Curing method comparison

Comparison of Heating and Curing Methods for Thermosetting and UV Curable Powders... 

Comparison of Structure and Thermal Degradation of Phosphate-Linked Epoxy Resins between Anhydride and Cationic Curing Methods... 

Determination of die mechanical properties of a cured polymer serves to characterize its macroscopic (bulk) features such as flexibility and hardness. Using standardized methods of the American Society for Testing and Materials (ASTM) and die International Standards Organization (ISO) allows direct comparison to otiier materials. The vast majority of polyurethane research and development is conducted in industry where mechanical properties are of vital importance because tins information is used to design, evaluate, and market products. General test categories are presented here with a few illustrative examples. 

Figure 2.8, is generated, presenting peaks correspondent to functional groups, such as epoxide, primary and secondary amines, and hydroxyl. The values of the absorption bands for these groups can be found in the papers referenced earlier. The basic principle of all these methods is the comparison between the spectrum of reference substances and spectra of the reactants and products of a curing reaction subjected to radiation. A qualitative and quantitative identification of the components is then possible. 

Figure 7.23 Applications of the NMR-MOUSE to elastomer materials (a) T2 values for a curing series of carbon-black filled NR. Comparison of values obtained at high homogeneous field (DMX 300) and with the NMR-MOUSE, (b) cross-link series of unfilled SBR with different sulfur content, (c) T2 versus glass-transition temperature Tg of unfilled SBR by the CPMG and the steady-state CPMG methods, (d) normalized Hahn-echo decay curves for poly(butadiene) latex samples. Different decay rates are obtained for small medium and large cross-link densities...

Films. Both structural and nonstructural adhesives are commonly available in film form. Adhesives applied in the form of dry films offer a clean, hazard-free operation with minimum waste and excellent control of film thickness. However, the method is generally limited to parts with flat surfaces or simple curves. Optimum bond strength requires curing under heat and pressure, which may involve considerable equipment and floor space, particularly for large parts. Film material cost is high in comparison to liquids, but waste or material loss is the lowest of any application method. 

Powers, H. R., "Comparison of Energy Requirements for Various Methods of Curing Coil Coatings". Sherwin-Williams Company, 1973. 

Figure 5. Comparison of cure curves obtained by dynamic and by steady-shear methods.

Thus, the comparison of the results of viscometric ami dynamical mechanical measurements is the physically substantiated method for characterizing the gelpoint in curing compositions. 

Among physicochemical methods for studying curing processes, rheokinetics is the closest to calorimetry, also yielding combined characteristics of the chemical dynamics of the process. Due to this, there was carried out a comparison of quantitative curing parameters obtained by rheological and calorimetric methods. 

The linear acenes, benzene to pentacene, are used as examples of the CURES-EC procedure. The results obtained utilizing MINDO/3 and AMI are compared. In addition to calculating the Ea by subtracting the energies of the optimized form, the LUMO of the neutral is compared with the experimental Ea. The electron affinity of hexacene has been estimated from the electronegativity and experimental ionization potential. As a further example of the use of CURES-EC, both the ionization potential and electron affinity of heptacene are estimated. The Ea of octacene and nova-cene are calculated for comparison to values obtained by using Koopman s theorem and a semi-empirical method based on a variable-parameter modification of the Pariser Parr Pople (PPP) approximation to the Hartree Fock equation [10]. 

In Chapter 8 the electron affinities of atoms were evaluated. In this chapter the electron affinities of diatomic and triatomic molecules and SF (n= 1 to 6) will be considered. The ECD has been used to study CI2, Br2, I2, NO, 02, C02, COS, CS2, N20, N02, SO2, SF6. All the Ea for these molecules have been calculated by the CURES-EC method. The comparison of the relative electron affinities of COS, CS2, and N20 will be illustrated by READS-TCT calculations. 

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