Debinding

Water-soluble polymeric dyes have been prepared from water-insoluble chromophores, viz., anthraquinone derivatives. Unreacted chromophore and its simple derivatives, which are all water-insoluble, remain in solution due to solubilization by the polymeric dye. A method has been developed to separate and quantitate the polymeric dye and these hydrophobic impurities using Sephadex column packing. The solvent developed has the property of debinding the impiirities from the polymer, and further allows a separation of the imp irities into discrete species. This latter separation is based on the functional groups on the impurity molecules, having a different interaction with the Sephadex surface in the presence of this solvent. The polymer elutes at the void volume... 

The intensity of SR is high enough for crystallographic data to be collected in real time to give direct time resolution of dynamic events in a protein molecule. Bartunik et al. (1982) collected monochromatic test data on a millisecond time scale on carbon-monoxy myoglobin, where structural changes are induced by the debinding of the... 

The most complex mechanistic behavior is displayed by an allosteric system in which metal binding/debinding events trigger structural changes not just in and around the active... 

Thus, simple deproteinization of plasma with trichloroacetic acid, perchloric acid, phosphoric acid, or acetonitrile, followed by centrifugation and direct injection of the supernatants, yielded low recoveries of malachite green and leuco-malachite green, probably due to insufficient debinding of the analytes (495). Acidification or alkalinization of plasma and subsequent extraction with ethyl acetate also resulted in poor recoveries. In contrast, protein denaturation with a mixture of either acetonitrile or methanol and citric acid could substantially improve Ute recovery of the analytes, possibly due to the pairing-ion function of Ure citrate ions. 

The conventional way to obtain ceramic microstructures is to prepare a feedstock or a slurry, fluid or plastic molding, injection molding or casting (CIM, HPIM and tape casting), demolding, debinding and sintering. Most ceramic materials will... 

The debinding of powder injection molding workpieces, which consist of about 60 vol.% of a solid matrix (metal or ceramic powders) and thermoplastic polymer binders, was examined by extraction with scC02 [1]. By this technique the debinding time could be reduced from 1-2 days for pyrolysis to 1-2 hours for SFE. 

Binder removal can be accomplished by thermal decomposition or by dissolutiion. In ceramics, the thermal decomposition method is commonly used and will be considered here. The process is referred to as thermal debinding or, more simply, as binder burnout. In thermal debinding of ceramic green bodies, both chemical and physical factors are important. Chemically, composition of the binder determines the decomposition temperature and the decomposition products. Physically, the removal of the binder is controlled by heat transfer into the body and mass transport of the decomposition products out of the body. 

In practice, binder system may consist of three or four additives that differ in their volatility and chemical decomposition. Furthermore, interactions between the binder and the particle surfaces may alter the decomposition kinetics of the pure polymer. In view of its complex nature, a detailed analysis of thermal debinding is not useful. Instead, we consider the basic features of the process for a simplified system consisting of a powder compact with a single binder [e.g., a high molecular weight thermoplastic polymer such as poly(methyl methacrylate), poly(propylene), or poly(vinyl butyral)]. 

Figure 1. Model for thermal debinding by oxidative degradation where the binder-vapor interface is at a distance L from the surface of the compact. (After Ref. 2.)...

Table 1. Effect of Process Variables on the Time for Thermal Debinding by Oxidative Degradation...

Fig. I. G-protein catalytic cycle. Debinding of GDP and binding of GTP follows interaction of the inactive complex with the ligand stimulated receptor (R). The active G .GTP complex and the complex are able to activate effectors, which include both enzymes and ion channels. Deactivation occurs as a consequence of a slow intrinsic GTPase activity manifest by G leading to G .GDP which recombines with Gp., to give the inactive G g. GDP heterotrimeric complex.

Defining Moiecuiar Modifications Resuiting from Binding- or Debinding Events... 

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