Compressive measurement barreling

Various techniques were tried, including cutting an actual tree into bits and then compressing them to find the volume of the tree, and putting wood in a barrel of known volume and adding measured amounts of water to calculate the volume of the barrel not occupied by the wood (ibid., p. 328). 

A Sieglaff-McKelvey capillary rheometer (Tinius-Olsen Testing Machine Company) was used for compression with the barrel plugged and for shear with an appropriate capillary. This rheometer is driven with nitrogen gas pressure applied to a piston, which exerts pressure on the material in the barrel. A barrel of 6.35 mm radius was chosen for this experiment. A predetermined amount of sample was charged and preheated in the barrel for 5 minutes before pressure was applied. Measurements were made at 100 °C and 150 C. 

The following three studies were performed injection velocity study, adiabatic compression study, and plastication study. Each study is detailed in the discussion section prior to presenting the results. For the studies a high flow polycarbonate (PC) resin was used, which was dried prior to processing. The barrel temperature profiles used for each study are available in Table 1. With the exception of the compression study, each of the runs was stabilized for 15 consecutive shots before data was recorded for five consecutive shots. For the injection velocity study and the screw recovery study the melt temperature was also measured with a hand held intrusive probe. Directly following data collection the injection unit was retracted, the machine was manually purged, and the melt temperature was measured using a hand held probe that had been preheated to the barrel temperature. 

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