MATE 315 POLYMERS PROCESSING

MATE 315POLYMERS PROCESSING Dr. Caroline Schauer Lebow 439A 215.895.6797 cschauer@coe.drexel.edu Department of Materials Science and Engineering Drexel University © Caroline Schauer 2008

Books • Polymer Process Engineering by Richard Griskey • The top 5 polymer processing books will be placed on reserve at the library. • Middleman: Fundamentals of Polymer processing • Tadmor: Principles of Polymer Processing • Osswald: Polymer Processing Fundamentals • Baird: Polymer Processing: Principles and Design • Wilkinson: Polymer processing and structure development • Weekly assigned readings from Polymer Process Engineering and the reserve books will help with homework © Caroline Schauer 2008

Class Notes • Class Syllabus • Hang onto your copy. All of the due dates for the quarter have been mapped out for you. • It is posted on In.Materials • Note that there are 4 homeworks, 1 midterm, 5 labs and one final © Caroline Schauer 2008

Kamikaze Egg Drop competition • 3 teams at 3 people per team *one team of 3* • Get an A for the lab if your design survives the first round • The team that does the best using the provided guidelines gets 5 extra class points • I need team names and groupings by next class (Wed.) © Caroline Schauer 2008

Lab notes • Wednesday 2-5 pm. • Valerie Binetti is lab TA. Her office is Bossone Graduate Office, Office hours 1-2 pm Monday. • 1st lab is Wednesday the 16th on Polymer Synthesis-PMMA and Nylon • Meet 1st in the MATE Lab conference room, Lebow 335 • Bring lab goggles and a good notebook to take notes for your lab reports © Caroline Schauer 2008

Any Questions? © Caroline Schauer 2008

Polymers (short review) • Thermosets - solidify after chemical crosslinking (ex. epoxy) • Elastomers - lightly crosslinked (ex. natural rubber) • Thermoplastics - polymers which solidify as they cool • Amorphous - remain disordered as they cool random molecular structure (ex. polystyrene) • Semi-crystalline - solidify with a certain order in their molecular structure (ex. polypropylene) © Caroline Schauer 2008

Polymers (review slide 2) • Tg = glass transition temperature – glass to rubber transition • Tm = crystalline melting point – typically 1.5Tg if the polymer can crystallize • T = service or “operation” temperature • At ≥ Tg +100˚C polymers form a melt © Caroline Schauer 2008

© Caroline Schauer 2008

Condensed History of Plastics • c.1000 BCLacquer work- A resin from a lacquer tree (Rhus vernicflua) used by the Chinese to form waterproof and durable coatings and until 1950s used to coat domestic tableware. • c.23-79 BCAmber- A thermoplastic resin from fossilized trees and is found mainly on the Baltic coast. The material can be mixed into lacquers or small pieces can be pressed into compression molds to produce small articles. Amber is first described by Pliny the Elder in his work Natural History. © Caroline Schauer 2008

Condensed History of Plastics (cont) • c.0Horn- A typical thermoplastic, which can be split and molded into shape after heating in hot water. 1620s Layers can be laminated together to build thicker products or pressed into wooden molds to form snuff boxes or buttons. The raw material can also be ground up and mixed with a binder (blood) before being compression molded into buttons. *The ability to produce molded products more cheaply and quickly than their carved counterparts is the prime motivating force behind the development of plastics and the plastics industry © Caroline Schauer 2008

Condensed History of Plastics (cont) • 1731 Charles Marie de la Condamine reports natives in Amazon using rubber for waterproofing and flexible bottles. Rubber was imported into Europe in 1736 but used by natives for several thousand years. • 1844 Thomas Hancock and Charles Goodyear prefect the vulcanization process of cooking rubber in sulfur, which joined separate isoprene polymers improving the material’s structural integrity © Caroline Schauer 2008

Condensed History of Plastics (cont) • 1909 Leo Hendrik Baekelund finds mixtures of phenol and formaldehyde produce and extremely hard material when heated, mixed and allowed to cool. Known as phenolic or phenol-formaldehyde he calls the new material bakelite and is the first synthetic thermosetting resin • 1927 Wallice Carothers develops the first molecular design of materials © Caroline Schauer 2008

The Development of Plastic • 1868 cellulose nitrate • 1909 phenol-formaldehyde • 1927 cellulose acetate and polyvinyl chloride • 1929 urea formaldehyde • 1931 Duprene • 1935 ethyl cellulose • 1936 acrylic and polyvinyl acetate • 1938 nylon • 1942 polyester and polyethylene terephthalate • 1943 silicone • 1947 epoxy and polypropylene © Caroline Schauer 2008

The Graduate (1968) © Caroline Schauer 2008

CHEMISTS Materials Engineers: The linkage between processing– structure & properties CHEMICAL ENGINEERS © Caroline Schauer 2008

Polymers Processing • Goal: To convert raw plastics to useful final products with desirable properties • Plastics  Polymers • (Plastics = Polymer + Additives) © Caroline Schauer 2008

Case Example Polyethylene Shampoo Bottle Polyethylene is the most popular plastic in the world. This is the polymer that makes grocery bags, shampoo bottles, children's toys, and even bullet proof vests © Caroline Schauer 2008

Polyethylene is polymerized from ethylene a byproduct of the refining of crude oil and is a component of natural gas. A large oil company separates ethylene from crude oil in a refinery and sells the ethylene to a relatively small company that owns an ethylene pipeline.Ethylene pipelines exist throughout the southern United States along the Gulf Coast. The pipeline company is usually a small company due to the high liability associated with the maintenance of this critical system (pipelines periodically blow-up!).The pipeline industry is a high-risk/high-profit industry. Sales of ethylene, is a lower-risk, commodity industry that is basically subject to the price of oil. © Caroline Schauer 2008

Various grades offered by a large polyolefin producer are partly composed of blends of different branch content, molecular weight and density polyethylenes from different synthetic reaction conditions. A film blowing grade of polyethylene for clear bags might contain a blend of linear low density polyethylene, controlled branch content metallocene polyethylene and low density polyethylene. These blends might include polymers made in-house as well as some components from competitor olefin producers. Polyolefin producers often purchase or "rent" each others synthetic technology (license patents) and such patent royalties can often be a large component of profits for some polyolefin companies (Phillips Petroleum for instance). Blending of different grades and production of pellets from the usually powder reactor products involve a variety of processing steps and require process engineers. The polyethylene industry is a commodity product industry governed on the supply-side by the price of oil on the world market and on the demand-side by the consumer product, housing and automotive industries. metallocene © Caroline Schauer 2008

An example: A shampoo bottle is injection molded from a high density grade of PE sold by a company such as Equistar. The shampoo is sold by a company like P&G and there is extensive interaction between them, although P&G may never purchase Equistar PE at all. The purchaser of the PE pellets is usually a small processing company that owns a number of injection molders and proprietary molds. The molds are provided by P&G, for instance, under a proprietary license to the processing company. The processing company is typically a high throughput, low profit margin facility and may be producing bottles from competitive brands in the same facility! In the end, the bottle for the shampoo product may represent only a small fraction of the total cost of the product (1 to 5 cents) but may be of utmost importance to the consumer product company in terms of product recognition and in terms of effective storage and dispensing of the product. © Caroline Schauer 2008

Dec 28, 2004 • AP: Encouraged by a milk industry study that shows children drink more dairy when it comes in round plastic bottles, a growing number of schools are ditching those clumsy paper half-pint cartons • a 2002 Dairy Council study found milk consumption increased 18 percent in schools that tested bottles. The study also found that children who drank bottled milk finished more of it High density polyethylene (HDPE) © Caroline Schauer 2008

Nylon Everything came to an unfortunate halt with the outbreak of World War II, when nylon production was commandeered for the war effort. Women resorted to using makeup to decorate their legs, like drawing faux seams up the back of their legs with an eyebrow pencil. © Caroline Schauer 2008

RAW MATERIALS • Most polymers are supplied in particulate form (pellets, beads, granulates) which is convenient • transport and handle • blend (with additives) and compound • store • feed and process • mm < Size < mm © Caroline Schauer 2008

MIXING • Additives - a wide range of second phases added to polymers for processing and/or properties • Stabilizers (degradation), Colors (pigments and dies), Plasticizers (molecular level) Fillers and Reinforcements, Lubricants (granule level). • Other polymers (co-extrusion, co-injection molding etc.) • UNIFORMITY IS A MAJOR ISSUE!... © Caroline Schauer 2008

DEVOLATILIZATION • Entrapped air (between granules) • source of defects • Absorbed gases and humidity • greatly affect processing and properties • Water (solvent) • Residual monomers © Caroline Schauer 2008

PROCESSING IN THE MELT • The majority of processing operations for polymers are performed in the liquid stage at temperatures between RT and 300-400oC • Essential knowledge: • thermal aspects of melting • cooling and effect on properties • Melting is often the rate limiting step!... © Caroline Schauer 2008

FLOW UNDER PRESSURE • The molten plastic is forced through “channels” in order to be shaped into products. Size of machine is an issue. • EXTRUSION (80% of plastics processed by extrusion) • INJECTION MOLDING • BLOW MOLDING • THERMOFORMING • COMPRESSION MOLDING © Caroline Schauer 2008

FINISHED PRODUCTS • Die forming • (profiles, fibers, blow molding) • Molding • (conventional, reaction molding, compression molding, casting, blow molding) • Secondary shaping • (fiber stretching, blowing, thermoforming) • Calendering (films and sheets) and coating • Mold coating © Caroline Schauer 2008

PROPERTIES • Shape/Size Tolerances • Mechanical Properties • Optical Properties • Electrical Properties • Appearance and Aesthetics © Caroline Schauer 2008

FUNDAMENTAL KNOWLEDGE REQUIREMENTS • Transport phenomena • Mixing principles • Solid Mechanics • Polymer Melt Rheology • Polymer Physics (Properties) • Polymer Chemistry © Caroline Schauer 2008

OTHER ISSUES • Empiricism vs Mathematical Modeling - Computer Modeling. • Equipment and Automatic Control • Properties, and Quality (control, statistics) • Cost, Investment, Financial Issues © Caroline Schauer 2008

MATE 315 POLYMERS PROCESSING