Thermo-physical and mechanical characteristics of composites based on high-density polyethylene (HDPE) e spent coffee grounds (SCG)

Mendes, Juliana Farinassi; Martins, Jéssica Trindade; Manrich, Anny; Luchesi, Bruno Ribeiro; Dantas, Ana Paula Silva; Vanderlei, Rafael Marques; Claro, Pedro Ivo Cunha; Neto, Alfredo Rodrigues de Sena; Mattoso, Luiz H. C.; Martins, Maria Alice

doi:10.1007/s10924-021-02090-w

Cited by 35 publications

(29 citation statements)

References 70 publications

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“…This may be due to the size of the hemp fibers, which do not greatly affect the crystallinity of the compound. Similar results where the position of the peaks did not change were reported by Farinassi et al, who incorporated spent coffee grounds in a HDPE matrix [ 58 ]. In this sense, the distance between crystalline lattices is 0.21 nm for the (110) planes, and 0.19 nm for (200) lattices, following Bragg’s equation [ 59 ].…”

Section: Resultssupporting

confidence: 88%

The Effect of Varying the Amount of Short Hemp Fibers on Mechanical and Thermal Properties of Wood–Plastic Composites from Biobased Polyethylene Processed by Injection Molding

et al. 2021

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Biobased HDPE (bioHDPE) was melt-compounded with different percentages (2.5 to 40.0 wt.%) of short hemp fibers (HF) as a natural reinforcement to obtain environmentally friendly wood plastic composites (WPC). These WPC were melt-compounded using a twin-screw extrusion and shaped into standard samples by injection molding. To improve the poor compatibility between the high non-polar BioHDPE matrix and the highly hydrophilic lignocellulosic fibers, a malleated copolymer, namely, polyethylene-graft-maleic anhydride (PE-g-MA), was used. The addition of short hemp fibers provided a remarkable increase in the stiffness that, in combination with PE-g-MA, led to good mechanical performance. In particular, 40 wt.% HF drastically increased the Young’s modulus and impact strength of BioHDPE, reaching values of 5275 MPa and 3.6 kJ/m2, respectively, which are very interesting values compared to neat bioHDPE of 826 MPa and 2.0 kJ/m2. These results were corroborated by dynamic mechanical thermal analysis (DMTA) results, which revealed a clear increasing tendency on stiffness with increasing the fiber loading over the whole temperature range. The crystal structure was not altered by the introduction of the natural fibers as could be seen in the XRD patterns in which mainly the heights of the main peaks changed, and only small peaks associated with the presence of the fiber appeared. Analysis of the thermal properties of the composites showed that no differences in melting temperature occurred and the non-isothermal crystallization process was satisfactorily described from the combined Avrami and Ozawa model. As for the thermal degradation, the introduction of HF resulted in the polymer degradation taking place at a higher temperature. As for the change in color of the injected samples, it was observed that the increase in fiber generated a clear modification in the final shades of the pieces, reaching colors very similar to dark woods for percentages higher than 20% HF. Finally, the incorporation of an increasing percentage of fibers also increased water absorption due to its lignocellulosic nature in a linear way, which drastically improved the polarity of the composite

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Section: Resultssupporting

confidence: 88%

The Effect of Varying the Amount of Short Hemp Fibers on Mechanical and Thermal Properties of Wood–Plastic Composites from Biobased Polyethylene Processed by Injection Molding

et al. 2021

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“…al. [46] observed a very similar structure for SCG powder when studying composites with high-density polyethylene (HDPE). It was also reported that SCG particles tend to form small aggregates due to their hydrophilic characteristic.…”

Section: Morphology Of Scgsmentioning

confidence: 86%

“…al. [46] reported a decrease in ε b of HDPE of approximately 50%, in relation to neat HDPE, for a 30 wt.% SCG content.…”

Section: Mechanical Properties Of Pla/scg Compositesmentioning

confidence: 97%

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Improving the Mechanical Ductility and Toughness of Injection-molded Polylactide Pieces by the Dual Incorporation of Liquor Waste Derived Spent Coffee Grounds and Oligomers of Lactic Acid

Terroba-Delicado

Fiori²,

Torres‐Giner

et al. 2021

Preprint

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This work puts the Circular Bioeconomy’s concept into action, originally valorizing residues from the beverage liquor coffee industry into reinforcing fillers for green composites of polylactide (PLA). The as-received spent coffee grains derived from liquor waste were first milled to obtain the so-called spent coffee grounds (SCGs), which were then incorporated at 20 wt.% into PLA by extrusion. With the aim of improving the compatibility between the biopolyester and the lignocellulosic particles, two oligomers of lactic acid (OLAs), namely OLA2 and OLA2mal, being the latter functionalized with maleic anhydride (MAH), were both added during the extrusion process at 10 wt.%. The resultant compounded pellets were finally shaped into pieces by injection molding for characterization. Results showed that, as opposite to most claims published in the literature of PLA composites based on lignocellulosic fillers derived from soluble coffee wastes, the incorporation of liquor waste derived SCGs increased the ductility of the pieces by nearly 280% due to their high coffee oil content. The incorporation of OLA2 and OLA2mal contributed to improve the impact strength of the pieces by approximately 6% and 12.6%, respectively. The higher performance of OLA2mal was ascribed to a reduction of crystallinity in the green composite due to the chemical interaction by the MAH groups. However, the incorporation of SCGs into PLA slighlty reduced the thermal stability and yielded a dark-to-brown color, whereas it also delayed the disintegration rate of the pieces in controlled compost soil. Therefore, the results attained herein open up novel opportunities for the development of green composites of PLA with higher ductility and toughness through the valorization of liquor coffee wastes.

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“…Nevertheless, a 13% increase in the elasticity was observed with 10 wt.% of SCG. The incorporation of SCG did not modify the thermal properties, so the same processing conditions were used as in the neat HDPE matrix [ 110 ].…”

Section: Scg Polymer Compositesmentioning

confidence: 99%

Valorization of Spent Coffee Grounds as Precursors for Biopolymers and Composite Production

et al. 2022

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Spent coffee grounds (SCG) are a current subject in many works since coffee is the second most consumed beverage worldwide; however, coffee generates a high amount of waste (SCG) and can cause environmental problems if not discarded properly. Therefore, several studies on SCG valorization have been published, highlighting its waste as a valuable resource for different applications, such as biofuel, energy, biopolymer precursors, and composite production. This review provides an overview of the works using SCG as biopolymer precursors and for polymer composite production. SCG are rich in carbohydrates, lipids, proteins, and minerals. In particular, carbohydrates (polysaccharides) can be extracted and fermented to synthesize lactic acid, succinic acid, or polyhydroxyalkanoate (PHA). On the other hand, it is possible to extract the coffee oil and to synthesize PHA from lipids. Moreover, SCG have been successfully used as a filler for composite production using different polymer matrices. The results show the reasonable mechanical, thermal, and rheological properties of SCG to support their applications, from food packaging to the automotive industry.

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Thermo-physical and mechanical characteristics of composites based on high-density polyethylene (HDPE) e spent coffee grounds (SCG)

Cited by 35 publications

References 70 publications

The Effect of Varying the Amount of Short Hemp Fibers on Mechanical and Thermal Properties of Wood–Plastic Composites from Biobased Polyethylene Processed by Injection Molding

The Effect of Varying the Amount of Short Hemp Fibers on Mechanical and Thermal Properties of Wood–Plastic Composites from Biobased Polyethylene Processed by Injection Molding

Improving the Mechanical Ductility and Toughness of Injection-molded Polylactide Pieces by the Dual Incorporation of Liquor Waste Derived Spent Coffee Grounds and Oligomers of Lactic Acid

Valorization of Spent Coffee Grounds as Precursors for Biopolymers and Composite Production

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