Upgrading Recycled Polypropylene from Textile Wastes in Wood Plastic Composites with Short Hemp Fiber

Abstract

This research reports the manufacturing and characterization of green composites made from recycled polypropylene obtained from the remnants of polypropylene non-woven fabrics used in the textile industry and further reinforced with short hemp fibers (SHFs). To improve the interaction of the reinforcing fibers with the recycled polymeric matrix, two types of compatibilizing agents (maleic anhydride grafted, PP-g-MA, and maleinized linseed oil, MLO) were added during melt-processing, the percentage of which had to remain constant concerning the amount of fiber loading to ensure complete reactivity. Standardized test specimens were obtained by injection molding. The composites were characterized by mechanical (tensile, impact, and hardness), thermal (DSC, TGA), thermomechanical, FTIR, and FESEM microscopy tests. In addition, color and water uptake properties were also analyzed. The results show that the addition of PP-g-MA to rPP was satisfactory, thus improving the fiber-matrix interaction, resulting in a marked reinforcing effect of the hemp fibers in the recycled PP matrix, which can be reflected in the increased stiffness of the samples. In parallel to the compatibilizing effect, a plasticizing effect was obtained by incorporating MLO, causing a decrease in the glass transition temperature of the composites by approximately 6 °C and an increase in ductility compared to the unfilled recycled polypropylene samples.

Green Composites from Partially Bio-Based Poly(butylene succinate-co-adipate)-PBSA and Short Hemp Fibers with Itaconic Acid-Derived Compatibilizers and Plasticizers

“…It can be seen that the adhesion and interaction between the lignocellulosic filler and the matrix is poor, due to the huge gap that exists between them. This is due to the filler being highly polar, while the matrix is mostly non-polar, promoting voids at the interface; this is indicative of some incompatibility between the polymer matrix and the fillers [ 56 ].The difference in polarity provokes a debonding phenomenon during the impact test, as was also observed by Burgada et al [ 35 ]. This poor adhesion is responsible for the poor mechanical properties observed in the previous section.…”

“…Figure 1 a shows the fracture surface of neat BioPBSA. The observed morphology is the typical rough surface ascribed to the plastic deformation of the polymer, which is indicative of its highly ductile behaviour [ 35 ], as it was stated in the mechanical properties due to an extremely high elongation at break. Figure 1 b shows the addition of hemp fibers into BioPBSA.…”

“…As a result of these strategies it is possible to produce components with a wide range of applications, such as indoor and outdoor furniture, manufacturing of automotive parts [ 30 ], building structures [ 31 , 32 ], or textile applications [ 33 ]. In particular, hemp fiber has been used effectively as a reinforcement in polymeric matrices such as polyethylene (PE), polypropylene (PP) and even polylactic acid (PLA) [ 34 , 35 , 36 ].…”

Peroxide-Induced Synthesis of Maleic Anhydride-Grafted Poly(butylene succinate) and Its Compatibilizing Effect on Poly(butylene succinate)/Pistachio Shell Flour Composites

“…In general, a direct relationship can be observed between the amount of this type of waste derived filler, based on lignocellulose and the total water absorbed in the polymer composite sample [ 91 ]. This fact is ascribed to the hydrophilic nature of lignocellulose due to the large amount of free –OH groups on the filler surface [ 92 ]. For instance, water uptake increased up to 2.23 wt.% for the green composite pieces filled with 10 wt.% PSF, that is, PBS-10PSF, whereas it reached a value of 6.14 wt.% for a 30 wt.% filler loading, that is, PBS-30PSF.…”

Multi-Scale Study of the Small-Strain Damping Ratio of Fiber-Sand Composites

“…The polypropylene fibers consist of a polymeric material (propylene-based synthetic) with average dimensions of 12 mm in length and 0.03 mm in diameter (circular cross section), with a specific gravity of 0.9 [1,17,18]. Note that this type of fibers may find, apart from geotechnical engineering, many applications in textile science, industrial engineering and also in the improvement of structural materials [46][47][48][49][50][51][52][53][54][55]. Apart from the composite materials of the 12 different laboratory created sands with polypropylene fibers, which were used for the resonant column tests (i.e., bulk samples) to investigate the small-strain damping ratio of fiber-reinforced sand, additional microscopic (grain-scale) experiments were performed so that to provide multi-scale insights on the behavior and energy dissipation mechanisms of these composites.…”