Curing times for

The ebonite compound before cure is a rather soft plastic mass which may be extruded, calendered and moulded on the simple equipment of the type that has been in use in the rubber industry for the last century. In the case of extruded and calendered products vulcanisation is carried out in an air or steam pan. There has been a progressive reduction in the cure times for ebonite mixes over the years from 4-5 hours down to 7-8 minutes. This has been brought about by considerable dilution of the reactive rubber and sulphur by inert fillers, by use of accelerators and an increase in cure temperatures up to 170-180°C. The valuable effect of ebonite dust in reducing the exotherm is shown graphically in Figure 30.3. 

Figure 4. Weighted concentration of effective strands versus humidity at constant cure time for different initial ratios of isocyanate to hydroxy. The cure time is chosen so that at equal isocyanate and hydroxy and H=0, the extent of reaction is 85%.

Figure 6. Flexural modulus as a function of cure time for fiber loadings between 0 and 60 wt.% with an incident light intensity of 480 mW/cm2.

Figure 19. The fraction of film remaining after electron beam exposure and development as a function of vacuum curing time for three negative...

Figure 9. Pendulum hardness as a function of curing time for several initiator concentrations. V 2% IV + 0.14% V 8% IV 6% IV A IV ...

Table 3.1 Relative critical cure time for ebonite...

Figure 6.5 Storage G and loss G" moduli as a function of frequency, at different cure times, for the same epoxy-diamine system as that represented in Figs 6.3 and 6.4. T, = 90°C. The parameter is the reaction distance from... 

Figure 15 A comparison of the change in the extent of the epoxide reaction as a function of cure time for the DGEB/DDS and DGEBA/DDS epoxy systems. (From Ref. 98.)...

Experiments with the metal-metal bonded polymers showed that the degradation rates depended on the curing time. For example, experiments showed that an increase in curing time of polymer 7 led to a decrease in the rate of photodegradation.62 This result was attributed to an increase in the fraction of the sample that is crystalline. It is well known that an increase in polymer crystallinity leads to a decrease in diffusion of particle or radicals in the polymer. It was hypothesized that the resulting decrease in diffusion (and the consequent increase in radical-radical recombination Scheme 10) leads to a decrease in the net rate of degradation. 

The pressure applied is normally in the range 3 to 5 MPa temperatures are similar to those used for HPL but with machine speeds of 5 to 30 m min -1 the cure times for resins are much shorter. 

Figure 5-15 Percentage cure and PC2 score as a function of curing time for AroCy L-10 resin. (Reprinted with permission from Ref. 18.)...

Variation of Substrate Temperature with Cure Time. For a thin substrate placed in an oven,set at a constant temperature,... 

Figure 4. TGMDA and DDS Concentrations Versus Cure Time for TGMDA/DDS (25t) at 177°C.

Figure 1. Plot of conversion vs. curing time for samples...

Figure 5 gives plots of 0 . and versus cure time for the Ashland polyester resin, and Figure 6 gives similar plots for the Dow vinyl ester resin. 

Figure 1. Shear storage modulus vs. cure time for 10 phr filler loading.

Table 17. Network chain density data obtained at different curing times for (V)-EPTM and ENB-EPDM... 

Cure time for compression molding is influenced by the molding thickness, and very thick moldings may require more time than thin ones. Compared to this, injection molding is much less influenced by the molding thickness, and very thick moldings may require a little more cure time that thin ones. 

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