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Photocalorimetry DPC

The polymerization and/or cross-linking of photoinitiated systems is an important process in many industries, including semiconductor, electronics, information storage, printing and dental. UV- and blue light-curable materials include [Pg.154]

In a kinetic study the conversion-time or conversion-rate of conversiontime data can be fit to kinetic equations. This fitting process will allow the experimenter to determine whether the reaction follows n order or autocata-lytic kinetics and to obtain rate constants (k) and reaction orders (n or m). The activation energy may be obtained from an Arrhenius plot of In A versus the reciprocal of absolute temperature (see discussion in Traditional Isothermal Kinetics in Section 2.10). [Pg.156]

If the reaction is incomplete after the first irradiation, a residual heat of reaction will be detected on the second irradiation. A good practice is to repeat irradiation cycles until two cycles are obtained that are indistinguishable from each other. This same methodology can be used to ascertain the completeness of cure of samples cured in laboratory and production processes, although additional measurement of Tg as an indicator of conversion is recommended. [Pg.156]

Commercial photocalorimetry accessories are now offered by several instrument manufacturers with a choice of light sources and optical configura- [Pg.156]

Reflector HG-orXe- Condenser Monochromator Shutter splitter lamp [Pg.157]


Differential photocalorimetry (DPC) is included here since the instrument used is essentially an adaptation of DSC instrumentation. The photocalorimeter comprises a DSC instrument with a UV/visible source mounted on top, such that light of appropriate wavelength or wavelength region from the source is focused onto the measuring head (both reference and sample pans). The most frequent use of DPC is in the study of polymer cure reactions, but it may also be used to follow such as UV degradation. [Pg.438]

Polymerization Behavior. Both Fourier-transform infrared spectroscopy (FTIR) and differential scanning photocalorimetry (DPC) were used to characterize the polymerization behavior, curing time, and maximum double bond conversion in these systems. [Pg.192]

Differential Photocalorimetry (DPC) (19.201. The polymerization being an exothermal process, the reaction can be monitored in real time by differential scanning calorimetry (DSC). From the recorded thermogram which shows the variation of the heat flow with the irradiation time, the rate of polymerization can be directly calculated, provided the standard heat of polymerization (AHq) is known. For acrylic monomers, AHg values are usually in the range of 78 to 86 kJ mol depending on the monomer considered. [Pg.449]

Combined simultaneous techniques—many of these techniques can be combined to give simrilta-neous or sequential measurements on the same sample, eg, TG/MS, TG/IR, DSC/XDR, DSC/TG/MS, pyrolysis/GC, Differential photocalorimetry (DPC), etc. [Pg.8284]

The principal techniques that have been used in resin cure studies are differential scanning calorimetry (DSC Chapter 7), photocalorimetry (Sections 11.3.1 and 11.3.2), dielectric thermal analysis (DETA Section 12.2.1) and dynamic mechanical thermal analysis (DMTA Section 8.3.2). Earlier differential photocalorimetry (DPC) instruments were based on a DSC instrument. However, these were only partially successful in the analysis of photocurable polymers. The failure to develop a completely adequate system has been the result of two factors. The first and most significant is the change in the intensity of the light with time of operation - as much as an 80% reduction in the first 100 hours of operation. The second reason for the limited success was the lack of data analysis software to convert raw data into easy-to-understand results that could be correlated with actual performance. [Pg.175]

Groves IF, Lever TJ, Hawkins NA. Use of differential photocalorimetry (DPC) for the study of photoinitiator systems Polym Paint Color J 1993 43 8-16. [Pg.254]


See other pages where Photocalorimetry DPC is mentioned: [Pg.28]    [Pg.191]    [Pg.407]    [Pg.134]    [Pg.154]    [Pg.155]    [Pg.155]    [Pg.157]    [Pg.159]    [Pg.161]    [Pg.151]    [Pg.2]    [Pg.48]    [Pg.190]    [Pg.248]   


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