Integral photoinitiator

Changing the level of the photoinitiator concentration as a result of its photodecomposition, we accept, that and in accordance with Equation (4.5) does not depend upon time in the interval x-t after removing the given imit of PMPh volume. That is why, by integrating Equation (4.28) in accordance with condition P = 1 in a moment of time t for removal of PMPh, we obtain ... 

The variation in the photoinitiated polymerisation is complicated, since it is necessary to take into account the presence of a gradient of the light exposure in the layer of the photopolymerising composition. This effect indicates that the rate of polymerisation and conversion are functions not only of time, but also of the coordinates of a layer x from an illuminated surface (x = 0), and appear, thus, in differential performances of the process in a layer x, x + dx. The transition from differential characteristics P(x, t) and dP(x, t) / dt to experimentally determined, P(t) and dP(t) / dt, is carried out via integrated transformations ... 

First of all, let us assume, that the characteristic time of the photoinitiator decomposition td = (y Jo) is considerably more than the time t of polymerisation, therefore we can neglect the polymerisation by changing the photoinitiator concentration via time (typical approximation for long-chain processes) taking c = Cq. After integration, fj/fx=-ecj, we obtain the J=JqCxP 1-ZCqx and, after introduction of the latter into the left hand side of Equation (4.49) we obtain Equation (4.51) ... 

Spectroscopic investigations showed that such covering medical glass does not significantly distort the integral spectrum of an UV-illumination using a DRT-400 mercury-quartz lamp for the photoinitiator decomposition (see Figure 5.18). 

However, as a rule, the experimentally measured parameters of the photoinitiated polymerization are not the differential rate of the proce.ss dp/di, or relative depth of the polymerization P, but their integral, that is, the average of the layer analogs. They are determined by the expression ... 

With the photoinitiator concentration variations being constant as a result of its photodecomposition, we accept that Vjs and Ws in accordance with equation (6.5), do not depend upon the time interval r-t after removing the given volume of PMPh. Therefore, by integrating equation (6.28) in accordance with condition P=l at time t for the PMPh removal, we have... 

Another hybrid system has been proposed for resist applications the simultaneous chain polymerization of N-methylolacrylamide and the acid-catalyzed crosslinking of the resulting polymer with poly(vinyl alcohol) In dual cure plastisols, finally, a solid thermoplastic resin is dispersed in a multifunctional aciyrlate mixture which contains a thermal and a photoinitiator. These plastisols have been proposed for the encapsulation of integrated circuits... 

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