【摘要】 1.本實驗採用了Hoeppler平行板塑性計,按照定應力壓縮形變法的理論,在中温時對國產天然橡膠的本體粘性流動進行了流變學研究。 2.在30-90°與250-1500克/厘米～2的荷重範圍內,測定了貌似本體粘度η_a,內切模數G_i與貌似活化能ΔE_η。所測得的G_i=3.30×10～5達因/厘米～2與ΔE_η=12.7千卡/克分子,在一定温度範圍（50-90°）內爲不依賴於温度的常數。對所測天然橡膠估計所得的粘流鰱段長約30個碳原子。 3.從粘性流動的切變速率dγ/dt依賴於切應力σ的關係中,獲得了Eisenschitz早已衍導出的,但迄未在高聚物的本體粘性流動中獲得例證时非牛頓流動流公式。該式復以Saunder及Treloar的數據重加處理而證實之。 4.從切變速率對貌似本體粘度的影響上,檢驗了Debye-Bueche的理論式。現改用單位體積內彈性鍵段計算推遲時間,τ₁=2.84η₀·[J_e]∞,其中穩態彈性柔數[J_e]∞。係由彈性同復實驗測得。經如此處理後,該式在較低切變速率時筒能與實驗結果相符。 5.若以Eisenschitz式與Debye-Bueche式相結合,則亦可計得內切模數G_i,並藉知貌似本體粘度隨切變速率增高而降低的現象,乃係由於發生內切應變γ_i=σ/G_i之故。更多还原

【Abstract】 An investigation of the rheological relationships between shear stress shear rate apparent bulk viscosity temperature was carried out by examining the viscous flow of slightly milled native Hevea rubber （i） The Eisenschitz’s equation for non-Newtonian flow has been verified by the experiments on the dependence of shear rate on shear stress. By this equation, the apparent viscosity can be referred to the Newtonian viscosity η₀ （at σ=0）. The parameter （G_i=3.30×10⁵ dynes/cm²）, interpreted as an internal modulus of rigidity, was found to be practically independent of temperature in the range of 50-90℃, thus agreeing with the results by treating Saunder and Treloar’s data. （ii） For the shear rate dependence of apparent viscosity, when the number of Khun segments per unit volume was taken into account for the calculation of retardation time τ₁=2.84η₀ [J_e]_∞, the Debye-Bueche’s equation was found to be able to fit into our data at moderate low shear rates. The values of steady-state elastic compliance [J_e]_∞ were determined by elastic-recovery experiments. Furthermore, the internal shear modulus Gi could be thus calculated by combining the Eisenschitz’s equation with the Debye-Bueche’s one. （iii） From the experiments on the temperature dependence of viscous flow under various stresses, the apparent activation energy ΔE_η was found to be 12.7 kcal/mole; and therefrom, by estimation, the unit of flow-the Eyring segment would be 30 carbon atoms long. All determinations of the flow rate under constant stress were carried out in a Hppler parallel-plate plastometer, used as a viscoelasticity-rheometer according to the theory developed by Dienes.更多还原