The curing kinetics of a system containing 4,4′‐diglycidyloxy‐α‐methylstilbene (DOMS) and different functionality amines, N‐ethylaniline (NEA), aniline, benzenesulfonamide (BSA), and sulfanilamide (SAA), have been studied by differential scanning calorimetry (DSC) under isothermal conditions. The phase transformations during curing of the systems have been monitored by a crosspolarized optical microscope equipped with a hot‐stage and photo detector. It has been found that the growth of a nematic liquid crystal structure does not cause a discrepancy from the autocatalytic model for the reactions between aniline and epoxy. There is no liquid crystalline structure formed for the systems containing NEA or BSA, which follow the autocatalytic kinetic models within the temperature range of 120–150°C. For the curing reactions between DOMS and SAA, there is a big deviation from the autocatalytic model when the liquid crystals transfer from a nematic structure to a smectic structure. Unlike the usual decrease of reaction rate resulting from diffusion in a heterogeneous reaction, the reaction rate is enhanced. A modified kinetic model has been constructed for this reaction system by introducing a pseudoconcentration term caused from the liquid crystalline structure formation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1105–1124, 1997

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Microcellular foams in polypropylene containing rubber particles were produced in an injection molding process. The foams are generated because of the thermodynamic instability and are controlled by formation process. The effect of processing parameters on microcellular foaming was investigated in the injection molding process. Injection speed and pressure are less important factors but packing pressure plays an important role in controlling the foam density. A critical packing pressure, about 5 × 106 Pa, was found to generate microcellular foams in our polypropylene material system. Rubber particles inside the polypropylene seem to stabilize the microcellular foams.

A series of screws were evaluated with regard to their ability to convey two Newtonian fluids with nominal viscosity of 1000 Pa* s at room temperature. Screws with helix angles of 7, 17, 30 and 45 degrees were constructed with a diameter of 50 mm. Screws at several of the angles also had three flight depths. The extruder-screw pump was constructed so that both the screw and barrel could be rotated independently. We will present the data for the screw rotation of 11 screws. The results strongly suggest that the pumping, volumetric output per revolution, of the screw and the barrel are the same regardless of the screw flight height which had a maximum value of about 0.8 thus leaving the core at only 0.2 the barrel diameter. Since pressure back flow is a function of the first power of the flight with and the cube of the flight height, the measured outputs had to be corrected for this in order to calculate the actual screw forwarding ability.