Use of a capillary extrusion rheometer to measure curing of thermosetting plastics and rubbers

Abstract

SynopsisBy use of a modified, small-bore, capihry extrusion rheometer (MCER) with an Tnstron tensile testing machine, the flow and set-up properties of thermosetting plastics and rubbers were characterized. The majority of the experiments were performed with diallyl phthalate, where the rate of curing was also followed by infrared determination of the reduction in unssturation as the polymerization-curing proceeded. Phenol-formaldehyde was also characterized. Finally, the curing of ethylene-propylene and ethylenevinyl acetate copolymer rubbers with peroxide was studied and correlated with the type of peroxide used. The MCER data are shown to be of practical use for predicting the time-temperature-pressure relationships for processing thermosetting plastics and rubbers. Moreover, the history of the curing, as obtained by analysis of the continuously extruded strand, is also of theoretical interest for studying reaction kinetics and for evaluating the effectiveness of various curing systems. It is predicted the MCER will be widely used for studying the curing of thermosetting plastics and rubbers. 1911 1912 SALYER, HEYD, BRODBECK, IIARTZEL, BROWN tion as the polymerization proceeded. A second thermosetting polymer, phenol-formaldehyde, was also analyzed. Finally, the curing of ethylenepropylene and ethylene-vinyl acetate copolymer rubbers with peroxide was studied, and the results were correlated with the type of peroxide used. EQUIPMENTThe Monsanto capillary extrusion rheonieter, MCER (Fig. l), shown schematically in Figure 2, contains an insulated, electrically heated steel cylinder supported on a steel framework. The cylinder is insulated by two transite disks ( I ) , a cylinder of high temperature insulating wool (S), and an outer jacket of asbestos tubing (2). Four narrow-banded cylindrical heaters (4) , manufactured by the Watlow Electric Manufacturing Company, supply heat to the steel cylinder. A thin aluminum sleeve (5), inserted between the steel cylinder and the heaters, improves heat transfer and alleviates thermal gradients. To prevent burn-out of the heaters, a 1/2-in. dead air space separated the heaters and the asbestos tubing insulation. The tempered steel cylinder (6) is 8:/8 in. long, 2 in. in diam-Fig. 1. Monsanto capillary extrusion rheometer in position in Instron testing machine.

Effects of Crystal Orientation on Cellulose Nanocrystals–Cellulose Acetate Nanocomposite Fibers Prepared by Dry Spinning

“…Preparation of CA-CNC Fibers. The prepared solutions were dryspun using a custom built plunger style fiber spinner based on a capillary viscometer 40 with spinneret insert having a 30°conical Vtaper machined to a 4.38 mm for a 250 μm orifice (Bird Precision). This allows processing at shear rates similar to industrial processes (10 5 −10 6 /s) that is much higher than typical laboratory scale setups (10−10 2 /s).…”