Polymers chem
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Polymers chem

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Polymers chem Polymers chem Presentation Transcript

  • COMPOUNDING OF PLASTICS
  • MATERIALS FOR COMPOUNDING Resins Plasticizers Extenders/ Fillers Lubricants Catalyst/ Accelerators Stabilizers Coloring Agent
  • RESINS Basic binding material 30 – 100% In plastics Two types of plastics Thermoplastics Thermoset plastics
  • PLASTICIZERS Increase flexibility Enhance Flow properties E.g vegetable oil, camphor, esters of oleic, phthalic acid
  • FILLERS/EXTENDERS/REINFORCEMENT To reduce the cost of finished plastics To improve hardness ,tensile strength ,water resistance, electrical insulating properties. Enhance mechanical strength E.g Asbestos-heat & corrosion resistance Carbon black-tensile strength in natural rubber Quartz ,mica -hardness Saw dust ,paper pulp ,wood flour, graphite, cotton fiber, pumice
  • LUBRICANTS To impart the flawless glossy finish Prevent plastic material from sticking E.g waxes ,oils, soaps , stearates, oleates
  • CATALYST/ACCELERATORS Required only for thermosetting resins Accelerates the polymerization reaction E.g hydrogen peroxide, benzoyl peroxide, metals like Cu,Pb, ammonia and its salts.
  • STABILIZERS Improve the thermal stability during processing E.g White lead, Lead chromate, lead silicate
  • COLOURANTS/COLOURING AGENTS ORPIGMENTS Imparts colour Provide decorative appeal to the finished plastics E.g Organic dyestuffs, opaque inorganic pigments
  • FABRICATION OF PLASTICS
  • DEFINITION The process of making various products of plastics is known as fabrication of plastics.
  • METHODS OF FABRICATION Compression Moulding Injection Mould Transfer Moulding Extrusion Moulding Blowing Thermoforming
  • COMPRESSION MOULDING  P=100-500 atm  T=100-200ºC  Thermoplastics as well as thermoset resins.
  • INDUSTRIAL METHOD
  • EXAMPLES
  • INJECTION MOULDING PROCESS
  • PROCESS CONDITIONS T=90-250ºC For Thermoplastics resin only
  • http://www.petervaldivia.com/technology/plastics/Injection-molding.php
  • EXAMPLES
  • TRANSFER MOULDING
  • EXAMPLES
  • EXTRUSION MOULDING The plastic granules are moved down by the feed screw and heated up. The molten plastic is forced through the series of dies.
  • The plastic extrusion iscooled by passing itthrough a water bath orjets of air.The extrusion continuesuntil it reaches itspredetermined length.It is then cut off tolength and the cycle ofoperations continues.
  • EXAMPLES
  • BLOWING
  • CONTD.. Bubble casting For thermoplastic materials only
  • EXAMPLES
  • THERMO FORMING 3 Dimensional articles Combination of Extrusion and Compression Moulding. 2 Steps: Heating & Forming Forming can be achieved by i) Vacuums Thermoformingii) Pressure Thermoforming iii) Mechanical Thermoforming
  • VACUUM THERMOFORMING(HTTP://WWW.CUSTOMPARTNET.COM/WU/THERMOFORMING)
  • PRESSURE THERMOFORMING
  • MECHANICAL THERMOFORMING
  • EXAMPLES
  • CHEMISTRY OF THERMOPLASTICS & THERMOSET PLASTICS
  • IMPORTANT PLASTICS Polyethylene Polystyrene Poly Vinyl Chloride Teflon Bakelite Nylon
  • POLYETHYLENE Polymerization of ethylene 1000 5000 atm 150 250 C n[CH 2 CH 2 ] [ CH 2 CH 2 ] Ethylene Polyethylene
  • PREPARATION (i) Hydrogenation Of Acetylene H 2 / Pd CH CH CH 2 CH 2 Acetylene Ethylene(ii) Dehydration of ethanol Dehydration Catalyst CH 3CH 2OH CH 2 CH 2 H 2O Ethanol Ethylene(iii) Dehydrogenation of ethane Dehydrogen ation Catalyst CH 3 CH 3 CH 2 CH 2 H2 Ethane Ethylene
  • TYPES OF PE LDPE BenzoylPeroxide 80 250 C 1500 atmn[CH 2 CH 2 ] [ CH 2 CH 2 ]n HDPE Al ( C2 H 5 ) 3 120 C 6 7 atm n[CH 2 CH 2 ] [ CH 2 CH 2 ]n
  • Low Density PE High Density PE Obtained at High P  Obtained at low P Branched Structure  Linear structure Low density 0.91-0.925  High density 0.95- g / cm 3 0.97 g / cm 3 Low M.P(115ºC) Low Crystallinity  High M.P(135ºC) High Water & gas  High Crystallinity permeability  Low Water & gas Used for making toys , permeability mugs , carry bags.  For making milk bottles ,industrial containers , for domestic water & gas piping.
  • PROPERTIES OF PE Rigid, waxy, white, translucent, non-polar material Chemical resistance to strong acids, alkalis and salt solution Good electrical insulator Resistant to atmospheric conditions
  • ENGINEERING APPLICATIONS
  • POLYSTYRENE Free radical addition polymerization Initiator is Benzoyl peroxide Styrene Polystyrene
  • PREPARATION + H2
  • PROPERTIES Transparent & light weight polymers Resistant to moisture Low M.P (90-100ºC) High electrical insulators Good chemical resistant Transmit light through curved section.
  • APPLICATION
  • POLY VINYL CHLORIDE (PVC) Prepared by polymerization of VC Free radical chain polymerization Heated in water Emulsion with catalyst under pressure.
  • PREPARATION OF VINYL CHLORIDE 60 80 C MetalChlorideCatalystCH CH HCl CH 2 CHCl Acetylene Vinyl Chloride
  • PROPERTIES OF PVC Colorless & odorless powder Chemically inert & nonflamable High resistance to light, Atmospheric Oxygen, Acids & Alkalis. Soluble in Chlorate