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花花太岁

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专业: 配位化学

[交流] 求助翻译，非常感谢（高分子物理结晶方向）

Giant screw dislocations in chain-folded polymer crystals, having axes necessarily parallel to chain stems, traverse lamellar thickness and,although without hollow cores, have large Burgers vectors, often in excess of 100 A ˚ . From a geometrical standpoint, their mode of formationwas recognized four decades ago by Geil and Reneker. On a molecular scale, however, mechanisms by which shear forces, and necessaryplanes of easy shear oblique to growth faces (effectively tears or slits), arise during crystallization by chain folding have long remainedobscure. For some time shear has credibly been associated with lamellar warping under the inﬂuence of inhomogeneously distributedcongestion in fold surfaces. A study of dendritic crystals in polyethylene has now shown how on occasion impingements inherent in layer spreading by folded chains, combined with kinetic barriers of entropic character, can produce defects that permit shear across nominal fold
planes with little or no encumbrance from bridging folds. Evidence for this mechanism is particularly clear for dislocations initiated at reentrant corners and, although not readily amenable to direct observation, similar behavior likely underlies marked increase in dislocation densities observed with transition from Regime I to Regime II in crystallization from the melt. Proposed mechanisms do not rely upon
speciﬁc characteristics of the experimental system studied.

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lixiaod001

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花花太岁(金币+1,VIP+0): 11-1 15:17

在巨型螺旋位错链折叠聚合物晶体，具有一定平行轴链茎，穿越层厚度，虽然没有空心核心，常常在超过100甲˚载体大汉堡。从几何角度来看，他们的formationwas方式承认40年前由Geil和Reneker。在一个分子尺度，但是，机制，使剪切力，以及易于剪切斜增长necessaryplanes面（有效眼泪或狭缝），由链中出现结晶折叠早已remainedobscure。一段时间以来一直令人可信的剪切下的非均匀distributedcongestion影响力层表面整相关倍。在聚乙烯的树突状晶体研究已经展示了如何在有时impingements层固有的特性与动力学障碍熵折叠链相结合，传播，可以产生缺陷，允许跨名义剪切褶皱

飞机很少或没有衔接倍累赘。这个机制的证据是明确的，特别是在折返角落开始混乱，虽然不是容易地直接观察，类似的行为可能的基础显着位错密度增加，观察到从体制过渡的结晶，我在第二政权从熔体。拟议的机制不依赖

实验系统研究的具体特点