Access restricted to higher education institution's students and staff
undergraduate thesis
Strukturne promjene polimernih cjevčica za slušne aparate izazvane termičkim starenjem

Deni Uršičić (2016)
Metadata
TitleStrukturne promjene polimernih cjevčica za slušne aparate izazvane termičkim starenjem
AuthorDeni Uršičić
Mentor(s)Srećko Valić (thesis advisor)
Abstract
Slušne aparate je potrebno održavati kako bi ispravno funkcionirali. Na održavanje se odnosi i mjenjanje određenih potrošnih dijelova kao što su cjevčice za slušni aparat. Nošenjem slušnog aparata cjevčica degradira, mijenja svoja mehanička svojstva- otvrdne te tako postane neprikladna za korištenje. Pretpostavlja se da bi jedan od glavnih uzroka te degradacije mogla biti toplina ljudskog tijela pa je stoga poželjno provesti istraživanje na tu temu. Uzorci cjevčica su zagrijavani na temperaturama od 90 ° C i 120 ° C kroz različite vremenske periode. Zatim je izvršena analiza metodom IR spektroskopije kojom se nastojalo identificirati vrstu polimernog materijala te pratiti promjene u strukturi polimera nastale termičkim starenjem. Kako bi se dobio bolji uvid u promjene u strukturi također je napravljen i test bubrenja. IR spektroskopija pokazala je da je polimer od kojeg je građena cjevčica za slušni aparat po svojoj kemijskoj strukturi sličan polietilen tereftalatu. Spektri su pokazali prisutnost C=O, C―C(=O)―C i C―O―C skupina u strukturi istraživanog polimera što potkrepljuje pretpostavku da je istraživani polimer sličan polietilen tereftalatu. IR spektri također ukazuju na prisutnost OH skupina u termički starenim uzorcima, kao posljedica gubitka udjela navedenih triju skupina. IR spektar termički degradirane cjevčice pokazao je mnogo slabiji intenzitet pikova C=O, C―C(=O)―C i C―O―C skupina pa stoga se može zaključiti da gubitak tih skupina uzrokuje očvršćivanje cjevčice koje se koriste za provođenje audiovalova kod slušnih aparata. Učinak termičkog starenja na gubitak navedenih skupina je relativno mali pa je logično zaključiti da utjecaj topline nije glavni uzrok degradacije cjevčica. Stupanj bubrenja se blago smanjuje s produljenjem vremena izloženosti uzoraka termičkom starenju pri temperaturi od 90 °C, što ukazuje da najvjerojatnije dolazi do umrežavanje polimernih lanaca. Međutim, to umrežavanje nije dovoljno da bi se moglo tvrditi da je toplinski utjecaj glavni uzrok degradacije materijala. Suprotno tome, zagrijavanje pri 120 °C uzrokuje kidanje lanaca te omekšavanje cjevčice, a to je praćeno povećanim stupnjem bubrenja.
Keywordshearing aid tube polymer thermal ageing IR.
Committee MembersMarin Tota (committee chairperson)
Gordana Žauhar (committee member)
Srećko Valić (committee member)
GranterSveučilište u Rijeci
Medicinski fakultet
Lower level organizational unitsKatedra za kemiju i biokemiju
PlaceRijeka
StateCroatia
Scientific field, discipline, subdisciplineBIOMEDICINE AND HEALTHCARE
Basic Medical Sciences
Medical Biochemistry
Study programme typeuniversity
Study levelundergraduate
Study programmeStudy of Sanitary Engineering
Academic title abbreviationuniv. bacc. sanit. ing.
Genreundergraduate thesis
Language Croatian
Defense date2016-09-20
Parallel abstract (English)
Hearing aid should be maintained in order to function properly. This maintenance also concerns replacing of certain wear parts such as tubes for a hearing aid. By wearing the hearing aid tube degrades, changing its physical properties and becomes hard and useless. It is assumed that one of the main causes of this degradation could be the heat of the human body and therefore, it is interesting to carry out research on the subject. Tube samples were heated at temperatures of 90 ° C and 120 ° C for different periods of time. Then, the analysis of samples was made by infrared spectroscopy to identify the type of polymer material and to investigate changes in the structure of the polymer caused by thermal aging. Swelling experiments were done to get more insight into the structural changes. IR spectroscopy indicates that the polymer from which the tube of a hearing aid is made, according to its chemical structure, is similar to polyethylene terephthalate. Spectra showed the presence of C = O, C-C (= O) -C and C-O-C group in the structure of the studied polymer and this fact supports the assumption that the investigated polymer is similar to polyethylene terephthalate. IR spectra also indicate the presence of OH groups in the thermally aged samples, as a result of the loss of the amount of these three groups. The IR spectrum of thermally degraded tubes showed a much weaker intensity of the peaks for C-O, C-C (= O) -C and C-O-C group and therefore, it can be concluded that the loss of these groups is caused by curing the tubes used for audio-waves conduction in the hearing aids. The effect of thermal aging on the loss of these groups is relatively small, so it is logical to suppose that the impact of heat might not the main cause of degradation of the tubes. The degree of swelling decreases slightly with the extension of the time of exposure of samples to the thermal aging at a temperature of 90 ° C, indicating a possible crosslinking of the polymer chains. However, this crosslinking is not strong enough to argue that the thermal ageing is the main cause of the material degradation. In contrast, heating at 120 ° C causes chain scission and softening the tube, followed by an increasing in the degree of swelling.
Parallel keywords (Croatian)slušni aparat cjevčica polimer termičko starenje IR.
Resource typetext
Access conditionAccess restricted to higher education institution's students and staff
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:184:102632
CommitterBosa Licul