior in tensile, flexion and impact strength and absorption of water compared to the untreated composite. The morphological analysis showed a better interaction between the fiber and the polymeric matrix for the composites with YM/APTS and YM/PP‐g‐MA, which corroborates the results of tensile and flexural strength, as well as with the spectra of FTIR in which the chemical modification of the fibers is observed. However, the results show that these treatments are promising in obtaining composites with recycled matrix with better properties.

Tetrafluoroethylene–perfluoroalkyl vinylether copolymer (PFA) has a broad application ranging from biomedical and aerospace to corroding environments in the chemical industry. Despite a low share in end‐of‐life products, PFA processing can produce up to 30% of waste. Thus, understanding how recycled fluorinated polymers affect product performance is crucial to ensure primary recycling, besides economic and environmental reasons. In this paper, the utilization feasibility of PFA waste materials is investigated, i.e., recycled PFA (PFAr) in closed‐loop recycling. The effect of PFAr loading (5–100 wt.%) on the thermal, mechanical, rheological, and color properties and chemical resistance are studied. Thermal properties and chemical resistance showed no significant changes in all ranges of PFAr content tested. The addition of higher loads of PFAr (≥50 wt.%) leads to a reduction in mechanical properties, particularly stress‐strength analysis and elongation at break. However, elastic modulus and hardness have improved concurrently with an increase in the degree of crystallinity. The decrease in complex viscosity and yellowing of the samples occurred probably induced by a polymer chain degradation. Despite that, the addition of up to 10 wt.% of PFAr proved to be an effective alternative to reusing PFA residues based on mechanical recycling.

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A new oleic acid derivative plasticizer, epoxidized trimethylolpropane trioleate (EPO), has been synthesized and its application in PVC formulations compared with di(2-ethylhexyl) 1,2-cyclohexanoate (DOCH/DEHCH), a commercial phthalate-free plasticizer of petrochemical origin. EPO and their blends with DOCH were added to PVC resin (50 PHR) and the plasticized PVC has been characterized by thermal and mechanical measurements. EPO demonstrated good compatibility with the PVC resin improving the thermal stability and elongation at break. Due to EPO high molar mass, a slight increase in the glass transition temperature and hardness was observed as the content of EPO in the plasticizer blend increased. The results indicate that EPO is a potential plasticizer for PVC when pure and, by replacing 50% of DOCH, the PVC compound shows similar properties to pure DOCH, but better elongation at break and thermal stability.

The aim of this work was to evaluate the influence of the use of coupling agent (CA) on the properties of thermoplastic composites produced from post-consumer polypropylene (rPP) and malt bagasse fibers (MB) of brewing industry. The CA used was maleic anhydride graft polypropylene copolymer (MAgPP). The study was carried out in two stages: in first step the best concentration of MB fibers was verified, where was varied the fiber contents between 0, 10, 20 and 30% (w/w); in the second step, the best MB concentration evaluated was used with different CA concentrations (0, 1, 3, 5 and 7% w/w). Of the three MB concentrations evaluated as reinforcing filler, the sample with a 30% (w/w) ratio presented 44% lower deformation than the others, presenting better mechanical resistance, although it also presented the highest water absorption. Thus, the 30% MB fiber content was chosen for two step, where the results showed that the PP/MB-30 composite treated with 3% (w/w) CA had a modulus of elasticity 10.3% higher than the same composite without CA, corroborating with the morphological analysis, which indicated better interfacial adhesion between composite components when CA was used. The PP/MB-30 composite treated with 1% (w/w) CA showed the highest thermal stability among all samples.

To evaluate the hydrophilic capacity, polypropylene and surfactant (polyether siloxane) samples were extruded in the proportions of 0.0, 0.5, 1.0 and 3.0 (wt%) and films were obtained in a heated press. The samples were submitted to measurements of contact angle, surface tension, melt flow index and surface roughness. The results indicated that increasing surfactant content promoted better wettability and consequently higher hydrophilicity. Using water, the increase in the surfactant content reduced the contact angle (92.58° to 68.10°) and increased the surface tension (26.7 to 56.9 mN.m-1). However, with ethylene glycol, increasing the surfactant content promoted a small variation on the contact angle (59.14° to 65.10°) and on the surface tension (5.5 to 5.0 mN.m-1). The surfactant promoted a slight change in the melt flow index but not affected the roughness of the samples.