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We recently discovered that wheat gluten could be formed into a tough, plasticlike substance when thiol-terminated, star-branched molecules are incorporated directly into the protein structure. This discovery offers the exciting possibility of developing biodegradable high-performance engineering plastics and composites from renewable resources that are competitive with their synthetic counterparts. Wheat gluten powder is available at a cost of less than dollars 0.5/lb, so if processing costs can be controlled, an inexpensive alternative to synthetic polymers may be possible. In the present work, we demonstrate the ability to toughen an otherwise brittle protein-based material by increasing the yield stress and strain-to-failure, without compromising stiffness. Water absorption results suggest that the cross-link density of the polymer is increased by the presence of the thiol-terminated, star-branched additive in the protein. Size-exclusion high performance liquid chromatography data of molded tri-thiol-modified gluten are consistent with that of a polymer that has been further cross-linked when compared directly with unmodified gluten, handled under identical conditions. Remarkably, the mechanical properties of our gluten formulations stored in ambient conditions were found to improve with time.

A multifunctional macromolecular thiol (TPVA) obtained by esterification of poly(vinyl alcohol) (PVA) with 3-mercaptopropionic acid was characterized by a combination of NMR, IR, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC), and was used as a wheat gluten (WG) reactive modifier. The effect of TPVA molecular weight (M(w) = 2000, 9500, 50 000, and 205 000) and blend composition (5, 20, and 40% w/w TPVA/WG) on the mechanical properties of compression-molded bars indicates that TPVA/WG blends increase the fracture strength by up to 76%, the elongation by 80%, and the modulus by 25% above WG. In contrast, typical WG additives such as glycerol and sorbitol improve flexibility but decrease modulus and strength. Preliminary investigations of suspension rheology, water uptake, molecular weight distribution and electron microscopy of TPVA/WG and PVA/WG blends illustrate the different protein interactions with PVA and TPVA. Further work is underway to determine whether TPVA and WG form protein conjugates or microphase-separated morphologies.

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New materials offer the promise of innovative applications in transportation. One such new material is basalt fiber, which is used in other industries because of documented strengths [Ramakrishnan et al., "Performance Evaluation of 3-D Basalt Fiber Reinforced Concrete and Basalt Rod Reinforced Concrete," NCHRP-IDEA Program Project Final Report, Transportation Research Board, Washington, DC, 1998]. Use in transportation, however, requires a better knowledge of many properties. This article discusses initial work with basalt-reinforced polymer composites. Polymer composites reinforced by basalt fabric and glass fabrics were produced for these tests. Void content below 3% were measured for all the composites produced for the testing program. No significant differences in Young's modulus, tensile strength, flexure strength, shear strength, and compression strength were found between basalt composites and glass composites. Environmental durability testing of basalt composites is ongoing. POLYM. COMPOS., 27: 41-48, 2006.

Management of carpet wastes has become a substantial environmental issue in the United States. Specifically, reutilization of polyethylene terephthalate (PET) from waste carpet is increasingly problematic because of the steadily growing market share of PET-based carpets and the very low value of their wastes. In this work, we investigate pyrolysis as an option for repurposing PET carpet wastes. In particular, slow and fast, thermal and catalytic pyrolyses, with and without the co-feeding of steam, are investigated in terms of their selectivity to monoaromatic products. It is seen that higher temperatures increase the conversion of PET to aromatic hydrocarbons. Pyrolysis at slow heating rates is very selective to benzene production. Thermal pyrolysis of waste carpet produces significant amounts of benzoic acid and acetylbenzoic acid as liquid products, whereas catalytic pyrolysis enhances the decarboxylation of these acids, producing aromatic hydrocarbons. ZSM-5 and CaO are effective catalysts for enhancing deoxygenation reactions during catalytic pyrolysis of waste carpet but with significantly different selectivities. Catalytic steam pyrolysis is seen to accomplish the highest selectivity to benzene among all the pyrolysis options studied, due to the enhancement of hydrolysis reactions. The essentially pure benzene organic liquid product from steam pyrolysis of carpet-originated PET presents a unique opportunity for the reutilization of this unsustainable waste.

A three‐dimensionally woven fabric is proposed as a standard reference material for permeability characterization. The 3‐D woven fabric requires care in cutting and handling, although it is more robust than 2‐D woven or braided fabrics. If prepared carefully, the permeability of the 3‐D woven fabric can be measured reproducibly within 15% in either radial flow or saturated 1‐D flow geometries. The material was characterized for permeability in radial, unsaturated and saturated 1‐D, and through‐thickness flow geometries. The transient results demonstrated the importance of structural heterogeneity on the unsaturated flow behavior, and agree qualitatively with a simplistic model of flow in heterogeneous unsaturated porous media. The effects of heterogeneity were manifested in the proposed SRM by an increasing trend in the “unsaturated permeability.” Experiments were also conducted with a random mat that displayed transient flows dominated by wicking. The effects of wicking on the macroscopic flow behavior were manifested by transients in the “unsaturated permeability” in which a decreasing trend was observed.

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