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Graphene Oxide Network Formation and Crosslinking in Polybenzoxazines and Poly[(R)-3-hydroxybutyrate]

Rodriguez Arza, Carlos LU (2014)
Abstract
The search for improvement of the physical properties of two very dissimilar polymeric materials is the aim

of this doctoral thesis. The high performance properties of polybenzoxazines are tackled via the preparation of novel

amino-functional benzoxazine monomers, as well as by the addition of graphene oxide (GO) for the preparation of

polybenzoxazine nanocomposites. The synthesis of the amino-functional benzoxazine monomers is attempted by

employing two different approaches. Both amino-monofunctional and bifunctional benzoxazine monomers (P-a-

NH2 and P-ddm-NH2) are successfully prepared via deprotection of amine-protected benzoxazines.

Tetrachlorophthalimide and trifluoroacetyl are... (More)
The search for improvement of the physical properties of two very dissimilar polymeric materials is the aim

of this doctoral thesis. The high performance properties of polybenzoxazines are tackled via the preparation of novel

amino-functional benzoxazine monomers, as well as by the addition of graphene oxide (GO) for the preparation of

polybenzoxazine nanocomposites. The synthesis of the amino-functional benzoxazine monomers is attempted by

employing two different approaches. Both amino-monofunctional and bifunctional benzoxazine monomers (P-a-

NH2 and P-ddm-NH2) are successfully prepared via deprotection of amine-protected benzoxazines.

Tetrachlorophthalimide and trifluoroacetyl are found to be suitable protecting groups. The reactivity of the aminofunctionalized

benzoxazine monomers is confirmed through reaction with acid chlorides. Amide-containing

benzoxazine model compounds along with polyamides containing benzoxazine moieties in the main chain are

prepared accordingly. Thermal properties of the crosslinked poly(amide-benzoxazine)s demonstrate the potentiality

of such materials for high performance applications. GO-base polybenzoxazine nanocomposites are also successfully

prepared. The focus of this study is placed rather on the degree of dispersability of GO nanoparticles. Rheological

analysis of the nanocomposites prepared using two different benzoxazines as matrices, both prior and after

polymerization, reveals the importance of the interfacial interactions between GO surface and the polybenzoxazines

in order to favor dispersability and thus to modify the physical properties of the nanocomposites.

The biobased and biodegradable linear polyester poly[(R)-3-hydroxybutyrate] (PHB) degrades at temperatures close

to its melting temperature (175 oC). The mechanism for the thermal degradation involves the random formation of

shorter polymer segments containing crotonyl and carboxyl end groups. Different additives known to react with

carboxyl groups and influence the melt stability of well-established polyesters are added to PHB. Their effect on the

thermal degradation is analyzed by rheological means and by molar mass measurements. Among the additives

employed, multifunctional epoxide and carbodiimide cause minor improvements on the melt rheology. No effect in

the rheological behavior is observed when aryl phosphites are employed. Lastly, the use of bifunctional oxazoline and

epoxide, and trifunctional aziridine increases the rate of thermal degradation by drastically decreasing the melt

stability and thus the molar mass of PHB. GO was also employed as a means to modify the physical properties of

PHB. Moderate influence on the thermal properties is observed using DSC and TGA. Although the temperature of

decomposition of PHB remains unaltered with the addition of GO, molar mass measurements show an increase of

the rate of thermal degradation of PHB in the nanocomposites. The rheological properties, on the other hand, are

greatly influenced by the addition of GO nanoparticles. Micromechanical effect and GO network formation are

observed to be the cause for such enhancement. In addition, the dynamic properties in the solid state are analyzed

according to the modified Halpin-Tsai model for platelet reinforcement.

The linear viscoelastic behavior of both GO-based benzoxazine and PHB nanocomposites were analyzed using

scaling concepts for fractal networks. In both cases, small percolation volume fractions for the formation of spacefilling

network of GO nanoparticles are determined. Finally, the results from the analysis are used to quantify the

degree of dispersion and are employed for comparison purposes. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • professor Gedde, Ulf, Department of Fibre and Polymer Technology, Royal Institute of Technology, Stockholm, Sweden
organization
publishing date
type
Thesis
publication status
published
subject
publisher
Centre for Analysis and Synthesis
defense location
Lecture hall B, Center for Chemistry and Chemical Engineering, Faculty of Engineering, Lund University
defense date
2014-04-25 10:15
ISBN
978-91-7422-350-7
language
English
LU publication?
yes
id
4adafdd3-d746-4433-a1f1-4d769e131939 (old id 4362746)
date added to LUP
2014-04-01 10:37:53
date last changed
2016-09-19 08:45:12
@misc{4adafdd3-d746-4433-a1f1-4d769e131939,
  abstract     = {The search for improvement of the physical properties of two very dissimilar polymeric materials is the aim<br/><br>
of this doctoral thesis. The high performance properties of polybenzoxazines are tackled via the preparation of novel<br/><br>
amino-functional benzoxazine monomers, as well as by the addition of graphene oxide (GO) for the preparation of<br/><br>
polybenzoxazine nanocomposites. The synthesis of the amino-functional benzoxazine monomers is attempted by<br/><br>
employing two different approaches. Both amino-monofunctional and bifunctional benzoxazine monomers (P-a-<br/><br>
NH2 and P-ddm-NH2) are successfully prepared via deprotection of amine-protected benzoxazines.<br/><br>
Tetrachlorophthalimide and trifluoroacetyl are found to be suitable protecting groups. The reactivity of the aminofunctionalized<br/><br>
benzoxazine monomers is confirmed through reaction with acid chlorides. Amide-containing<br/><br>
benzoxazine model compounds along with polyamides containing benzoxazine moieties in the main chain are<br/><br>
prepared accordingly. Thermal properties of the crosslinked poly(amide-benzoxazine)s demonstrate the potentiality<br/><br>
of such materials for high performance applications. GO-base polybenzoxazine nanocomposites are also successfully<br/><br>
prepared. The focus of this study is placed rather on the degree of dispersability of GO nanoparticles. Rheological<br/><br>
analysis of the nanocomposites prepared using two different benzoxazines as matrices, both prior and after<br/><br>
polymerization, reveals the importance of the interfacial interactions between GO surface and the polybenzoxazines<br/><br>
in order to favor dispersability and thus to modify the physical properties of the nanocomposites.<br/><br>
The biobased and biodegradable linear polyester poly[(R)-3-hydroxybutyrate] (PHB) degrades at temperatures close<br/><br>
to its melting temperature (175 oC). The mechanism for the thermal degradation involves the random formation of<br/><br>
shorter polymer segments containing crotonyl and carboxyl end groups. Different additives known to react with<br/><br>
carboxyl groups and influence the melt stability of well-established polyesters are added to PHB. Their effect on the<br/><br>
thermal degradation is analyzed by rheological means and by molar mass measurements. Among the additives<br/><br>
employed, multifunctional epoxide and carbodiimide cause minor improvements on the melt rheology. No effect in<br/><br>
the rheological behavior is observed when aryl phosphites are employed. Lastly, the use of bifunctional oxazoline and<br/><br>
epoxide, and trifunctional aziridine increases the rate of thermal degradation by drastically decreasing the melt<br/><br>
stability and thus the molar mass of PHB. GO was also employed as a means to modify the physical properties of<br/><br>
PHB. Moderate influence on the thermal properties is observed using DSC and TGA. Although the temperature of<br/><br>
decomposition of PHB remains unaltered with the addition of GO, molar mass measurements show an increase of<br/><br>
the rate of thermal degradation of PHB in the nanocomposites. The rheological properties, on the other hand, are<br/><br>
greatly influenced by the addition of GO nanoparticles. Micromechanical effect and GO network formation are<br/><br>
observed to be the cause for such enhancement. In addition, the dynamic properties in the solid state are analyzed<br/><br>
according to the modified Halpin-Tsai model for platelet reinforcement.<br/><br>
The linear viscoelastic behavior of both GO-based benzoxazine and PHB nanocomposites were analyzed using<br/><br>
scaling concepts for fractal networks. In both cases, small percolation volume fractions for the formation of spacefilling<br/><br>
network of GO nanoparticles are determined. Finally, the results from the analysis are used to quantify the<br/><br>
degree of dispersion and are employed for comparison purposes.},
  author       = {Rodriguez Arza, Carlos},
  isbn         = {978-91-7422-350-7},
  language     = {eng},
  publisher    = {ARRAY(0x9405790)},
  title        = {Graphene Oxide Network Formation and Crosslinking in Polybenzoxazines and Poly[(R)-3-hydroxybutyrate]},
  year         = {2014},
}