TY - JOUR
T1 - Thermal volume expansion in polymeric PTC composites
T2 - A theoretical approach
AU - Yi, Xiao Su
AU - Shen, Lie
AU - Pan, Yi
N1 - Funding Information:
The authors thank the National Advanced Materials Committee of China (Grant 863-715-007-0080) and Science and Technology Commission of Zhejiang Province and National Natural Science Foundation of China (Grant 59683003) for their supports to make this study feasible.
PY - 2001/5
Y1 - 2001/5
N2 - Polymeric PTC (positive temperature coefficient) composites have been prepared by incorporating carbon black into polyethylene matrices. The dependence of conductivity upon filler loading level obeys a mixtures rule, which was determined by fitting the experimental data into the general effective medium (GEM) equation. A phenomenological model is proposed which is based on the GEM equation and the dilution effect of filler volume fraction due to thermal volume expansion. By using this model, the contribution of the thermal expansion of the matrix to the jump-like PTC switch transition of the composite is quantitatively estimated, and a mechanical explanation is given. The thermal-expansion-dependent percolation curves can also be predicted. Comparisons between predicted and measured PTC effects reveal that thermal expansion is one of the leading factors responsible for the thermal switch effect. Other factors influencing the composite resistivity are discussed.
AB - Polymeric PTC (positive temperature coefficient) composites have been prepared by incorporating carbon black into polyethylene matrices. The dependence of conductivity upon filler loading level obeys a mixtures rule, which was determined by fitting the experimental data into the general effective medium (GEM) equation. A phenomenological model is proposed which is based on the GEM equation and the dilution effect of filler volume fraction due to thermal volume expansion. By using this model, the contribution of the thermal expansion of the matrix to the jump-like PTC switch transition of the composite is quantitatively estimated, and a mechanical explanation is given. The thermal-expansion-dependent percolation curves can also be predicted. Comparisons between predicted and measured PTC effects reveal that thermal expansion is one of the leading factors responsible for the thermal switch effect. Other factors influencing the composite resistivity are discussed.
KW - General effective medium equation
KW - PTC switch transition
KW - Percolation behavior
KW - Thermal volume expansion
KW - Volume fraction dilution
UR - http://www.scopus.com/inward/record.url?scp=0035333005&partnerID=8YFLogxK
U2 - 10.1016/S0266-3538(00)00191-3
DO - 10.1016/S0266-3538(00)00191-3
M3 - Article
AN - SCOPUS:0035333005
SN - 0266-3538
VL - 61
SP - 949
EP - 956
JO - Composites Science and Technology
JF - Composites Science and Technology
IS - 7
ER -