The potential use of Resadiye/Tokat bentonite as a reinforcement in
polypropylene (PP) and linear low density polyethylene (LLDPE) polymer
matrix nanocomposites filler was investigated. At first, organoclays (OC)
were prepared by cation exchange reaction (CER) between the raw
bentonite (RB) and three quaternary ammonium salts with long alkyl tails
(QA): hexadecyl trimethyl ammonium bromide [HMA] [Br], tetrabutyl
ammonium tetrafluoroborate [TBA] [BF4], tetrakisdecyl ammonium bromide
[TKA] [Br] and one quaternary phosphonium (QP) salt: tetrabutyl
phosphonium tetrafluroborate [TBP] [BF4]. Characterization of resulting
materials by XRD, TGA, FTIR and chemical analysis confirmed the
formation of organoclays. Ternary composites of PP/organoclay/ maleic
anhydride grafted polypropylene (MAPP) were prepared with two different
grades of PPs in a co-rotating twin screw extruder. Composites prepared
with these organoclays and PPs showed microcomposite formation.
In the second part of the study, raw bentonite was purified by
sedimentation, and characterization of purified bentonite (PB) by XRD,
cation exchange capacity (CEC) measurement and chemical analysis (ICP) confirmed the success of purification method. PB was then modified with
two QA`s: dimethyl dioctadecylammonium chloride [DMDA] [Cl], tetrakis
decylammonium bromide [STKA] [Br] and one QP: tributyl hexadecyl
phosphonium bromide [TBHP] [Br].
Organoclays from PB were used with the PP with lower viscosity, and
ternary nanocomposites (PP/Organoclay2/MAPP5) were prepared in the
extruder followed by batch mixing in an intensive batch mixer. Use of
DMDA and TBHP OCs resulted in nanocomposite formation, while STKA
resulted in microcomposite formation as observed by XRD and TEM.
Young`s modulus and yield stress of the samples were enhanced through
nanocomposite formation.
In the last part of the study, ternary composites of LLDPE/Organoclay/
compatibilizer, a random terpolymer of ethylene, butyl acrylate and maleic
anhydride (E-BA-MAH, Lotader® / 3210), were prepared by melt
compounding in the batch mixer at two different clay concentrations (2 and
5 wt %) and fixed compatibilizer/organoclay ratio (&alpha / =2.5). A commercial
organoclay, I34, was also used in LLDPE based nanocomposites to make
a comparison. XRD and TEM analyses of the compounds prepared by
DMDA and TBHP showed mixed nanocomposite morphologies consisting
of partially intercalated and exfoliated layers. Young`s modulus and tensile
strength of nanocomposites prepared with DMDA and TBHP showed
generally higher values compared to those of neat LLDPE, while results
were the highest in the composites prepared with commercial organoclay
I34. Parallel disk rheometry was used as a supplementary technique to
XRD, TEM and mechanical characterizations, and it was shown to be a
sensitive tool in assessing the degree of dispersion of clay layers in the
polymer matrix.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612204/index.pdf |
| Date | 01 July 2010 |
| Creators | Tijen, Seyidoglu |
| Contributors | Yilmazer, Ulku |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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