Career in Polymer Technology PDF

“Career in Polymer Technology” Dr. Aftab Alam M.Tech, Ph.D (DCE) Department of Polymer Technology Delhi Skill and Entrepreneurship University (A State University Established Under Govt of NCT of Delhi ) Guru Nanak D...

“Career in Polymer Technology” Dr. Aftab Alam M.Tech, Ph.D (DCE) Department of Polymer Technology Delhi Skill and Entrepreneurship University (A State University Established Under Govt of NCT of Delhi ) Guru Nanak Dev DSEU Rohini Campus Sector-15, Rohini New Delhi -110089  Why Plastics materials are so important Low cost due to – low cost of production, low density, complex design flexibility Good chemical and corrosion resistance Non toxic and odourless Transparent/ translucent Permanent colorability Gas, vapour and moisture reistance Easily recyclable and re-useable  Growth of Polymer Industries In 2021-22 the Indian plastic sector has achieved the target of exports of $13billion, which has seen the growth of 30%. The Indian government has set the target of exporting$25billion by 2025. Hence, Polymer is one of the fastest growing industries in India, plays a vital role in Indian economy. Technical manpower employed in Indian polymer industries grew at the pace of around 6.5 to 7.5% during the last decade.  Global Polymer Production Scenario “Plastindia Foundation status report on Plastic Industry FY 2021-22 & 1H 2022-23 Need to create new opportunity to catchup world production and increase employment  Production of Polymer-based Products Primary Basic Polymer End Resources Petrochemical Materials Products Plastics Crude HDPE Oil LDPE Ethylene LLDPE Propylene PP Elastomer Styrene PVC Vinyl Chloride ABS Butadiene PA Cyclohexane Acetal Acetylene PC Fibers PUR Natural PBT Gas etc. Adhesives + Coatings  Polymer Poly mer many repeat unit (building blocks) 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) Poly(vinyl chloride) (PVC) Polypropylene (PP) Carbon chain backbone 6  Chemistry and Structure of Polyethylene Tetrahedral arrangement of C-H Polyethylene is a long-chain hydrocarbon. Top figure shows repeat unit and chain structures. Other figure shows zigzag backbone structure. 7  Classification of Polymers ORIGIN Natural & Synthetic THERMAL Thermoplastic & Thermosetting SYNTHESIS Addition & Condensation STRUCTURE Linear, Branched, & Crosslinked APPLICATION Plastics, Rubber & Fibres CRYSTALINITY Amorphous & Crystalline  ORIGIN Natural Polymers: They are available in natural Like, Natural Rubber, Silk, Cellulose, Starch Synthetic Polymers: They are man made polymers prepared synthetically like PE, PS, PVC , PP etc  THERMAL Thermoplastic Polymers: They can be softened or plasticized repeatedly on application of thermal energy like PE, PP, PET, PS, PVC Thermosetting Polymers: They can be obtained in soluble or fusible forms (pre- polymeric) stage, but get set or cured when further heated/cured. Like UF, MF, epoxy resin etc  Molecular Structures- Branched Linear Branched Cross-Linked Network Where side-branch chains have connected to main chains, these are termed branched polymers. Linear structures may have side- branching. HDPE – high density polyethylene is primarily a linear polymer with minor branching, while LDPE – low density polyethylene contains numerous short chain branches. Greater chain linearity and chain length tend to increase the melting point and improve the physical and mechanical properties of the polymer due to greater crystallinity. 11  Molecular Structures – Cross-linked, Network secondary bonding Linear Branched Cross-Linked Network In cross-linked polymers, adjacent linear chains are joined to one another at various positions by covalent bonding of atoms. Examples are the rubber elastic materials. Small molecules that form 3 or more active covalent bonds create structures called network polymers. Examples are the epoxies and polyurethanes. 12  Crystallinity basis Amorphous:  Crystalline  Amorphous Vs Crystalline Amorphous – random st. Crystalline – ordered st. Clear Opaque Low shrinkage High Shrinkage Soften – No melt Melt – No softening High Impact Strength Low Impact Strength Poor Chemical Resistance Good Chemical Resistance Poor Lubricity Good Lubricity Like ABS, PS, PU, PVC Like Nylon, PE, PP, PET, PEEK ABS is not clear, but translucent  Polymer Crystallinity Polymers are rarely 100% crystalline Difficult for all regions of all chains to become aligned crystalline region Degree of crystallinity expressed as % crystallinity. -- Some physical properties depend on % crystallinity. -- Heat treating causes crystalline regions to grow and % crystallinity to increase. amorphous region 16  Polymer Families Plastics Thermosets Thermoplastics Commodity Engineering High Performance Amorphous Crystalline Amorphous Crystalline Amorphous Crystalline Blends PMMA PE ABS PBT PEI PC/PBT PPS PVC PP PC/ABS PA PEEK PPO/PA PS ASA POM ABS/PA PC MPPO  Plastics Tree HIGH PERFORMANCE PLASTICS PEI LCP PPS PSU PA PC PA ENGINEERING PLASTICS blends PPE / PS PC PBT blends blends blends PBT POM PMMA ABS PET Polypropylene COMMODITIES PS PVC HIPS Polyethylene AMORPHOUS SEMICRYSTALLINE  History of Major Plastics PS 1930 Germany PMMA 1934 UK PVC 1933 Germany/US LDPE 1939 UK PA 1939 US Teflon 1943 US Silicone 1943 US ABS 1952 US PET 1953 US HDPE 1955 Germany PP 1957 Italy PC 1959 Germany/US  Polymer Morphology Glass Transition Temperature (TG) TG Glassy Rubbery Raise Temperature of Polymer Both amorphous and crystalline polymers exhibit a glass transition temperature.  Importance of Tg The Tg is used as a measure of flexibility of polymers, and hence response of polymers towards mechanical stresses. The Tg decides whether a polymer at the ‘Service temperature’ will behave like rubber or plastic. This help in chossing the right processing temp. The HDT is closely associated with Tg  Factors affecting Tg Chain Length Plasticizers Chain stiffness and side groups Copolymers Pressure Test conditions, length of test, and types of impurities in sample Polymer chain factors  Chain Length As molecular weight increases, Tg also increases As molecular weight decreases, Tg also decreases – More end groups – Easier movement of molecules – More inherent free volume in the polymer Tg = Tg – C ∞ X Where: C = constant for each polymer X = degree of polymerization  Plasticizers Small organic molecules mixed into a polymer having the effect of reducing its Tg Have the effect of increasing the free volume – Their small molecules fit in between the chains – Causes chains to be less tight amongst themselves – Plasticizers technically do not effect Tg but practically do  Chain stiffness and side groups Chains that have difficulty uncoiling have higher Tg Chain stiffness is related to higher energy level Bulky side groups hinder rotation  Copolymers Made from two different monomers Tg will be some kind of average between the two monomeric materials – Assuming they were converted into polymer – Will be based roughly on the weight % of each material present in the copolymer Volume Fraction Tg = VFa x Tga + VFa x Tgb 1 = Wf1 + Wf2 Tg Tg1 Tg2  Pressure A noticeable increase in Tg occurs at several thousand psi. Pressure pushes molecules together Removes free volume Rate dependence of Tg The Average Molecular Weight The Number Average and Weight Average molecular weight From little molecules to big molecules H – (CH2)n – H L. H. Sperling, Introduction to Physical Polymer Science, Wiley, 2006 increase in molecular weight  Molecular Weight and Average concept A simple compound has a fixed moleculr weight e.g. The M.W. Of Aceton is 58, regardless of how it is made In case of polymers or macromolecules comprises molecules –chain of different molecular weight, hence MW is expressed in “AVERAGE” value. Chemistry and Structure of Polyethylene Adapted from Fig. 14.1, Callister & Rethwisch 8e. Note: polyethylene is a long-chain hydrocarbon - paraffin wax for candles is short polyethylene 32  In case of Polyethylene In (CH2-CH2)n The value of n in polyethylene molecule is not fixed The chain termination process is random, hence, PE chain has different number of monomer units thus different MW  R-(CH2-CH2)500 MW is app. 14000 R-(CH2-CH2)550 MW is app. 15400 R-(CH2-CH2)600 MW is app. 16800 These three molecules have different sizes, their MWs are different, But their chemical nature is same, as all are Polyethylene Polymer is mixture of same chemical types, but different molecular weight, Hence expressed as AVERAGE When we talk about molecular weight in terms of polymers, we are really talking about the length of the individual chains. The polymerization process is subject to variation so there is no single chain length, there is actually a wide range of lengths, so when we discuss molecular weight, we really mean the average molecular weight of the material.  MOLECULAR WEIGHT Molecular weight, M: Mass of a mole of chains. Low M high M During the polymerization process not all chains in a polymer grow to the same length, so there is a distribution of molecular weights. There are several ways of defining an average molecular weight. The molecular weight distribution in a polymer describes the relationship between the number of moles of each polymer species and the molar mass of that species. 36 The Number Average & Weight Average concept Consider a basket of vegitables Vegitable No. Of Unit Weight of Total weight Number Weight (n) each unit of each unit Average Average (w) g (n*w) (No fraction Wt fraction x weight X total wt Onions 2 10 20 2/15x10 20/1450 x =1.33 g 10 = 0.14 g Brinjals 4 20 80 4/15x20 80/1450 x =5.33 g 20 = 1.10 g Cabbages 6 100 600 6/15x100 600/1450 x =40.0 g 100 = 41.38 Cauliflowers 3 250 750 3/15x250 750/1450 x =50.0 g 250 = 129.3 15 1450 96.66 g 171.93 g Number-average molecular weight (n) – based on methods of counting the number of molecules in a given weight of polymer the total weight of a polymer sample, w, is the sum of the weights of each molecular species present   w   wi  N i M i N = number of molecules M = molecular weight i 1 i 1  w M N i i Mn    i 1  N i 1 i N i 1 i Weight-average molecular weight (w) determination of molecular weight based on size rather than the number of molecules – the greater the mass, the greater the contribution to the measurement   w M i i N M i i 2 w = weight fraction M = molecular weight Mw  i 1   i 1  N = number of molecules w i 1 i N M i 1 i i  Degree of Polymerization, DP DP = average number of repeat units per chain Mn DP  m where m  repeat unit molecular weight Example for PVC: m = 2(carbon) + 3(hydrogen) + 1(Clorine) (from front of book) = 2(12.011) + 3(1.008) + 1(35.45) = 62.496 g/mol DP = 21,150 / 62.496 = 338.42 40 Plastic Myths Vs Reality  Emit Poisonous gages when burnt Plastic bags do not produce any toxic gas as such by burning. Carbon and Hydrogen which are main constituent of plastic convert into CO2 and Water. The largest component of all MSW is Plastic Even in developed countries, the plastic waste by weight is about 7% as against paper (36%) and Metal (10%) and Glass (8%) But plastic waste attracts media due to its low density and colorful nature.  Plastic reduce fertility of Soil Why plastic is going to Soil/ Agriculture land? We may prevent it by the proper management of Plastic Waste Plastic is not good for Food Contact All plastic material are FDA approval for food contact application suits to Food, Pharmaceutical, and drinking water too  Animals eat plastics Animals can easily distinguish between food and plastic. They eat plastic due to aroma of food packed in it. Proper Waste management can solve this.  Plastic bags block drains Dumping of all types of waste by public into open roads leads to block of drains. Its contain mixed waste ie cloths, wood, paper, glass etc.  Is Plastic Eco-friendly Plastic protect environment by conserving precious natural resources and energy. In agriculture helps in water and food management. Plastic films used in nursery bags, green house and ultimately results in increase of agriculture crops Plastics products needs lowest energy in conversion into useful shapes (Green processing ie low CO2 emission Don’t consumes water  Environmental Implication of Paper Vs Plastic (A case study) For production of 1000 Kiloton per annum of paper Needs 15 millions of tree Needs 300 millions m3 water (It is sufficent for 3 cr families) Around 2 times more energy required as compare to plastic Its generates 5.8 millions tons of solid waste and 225 millions m3 of water waste  Plastics in Infrastructure Geosynthetic and Geotextiles in Civil Engg Plastic Wire and cable for power distribution HDPE ducting for optical fibre Gas distribution through Plastics Corrosion Resistance with Plastics  Plastic in Healthcare and Safety Benefits of plastic as medical products Flexible, ductile, tough and light weight Low coff of friction to withstand pressure and easy flow of fluid Inert in contact with blood, tissue and other body fluids Less cost and easy recyclable Almost everywhere in Health System  Ideal Material for drug delivery Joint replacement/ joint replacement (HDPE) Growing human organs Artificial Kidneys Heart Valves and Pacemaker Soluble Sutures (Polyglycolic acid) & Normal sutures (PET/PP) And many more like use of plastic in disposable products  Plastic in Automobiles Interior: Seats, Door panel, Instrument panel, Steering, wheel, Roof liners, Upholstery, Air duct, safety baloons Exterior: Bumper, Weather seal, Head lamp, Reflector, Door panel, body paint Engine and power train: Engine components, Cooling system, Under bonnet structure, fuel tank, Suspension, steering, Brakes Electrical: Ignition, Battery, Boxes, electrical and electronics equipments 200Kg Plastic is uses in car and it is reduces app 800 Kg weight of car