No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

A cation-responsive electrode system has been developed which incorporates aza-substituted crown ethers as ligands. In a novel application, uncomplexed crown ethers were used in the pelletized form for ionic transport. Electrodes have been produced which can be conditioned for a particular ion and following their use, be reconditioned and reused for other ions. Preparation method and lifetime studies are included. The responses of two crown ethers with plasticizers were evaluated for thirteen representative cations. The concentration range covered in each evaluation was 1 x 10-1 to 1 x 10-7 M. For those ions exhibiting Nernstian or near-Nernstian response, selectivity coefficients were derived.

The objective of this study was to investigate the effects of melamine and ether contents on the curing and performance properties of UF resins as binders for wood composites. Various UF and UMF resins were synthesized with three different synthesis procedures. These resins were examined by 13C NMR, rheometer, and other methods and evaluated as particleboard binders. Three-layer particleboards were prepared with the resins catalyzed with various catalysts and levels, applied in face and core layers. The board test results were compared. Only about half of added melamine had reacted with formaldehyde. UMF resins were found to be catalyzed with stronger catalysts at suitable levels depending on melamine levels and on which layer of particleboard the UMF resins are to be applied. Even catalyzed with a stronger catalyst, the curing rates of UMF resins were still slower, and storage stabilities were shorter than UF resins, but the pot lives were longer, and internal bond strength and water resistance were higher. Moreover, resins synthesized with procedures 2 and 3 showed obviously longer storage times, longer pot lives, and longer gel times, and the particleboards bonded with these resins showed significant improvements in internal bond strength and water absorption values but the formaldehyde contents increased. The increased formaldehyde content test values indicated that linear methylene-ether groups in UF resins decompose in the hot-pressing of boards to emit formaldehyde, most of which is not captured back into the UF resin matrix. Uron-type methylene-ether groups decompose in the hot-pressing of boards to participate in the curing process and enhance the bonding of boards, but it could also emit extra formaldehyde which may not be effectively captured by UF resins but more effectively by UMF resins if the amount of melamine is high enough because of the increased reactive capacities of melamine. The results of this research offered a new hypothesis that the linear methyleneether bonds in UF resins might be a major contributor of the high free formaldehyde contents of particleboards. Decreasing the linear methylene-ether groups contents might effectively bring down the formaldehyde content of boards.

The structural evolution of micromolded poly(ε-caprolactone) (PCL) and its miscible blends with noncrystallizable poly(vinyl methyl ether) (PVME) at the nanoscale was investigated as a function of deformation ratio and blend composition using in situ synchrotron smallangle X-ray scattering (SAXS) and scanning SAXS techniques. It was found that the deformation mechanism of the oriented samples shows a general scheme for the process of tensile deformation: crystal block slips within the lamellae occur at small deformations followed by a stressinduced fragmentation and recrystallization process along the drawing direction at a critical strain where the average thickness of the crystalline lamellae remains essentially constant during stretching. The value of the critical strain depends on the amount of the amorphous component incorporated in the blends, which could be traced back to the lower modulus of the entangled amorphous phase and, therefore, the reduced network stress acting on the crystallites upon addition of PVME. When stretching beyond the critical strain the slippage of the fibrils (stacks of newly formed lamellae) past each other takes place resulting in a relaxation of stretched interlamellar amorphous chains. Because of deformation-induced introduction of the amorphous PVME into the interfibrillar regions in the highly oriented blends, the interactions between fibrils becomes stronger upon further deformation and thus impeding sliding of the fibrils to some extent leading finally to less contraction of the interlamellar amorphous layers compared to the pure PCL / National Natural Science Foundation of China (21204088 and 21134006). This work is within the framework of the RCUK/EPSRC Science Bridges China project of UK−China Advanced Materials Research Institute (AMRI).