Fibrous polymer.ppt
- 1. Chemistry of Fibrous Polymers TC-5002 Dr. Wasif Razzaq
- 2. B.Sc. in Chemical Engineering (Polymer) University of Engineering and Technology Lahore, Pakistan M.Sc. in Polymer Engineering University of Engineering and Technology, Lahore, Pakistan Ph.D. in process engineering – Polymer Science and Engineering University of Strasbourg, France 2 Dr. Wasif Razzaq
- 3. CONTENTS Introduction Brief History of polymer Types of Polymer Classification of Polymer Based on origin Based on chemistry Based on Properties Based on usage 2
- 4. Definition : A polymer is a large molecule (macromolecule) composed of repeating structural unit connected by covalent chemical bonds. - The word is derived from the Greek words (poly), meaning "many"; and (meros), meaning "part" Example:- Polystyrene, poly-vinyl-chloride etc. - They are complex and giant molecules and are different from low molecular weight compounds. -`Macro-molecules’ are made up of much smaller molecules. 4
- 5. 5 History of Macromolecules and Polymers 1846 Christian Schönbein invented nitrocellulose (gun cotton). Cellulose nitrate is a hard elastic material which is soluble and easy to be shaped. 1862 Alexander Parkes made articles from plasticized cellulose nitrate 1870 John and Isaiah Hyatt patented celluloid 1892 Charles Cross, Edward Bevan, and Clayton Beadle patented regenerated cellulose, i.e., viscose rayon fibers and cellophane films
- 6. 6 History of Macromolecules and Polymers
- 7. 7 History of Macromolecules and Polymers 1977 Alan Heeger, Alan MacDiarmid, and Hideki Shirakawa discovered and developed conducting polymers
- 8. Linear Polymers: A polymer in which the molecules form long chains without branches or cross-linked structures. examples: nylon, polyester, PVC etc. 8
- 9. Branched Polymer: A polymer chain having branch points that connect three or more chain segments. Examples: polythene, glycogen, starch etc 9
- 10. Cross linked Polymer: Cross-links are bonds that link one polymer chain to another. They can be covalent bonds or ionic bonds. Examples: malamine formaldehyde resin etc 10
- 11. Linear & Branched Polymers are know as thermoplastic materials. Cross linked Polymer are know as thermosetting materials. 11
- 12. (c)ladder polymer (b) comb polymer (a) star polymer (d) semi- ladder (or stepladder) polymer Representation of polymer architectures
- 13. Representation of polymer architectures (f) polycatenane (e) polyrotaxane (g) dendrimer A rotaxane is a mechanically-interlocked molecular architecture consisting of a "dumbbell shaped molecule" which is threaded through a "macrocycle" A catenane is a mechanically-interlocked molecular architecture consisting of two or more interlocked macrocycles.
- 14. 14 1) Natural and Synthetic Polymers. 2)Organic and Inorganic Polymers. 3)Thermoplastic and Thermosetting Polymers. 4)Plastics, Elastomers, Fibers, and Liquid Resins
- 15. 1. Natural and Synthetic Polymers ( Origin Based ) Natural Polymers Synthetic Polymer -Cotton -Polyethylene -silk -PVC -wool -Nylon -rubber 15
- 16. 16 2) Organic and Inorganic Polymers ( Chemistry Based) A Polymer whose backbone chain is essentially made of carbon atoms is termed an Organic polymer. Examples- cellulose, proteins, polyethylene, nylons. A Polymer which does not have carbon atom in their backbone chain is termed as Inorganic polymer. Examples- Glass and silicone rubber
- 17. 17 Polymers (Based on Properties) Thermoplastics Elastomers Thermosets e.g. polystyrene (amorphous), Polyethylene (crystalline), etc. e.g. phenol resin, epoxy resin, etc. Thermoplastic Elastomers (TPE) Vulcanized Elastomers e.g. polystyrene-b-poly butadiene-b-polystyrene (Kraton®) e.g. styrene-butadiene rubber (SBR) Polymer Classification
- 18. Thermoplastics • Linear or branched polymers which can be melted when heat is applied. • Can be molded into any shape with processing techniques such as injection molding or extrusion. • Most common “plastics”
- 19. Thermoplastics •Plastics – bottles, grocery bags, water piping, rope, fishing line, car parts •Most are recyclable •Natural thermoplastics – silk, cellulose (proteins), polylactic acid
- 20. Codes for Plastics • 1 – PE – soft drink bottles • 2 – LDPE – plastic bags, toys • 3 – PVC – water pipes • 4 – HDPE – milk jugs • 5 – PP – bottle caps
- 21. Thermosets • Thermosets, materials that can not be softened on heating. In thermosetting polymers, the polymer chains are joined (or cross-linked) by intermolecular bonding. • Normally are rigid materials. • Network polymers in which chain motion is greatly restricted by a high degree of crosslinking. • Cannot be reshaped once formed. epoxy
- 22. Thermosets •Uses – high temperature electrical applications, super glue, counter top laminates, epoxy resins, tires (vulcanized rubber) •Cannot be recycled (burn with heat) •Natural* thermosets – vulcanized rubber
- 23. THERMOSETTING VS THERMOPLASTIC THERMOPLASTIC (1) These soften and melt on heating. (2) These can be remolded recast and reshaped. (3) These are less brittle and soluble in some organic solvents. (4) These are formed by addition polymerization. (5) These have usually linear structures. THERMOSETTING (1) These do not soften on heating but rather become hard in case prolonged heating is done these start burning. (2)These can not be remolded or reshaped. (3) These are more brittle and insoluble in organic solvents. (4)These are formed by condensation polymerization. (5) These have three dimensional cross linked structures. 23
- 24. Elastomers • Cross linked (networked) rubbery polymers that can be stretched easily (3-10x original size) • Rapidly recover original dimensions when applied stress is released. • Low degree of cross linking
- 25. Elastomers •Uses – examination gloves, rubber bands, bouncing balls •Not recyclable Degrades (burns) when heat is added •Natural elastomers – natural rubber, latex
- 26. 26 4) Plastic, Fibers and Liquid Resins (Usage based) Plastic A polymer is shaped into hard and tough utility articles by application of heat and pressure, it is used as ‘plastic’ e.g. PVC Fiber If drawing into long filament-like materials whose length is 100 times than its diameter, polymers are said to be converted into Fibers
- 27. Liquid Resins: 27 Liquid resin is a synthetic fluid that when mixed with a hardening agent quickly dries into an extremely durable solid. Some of the most common liquid resins are epoxy, polyurethane, silicone, and polyester.