PhD Dissertation: Gizem KURTULMUŞ
REDUCTION OF VOLATILE ORGANIC COMPOUNDS IN WOOD PLASTIC COMPOSITES USING FUNCTIONALIZED HALLOYSITE NANOTUBES
Gizem KURTULMUŞ
Material Science and Nano Engineering, PhD Dissertation, 2025
Thesis Jury
Prof. Dr. Yusuf Ziya MENCELOĞLU (Thesis Advisor)
Prof. Dr. Hacer Ayşen ÖNEN
Prof. Dr. Nilgün KIZILCAN
Assoc. Prof. Dr. Serkan ÜNAL
Prof. Dr. Fevzi Çakmak CEBECİ
Date & Time: July 23rd, 2025 – 10:00 AM
Place: FENS L067
Zoom Link: https://sabanciuniv.
Keywords : Volatile Organic Compounds (VOC), Odor, Wood fiber (WF), Polypropylene (PP), recycled Polyolefin (rPO), Polyamide 11(PA11), Halloysite nanotube (HNT), Modified Halloysite Nanotube (Mod-HNT), Functionalization
Abstract
This thesis investigates the formulation of next-generation wood–plastic composites (WPCs) that meet the dual criteria of environmental responsibility and advanced material performance. It responds to increasing regulatory demands for eco-conscious material solutions, particularly in indoor environments where volatile organic compound (VOC) emissions generate unpleasant odors that hinder use in applications such as automotive interiors. The study investigates halloysite nanotubes (HNTs), their functionalized derivatives (Mod-HNTs), and β-cyclodextrin (β-CD) with regard to the capture of volatile organic compounds (VOCs) in Wood-plastic composites (WPCs), and their capabilities in odor reduction and structural changes. HNTs are naturally obtaining aluminosilicate nanotubes which have a high aspect ratio and being able to modify their internal and external surfaces. To improve their interaction with non-polar polymer matrices and polar VOCs, HNTs were surface-functionalized through aminosilane grafting and termed as Mod-HNT. β-CD which has a cyclic oligosaccharide with a toroidal molecular structure, enables the selective inclusion of odor-causing VOCs through host–guest complexation. WPCs were produced with high-shear thermo-kinetic mixing followed by injection moulding. The formulations consisted of 30 wt.% wood fiber (WF) and additive concentrations of 2 wt.% and 5 wt.%. Analytical techniques used included HS-GC-MS for VOC emissions, sensory jar testing for odor evaluations, TGA and DSC for thermal analysis, FTIR for interfacial chemistry investigation , SEM for morphological analysis, and tensile testing for mechanical property measurement. The results revealed that unmodified HNTs increased stiffness and slightly decreased VOC levels, while Mod-HNTs showed a reduction in VOCs up to 96% and improved the interaction between fiber and matrix. β-CD revealed selective binding attraction for aromatic and aldehydic compounds, causing increased ductility and strain-at-break. The combination of 5 wt.% Mod-HNT and 2 wt.% β-CD generated synergistic effects, improving both environmental and structural outcomes. Mechanical tests suggested a tensile strength increase up to 12%, as confirmed by SEM analysis. FTIR analysis proved chemical interactions between additives and polymers. Matrix polarity affected filler dispersion and performance. PA11- and rPO-based WPCs exhibited distinct morphologies and mechanical profiles. This study presents a framework for producing high-performance, low-emission composites complied with circular economy principles, using petroleum-based, renewable, and bio-based matrices.