1. PVC
n= 625 to 2700 (Mw = 39000-168000 g/mol)
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2. Year 2000
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3. Bahan Mentah
2CH 4 → C 2 H 2 + 3H 2
H 2 C = CH 2 + Cl 2 → ClH 2 C − CH 2 Cl → HCl + H 2 C = CHCl
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4. Kandungan Klorin
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5. Vinyl & Fire
☺Kandungan ~ 50 % klorin
⇒ Hanya menyediakan setengah
bahan bakar daripada polimer lainnya
☺Perangkap radikal, peracunan mekanisme api
R− X
+
Flame
retardant
H ~~~~~~~
→ R•
Bahan Bakar
Hidrogen
+
Flame retardant
fragment
H − Cl
+
• ~~~~~~~~
Bahan Bakar,
kekurangan
hidrogen
☺ Karbon monoksida
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6. Polimerisasi
 Polimerisasi
radikal bebas
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7. Polimerisasi
VCM vs. Oksigen
O2 tidak diinginkan
O2 ⇒ R-O-O-R' +VCM
⇒ poli (vinil klorid
peroksida
O2 dideteksi , Kenapa?
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VCM vs. Nitrogen
N2 larut dalam VCM
(Jadi, apa??)
1. Pengangkutan monomer
2. Menekan pembangunan
Bagaimana bisa kita bergerak monomer???
Monomer digerakan oleh:
 Pompa
 Pemanasan
 Grafitasi
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8. Polimerisasi
Suspensi polimerisasi banyak digunakan,
karena :
1. Titik didih monomer yang rendah.
(Stabilitas PVC)
2. PVC saling larut dengan monomer nya.
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9. PVC solubility in its monomer
PVC tidak larut dalam monomernya sendiri. PVC
sebagai endapan partikel kecil selama polimerisasi.
Ini aglomerat yang struktur internal berpori.
VCM ini cukup larut dalam PVC:
 PVC melunak dengan monomer.
 Tingkat polimerisasi VCM dalam partikel yang
bengkak secara substansial lebih cepat dari laju
polimerisasi dalam fase cair (Mengapa?)
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10. Kelarutan PVC dalam monomernya
Percepatan Auto
Seiring dengan peningkatan konversi  polimer Lebih
terbentuk  monomer Lebih mengalami
pembengkakan didalam polimer
For long half-life initiator, R ∝ Conversion
p
However, long half-life initiators are not used, so
reaction acceleration tends to drop off as the active
initiator is consumed.
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11. Polimerisasi kinetika
Eksotermik: panas yang dihasilkan oleh reaksi
Panas total beban: panas aktual harus
dihilangkan
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12. berat molekul
Mw of PVC is controlled by altering the
polymerization temperature, chain transfer to
monomer controls the Mw.
T ↑ Mw↓ (why?)
Karena kenaikan suhu, meningkatkan laju perpindahan
rantai lebih cepat daripada tingkat perambatan rantai.
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13. MWD
Isothermal ⇒ Narrow MWD
Temperature ramped ⇒ Broad MWD
T
t
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14. Polimerisasi Suhu Reaksi
Suhu Polimerisasi 50 ° C – 70 ° C
T < 50 ° C:
Tingkat Polimerisasi terlalu lambat dan MW
terlalu tinggi.
T > 70 ° C: P terlalu tinggi
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15. Pemindah rantai untuk monomer
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16. Perpanjangan berat molekul
To produce high-Mw PVC, there are two options:
1.
2.
Lower temperature (T<50° C) BUT…
Add multifunctional monomer as di-allyl
phthalate, Be careful…
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17. Perpanjangan Berat Molekul
More challenging task…
To produce low-Mw PVC, there are two options:
1. Reduce temperature, BUT…
2. Use chain-transfer agent
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18. Struktur
PVC memiliki struktur linier
Head to tail is most common
PVC shows a tendency to add via syndiotactic
placement ⇒ low crystallinity
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19. PVC facts
Other 5%
Annual demand close to 30 Mton
Transport 7%
Annual growth of 4%
Electronics 8%
75% by suspension polymerization
Consumer
goods 10%
Wide variety of applications
Building 60%
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Packaging 10%
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20. Stability
PVC is the least stable polymer in commercial use.
PVC degrades as it is exposed to high temperatures, high
mechanical stress or ultraviolet (UV) light.
This may take place during processing, storage and
utilization.
Degradation causes discoloration, deterioration of
mechanical properties and lowering of chemical resistance.
Degradation of polymer occurs by successive elimination of
HCl (dehydrochlorination) yielding polyenes.
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21. Stabilitas
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22. Stabilitas
Stabilization mainly proceeds by the addition of
compounds as: metal oxides, carbonates, fatty acid
salts as well as HCl acceptors as ethylene oxide
compounds.
These additives stabilize PVC by:
1. slowing down the dehydroclorination reaction.
2. absorption of the evolved HCl.
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23. Thermal stability
Polymer microstructure
tertiary chlorine
Chain branches
Structural defects
• Long chain branches
(R > 4 C atoms)
• Short chain branches
(R ≤ 4 C atoms)
C l
C l R
C l
Internal double bonds
allylic chlorine
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24. Stabilitas
 Thermal stability decreases when monomer conversion
increases (WHY?)
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25. Plasticization
It is defined as converting PVC, which is a rigid
polymer, to flexible PVC.
Plasticization improves flexibility by acting as an
internal lubricant between PVC chains.
 For a plasticizer to be effective, it must be
thoroughly mixed and incorporated into the PVC
polymer matrix.
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26. Plasticization
 Plasticization theories:
Lubricating theory: as the system is heated, the
plasticizer molecules diffuse into the polymer and
weaken the polymer-polymer interactions (van der
Waals' forces). According to this theory the
plasticizer molecules act as shields to reduce
polymer-polymer interactive forces and prevent the
formation of a rigid network.
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27. Plasticization
 Plasticization theories:
Gel theory: considers the plasticized polymer to be
neither solid nor liquid but an intermediate state,
loosely held together by a three-dimensional
network of weak secondary bonding forces. These
bonding forces acting between plasticizer and
polymer are easily overcome by applied external
stresses allowing the plasticized polymer to flex,
elongate, or compress.
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28. Copolymers
¤ VCM does not copolymerize well. It has an unfavorable reactivity
ratio with just about every other monomer except vinyl acetate
(VAC).
¤ Because of the unfavorable reactivity ratios, making other
copolymers usually involves long reactions with slow metering of
one of the monomers (the one that reacts fastest).
¤ PVC is insoluble in the monomer and this produces the porous
internal structure. One of the reasons for this insolubility is that
the polymer has a certain level of crystallinity ⇒ This produces a
non-porous particle.
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29. Copolymers
¤ most copolymers are made using microsuspension or emulsion
methods , because these processes produce small particles that can
be stripped of residual monomer.
¤ Copolymers entangle and fuse at lower temperatures and flow
more easily at lower melt temperatures, because they have low or
no crystallinity.
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