AECH 1103 - Topic 4 Polymers And Petrochemicals PDF

Topic 4 Polymers and Petrochemicals AECH 1103 Industrial Process Overview  Polymers – What are they? Polymers are a special kind of macromolecule. The word polymer comes from the Greek words “poly,” meaning “many”, and “meres,” meaning “parts” or “repeating units”....

Topic 4 Polymers and Petrochemicals AECH 1103 Industrial Process Overview  Polymers – What are they? Polymers are a special kind of macromolecule. The word polymer comes from the Greek words “poly,” meaning “many”, and “meres,” meaning “parts” or “repeating units”. A Polymer consists of a large chain of repeating molecules (monomers) that are attached in an end to end fashion. Poly mer many repeat unit repeat repeat repeat unit unit unit H H H H H H H H H H H H H H H H H H C C C C C C C C C C C C C C C C C C H H H H H H H Cl H Cl H Cl H CH3 H CH3 H CH3 Polyethylene (PE) Polyvinyl chloride (PVC) Polypropylene (PP) 2 Naming Polymers 3  Polymers – How are they linked? Polyester coat Polyester fibers small (micro) ester ester ester ester Strings of ‘ester’ Joined by Large compounds covalent bonds (macro) 4  Characteristic of Polymers Polymers can be very resistant to chemicals. Polymers can be both thermal and electrical insulators. Generally, polymers are very light in weight with significant degrees of strength. Polymers can be processed in various ways. Polymers are materials with a seemingly limitless range of characteristics and colors. Polymers are usually made of petroleum, but no always. 5  Characteristic of Polymers Toilet paper contains a polymer called cellulose. See-through Flexible Can’t see through Flexible Can’t see through Rigid, stiff Water loves cellulose ! This makes TP absorbent ! 6  Examples of Common Polymers Polymer Abbreviation Uses Low-density LDPE Squeeze bottles, toys, flexible pipes, insulation cover (electric wires) etc. polyethylene High-density HDPE Bottles, pipes, inner insulation (dielectric) of coax cable, plastic bags, etc. polyethylene Polypropylene Auto parts, industrial fibers, food containers, liner in bags, dishware and PP as a wrapping material for textiles and food Polystyrene PS Petri dishes, CD case, plastic cutlery Polytetrafluoroeth Low friction bearings, non-stick pans, inner insulation (dielectric) of coax PTFE ylene cable (see also HDPE), coating against chemical attack etc. Polyvinyl chloride Pipe, fencing, lawn chairs, hand-bags, curtain clothes, non-food bottles, PVC raincoats, toys, vinyl flooring, electrical installation insulations, etc. Styrene Butadiene SBR Adhesive, bonding agent Rubber 7  Classification of Polymers Based on origin of Based on Based on mode of Based on structure source molecular forces polymerization 1. Natural 1. Linear 1. Addition 1. Elastomers polymers Polymers Polymers 2. Semi-synthetic 2. Branched 2. Condensation 2. Fibres polymers chain polymers Polymers Synthetic 3. Cross-linked 3. Thermoplastics polymers polymers 4. Thermosetting polymers 8  Classification of polymers based on source 1. Natural polymers: These polymers are found in nature , example plants and animals. Examples are proteins, cellulose, starch, resins and rubber. 2. Semi-synthetic polymers: The polymers obtained by simple chemical treatment of natural polymers to change their physical properties like Starch, silicones. 3. Synthetic polymers: The fibers obtained by polymerization of simple chemical molecules in laboratory are synthetic polymers, ex.. Nylon, polyethylene, polystyrene, synthetic rubber, PVC, Teflon…. etc. 9  Classification of polymers based on the structure There are three different types based on the structure of the polymers: 1. Linear polymers on Structure In these polymers monomers are linked with each other and form a long straight chain. These chains has no any side chains, ex. Polyethylene, PVC, Nylons, polyesters etc. Their molecules are closely packed and have high density, tensile strength. 10  Classification of polymers based on the structure 2. Branched chain polymers They have a straight long chain with different side chains. Their molecules are irregularly packed hence they have low density, tensile strength and melting point, ex… polypropylene , amylopectin and glycogen. 11  Classification of polymers based on the structure 3. Cross-linked or Network polymers Those polymers in which two linear chains are joined together by covalent bonds and it have three dimensional. Degree of crosslinking is a number of junction point per unit volume. Polymers crosslinking are hard, rigid and brittle due to their network structure. Polymers Cross-linked do not dissolve in solvents because all the polymer chains are covalently tied together, but they can absorb solvents. Ex. Bakelite, melamine, formaldehyde resins, etc. Loosely cross-linked Tightly cross-linked or network 12 Covalent chain configurations and strength Linear Branched Cross-Linked Network Direction of increasing strength 13  Classification of polymers based on mode of polymerization 1. Addition Polymers: During the process of polymeric chain growth if there is only addition of monomers with out any loss of small molecules like H2O, NH3, alcohol etc. and the polymer is an exact multiple of used monomer unit. Examples: Polymers as PE PVC, PP etc. 14 Mechanism of Addition Polymerization 15  Classification of polymers based on mode of polymerization 2. Condensation Polymers: During the process of polymeric chain growth if chemical reaction takes place between different functional group of single monomer or different monomers with the loss of compound like HCl, H2O or other compounds and the polymer is not an exact multiple of used monomer unit then the polymerization process. Examples: Polymers as Nylon, PET, Vulcanized rubber Bakelite (PF), Melamine formaldehyde(MF), etc. 16  Classification of polymers based on molecular forces 1. Elastomers: are a class of materials known for their exceptional elasticity, high tensile strength, flexibility, and resilience. They can deform under stress and return to their original shape once the stress is released, thanks to their unique polymer structure. Examples: Natural rubber, polyurathanes, polybutadiene and silicone. 17  Classification of polymers based on molecular forces 2. Fibers: are essential materials with a long history of use in various industries due to their remarkable strength, flexibility, and versatility. These elongated structures, derived from natural or synthetic materials, play a role in packaging materials, including paper, cardboard, and non-woven fabrics. Examples: natural - cotton, wool, and silk synthetic - polyester, nylon, and acrylic 18  Classification of polymers based on molecular forces 3. Thermoplastic: molecules in a thermoplastic are held together by relatively weak intermolecular forces so that the material softens when exposed to heat and then returns to its original condition when cooled. Examples: Polyethylene, Nylon, Polyvinyl chloride 19  Classification of polymers based on molecular forces 4. Thermosets: a thermosetting plastic, or thermoset, solidifies of “sets” irreversibly when heated. Thermosets cannot be reshaped by heating. Thermosets are strong and durable. They are used in automobiles and constructions. Some common examples are Bakelite, urea-formaldehyde resins, epoxy resins, phenolic resins. Examples: Vulcanized rubber, Bakelite, Polyurethane, Epoxy resin, and Vinyl Ester Resin 20 Difference between Thermoplastics & Thermosetting plastics THERMOPLASTICS THERMOSETTING PLASTICS Formed by addition polymerization Formed by condensation polymerization Three dimensional network structure joined by Long chain linear polymers strong covalent bonds Soften on heating and stiffen on cooling Do not soften on heating Can be remolded Cannot be remolded Usually soft, weak & less brittle Usually hard, strong and more brittle Can be reclaimed from wastes Cannot be reclaimed from wastes Soluble in organic solvents Insoluble in organic solvents 21  Copolymers 1. Homopolymers: Synthesized from a single type of monomer. 2. Copolymers: Composed of two or more different monomer subunits linked to create a polymer chain. 22  Plastic Additives Pigment – gives colour Stabilizer – prevent degradation Lubricant – makes moulding easier Filler – add strength to plastic Plasticizer – increase flexibilty 23  Videos The Story of Vulcanized Rubber: Goodyear's Remarkable Discovery https://www.youtube.com/watch?v=r6kNX7CS1V4&ab_channel=TheMatSciGuy How Nylon Was Discovered https://www.youtube.com/watch?v=1fnHKatL-68&ab_channel=TheRoyalInstitution All Things Bakelite: The Age of Plastic" https://www.youtube.com/watch?v=xIrGqiFsa-4&ab_channel=THEL.H.BaekelandProject%2CLLC 24  Petrochemicals Petrochemicals are a category of organic chemicals derived principally from two feedstocks: 1. Natural Gas Liquids (NGL) obtained from natural gas processing plants, and 2. Oil refinery streams such as naphtha and light gas oil. NGL (principally ethane, propane, butanes) are "cracked" at high temperatures to yield the primary petrochemical building blocks of ethylene, propylene, butylene and butadiene. Cracking crude oil-based feedstocks such as naphtha or gas oil yields higher ratios of the ethylene co-products propylene, butylene and butadiene plus the aromatic products benzene, toluene, xylenes along with other co-products. 25  26 https://2b1stconsulting.com/ethylene/  27 https://www.eia.gov/todayinenergy/detail.php?id=5930  Ethane to Ethylene Feedstock: Ethane & Propane Major Equipment: 1. Furnace (815 oC) – Larger molecules broken up & reformed to smaller molecules (Ethylene, Propylene) 2. Compressors 3. Distillation Column (to separate ethylene, propylene, fuel gases) Video: What is Cracking_ Dow Chemical Builds New Ethylene Production Plant at Dow Texas Operations https://www.youtube.com/watch?v=haJmhXMZ7Gs 28  Vinyl Chloride Monomer (VCM) Feedstock: Ethylene, Chlorine 1a. Direct chlorination EDC (ethylene dichloride) is prepared by reacting ethylene and chlorine. CH2=CH2 + Cl2 → ClCH2CH2Cl (Exothermic reaction ), catalyst: Iron(III) Chloride 1b. Oxychlorination CH2=CH2 + 2 HCl + ​1⁄2 O2 → ClCH2CH2Cl + H2O (Exothermic), catalyst: Copper (II) Chloride 2. Thermal cracking: Fired Heater (500oC, 1.5 to 3MPa= 15 to 30 bar) ClCH2CH2Cl → CH2=CHCl + HCl (Endothermic), catalyst: Iron(III) Chloride 29 Simplified VCM Process Block Diagram 1a. Direct chlorination 2. Thermal cracking 1b. Oxychlorination 30  Polyvinyl Chloride (PVC) Feedstock: Vinyl Chloride, additives Additives : Plasticizers, Metal Stabilizers, Heat stabilizers Reaction: Exothermic Water is continually added to the mixture to maintain the suspension Video: The PVC production process explained https://www.youtube.com/watch?v=PvlrXifViVM 31  Production of Low Density Polyethylene (LDPE) Major Equipment: 1. Ethane Compressors: Primary centrifugal compressor up to 300 bar Secondary centrifugal compressor: 1500 to 3000 bar 2. Tubular reactors (with jackets – Heating/cooling), Connected by U-bends in series 3. Cycle Valve: Reduce pressure from 3000 to 2000 bar 4. Separators: HP/LP Separator: To remove unreacted monomer 5. Extruder: Forces the products through a die with multiple holes Video: Low Density Polyethylene (LDPE) Production Overview 6. Drier: Centrifugal drier to dry the product - LDPE Initiator: Oxygen or Peroxide (Optional - to increase https://www.youtube.com/watch?v=5NyjH26RIPI conversion), increase the length of reactor 32