Abstract
Synthetic routes were developed for the preparation of 2-alkoxy-4-hydroxybenzoic
acids and 2-alkoxyhydroquinones, and a large-scale synthesis was
developed for the preparation of 2-thioalkoxyhydroquinones. The
2-alkoxy-4-hydroxybenzoic acids, which contained alkyl side chains of
different length, were used in the synthesis of new main chain liquid
crystalline (LC) homo-, random, and block co-oligomers. In addition,
oligomers of terephthaloyl chloride and 2-thioalkoxyhydroquinones
and oligomers of terephthaloyl chloride and 2-alkoxyhydroquinones
were produced.
All the oligomers were blended with aliphatic polyamide 11
(PA 11). The effect of alkyl side chain length on the compatibility
behavior of the LC oligomers towards the aliphatic polymer was characterized
by DSC and FTIR, and the effect of side chain length on the flexural
properties of the blends was investigated with a three-point bending
test.
The miscibility studies showed variable interfacial adhesion
between the blended compounds. The strongest adhesion was achieved
between PA 11 and the homo-oligomers of 2-alkoxy-4-hydroxybenzoic
acids with short or medium long substituents (C4-C10),
but the interactions between PA 11 and the oligomer with long aliphatic
side chain (C18) were poor, as were those
between PA 11 and the wholly aromatic oligomer of 4-hydroxybenzoic
acid. The compatibility between PA 11 and the co-oligomers of 2-alkoxy-4-hydroxybenzoic
acids was slightly lower than the compatibility of the corresponding
homo-oligomers. DSC and FTIR analyses of the blends of oligomers
of terephthaloyl chloride and 2-thioalkoxyhydroquinones and oligomers
of terephthaloyl chloride and 2-alkoxyhydroquinones with PA 11 implied
that the interactions between the blended compounds were poor.
FTIR spectra and viscosity measurements confirmed that all
the oligomeric structures could self-associate, with effect on the
final mechanical properties of the polyamide. The strength of PA
11 in a three-point bending test was increased by the addition of
only 1% of LC oligomers to the matrix. The results also
showed that the strengthening ability of the oligomers is directly
proportional to the total amount of aliphatic carbons. The best
strengthening results were obtained with unsubstituted oligomers,
random co-oligomers of 2-alkoxy-4-hydroxybenzoic acids, and homo-oligomer
of 2-butoxy-4-hydroxybenzoic acid.
DSC investigations of a ternary blend of the oligomer of 2-decanyloxy-4-hydroxybenzoic
acid, PA 11, and wholly aromatic commercial LC polymer showed the
promising compatibilizing effect of the oligomer.
| Identifer | oai:union.ndltd.org:oulo.fi/oai:oulu.fi:isbn951-42-5091-5 |
| Date | 18 November 1998 |
| Creators | Moilanen, A. (Anu) |
| Publisher | University of Oulu |
| Source Sets | University of Oulu |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess, © University of Oulu, 1998 |
| Relation | info:eu-repo/semantics/altIdentifier/pissn/0355-3191, info:eu-repo/semantics/altIdentifier/eissn/1796-220X |
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