Characterization and chemometric modelling of mechanically recycled polypropylene for automotive manufacturing

Bunjes, Alexander; Arndt, Jan‐Hendrik; Geertz, Guru; Barton, Bastian

doi:10.1016/j.polymer.2022.124823

Cited by 10 publications

(6 citation statements)

References 27 publications

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“…11a Mihelčič et al investigated mechanical, thermal and rheological properties of recycled PP with and without stabilization, 22 and Bunjes et al additionally included additive analytics in their study of virgin and recycled PP. 23 Considering levels of 500-3000 ppm of stabilizers are commonly used to protect the polymers during the first loop, the levels of active species (e.g., phosphite) found in recyclates (Table 1) are often not sufficient anymore to protect the polymer from degradation during reprocessing and re-use. In addition, impurities and contaminations have an impact on the stability of (and stabilization strategy for) recyclates.…”

Section: Plastic Additives In the Recycling Of Polyolefinsmentioning

confidence: 99%

“…On the other hand, the foundational work on the importance of stabilization of polyolefins in recycling by Pfaendner et al has recently been reviewed 11a . Mihelčič et al investigated mechanical, thermal and rheological properties of recycled PP with and without stabilization, 22 and Bunjes et al additionally included additive analytics in their study of virgin and recycled PP 23 …”

Section: Introductionmentioning

confidence: 99%

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Elucidating pathways of polypropylene chain cleavage and stabilization for multiple loop mechanical recycling

von Vacano,

Reich,

Huber

et al. 2023

Journal of Polymer Science

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Mechanical recycling is a decisive contribution for a sustainable circular economy of polypropylene (PP) but faces the challenge of processing‐induced and use‐phase accumulated molecular damage, exacerbated by multiple loop recycling. In this contribution, the molecular origin of degradation of PP under up to 30 repetitive reprocessing loops is analyzed together with the influence of stabilization, and processability data linked to changes of the entire molecular weight distribution. By comparison of experiments with simple Monte Carlo simulations, a coupled mechanism of random scission and shear‐induced cleavage can be inferred, while stabilizing additives effectively protect the material from progressing along this combined degradation pathway.

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Section: Plastic Additives In the Recycling Of Polyolefinsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Elucidating pathways of polypropylene chain cleavage and stabilization for multiple loop mechanical recycling

von Vacano,

Reich,

Huber

et al. 2023

Journal of Polymer Science

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“…7 Among the polymer resins, polypropylene is widely used due to its low density, chemical resistance, recyclability, and low cost. 2,8,9 Recently, different nanoscale and microscale reinforcement have been used for making a multifunctional composite such as carbon nanotube, graphene, talc, graphene oxide, boron nitride, 4,[10][11][12][13][14][15][16] but among the reinforcements, carbon fibers are preferred in the aerospace, windmill, and sporting goods sector. However, their adoption in the automotive sector is constrained by cost.…”

Section: Introductionmentioning

confidence: 99%

“…The high strength and stiffness of composites lead to reduce vehicle weight and help in increasing the range of electric vehicles 7 . Among the polymer resins, polypropylene is widely used due to its low density, chemical resistance, recyclability, and low cost 2,8,9 …”

Section: Introductionmentioning

confidence: 99%

The synergy of the matrix modification and fiber geometry to enhance the thermo‐mechanical properties of basalt fiber‐polypropylene composites for automotive applications

Balaji,

Shirvanimoghaddam,

Yadav

et al. 2024

J of Applied Polymer Sci

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Basalt fiber reinforced polypropylene composites with two initial fiber lengths (3.2 and 6.4 mm) were fabricated using twin‐screw extrusion compounding. In the case of composites with smaller initial fiber length, basalt fibers predominantly served as nucleating agents for polypropylene thereby resulting in an increase in the degree of crystallinity. The addition of polypropylene‐g‐maleic anhydride (PP‐g‐MA) caused the matrix to become amorphous, which was due to the establishment of a fiber–matrix interphase. This behavior was different for the composites with relatively larger initial fiber length especially at higher fiber content. The reduction in fiber length in the composites caused a decrease in crystallinity, as this hindered the ability of the polypropylene matrix to form crystals. Addition of PP‐g‐MA established a fiber–matrix interphase thereby synergistically contributing to the increased matrix amorphousness of the basalt fiber reinforced polypropylene composites with 6.4 mm initial fiber length. Reduced fiber length due to processing also accelerated the thermal degradation of the composites with an initial fiber length of 6.4 mm. However, the reduction in fiber length due to processing resulted in increased fiber orientation, which contributed to the improvement in tensile and flexural properties of the basalt fiber reinforced polypropylene composites with an initial fiber length of 6.4 mm. At 30% fiber content, the tensile strength and modulus of basalt fiber reinforced matrix modified polypropylene composites with 6.4 mm initial fiber length improved by 18% and 13% as compared with the composites with 3.2 mm initial fiber length.

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“…This highlights the importance of the reprocessing methodology but also demonstrates the difficulty of comparing the performance of recycled materials in the literature. Furthermore, chemical analysis studies of recycled PE and PP have revealed their variability, degradation and the presence of impurities and contaminants [38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical Properties of Virgin and Recycled Polypropylene—High-Density Polyethylene Blends

Jones,

McClements,

Ray

et al. 2023

Polymers

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This paper provides evidence and discusses the variability in the thermomechanical behaviour of virgin and recycled polypropylene/high-density polyethylene blends without the addition of other components, which is sparse in the literature. Understanding the performance variability in recycled polymer blends is of critical importance in order to facilitate the re-entering of recycled materials to the consumer market and, thus, contribute towards a circular economy. This is an area that requires further research due to the inhomogeneity of recycled materials. Therefore, the thermal and mechanical properties of virgin and recycled polypropylene/high-density polyethylene blends were investigated systematically. Differential scanning calorimetry concludes that both the recycled and virgin blends are immiscible. Generally, recycled blends have lower overall crystallinity and melting temperatures compared with virgin blends while, remarkably, their crystallisation temperatures are compared favourably. Dynamical mechanical analysis showed little variation in the storage modulus of recycled and virgin blends. However, the alpha and beta relaxation temperatures are lower in recycled blends due to structural deterioration. Deterioration in the thermal and mechanical properties of recycled blends is thought to be caused by the presence of contaminants and structural degradation during reprocessing, resulting in shorter polymeric chains and the formation of imperfect crystallites. The tensile properties of recycled blends are also affected by the recycling process. The Young’s modulus and yield strength of the recycled blends are inferior to those of virgin blends due to the deterioration during the recycling process. However, the elongation at break of the recycled blends is higher compared with the virgin blends, possibly due to the plasticity effect of the low-molecular-weight chain fragments.

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Characterization and chemometric modelling of mechanically recycled polypropylene for automotive manufacturing

Cited by 10 publications

References 27 publications

Elucidating pathways of polypropylene chain cleavage and stabilization for multiple loop mechanical recycling

Elucidating pathways of polypropylene chain cleavage and stabilization for multiple loop mechanical recycling

The synergy of the matrix modification and fiber geometry to enhance the thermo‐mechanical properties of basalt fiber‐polypropylene composites for automotive applications

Thermomechanical Properties of Virgin and Recycled Polypropylene—High-Density Polyethylene Blends

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