Measuring Cure

The curve exhibits a number of features which are used to compare cure  

T5 The scorch time at lower temperature is of importance too. This can be obtained by using a Mooney Viscometer at lower temperature. A Mooney Viscometer is also used to measure the viscosity of the compounds (important for dictating injection-moulding behaviour). The viscometer is also used to assess the tendency to scorch, and sometimes the rate of cure of a compound. A useful estimate of scorch behaviour is represented by T5, the time taken from the beginning of the warm-up period to that at which the Mooney value rises five units above the minimum value. 

T90 The most useful information obtained from the rheometer curve is T90, which is defined as the time to achieve 90% cure. Mathematically, T90 is the time for the torque to increase to  

Cure rate A rise in the value of torque with time, the slope of the curve, gives the measure of cure rate. Sometimes cure rates of various cure systems are compared with T90-ts2 data. 

The brass coated steelcord used in adhesion tests was of a 3+9x 0.22-hI construction with a Cu content of 63%. The rabber to metal adhesion characteristics were determined according to ASTM 2229-85. The wire adhesion data quoted are averages of 10 individual tests. Wire adhesion samples were aged under the following conditions  

---

After extensive baseline studies, FTIR-RTM was used for measuring the level of cure. The primary reasons for this decision was the high reproducibility of measuring cure by following isocyanate... 

Rheometer measurements measure cure and cure rate characteristics of the rubber. The component manufacturer performs this test on unvulcanized rubber. The rheometer measures the viscosity of the rubber as a function of time at a constant temperature. As time increases, the degree of cure or cross-linking increases and thus the viscosity increases. 

Besides these specific methods, the general arsenal of techniques described in sec. 3.7 remains available. So, optical and Volta potential measurements cure often invoked to obtain structural information on the monolayers. These techniques do not basically differ from the corresponding ones for Langmuir monolayers. However, surface rheology differs drastically because for Gibbs monolayers transport to and from the bulk is possible. Differences start to appear if the molecules are not very small and therefore diffuse with time scales comparable (or shorter) than those of the measurements. Therefore this theme will be devloped separately before surfactant monolayers are discussed, see sec. 4.5. 

Data collection (compare actual to optimal) This step is the evaluation, where performance is measured against objective criteria for the processes or outcomes of care. Criteria may relate to indications (for selection of a particular medication or procedure), processes (drug dosing and administration, patient assessment and monitoring) or outcome measures (cure, relief of symptoms, treatment failure, adverse drug event, patient satisfaction). 

Theoretical treatment of this polymerization is difficult because of the presence of both primary and secondary amine reactions as well as tertiary amine catalyzed epoxy homopolymerization. To obtain kinetic and viscosity correlations, empirical methods were utilized. Various techniques that fully or partially characterize such a system by experimental means are described in the literature ( - ). These methods Include measuring cure by differential scanning calorimetry, infra-red spectrometry, vlsco-metry, and by monitoring electrical properties. The presence of multiple reaction mechanisms with different activation energies and reaction orders (10) makes accurate characterizations difficult, but such complexities should be quantified. A dual Arrhenius expression was adopted here for that purpose. 

The basis of the method described by Hands and HorsfaU [1] consists of calculating the tanperature distribution as a function of lime first, thoi evaluating the dis-ttibution of the cure. Taking a temperature profile, a technique is described enabling the evaluation of the state of cure. When the form of the relationship between cure and temperature history is known, the basic cure parameters can be obtained from experiments in which temperature varies with time. When the relationship is not known, it is preferable to conduct experiments at various fixed temperatures in order to separate the dependence on time and temperature. An apparatus was built for measuring cure as a function of time at a constant temperature. The data obtained from this isothermal apparatus and a new mathematical model of cure was used to predict the cure distribution obtained in nonisothermal experiments. 

Both set times are determined by employing the cohesion testing device, used to measure cure time of slurry seal, measuring the torque of a micro-surfacing mixture as it coalesces and develops cohesive strength. The amount of torque developed plotted over time shows how the mixture is developing resistance to movement. 

Combat risks at source, rather than taking palliative measures - cure problems not alleviate. 

Schoff [2] has described the use of dynamic mechanical techniques in the characterisation of commercial organic coatings. Such techniques have become valuable methods for the determination of basic viscoelastic properties, following and measuring cure, and... 

---