Curing tests

Rubber Reclaimers Association (RRA) cure test recipe for mixed elastomer and NR reclaim cured 20 min at 141°C. 

RRA cure test recipe for HR reclaim, cured 30 min at 160°C. HR is isobutylene—isoprene mbber (butyl mbber). 

A significant revision to the SMR scheme was introduced in 1991 in response to consumer desire for greater consistency in natural mbber (13). Other producing countries have similar specification schemes (14), as does the International Standards Organization (ISO) (15). An example of the specifications for TSR is given in Table 1 for the present Standard Malaysian scheme. Except for SMR 5, rheograph and cure test data (delta torque, optimum cure time, and scorch) are provided. 

The relative reactivity of thermosetting powders can be easily deterrnined by the gel time or stroke-cure test. A small amount of powder is placed on a hot plate, usually at 200°C, and the time until the coating composition gels, or no longer forms fibers, is deterrnined. Powders are characterized by relative gel times (cure rate) as shown in Figure 1. 

When required, perform adhesion tests, curing tests or tests for surface contamination. 

Since ozone attack on rubber is essentially a surface phenomenon, the test methods involve exposure of the rubber samples under static and/or dynamic strain, in a closed chamber at a constant temperature, to an atmosphere containing a given concentration of ozone. Cured test pieces are examined periodically for cracking. 

ASTM D 1144 provides a recommended practice for determining the rate of bond strength development for either tensile or lap shear specimens. However, peel and can-teliever tests can also be used effectively. Measured bond strength values of partially cured test specimens are compared with those of a reference (i.e., fully cured adhesive joint) to assess the extent of cure. This method may suit some applications, but it is limited in accuracy because it does not directly measure the degree of cure in the adhesive, and the effect on the joint design and substrates may override the effect of cure development. 

The composites were fabricated by mixing the inorganic additives with the resin, infiltrating fiber preforms with this mixture, pressing in a hydraulic press, and curing. Test specimens were then machined from the composites. Although mechanical properties of the four new composites were not measured, similar previously fabricated materials had tensile strengths and moduli of approximately 200 MPa and 8 GPa, respectively. 

At the end of a cure test, it is difficult to remove the sample because the rotor is embedded in the center of the cured sample. 

Physical-property tests are used to measure the properties of adhesives in the liquid or gelled states prior to curing and in the solid state after curing. Tests for the uncured state such as viscosity, visual examination, and surface energy or contact angle assure that fillers, if used, have not settled out, that the material has not exceeded its pot life or shelf life, and that the supplier has not changed the formulation. Visual examination and density after cure are performed to verify that voids are not present or, if present, meet specification requirements. Finally, light transmission and index of refraction measurements are important for adhesives used in optoelectronic applications. 

Weight Loss During Cure, Test Method PT-80, Ahlestik Electronic Materials (now Henkel). May 31, 1996. 

The mix design procedure for slurry seal according to ASTM D 3910 (2011) requires the execution of the following tests (a) consistency test, (b) set time test, (c) cure test and (d) wet track abrasion test, all described in ASTM D 3910 (2011). 

X No cure - test pieces separated on loading O Cured in refrigerator... 

Cured test article placed on process tooling to measure dimensional fidelity. 

Radiation Cure Testing. Equal weight fractions of vinylamide reactive diluents and/or difunctional A -vinylformamido compounds were compared in model formulations (Table I). 

Allyls (DAP and DAIP). The reflux apparatus described in Fig. 2.31 is the generally accepted cure testing procedure for allyls. Sections of a molded specimen are refluxed in boUing chloroform for 3 hr, after which the specimen is visually examined for evidence of a serious problem such as cracking, swelhng. Assuring, or actual crumbling of the surface. Surface hardness can be checked with a hardness tester, but this should not be done until... 

These techniques involve the analysis of the changes in the chemical and physical properties of a molded specimen as a function of temperature. They are not generally used for production or quality control but are quite useful in resolving problems that could be the result of insufficient cure and that are not readily detected by the more common visual or chemical tests. There is a rule-of-thumb test procedure that is a fairly reliable cure test, and it is based upon a visual inspection of the molded article for obvious defects such as... 

Cure 4kW mercury lamp (3.5 J.cnr 30 sec, then anaerobic cure. Test Methods ... 

Tested at room temperature and after 7 days cure Tested at room temperature and after 7 days water immersion... 

For each material a specific curing cycle has been adopted, as specified by the material s datasheet and by the curing test previously performed. It is important to note that the curing process of the matrices can vary in significant ways when the particles are embedded in it. Figure 6.45 shows the various methodologies and phases of the sample manufacturing. 

Conditioning of materials Assembly curing Test specifications... 

---