Date of Award

Fall 12-2010

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Polymers and High Performance Materials

Committee Chair

Jeffrey Wiggins

Committee Chair Department

Polymers and High Performance Materials

Committee Member 2

Robson Storey

Committee Member 2 Department

Polymers and High Performance Materials

Committee Member 3

Sergei Nazarenko

Committee Member 3 Department

Polymers and High Performance Materials

Abstract

This thesis is concerned with developing renewable resource thermoplastic materials to replace existing non-renewable or possibly hazardous industry standard products.

Cerenol TPU Incorporation

Dupont has recently developed a renewable source Polyol (Cerenol) which is derived from 1,3 propane diol processed from corn feeds. This material, which is a three carbon ether repeat unit, is in the pre-commercial stage and is meant to directly compete with petroleum based polyols as a drop-in replacement in thermoplastic polyurethanes. A model kinetic study was performed to compare relative reactivity of the Cerenol polyol to standard four carbon repeat unit petroleum-based polyol ether (PTMEG). A Mettler Toledo real time react-IR was used to monitor the reaction of the difunctional Polyol alcohol end groups with phenyl isocyanate, a mono-functional isocyanate with similar reactivity to the Methylene dipheynl diisocyante (MDI) used in TPU synthesis. ICiR software was used to analyze depletion of the isocyanate peak area from 2325 to 2200 cm-1. From this, the reactivity constants were determined to be 0.0652 1/M*s for 1,000 mw Cerenol and 0.0867 1/M*s for 1,000 mw PTMEG. Three different Cerenol-based TPUs were synthesized different shore hardness levels and compared to industry standard petroleum based polytetramethylene ether glycol (PTMEG) Polyol. The Shore hardness levels (70A, 85A and SOD) were chosen to cover a large range of possible TPU applications, from a soft elastic material to a tough rigid material. Mechanical tensile testing showed that at all hardness levels the Cerenol-based TPUs reached a higher ultimate elongation, while DMA data showed comparable glassy and rubbery modulus for all sets of TPUs. These results indicate that the renewable source Cerenol Polyol would be a viable drop-in replacement for petroleum-based Polyols at for a wide range of applications without sacrificing overall TPU performance.

Composite PLA Smoke Grenades

Cargill has developed a renewable source biodegradable Poly Lactic Acid (NatureWorks PLA 2002). This thermoplastic material has been reinforced with 1/32" milled glass fiber at various loading levels (0%, 10%, 20%, 30% and 40% glass fiber by total weight) by melt blending in a twin screw extruder. This was done in an effort to improve the thermo-mechanical properties of the PLA material so it can be used as a drop in replacement to metal M-18 smoke grenade canisters. Tensile and flexural data show a drastic increase in modulus as the glass content is increased from 0% to 40% with a slight drop off in ultimate stress levels (Tensile modulus goes from 28 16.5 to 4 702.16 MPa, while the Flexural modulus 3455.7 to 6631.2 MPa). Water uptake was performed on the composite PLA material and showed that as the % weight of glass fiber increased there was an increase in rate of water uptake. This could be due to poor polymer glass fiber interface and would lead to a porous material leading to wicking of water along the glass fiber.

To optimize properties and processing of the biodegradable PLA, a change in the canister design was necessary. The canister and lid were designed and optimized with Pro-E CAD software into a two-piece construction with a 0.05" nominal wall thickness with internal ribs for increased stiffness. The top included molded-in integral threads for trigger assembly and molded-in stress concentrators for spin-welding the top and canister during final part assembly. The final parts were injected and molded on a Cincinnati Milacron at every glass loading level and shipped to Ardec Picatinny for field burn testing.

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