Adsorption-curing process

Using a simple adsorption-curing process, Andresen et al. have grafted the antimicrobial ammonium compound octadecyldimethyl-(3-trimethoxysilylpropyl)ammo-nium chloride (ODDMAC) onto the surface of MEG from wood pulp (Eigure 8.17) [26]. 

Wedge test results suggest that the curing process (e.g., percent crosslinking) of the epoxy-polyamide primer system is not affected by the addition of organosilanes, but may be affected by NTMP. The results of substrate surface characterization, adsorption behavior of applied films, and evaluation of candidate inhibitors by chemical, mechanical, and electrochemical test methods are presented. Mechanisms to explain the observed behavior of the various phosphonate and silane polymer systems are discussed. 

EXPOSURE ROUTES rubber, tanning, fish processing, dye and surfactant industries ingestion of food cured meats and smoked fish drinking contaminated water breathing cigarette smoke contaminated ambient air percutaneous adsorption... 

Such differences can result from a chemical or catalytic influence of the substrate, or from preferential adsorption and immobilization of adhesive components on the substrate, or the substrate could even initiate phase separation, crystallization, or any other preferential molecular arrangement. The spatial constraint due to the polymer-substrate and polymer-atmosphere interfaces could alter the molecular mobility and diffusion of species significantly as well - not only for ultrathin Ims but also for closed joints. How all these alterations to the microscopic processes affect the emerging macromolecular structure in a curing polymer adhesive is widely unknown, but there is much empirical evidence that they result in modified technical properties. 

Diatomite (Kieselguhr). Diatomaceous earth (as it is also called) is chemically ineit, but it has high adsorptive power. This can account for adsorption of curing ingredients that interfere with accelerated-sulfur vulcanization. However, diatomite is used as a filler in silicone rubber. Because of its high adsorptive capacity, it is used as a process aid in high-oU rubber compounds. 

Reaction process Adsorption Catalytic reactions Crystallisation Polymerisation Curing Desorption Melting Vapourisation Sublimation Desolvation (drying) Solid-solid transition Solid-liquid reaction Solid-gas reaction Solid-solid reaction Decomposition... 

FIGURE 9.6 XRD pattern of a clay-epoxy system (epoxy/DM-clay) before and after curing prepared by the exfoliation-adsorption process, and for comparison, bis(2-hydrox-yethyl)methyl tallow alkylammonium-modified MMT (Epoxy/clay-30B). (From Ref. 43, copyright 2004, American Chemical Society, with permission.)... 

From what was said above, it follows that the IPN components have various affinity to solid surfaces, and, therefore, in the course of their synthesis, the processes of selective adsorption at the interface must be observed. In reality, for various IPNs (polyurethane-polyesteracrylate, polyurethane-polybutyl methacrylate), it was found that near the interface, the composition of the surface la er differs from the composition in the bulk. IR-ATIR method was used. Supports were glass and poly(ethylene terephthalate). It was discovered that at the interfaces IPN-solid and IPN-air, the surface layers had very different compositions. For PU-PEA IPN, the layer formed at the interface with glass is enriched with PEA, whereas at the interface with air, excess concentration of PU was found. This effect of surface segregation is increasingly more pronounced with diminishing distance from the interface. For the interface with poly(ethylene terephthalate) in IPN based on PU and PBMA, the surface layer is enriched in PBMA. The effects depend on the IPN composition. It was established that the composition of the layers strongly depends on the kinetic conditions of curing. ... 

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