Philippa Eshun. Lincoln Leadership Academy Charter School (Allentown, PA)

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1 Outreach Program: Plastics are all around us. Support: NSF Polymer Program NSF (PI: Chang Ryu)/RPI Polymer Center Understanding FTIR and Polymer Plastics Philippa Eshun Lincoln Leadership Academy Charter School (Allentown, PA)

2 Doodle Pen & Polymers 3D Doodle Pen: The plastic is inserted in the pen, the pen is heated and melts the plastic, allowing it to come at the end of the pen and be used for sketching. We were given two different plastics: ABS & PLA. ABS (acrylonitrile, butadiene, and styrene copolymer) is an amorphous polymer (Tg of 105 o C). It needs high heating setting in 3D Doodle pen. It was easily molded into shapes and easier to sketch with. PLA (polylactic acid) is a semicrystalline polymer (Tg of 60 o C & Tm of 150 o C.) It is stickier, more flexible, and melts faster, so it was more difficult to sketch with.

3 ABS & Its Applications ABS is commonly used in musical instruments, computer parts, medical supplies, auto body parts, protective headgear, lego blocks, and many other items.

4 PLA and Its Common Applications PLA (biodegradable polymer) is commonly used in plastic films, bottles, and medical devices such as screws, pins, and rods. PLA bottle 3D FDM Printing Filament

5 Polymer Uses & FTIR PLA and ABS are just two examples of polymers used in the world. Other polymers include polyethylene (most common plastic), polystyrene, and polypropylene. Polymers are further used in paints, contact lenses, rubber, airplanes, cars, and candles. It is also important that we are able to identify polymers and their chemical composition to progress in Polymer Chemistry. This is why the use of the FTIR machine can be helpful. Candle wax and poly(ethylene) have the same chemical repeating unit structure. (but they have different molecular weight.) -[CH 2 CH 2 ] n -

6 FTIR (Fourier Transform Infrared Radiation) FTIR is a method of infrared spectroscopy, in which the infrared light passes through the sample, light is absorbed by that sample, and that absorbed light is then shown in an FTIR scan. In other words, the machine uses light as a probe to catch the chemical bond vibrations. FTIR is useful in identifying unknown materials and impurities in a substance. A BROAD peak around ~ 3300 cm -1 indicates the presence of an OH group (in carboxylic acid or alcohol). A peak around 1700 (about 1750) cm -1 indicates the presence of a ketone group (C=O).

7 FTIR Comparison: Water vs. Methanol OH HOH (water) Broad peak 3000 cm -1 OH Broad peak CH 3 OH (methanol) sp3 C-H bond vibration Wave number (cm -1 )

8 FTIR Comparison: Water vs. dish soap vs. lotion OH Broad peak X H 2 O (water) sp3 C-H Dish soap sp3 C-H Lotion 3000 cm -1 Wave number (cm -1 )

9 Indications from FTIR Graph The FTIR scan indicates that water is a main component in both the dish soap and lotion. This can further be concluded when looking at the ingredients on a lotion bottle or dishwashing detergent container, in which water is usually within the first three things listed, indicating its abundance in the sample. CETAPHIL DOVE DAWN PALMOLIVE OXY (Purified) Water Glycerin Hydrogenated- Polyisobutene Water Glycerin Stearic Acid Water Sodium- Lauryl-Sulfate Sodium- Laureth- Sulfate Water Sodium-Laureth- Sulfate Lauramidopropyl Betaine

10 SUMMARY Polymer plastics are used in various items all around us such as water bottles, cars, and even airplanes. Two common polymer plastics used in 3D printing are ABS and PLA. Using the 3D Doodle Pen can give you a hands-on experience of the differences and properties of ABS and PLA. ABS is more solid and easier to sketch with, while PLA is stickier and more difficult to sketch with. FTIR can be used to characterize chemical bonds and identify components of samples and unknown materials, giving an understanding of the key components in a substance such as water is a main component in both dishwashing detergents and lotions.