Unraveling the complex interplay between thermal properties and hydration is a part of understanding the fundamental properties of many soft materials and very essential for many applications. Here we show that graphene oxide (GO) demonstrates a highly negative thermal expansion (NTE) coefficient owing to unique thermohydration processes related with fast transport of water between the GO sheets, the amphiphilic nature of nanochannels, and close-to-zero intrinsic thermal expansion of GO. The humidity-dependent NTE of GO layered assemblies, or "pseudonegative thermal expansion" (PNTE), differs from that of other hygroscopic materials due to its relatively fast and highly reversible expansion/contraction cycles and occurrence at low humidity levels while bearing similarities to classic NTE. Thermal expansion of polyvinyl alcohol/GO composites is easily tunable with additional intricacy of thermohydration effects. PNTE combined with isotropy, nontoxicity, and mechanical robustness is an asset for applications of actuators, sensors, MEMS devices, and memory materials and crucial for developing methods of thermal/photopatterning of GO devices.

This article describes the efforts that led to the development of low‐cost interlayer materials that may be used to significantly improve the compression‐after‐impact strength of composite laminates and to, correspondingly, dramatically reduce the area of damage because of impact. Moreover, with the proper selection of the interlayer material, other mechanical properties such as open‐hole compression and shear strength are unaffected or improved over laminates made from identical materials, but without the interlayer. These interlayer materials comprise very lightweight nonwoven veils that may either be melt‐bonded or knitted into noncrimped unidirectional and multiaxial fabric forms using commercial, production equipment. Other than some nominal set‐up costs, these materials add nothing to fabric manufacturing costs than the cost of the materials themselves. Fabrics made using the interlayers may be handled and infused with resin in exactly the same manner as fabrics without the interlayer veils. Proper selection of the veil material is essential, however. An improperly selected interlayer veil material can significantly reduce a composite material's performance. This technology represents a key enabler for the use of low‐cost vacuum‐assisted resin transfer molding processes, low‐cost preforms, and liquid‐molding resins to supplant prepreg as the building‐block material of choice for composite structures. Details of the test methods, results, and conclusions are contained herein. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.

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6F-Polyimides with a phenylethynyl endcap (HFPE) were fabricated into carbon fiber composites using the standard polymerization of monomer reactant (PMR) approach via the ester/acid route. T650-35/HFPE carbon fiber composites were evaluated against the corresponding T650-35/PMR-II-50 composites with nadic endcap at 315ï370 C (600ï700 F) for their physical and mechanical properties as well as thermo-oxidative stability. In addition, concentrated HFPE monomer solutions were infused into stitched AS4 and T650-35 preforms and their mechanical properties were compared with those of the commercial BMI-5270 composites from cryogenic temperature to 343 C (650 F). The stitched HFPE composites out-performed BMI-5270 composites in terms of property retention at elevated temperature and microcrack resistance during thermal cycling from ï54 to 288 C (ï65 to 550 F). The stitched composites also showed more resistance toward blistering and delamination than conventional laminate composites during a rapid heating rate simulating launch and re-entry of reusable launch vehicles (RLV).

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