Autoclave typical cycle

Fig. 4. Typical nylon-6,6 autoclave polymerisation cycle showing the changes in pressure (—) and temperature (---). To convert MPa to psi, multiply by...

The autoclave cure of advanced composites serves as a good illustration of this sort of complex control problem. A typical autoclave cure cycle is shown in Figure 15.1. The temperature is usually increased in stages until some maximum cure temperature is reached. It is then held at maximum cure temperature until complete cure is certain. During this temperature cycle, the pressure is applied to achieve compaction. The 11 items capitalized in Figure 15.1 are all variables. It is clearly not possible to perform an exhaustive study of all variations of all of these variables with finite time and money. In addition, although the preceding template is common, it is not the only possibility. It would also be possible to heat... 

Figure 9.12 Typical autoclave cure cycle for a graphite/epoxy composite (TGDDM-DDS). 

Apply vacuum bag cure in autoclave (see Table 6.46 for a typical cycle)... 

A typical vacuum bag lay-up is shown in Figures 21.76 and 21.77, whilst Figure 21.78 depicts a characteristic autoclave cure cycle. 

Figure 3.20 Typical autoclave cycle for batch polymerization of PA-6,6.5...

Figure 6.2 Curing cycle temperature-time profile for typical graphite-epoxy composite in a vacuum bag autoclave process. Autoclave pressure is applied during the 135°C (275°F) hold...

This section describes some of the tools available for intelligent development of process cycles, such as the time-temperature cycles used in curing composites. Current industrial practice is typically limited to the use of cure cycles. The cycles are based on a series of autoclave temperature and pressure states so that traditional linear, regulatory process control methods can be used. These recipes may not be the ideal method for process control of batch processes because they do not ... 

In a typical run, 10% Pd/C (0.5 mmol of Pd) was weighted, then introduced into the autoclave. Two argon-vacuum cycles were performed before addition of 8 ml of toluene, 50 mmol (7.01 g) of substrate and 5 mmol of hydrochloric acid (CH3OH + CH3COCl). The autoclave was pressurized with 30 bar of carbon monoxide, and heated to 100°C. 

Closure sterilization, following the cleaning cycle, is typically done by autoclaving with saturated steam. The temperatures achieved in such treatments are not sufficient to eliminate significant endotoxin contamination. 

A typical cure cycle is shown in Fig. 9.12. Somewhere in the plateau at 135°C the autoclave pressure is applied. This step provokes the elimination of resin, which is absorbed by the bleeder cloth, and the increase in the fiber... 

Autoclave sterilization is one of the most difficult common sterilization environments for a medical adhesive, and it is commonly used in hospitals and health care facilities for reusable devices. Autoclaves sterilize with high-pressure steam. Temperatures inside the sterilization chamber typically can reach 130°C with pressures above ambient. Certain adhesive systems, such as polyurethanes, may show hydrolytic degradation in such environments especially after multiple cycles. Epoxies perform the best under multiple autoclave exposures. However, on certain substrates, light-cured acrylics and cyanoacrylates will also perform fairly well. 

First of all, thermal sterilization, which includes the use of steam or dry heat, is the earliest method used. Steam sterilization is up to now the most widely employed sterilization process. It is carried out in a chamber called autoclave. A typical autoclave cycle corresponds to a period of 15 minutes at 121 °C. In the case of dry-heat, the process is undertaken in an oven with heated and filtered air, distributed uniformly. The cycle is of two hours at 160 °C. 

In autoclave curing best results can be obtained with high pressure and curing temperatures, i.e., at 3 to 4 kg/cm2 pressure and 134 °C to 144 °C temperature. The usual procedure followed is to subject the rubber lined vessel to air pressure of about 2 kg/cm2 at the beginning of the cure cycle which ensures good contact between metal and rubber and then introduce steam and raise pressure and temperature to complete the cure. Typical cure cycles for ebonite and soft rubber are represented in the curves as shown in Figures 6.2a and 6.2b. 

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