Processing Characteristics Curing and Cross-linking

Modifying Processing Characteristics Curing and Cross-linking 

Function Effecting cross-linking of thermosetting resins initiation of reaction. control of speed of reaction. 

Properties affected Resin production fundamental to development of desired mechanical and chemical properties. 

Materials/characteristics Organic peroxides. Cobalt/amine/vanadium compounds. Aliphatic amines. Ketones, anhydrides, etc. 

Disadvantages Special precautions required in storage and use danger of lire, health and safely precautions must be observed. 

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Modifying Processing Characteristics Curing and Cross-linking 153... 

Another of the monomers used in addition to ENB is dicyclopentadiene (DCPD), which is shown in Figure 8.9. As can be seen from the structure, there are two double bonds in DCPD. Each of the two dienes will have different tendencies for long chain branching, which will influence processing rates and cross-linking by sulfur or peroxide cures [3], Table 8.5 shows some of the characteristics of the two dienes [5], In addition, Table 8.6 shows general features of ethylene-propylene elastomers as related to the ter-... 

Curing In the curing process, the adhesive molecules are cross-linked to create a strong adhesive joint. To solidify the adhesives, several methods are utilized such as heat, pressure, time, catalyst, vulcanizing, reactivation, and radiation based on characteristics of adhesives (Fig. 6) (Cognard 2006). 

Figure 1 illustrates the curing process as measured by a rheometer. The rheometer follows the development of cure state as a function of time. Vulcanization characteristics such as minimum torque Ml (a measure of compound green viscosity), onset of cure (T1 pt rise), Mh (a measure of maximum cure state reached), and T90% cme (time required to reach 90% cure state) are valuable properties defining cure behavior. Likewise the rheometer cure profile can be broken into three regions of interest, an estimate of scorch safety, an idea of what the cure state development looks like during the cross-linking phase, and how the cross-linked vulcanizate network matures with additional heat. 

Polymer mechanical properties are one from the most important ones, since even for polymers of different special-purpose function a definite level of these properties always requires [20]. Besides, in Ref [48] it has been shown, that in epoxy polymers curing process formation of chemical network with its nodes different density results to final polymer molecular characteristics change, namely, characteristic ratio C, which is a polymer chain statistical flexibility indicator [23]. If such effect actually exists, then it should be reflected in the value of cross-linked epoxy polymers deformation-strength characteristics. Therefore, the authors of Ref [49] offered limiting properties (properties at fracture) prediction techniques, based on a methods of fractal analysis and cluster model of polymers amorphous state structure in reference to series of sulfur-containing epoxy polymers [50]. 

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