Procédés d'extrusion réactive et de mélange de polymères : synthèse contrôlée de copolymères greffés à base de polystyrène et de polyamide : et étude de l'efficacité de compatibilisation de ces copolymères, Réactive and polymer blending process : controlled synthesis of polystyrene and polyamide graft copolymers and compatibilizing efficiency of these copolymers

Cai-Liang Zhang

Description

Sous la direction de Guo-Hua Hu, Lian-Fang Feng
Thèse soutenue le 10 novembre 2008: Université de Zhejiang - Chine, INPL
Les mélanges de polymères ouvrent une importante voie à l’obtention de nouveaux matériaux dont les propriétés peuvent être très différentes de celles de chacun des constituants des mélanges. La plupart des polymères sont immiscibles. Ainsi leurs mélanges constituent des phases distinctes et les propriétés de ces mélanges sont souvent médiocres. Afin de relever ce défi, copolymères à bloc ou greffés synthétisés séparément ou générés in-situ lors du procédé de mélanges sont souvent utilisés en tant que agents compatibilisants. Beaucoup d’études ont porté sur l’efficacité de compatibilisation de copolymères à bloc et peu d’études sur celle de copolymères greffés, en partie en raison des difficultés dans le contrôle de leurs structures moléculaires. Cette thèse porte sur l’étude de l’efficacité d’émulsification de copolymères greffés. Elle est composée de trois parties : (1) développement d’un nouveau procédé d’extrusion réactive pour la synthèse de copolymères greffés avec polystyrène (PS) comme squelette et polyamide 6 (PA6) comme greffons ; (2) efficacité d’émulsification du copolymère greffé, PS-g-PA6 pour les mélanges à base de PS et PA6 ; et (3) développement d’un nouveau concept dit d’agent émulsifiant – traceur
-Procédé d'extrusion réactive
-Copolymère greffé
-Mélange de polymères
-Compatibilisation
Polymer blending offers an important route to new materials with combinations of properties not available in constituent polymers. Most polymer pairs are immiscible, leading to phase separation at equilibrium and yield a material with poor properties. To address this challenge, block or graft copolymers pre-made or generated in-situ by reactive blending are often used as compatibilizers. Most studies are focused on the compatibilizing efficiency of block copolymers and few studies address that of graft copolymers, partly because of difficulties of controlling their molecular structures.This thesis is devoted to the study of the emulsification efficiency of graft copolymers. It is composed of three parts: (1) development of a novel reactive extrusion process for synthesizing graft copolymers with polystyrene (PS) as backbone and polyamide 6 (PA6) as grafts; (2) emulsification efficiency of PS-g-PA6 graft copolymers for PS/PA6 blends; and (3) concept of emulsifier- tracer
-Reactive extrusion process
-Polymer blends
-Compatibilisation
Source: http://www.theses.fr/2008INPL067N/document

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• Publié par: Thesee
• Nombre de lectures: 225
• Langue: English
• Poids de l'ouvrage: 4 Mo

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Ecole Nationale Supérieure des
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en co-tutelle avec Zhejiang University
Ecole Doctorale Laboratoire des Sciences
Ressources Procédés Produits Environnement du Génie Chimique
(RP2E) (LSGC-CNRS UPR 6811)


Procédés d’extrusion réactive et de mélange de polymères :
Synthèse contrôlée de copolymères greffés à base de
polystyrène et de polyamide ; et étude de l’efficacité de
compatibilisation de ces copolymères

THESE

présentée en vue de l’obtention du

DOCTORAT DE L’INSTITUT NATIONAL POLYTECHNIQUE DE
LORRAINE

Spécialité : Génie des Procédés et des Produits

par

Cai-Liang ZHANG
Master en Génie des Procédés
Zhejiang Université, Hangzhou, Chine

Soutenance prévue le 10 novembre 2008 à 9h

Composition du jury :

Rapporteurs : M. Luc AVEROUS Professeur (Université de Strasbourg)
M. Ming-Qiang ZHONG Professeur (Zhejiang University of
Technology, Chine)

Examinateurs : M. Guo-Hua HU Professeur (Nancy-Université, INPL) et
membre de l’IUF
M. Lian-Fang FENG Professeur (Zhejiang University, Chine) Acknowledgments
First and foremost I would like to express my gratitude to my advisors Dr.
Guo-Hua HU and Dr. Lian-Fang FENG. Besides their creactive ideas of research,
continuous guidance and inspiring discussion, their consistently encouraging and
supporting to my study and research have been the key to the success of my Ph.D. I
am thankful to them for providing me with a great research environment, resources,
advice, and flexibility in my work. From them I have also learnt more than just how to
do good research. Special thanks are given Dr. Sandrine HOPPE, Xue-Ping GU and
Dr. Jia-Jun WANG for providing helps and suggestions for this study.
I am thankful to my mates both in Chinese and French research group —
Guang-Zan LI, Xian-Ming ZHANG, Yu-Hua XUE, Jing CHANG, Jian ZHAO,
Feng-Yong LI, Wen-Feng ZHANG, Xiao-Bo SONG, Sha-Sha CUI, Jin-Xia Li, Chao
ZHAO, Yan-Fei TANG, Zheng-Hui LI, Fang SHAO, Guo-Long JI, Shan-Shan DAI,
Jing-Gang GAI, Christian PENU, Jean-Marie BOISSIERE, Marina MAGATON,
Ahmed BHRAN, Jonathan LEBLANC who helped in varying ways to understand
some of the fascinating science of polymers. Of all these names, Jian ZHAO deserves
a special mention, who has participated in the research work about the efficiency of
graft copolymer at stabilizing the co-continuous phase. I would like to express my
great appreciation to Tao-Tao FU, Dong AN, Yuan FANG who have contributed to my
wonderful life in France.
This research would not have been possible finished without the generous
financial support of the National Natural Science Foundation of China (grant numbers
50390097 and 20310285), the Ministry of Science and Technology of China through
an international cooperation program (grant number: 2001CB711203), and the
Association Franco-Chinoise pour la Recherche Scientifique et Technique-AFCRST
(grant number: PRA Mx02-07). I would like to thank China Scholarship Council for
supporting my study in France.
The completion of this thesis would not have been possible without the support
of my family. I owe a debt of gratitude to my parents for their patience and
understanding. I will give my final note of thanks to my wife, Ling-Li HU. Her love,
constant understanding and encouraging and sharing every feeling are the ultimate
support to the success of this thesis.
IAbstract
Abstract
Polymer blending offers an important route to new materials with combinations of
properties not available in constituent polymers. Most polymer pairs are immiscible,
leading to phase separation at equilibrium and yield a material with poor properties.
To address this challenge, block or graft copolymers pre-made or generated in-situ by
reactive blending are often used as compatibilizers. Most studies are focused on the
compatibilizing efficiency of block copolymers and few studies address that of graft
copolymers, partly because of difficulties of controlling their molecular structures.
This thesis is devoted to the study of the emulsification efficiency of graft
copolymers. It is composed of three parts: (1) development of a novel reactive
extrusion process for synthesizing graft copolymers with polystyrene (PS) as
backbone and polyamide 6 (PA6) as grafts; (2) emulsification efficiency of PS-g-PA6
graft copolymers for PS/PA6 blends; and (3) concept of tracer-emulsifier.
The underlying chemistry for the synthesis of PS-g-PA6 graft copolymers was
based on the use of a copolymer of styrene (St) and 3-isopropenyl- α,
α-dimethylbenzene isocyanate (TMI), PS-co-TMI, to activate/e the polymerization of
ε-caprolactam (CL) in the presence of sodium ε-caprolactam (NaCL) as an anionic
catalyst. The structure of a graft copolymer is mainly determined by the following
three parameters: backbone length, graft density, and graft chain length. The backbone
length of the PS-g-PA6 depended only on the molar mass of the initial PS-co-TMI and
the PA6 graft density was dictated by the TMI content in PS-co-TMI.
The efficiency of graft copolymers at compatibilizing the dispersed phase/matrix
morphology of PS and PA6 blends and stabilizing the co-continuous morphology of
the blends during quiescent annealing were studied. Results showed that for graft
copolymers with similar backbone and graft density, the longer the grafts, the higher
their efficiency. For a given backbone/graft composition, graft copolymers having
fewer and longer grafts were more efficient at comaptibilizing and stabilizing the
morphology.
Feeding mode had a very significant effect on the size of the dispersed phase
domains at short mixing time and its effect decreased or became negligible at long
mixing time. This indicates that feeding mode affected mostly the time necessary for
the PS-g-PA6 compatibilizer to reach and emulsify the interfaces between PS and PA6.
A good feeding mode should meet the following two requirements: first, the matrix
should melt faster than the dispersed phase in order to avoid the phase inversion;
IIAbstract
second, the compatibilizer should be present as soon as the blending process starts,
namely, the dispersed phase begins to melt.
Building up an emulsification curve may not always be practical because of
limited amounts of copolymers available. This is especially true for an industrial
polymer blending process. A so-called concept of emulsifier-tracer was developed to
solve the problem. Very small amounts of fluorecent moities such as anthracene were
incorporated in PS-co-TMI. When the latter was used to activate the polymerization
of CL, the resulting PS-g-PA6 graft copolymer contained fluorescent moities. An
original method for constructing the emulsification curve of a polymer blend in a
continuous mixer such as a twin-screw extruder was developed based on the
tracer-emulsifier concentration distribution (i.e. the residence time distribution) and
the corresponding dispersed phase domain size distribution of the blend system. The
resulting emulsification curves exhibited unique features that would open a new
research field for polymer blending.

Keywords: Reactive extrusion process; polymer blends; compatibisation.
IIIRésumé
Résumé
Les mélanges de polymères ouvrent une importante voie à l’obtention de
nouveaux matériaux dont les propriétés peuvent être très différentes de celles de
chacun des constituants des mélanges. La plupart des polymères sont immiscibles.
Ainsi leurs mélanges constituent des phases distinctes et les propriétés de ces
mélanges sont souvent médiocres. Afin de relever ce défi, copolymères à bloc ou
greffés synthétisés séparément ou générés in-situ lors du procédé de mélanges sont
souvent utilisés en tant que agents compatibilisants. Beaucoup d’études ont porté sur
l’efficacité de compatibilisation de copolymères à bloc et peu d’études sur celle de
copolymères greffés,