受應力拉伸時,橡膠溫度明顯上升;縮放回原長,橡膠溫度驟降。由文獻得知橡膠內部具有特殊的鍵鍊結構,在一般的情況下,交鏈分子糾結成一團,狀態複雜;受外力拉伸時,交鏈分子依橡膠長度之增加而伸展,排列較為整齊,狀態之複雜度減小。根據熱力學第一定律,當內能變化為零,則外力作功會造成能量變化。在定溫之下,橡膠內能變化為零,當其受應力拉伸,使其內部交鏈分子排列複雜度降低,造成橡膠熵值減小,而有能量(dQ=TdS)的釋出。測量此一能量dQ 變化,即可計算出熵與狀態數之變化The temperature of rubber rises as it is stretched, its temperature comes back again while it restores to its original length. It is known that the rubber is consisted of long-chain molecules, the long-chain molecules strangle each other at normal state, however, they become more order when the rubber is stretched. Based on the 1st law of thermodynamics dU=dQ+dW, The deformation caused by applied force supplies energy to the rubber and reduce its entropy, the heat dQ (=TΔS) released by the reduction of entropy causes the temperature rise of rubber as dU=0. We report the study on the correlation of thermal properties and the molecular network in rubber, from the measurements of temperature change, the changes of entropy and the changes of states’ number were estimated.
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