Resin flow rate

This model can also provide resin pressure gradients, resin flow rates, consolidation profiles, and, when combined with the void model, void profiles at any point in the laminate. 

The cure of thermoset resins involves the transformation of a liquid resin, first with an increase in viscosity to a gel state (rubber consistency), and finally to a hard solid. In chemical terms, the liquid is a mixture of molecules that reacts and successively forms a solid network polymer. In practice the resin is catalyzed and mixed before it is injected into the mold thus, the curing process will be initialized at this point. The resin cure must therefore proceed in such a way that the curing reaction is slow or inhibited in a time period that is dictated by the mold fill time plus a safety factor otherwise, the increase in viscosity will reduce the resin flow rate and prevent a successful mold fill. On completion of the mold filling the rate of cure should ideally accelerate and reach a complete cure in a short time period. There are limitations, however, on how fast the curing can proceed set by the resin itself, and by heat transfer rates to and from the composite part. 

Resin Flow Rate (L/min) Mean Bead Diameter (mm) Pressure Drop (bar/cm) Calculated Measured ... 

It is obvious that the pump handles only clear liquid which is forced into the top of a pressurized tank to move the settled resin bed as a dense slurry out of a pipe near the base of the tank. Systematic studies done on this phenomenon showed that the slurry moved along the pipe as closely packed as in the settled bed itself. The voidage of the delivered sluny was proved to be constant. This technique can be used for accurate control of resin flow rates since the flow rate of slurry is a constant fraction of the flow rate of displacing liquid. ... 

The easiest indication of realtive molecular weight is melt viscosities at 315 C in a plastometer. Extrusion rates with a long (3.175 cm) orifice and a 325 g load are used to characterize low molecular weight polymers such as coating resins. Flow rates with a short (0.80 cm) orifice and a 5.0 kg load are used for injection molding grades. 

Depending on the needs and expectations, one should dedde what type and capadty of the injection equipment to purchase. Usually, the initial investment cost of a flow rate-controlled injection equipment is higher than a pressure-controlled equipment. Figure 9.16a shows a flow-rate controlled injection equipment from Radius Engineering Inc. Its major components are (1) a resin cylinder (with a capacity of 2100 cc for this model) with a heater jacket, (2) an electric stepper motor which drives a piston at a desired resin flow rate, (3) a control console to input the process parameters and monitor process variables, (4) communication interfaces to control the equipment through a personal computer instead of the control console if desired and (5) a frame and stand with wheels. 

In fiber tows, the resin flow rates are very low because of the low permeability of fiber tows. Moreover, the spaces in between individual fibers are narrow and low contact angle condition is always satisfied because this is characteristics for LCM processes. Thus these conditions boost the importance of capillary action. 

Factor Level Mold Temp. Diff. fC) Mold Temp (C) Combined Resin Flow Rate (g/sec) Relief Vent Pressure (psi) Resin Temp (C)... 

---