Vinyl chloride polymerization in microdroplet reactor - Les thèses en ...

Chapter I : Bibliographic review
PVC morphology development
Particle Unit
Grain
Sub-grain
Approximate size
Range
Average
(µm)
(µm)
50 – 250 100 – 130
10 – 150 40 – 60
Origin or description
Visible constituents of free flowing powders,
made up of more than 1 monomer droplet.
Polymerized monomer droplet.
Agglomerate
3 – 10 ~ 5
Formed by coalescence of primary particles (1
µm); grows with conversion (50 – 70 %).
Primary
particle
0.6 – 1.5 ~ 1
Grows from domain. Formed at low conversion
by coalescence of microdomain until the
formation of continuous network in droplets (up
to 15 – 30 % conversion).
Domain
Nano-domain
0.1 – 0.3 ~ 0.2
0.1 – 0.02 ~ 0.02
Primary particle nucleus. Contains about 10 3
nano-domains. Only observed at low conversion
(5 – 10 %) and is stabilized by charge (negative
chrge resulting from the presence of HCl)
Smallest species so far identified. Aggregate of
polymer chains (10 – 30 monomer units) at les
than 0.01 % conversion.
Table I- 3 : PVC morphology development according to Xie et al. (1991b)
The evolution of primary PVC particles is schematically represented in Figure I- 5.
Nano-domains
Domains
80 – 200 nm
Primary Particles (PP)
0,2 – 1,5 µm
PP Agglomerates
1 – 10 µm
Growth and fusion of Agglomerates
1 – 10 µm
X