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PVC
 

PVC

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  • PVC was first produced commercially in the late 1920s and is now one of the most widely used plastics. <br /> PVC is used in :-medical applications (due to its safety, chemical stability and compatibility) <br /> -transport (floor modules of cars etc., good because of its low energy consumption) <br /> -building and construction (50% of western consumption, mostly piping, flooring and profiles)-light, easy to install, fire resistant) <br /> -consumer goods and daily life <br /> -packaging <br /> It was not until the late 1920s that the first commercial production of PVC took place in the USA.  PVC was first used instead of rubber to insulate the wires in electrical cables during Word War II, when rubber was in short supply. Since then it has replaced rubber for insulation and found many other applications. <br /> Today PVC is the second most popular plastic in the world. <br /> 30% of total thermoplastic manufacturing <br />

PVC PVC Presentation Transcript

  • PVC n= 625 to 2700 (Mw = 39000-168000 g/mol) October 30, 2013 PVC 1
  • Year 2000 October 30, 2013 PVC 2
  • 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 October 30, 2013 PVC 3
  • Kandungan Klorin October 30, 2013 PVC 4
  • 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 October 30, 2013 PVC 5
  • Polimerisasi  Polimerisasi radikal bebas October 30, 2013 PVC 6
  • Polimerisasi VCM vs. Oksigen O2 tidak diinginkan O2 ⇒ R-O-O-R' +VCM ⇒ poli (vinil klorid peroksida O2 dideteksi , Kenapa? October 30, 2013 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 PVC 7
  • Polimerisasi Suspensi polimerisasi banyak digunakan, karena : 1. Titik didih monomer yang rendah. (Stabilitas PVC) 2. PVC saling larut dengan monomer nya. October 30, 2013 PVC 8
  • 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?) October 30, 2013 PVC 9
  • 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. October 30, 2013 PVC 10
  • Polimerisasi kinetika Eksotermik: panas yang dihasilkan oleh reaksi Panas total beban: panas aktual harus dihilangkan October 30, 2013 PVC 11
  • 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. October 30, 2013 PVC 12
  • MWD Isothermal ⇒ Narrow MWD Temperature ramped ⇒ Broad MWD T t October 30, 2013 PVC 13
  • 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 October 30, 2013 PVC 14
  • Pemindah rantai untuk monomer October 30, 2013 PVC 15
  • 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… October 30, 2013 PVC 16
  • Perpanjangan Berat Molekul More challenging task… To produce low-Mw PVC, there are two options: 1. Reduce temperature, BUT… 2. Use chain-transfer agent October 30, 2013 PVC 17
  • Struktur PVC memiliki struktur linier Head to tail is most common PVC shows a tendency to add via syndiotactic placement ⇒ low crystallinity October 30, 2013 PVC 18
  • 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% October 30, 2013 PVC Packaging 10% 19
  • 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. October 30, 2013 PVC 20
  • Stabilitas October 30, 2013 PVC 21
  • 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. October 30, 2013 PVC 22
  • 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 October 30, 2013 PVC 23
  • Stabilitas  Thermal stability decreases when monomer conversion increases (WHY?) October 30, 2013 PVC 24
  • 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. October 30, 2013 PVC 25
  • 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. October 30, 2013 PVC 26
  • 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. October 30, 2013 PVC 27
  • 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. October 30, 2013 PVC 28
  • 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. October 30, 2013 PVC 29