Polypropylene/pecan nutshell/ammonium polyphosphate biocomposites: a flame-retardant behavior

• Published in: Iranian polymer journal Vol. 32; no. 3; pp. 353 - 363
• Main Authors: Cabrera-Álvarez, Edgar Nazareo, Hernández-Gámez, José Francisco, Ramos-deValle, Luis Francisco, Sánchez-Valdés, Saúl, del Carmen Reyes-Vázquez, Nohemí, de León, Arxel, Córdova, Teresa, de León-Gómez, Ramón Enrique Díaz
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2023; Springer Nature B.V
• Subjects: Biomedical materials; Burning rate; Ceramics; Chemistry; Chemistry and Materials Science; Combustion; Composite materials; Composites; Elastic properties; Flame retardants; Glass; Heat release rate; Maleic anhydride; Natural Materials; Original Research; Particle size; Polymer Sciences; Polypropylene; Stiffness; Thermal stability; Flame retardant; APP; Pecan nut shell; Polypropylene; Biocomposites
• ISSN: 1026-1265; 1735-5265
• DOI: 10.1007/s13726-022-01128-7

This work focused on the study of physical, mechanical and flame-retardant properties of polypropylene (PP)/pecan nutshell (PNS) and ammonium polyphosphate (APP) biocomposites. The effect of PNS particle size and APP content on the final properties of the biocomposites was studied. Cone calorimetry showed that the addition of 30% (by weight) of PNS to PP reduces the pHRR (peak of the heat release rate) to 41% and improves the flame retardancy of PP. PNS with APP acts synergistically and further reduces the pHRR to 69%, due to the formation of a char layer during the combustion of materials. TGA showed that PNS particle size affects the thermal stability of the compounds, and all biocomposites have two stages of decomposition and formation of a carbonaceous residue. Further, DSC showed that PNS works as a nucleating agent, reduces ΔH c and increases T c of biocomposites, and this effect is more pronounced with 325 mesh particle size. UL 94 tests showed that PNS particle size affects the burning rate of the compounds and PP/PNS/APP reaches V2 rating. Finally, the addition of PNS in combination with APP produced an increase in the stiffness of the compounds, although the addition of maleic anhydride-grafted PP (PP- g -MA) provided elastic properties to PP/PNS/APP biocomposites. Graphical abstract