英语翻译1.IntroductionWater uptake in epoxy systems is a challenging issue due to the irreversible changes that water operates on the polymer properties.It is believed and there are enough experimental evidences that entrance of water induces:(a)
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英语翻译1.IntroductionWater uptake in epoxy systems is a challenging issue due to the irreversible changes that water operates on the polymer properties.It is believed and there are enough experimental evidences that entrance of water induces:(a)
英语翻译
1.Introduction
Water uptake in epoxy systems is a challenging issue due to the irreversible changes that water operates on the polymer properties.It is believed and there are enough experimental evidences that entrance of water induces:(a) swelling of the system and build-up of residual stresses at and near the interfaces [1],(b) rupture of adhesive bonding between the system and a given substrate [2],(c) aperture of oxirane remaining groups [3],(d) modification of the local stress state and creation of microcrazes through environmental stress cracking [4].
There is no universal model to cover all types of water diffusion [1].Several mechanisms for the water entrance have been proposed:(a) diffusion governed by Fick’s law through the free volume of the polymer [5],(b) case II diffusion mechanism by which osmotic swelling is limited by polymer creep [6],(c) swelling induced by a favourable polymer–solvent parameter,(d) osmotic phenomena due to the presence of micropores,channels and other defects in the polymer [7].
It is also frequently found in the literature that the water diffusion coefficient in different epoxy systems is around 10−8 to 10−10 cm2 s−1 [1,2,8],even for rubber modified compositions [8].Similar values are obtained for other glassy polymer systems [2].Diffusion coefficient measures the initial rate of water absorption and,in principle,it should be dependent on the chemical nature of the polymer system and on the cross-linking degree for cross-linked systems such as epoxy’s.But,as it will be shown in this paper,similar diffusion coefficients are found even for not fully cured systems.
In an effort for designing water resistant epoxy systems,it is necessary to know which material parameters are really involved and control the process of water absorption.In this paper,we study the water absorption properties of a new epoxy formulation based in the use as hardener of a reactive derivative of a hydrophobic polymer,such as polysiloxane.It will be shown that when common bisphenol-A diglycidyl ether (DGEBA) resins are cured in the presence of poly(3-aminopropylmethylsiloxane) (PAMS),equilibrium properties are greatly enhanced.In addition,due to the special characteristics and morphology of this epoxy system [9],a different behaviour against postcuring temperature is found.
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英语翻译1.IntroductionWater uptake in epoxy systems is a challenging issue due to the irreversible changes that water operates on the polymer properties.It is believed and there are enough experimental evidences that entrance of water induces:(a)
1 .导言
吸水环氧树脂系统是一项具有挑战性的问题,由于不可逆转的变化,水运作的聚合物性能.据信,并有足够的实验证据的入口处水诱导: (一)膨胀的制度和建立残余应力及其附近的接口[ 1 ] , (二)破裂之间的粘接系统和一个由于基板[ 2 ] , (三)光圈环氧乙烷其余群体[ 3 ] , ( d )项修改地方应力状态和建立microcrazes通过环境应力开裂[ 4 ] .
没有通用的模式,以涵盖所有类型的水分子扩散[ 1 ] .几个机制水入口已经提出: (一)由菲克扩散的法律通过自由体积的聚合物[ 5 ] , ( b )个案二扩散机制的渗透肿胀是有限的聚合物蠕变[ 6 ] , (三)肿胀诱导有利聚合物溶剂参数, ( d )项渗透现象由于微孔的存在,渠道和其他缺陷聚合物[ 7 ] .
这也是常见的文献,水扩散系数在不同的环氧树脂系统大约10月8日至10月10日平方厘米的S - 1 [ 1,2,8 ] ,也可用于橡胶改性成分[ 8 ] .相似的价值得到了其他玻璃状聚合物系统[ 2 ] .扩散系数措施最初率吸水率和原则,应该依赖于化学性质的聚合物系统和交联度的交联系统,如环氧树脂的.但是,因为这将显示在这个文件,类似的扩散系数被发现即使不能完全治愈系统.
在努力为设计抗水环氧系统,有必要知道哪些材料参数的真正参与和控制的过程中水分的吸收.在本文中,我们研究了水分的吸收性能的一个新的总部设在环氧树脂配方中使用的硬化剂的反应导数的疏水性聚合物,如聚硅氧烷.这将是表明,当共同的双酚A二缩水甘油醚( DGEBA )树脂固化,在场的聚( 3 - aminopropylmethylsiloxane ) (参与机构调动系统) ,平衡性能大大增强.此外,由于特殊的特点和形态的环氧系统[ 9 ] ,不同的行为,发现postcuring温度.