บทที่ 9 พลาสติก

1 1 9 2 Scope Thermoplastics Thermosetting Plastics Polymer Processing Technology 3 (Plastics) = Plastikos = : 1. (Thermoplastics) - - (viscous liquid) - - - * = 2 - : * (functionality): 4 5 2. (Thermosetting plastics or thermoset) - (crosslinking polymer) - crosslink ( ) (mold)

2 - 200 300 C crosslink mold - mold - - - > 2 - 6 Thermoplastics Thermosets - = 2 - - - - - - 1 > 2 - - - - crosslink - 7 (Thermoplastics) 1. Polyethylene (PE) - - monomer = ethylene (CH2 = CH2) - Addition polymerization Addition polymerization Polyethylene 8 Low-density Polyethylene (LDPE) - g/cm3 - Tm 110 C - Crystallinity 60 70% - Branch PE - - : 9 Linear Low-density Polyethylene (LLDPE) - copolymer ethylene butane pentene hexene (4 10%) - Branch PE LDPE linear.

3 10 High-density Polyethylene (HDPE) - g/cm3 - Tm 135 C - Crystallinity 80 95% ( LDPE) - Linear PE - LDPD - : 11 2. Polypropylene (PP) - (Ziegler Natta polymerization) Karl Ziegler (Germany) and Giulio Natta (Italy) - Catalysts: metal halides with organometallic reagents such as alkyl aluminum 12 Polypropylene (PP) - Isotactic 95 98% - g/cm3 - Tm 165 C - %Crystallinity - 140 C ( PE) - - RT Temp.

4 > 80 C - : 13 3. Polyvinylchloride (PVC) - vinyl chloride - addition polymerization free radical - suspension polymerization - atactic - % crystallinity 14 Polyvinylchloride (PVC) PVC - - g/cm3 - - - - PVC (plasticizer, antioxidant, UV stabilizer) - Plasticizer Ex. Dioctyl phthalate (DOP) < 25% PVC > 25% PVC 15 Polyvinylchloride (PVC) - : - PVC 16 17 4.

5 Polystyrene (PS) - styrene - addition polymerization free radical 18 Polystyrene (PS) PS - - - - - - PS 1. General purpose PS (GPPS) 2. PS (High impact PS, HIPS) copolymer styrene butadiene (5%) 19 Polystyrene (PS) PS (plasticizer, stabilizer) - - - - - - Expanded polystyrene foam (EPS) - foaming agent pentane hexane - PS VDO 20 5.

6 Polymethyl methacrylate (PMMA) - : Plexiglass Lucite Perspex - methyl mathacrylate monomer - - Amorphous - Tg 105 C - Tm > 200 C - (organic glass) - 21 Polymethyl methacrylate (PMMA) - 22 6. Polycarbonate (PC) - (polycondensation) bisphenol-A phosgene 25 35 C (CH2Cl2) - (stiffness) - - -O- - Amorphous 23 Polycarbonate (PC) - : 24 7.

7 Polyvinyl acetate (PVAc) - - vinyl acetate monomer emulsion polymerization 75 80 C 2 - Amorphous polymer atactic - Tg 28 C - RT - Temp. RT 25 Polyvinyl acetate (PVAc) - : adhesive (water based emulsion paint or latex paint) PVOH 26 8. Polyvinyl alcohol (PVOH) - PVAc alcoholysis methanol ethanol - - PVOH vinyl alcohol (VA) monomer VA isomerization acetaldehyde heat + CH3 COOCH3 (methyl acetate) CH3 COH CH2=CHOH Vinyl alcohol acetaldehyde 27 Polyvinyl alcohol (PVOH) - (> 80 C) - : 1.

8 PVOH (thickening agent) 2. PVOH - (wet spinning) Na2SO4 - 1 3 OH PVOH CH2O) - 28 9. acrylonitrile -butadiene-styrene (ABS) - copolymer polymer - acrylonitrile 20 30 % butadiene 6 35% styrene 45 70% - monomer acrylonitrile ABS butadiene styrene (stiffness) - ABS 29 acrylonitrile -butadiene-styrene (ABS) ABS 2 1.

9 Latex blending - styrene- acrylonitrile copolymer (SAN plastic resin) acrylonitrile -butadiene copolymer (NBR rubber) (mechanical blend) - ABS 2. Grafting polymerization - styrene acrylonitrile butadiene latex 50 C styrene- acrylonitrile copolymer butadiene - ABS butadiene (disperse phase) styrene- acrylonitrile copolymer (matrix) 30 2. Grafting polymerization (cont.) - butadiene ABS - Grafting polymerization latex blending - ABS monomer - : 31 10.

10 Polytetrafluoroethylene (PTFE) - Teflon (Du pont), Fluon (AGC Chemical Europe Ltd.) - fluoroethylene monomer free radical suspension polymerization - - Tm 327 C - 300 C - Crystallinity > 90% ( ) - fluoroethylene PTFE 32 Polytetrafluoroethylene (PTFE) - : 33 11. Polyethylene terepthalate, PET terepthalic aic (di-acid) ethylene glycol (di-alcohol) dimethyl terephthalate ethylene glycol bis-(2-hydroxyethylene) terepthalate transesterification esterification 250 C, MPa 150 C, atmosphere transesterification 270-280 C vacuum 34 Polyethylene terephthalate - linear polymer - - - - - 35 12.