Tretiranje lanenih vlakana natrijevom lužinom i utjecaj koncentracije na mehanička svojstva kompozita s epoksidnom matricom

master's thesis

• Title (english): Alkaline fiber treatment and the effect of concentration on mechanical properties of flax fiber reinforced epoxy based composites
• Author: Martina Žužić
• Mentor: Tatjana Haramina (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2021-07-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Mehanička svojstva kompozita lanena vlakna/epoksidna smola, ključna su za primjenu ovog kompozita u brodogradnji. Zbog hidrofilnosti prirodnih vlakana i posljedično tome slabe adhezivnosti prirodnih vlakana i polimerne matrice, mehanička svojstva takvog kompozita nedovoljna su i ne odgovaraju zahtijevanim svojstvima za primjene u brodogradnji. Za poboljšanje svojstava prirodnih vlakna, potrebno je provesti neki od procesa površinske modifikacije vlakana. U ovom su radu, alkalnom otopinom tretirana biaksijalno orijentirana (90°) lanena vlakna. Alkalne otopine bile su različitih masenih udjela od 2%, 5%, 10% i 15 % NaOH otopljenih u destiliranoj vodi. Alkalna obrada provedena je u trajanju od 30 minuta pri sobnoj temperaturi. Kompozit s epoksidnom matricom dobiven je postupkom ručnog laminiranja. Na dobivenim epruvetama provedeno je statičko rastezno ispitivanje, savojno ispitivanje te ispitivanje prividne međuslojne smične čvrstoće. Mehanička svojstva kompozita s tretiranim vlaknima uspoređena su sa zahtjevima propisanih od strane Hrvatskog registra brodova (HRB), ali niti jedan od izrađenih kompozita ne udovoljava zahtjevima. Uzroci lošijih svojstava su povećanje debljine od čak 60%, čime je smanjen sadržaj vlakana u odnosu na kompozit s netretiranim vlaknima. Najbolje rezultate pokazuju kompoziti čija su vlakna tretirana u alkalnoj otopini koncentracija 2 mas.% i 5 mas.% NaOH. Usmjeravanje slojeva vlakana u različitim smjerovima i poboljšani postupak izrade kompozita mogli bi osigurati prihvatljiva svojstva za primjene u brodogradnji.

Abstract (english)

The mechanical properties of flax fabric/epoxy composites are crucial for the acceptance of this composite in naval architecture. Due to the hydrophilicity of natural fibers and poor adhesiveness of natural fibers and polymer matrix, the mechanical properties of bio-composites can not meet the requirements for marine application. To improve the properties of natural fibers, it is necessary to carry out chemical or physical surface treatment procedures. In this paper, biaxially oriented (90°) flax fibers were treated with an alkaline solution. Alkaline solutions were with different mass fractions of 2%, 5%, 10% and 15% NaOH dissolved in distilled water. Alkaline treatment was performed for 30 minutes at room temperature. The epoxy matrix composites are produced by the hand lay-up process. The following tests were performed on the obtained samples: tensile tests, flexural tests and apparent interlaminar shear strength tests. The mechanical properties of composites reinforced with treated fibers were compared with the requirements prescribed by the Croatian Ship Registry (CSR) and none of the produced composites fulfill the requirements. An increase in thickness (of 60%) and a decrease in fiber content are the causes of the decrease in mechanical properties of the produced composites. The best properties show composites whose fibers were treated with 2 and 5 wt.% NaOH solutions. The orientation of the flax fiber layers in different directions and the improved composite production process could provide acceptable properties for marine application.

• Keywords: lanena vlakna; alkalna obrada; epoksidna matrica; kompozit; mehanička svojstva; brodogradnja
• Keywords (english): flax fibres; alkaline treatment; epoxy; composite; mechanical properties; naval architecture
• Language: croatian
• URN:NBN: urn:nbn:hr:235:200539
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-07-07 12:13:31