Particles epoxy activated

For protocol suggestions on conjugation to epoxy groups, see Chapter 2, Sections 1.7 and 4.1. Also, see Chapter 14, Section 4.11, Coupling to Epoxy Particles, for a method to attach affinity ligands to surfaces that are activated with epoxide groups. 

The three TS-1 catalysts with similar Ti contents have cuboidal morphology with comparable particle sizes of 0.2-0.3 pum (as shown in SEM pictures, Fig. 53). The EPR spectra of the samples in contact with aqueous H202 (46%) (Fig. 54) indicate that the ratio of the A to B superoxo species in various TS-1 samples increases in the order TS-1 (fluoride) < TS-1 (with anatase) < TS-1 (without anatase). Catalytic activity for phenol hydroxylation and allyl alcohol epoxi-dation (Table LIII) was found to parallel the A/B ratio of the oxo-Ti species (TS-1 (fluoride) < TS-1 (with anatase) < TS-1 (without anatase)). 

As can be seen from Fig. 12, the experiment is very well described by Eq. (35). Finally, measurements of the electric conductivity of the binary mixtures of the initial reagents have played an important role in substantiating Scheme (35) 149-152>. The electric conductivity of any binary mixture of the initial reagents (epoxy compounds, TA and alcohol) turned out to be over two orders of magnitude lower than that of the triple system. These experiments show that the interaction of all three reagents is essential for generation of the ionic particles. They have also completely rejected the possibility of formation of active sites directly via interaction of TA with alcohol139,... 

Thus, the above findings149) indicate that the first stage of the initiation of the epoxy compound polymerization under the action of the TA even in precision-cleaned systems may take place by the trimolecular mechanism to give quaternary ammonium alcoholates owing to impurity quantities of the proton donor or other electrophilic particles in the system. This reaction will not occur in the absence of such impurities. Upon appearance of the hydroxyl groups in the system due to the chain transfer to the counterion (see Sect. 3.3.3) the reaction according to Scheme (33) with participation of the unsaturated alcohol becomes the main source of the active growing sites. 

Table 11 presents one more result important for the chemistry of epoxy compounds, namely within the experimental error the rate constant of the free ion is the same for all counterions. This means that such strong nucleophilic particles as carbanions (and evidently alkoxy anions) are capable of opening the epoxy ring without additional electrophilic activation. This result explains the apparently contradictory results that, depending on the reaction conditions, either tri-140 144,166-I71) or bimolecular kinetics 175-I79> is observed. The bimolecular kinetics also can be explained in terms of the trimolecular mechanism, since proton-donor additives play a dual role. 

Manson and Chin 151) reported that the addition of filler to an epoxy binder reduces the epoxy s permeability coefficient (P), as well as the solubility of water in the resin (S) and that the reduction is stronger than expected from theory 1 2). Diffusion coefficients calculated from P and S for the unfilled resin were found to be somewhat higher than those for filled resin. The difference seems to be due to the formation of ordered layers, up to 4 pm thick, around every filler particle. The layers form because of residual stresses caused by the difference between the binder and filler coefficients of thermal expansion. The effective activation energy for water to penetrate into these materials, calculated in the 0-100 °C temperature range, is 54.3 kJ/mol151). 

Brittle, hollow glass beads have been found to be both an extender and an impact modifier for coatings and adhesives. The extender particles have to be designed in such a way that they actively dissipate deformation energy and hence reduce the likelihood of loss of adhesion between the epoxy and the substrate.25... 

A surface activated rubber particle, Vistamer, was recently introduced as a low-cost toughener for epoxy and polyurethane adhesives. The source of the rubber is reprocessed... 

Triazole particles can be made insoluble in water using a plasma polymerization technique. An ultratbin polymer film on the particles is formed, as confirmed hy secondary ion mass spectrometry. The encapsulated triazole slowly releases the active triazole and can be used as a paint pigment in a water-based epoxy coating. This technique could replace chromate pigments in paints. 

Chem. Descrip. Quaternary ammonium compd. of bentonite Uses Thixotrope in aliphatic and aromatic solv.-based coatings, alkyds, processed oils, epoxy-esters, and oil-modifled urethanes Features Qrganoclay easy to disp., self-activating Properties 90% < 90 pm particle size dens. 11.93 Ib/gal bulking value 0.084 gal/lb 2.5% max. moisture Tixogel KM ]Sud-Chemie Inc]... 

The kinetics of accumulation of the compound characterized by the band at 404 nm (Fig. 2.29, curves 4 and 6) indicates a dependence between the amount of pyridine halogenide introduced into the epoxy compound and the concentration of the product formed the maximum intensity of the absorption band in the visible region increases with the amount of additive. The character of the curves for accumulation and consumption of spectrally active particles differs for bromides and chlorides (curves 3 and 6). It follows from the data in Fig. 2.29 that the changes in the band with maximum at 404 nm (curves 4 and 6) are connected with consumption of epoxide groups (curves 8 and 10). 

---