PROBE LENGTH AND FILLING MATERIAL EFFECTS ON THERMAL-CONDUCTIVITY DETERMINED BY A MAXIMUM SLOPE DATA REDUCTION METHOD

The influence of probe length to diameter ratio (lambda) and filling m aterial on the thermal conductivity (k) probe technique was studied us ing glycerol with probes of four different lambda s (4.1, 7.5, 13.6, a nd 54.3) filled with either high k paste or air by applying a maximum slope data reduction method. Statistical analysis showed the highly si gnificant influence of lambda and significant influence of the filling material. Noncalibrated k values of the smallest lambda probes were 9 3% above the published value, whereas those of the largest lambda prob es were virtually identical to the published value. Separate measureme nts on chocolate pudding and starch gels showed that 7.5 lambda k were virtually identical to the largest lambda probe k when the former pro bes had been calibrated using glycerol. The use of short air-filled pr obes is not recommended when the maximum slope method is applied.