ポリエチレン単結晶集合体の粘弾性挙動 : 高分子固体のレオロジー

概要

論文の詳細を見る
In order to clarify the relaxation phenomena of crystalline phase in semicrystalline polymer, temperature dependence of complex dynamic modulus at frequencies of 3.5, 11 and 110c/s was measured for a mat of single crystals of polyethylene over a temperature range from -160℃ to 120℃. The single crystals prepared from 0.03% xylene solution of fractionated Marlex 9(M_υ=520 000) were so laminated as to lay their surfaces in parallel to each other by rapid filtration, and pressed at room temperature to from a film of about 100μ thickness. The structure of a single crystal and the layered structure of single crystals within the film, which was used for the viscoelastic measurements, were examined by means of electron microscope and X-ray diffraction technique. The temperature dependence of dynamic loss molulus E" at three different frequencies within the crystalline dispersion region, which was obtained by applying the stress in perpendicular direction to the molecular chain axis, were replotted as function of frequency at various temperatures. BY making the curve at 80℃ standard, and shifting the curves at various temperatures horizontally along the frequency axis, a master curve of E" as a function of angular frequency was obtained. The relaxation spectrum at 80℃ was calculated from this master curve by using Alfrey's zeroth order approximation ; H_ι(log τ)=4.6/π^<-1> E" (log 1/ω)/ From the measurements on reproducibility of the temperature dependence of E" performed by repeating the cycles of heating and cooling, it is confirmed that the effect of the changes in crystalline structure on the relaxation spectrum for crystalline absorption is negligible below 110℃. the slope of the relaxation spectrum is about -1/5 at a longer time side and about 1/3.5 at a shorter time side, and both of them are broader than those observed for the primary dispersion region of non-crystalline phase. The temperature dependence of the shift factor obtained for composing the master curve of E" is divided into two regions of different activation energies. This fact suggests that the relaxation mechanism of the crystalline dispersion can be classified into two different models. Taking it into consideration that the activation energy of the crystalline dispersion below 70℃, 16.2 Kcal/mole, is comparable to that of the secondary dispersion due to the local relaxation of the frozen main chains in the non-crystalline region and in the defective region within the crystal, the relaxation mechanism of this dispersion is reasonably ascribed to the occurence of the local torsional or twisting motion of main chains in the crystal lattice around their molecular axis. This dispersion is named here β_c dispersion. The activation energy of the crystalline dispersion above 70℃, 43.7 Kcal/mole, is larger than that for β_c dispersion. On the other hand, the fact that the lamella thickness of the single crystal of polyethylene thickens considerably above 110℃, suggests that the migrational motion of the molecular chains in the crystal lattice along the c-axis can occur in such a higher temperature region. Taking these facts into consideration, the relaxation mechanism of this dispersion can be ascribed to the large motion of the molecular chains in the crystal lattice, such as the migrational motion along the c-axis, and resembles that of the primary dispersion (α_a dispersion) in respect to the occurence of large motion of molecular chains. This dispersion is named here α_c dispersion.
社団法人日本材料学会の論文
1964-05-15

ポリエチレン単結晶集合体の粘弾性挙動 : 高分子固体のレオロジー

スポンサーリンク

概要

著者

関連論文

スポンサーリンク