Mechanical Properties of Functionalized Electrochemical Exfoliated Graphene in Polypropylene
Author
Hansen, Marc Hove
Term
4. semester
Education
Publication year
2018
Abstract
This thesis investigates how to improve the dispersion and mechanical performance of polypropylene–graphene nanocomposites when the graphene is produced by electrochemical exfoliation. Graphene was obtained by exfoliating graphite in sulfuric acid electrolytes at 0.1–1 M, and Hansen solubility parameter analysis indicated that higher acid concentration increases the hydrogen-bonding contribution and introduces more structural defects in the graphene. Guided by HSP and a small dispersion trial, the graphene was functionalized with octadecylamine (ODA) to enhance compatibility with polypropylene. Nanocomposites were prepared by melt compounding, extrusion, and injection molding, and characterized by optical microscopy, Raman spectroscopy, and X-ray diffraction, with thermal behavior assessed by differential scanning calorimetry and mechanical behavior by tensile and creep tests. The findings show that ODA-functionalized graphene disperses better in polypropylene than unmodified graphene. Creep resistance and maximum stress are slightly increased, whereas Young’s modulus decreases. In addition, graphene acts as a nucleating agent, raising the degree of crystallinity and the crystallization temperature.
Denne afhandling undersøger, hvordan dispersion og mekaniske egenskaber i polypropylen–grafen-nanokompositter kan forbedres, når grafen fremstilles ved elektrokemisk eksfoliering. Grafen blev produceret ved elektrokemisk eksfoliering af grafit i svovlsyreopløsninger på 0,1–1 M, og analyser med Hansen-solubilitetsparametre viste, at højere syrekoncentration øger hydrogenbindingsbidraget og medfører flere defekter i grafenstrukturen. På baggrund af HSP og en mindre dispergeringsprøve blev grafen funktionaliseret med octadecylamin (ODA) for at styrke interaktionen med polypropylen. Nanokompositterne blev fremstillet ved smelteblanding, ekstrudering og sprøjtestøbning og karakteriseret med lysoptisk mikroskopi, Raman-spektroskopi og røntgendiffraktion samt differential scanning kalorimetri; de mekaniske egenskaber blev vurderet ved træk- og krybeforsøg. Resultaterne viser, at ODA-funktionaliseret grafen disperserer bedre i polypropylen end ubehandlet grafen. Krybemodstand og maksimal brudspænding øges let, mens Youngs modul reduceres. Desuden fungerer grafen som nukleeringsmiddel, hvilket øger krystallinitetsgraden og krystallisationstemperaturen.
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