PhD Dissertation: Nargiz Aliyeva, DEVELOPMENT AND OPTIMIZATION OF NATURAL FIBER REINFORCED THERMOPLASTIC COMPOUNDS FOR SUSTAINABLE LIGHTWEIGHT AUTOMOTIVE COMPONENTS

DEVELOPMENT AND OPTIMIZATION OF NATURAL FIBER REINFORCED THERMOPLASTIC COMPOUNDS FOR SUSTAINABLE LIGHTWEIGHT AUTOMOTIVE COMPONENTS

Nargiz Aliyeva

Materials Science and Nano Engineering, PhD Dissertation, 2025

Thesis Jury

Prof. Burcu SANER OKAN (Dissertation Supervisor)
 Prof. Mehmet YILDIZ
Asst. Prof. Bekir DIZMAN
Assoc. Prof. Hatice Sinem ŞAŞ ÇAYCI
 Assoc. Prof. Bertan BEYLERGİL

Date & Time: December 18th, 2025 – 1:00 PM

Place: FMAN G056

Keywords : natural fibers, upcycled graphene, sustainable composites, lightweighting, life cycle assessment

Abstract

The transition toward sustainable and low carbon automotive manufacturing has increased the demand for recyclable and lightweight thermoplastic composites that can replace glass fiber reinforced polypropylene (PP). This research presents a multi-scale materials design strategy that integrates natural fibers, agricultural waste fillers, and sustainable nano carbon additives to develop high performance PP compounds with reduced environmental impact. Bast fiber reinforced PP formulations were developed to offer an alternative to long glass fiber (LGF)/PP used in semi structural components. Optimized pre-treatments for hemp and flax fibers reduced odor formation and improved interfacial adhesion, while a hybrid system containing bast fibers, compatibilizer, and upcycled graphene nanoplatelets achieved mechanical properties comparable to LGF/PP with lower density. Additional stiffness and strength were obtained through overmolding with biobased UD tapes. A broader set of agricultural residues, including walnut shell, coconut shell, rice husk, jute, kenaf, sawdust, etc. was evaluated to address applications that rely on short GF/PP. Flax/talc hybrid systems provided tunable mechanical performance, and talc contributed to higher melt flow and stable molding behavior. Sustainable nano carbon additives derived from waste tires, olive pomace, and similar biomass sources were also Non-Business incorporated. These graphene like nanosheets reinforced PP effectively at low loadings and demonstrated lower environmental impact than conventional graphene. Life Cycle Assessment confirmed cradle to gate CO2 reductions of about 24% for flax, GNP, and MAPP systems and up to 50% when recycled PP was used. The outcomes highlight a scalable route toward lightweight and environmentally responsible PP composites for automotive applications.