Yield Stress Enhancement in Polyethylene–Glassy Diblock Copolymers
Yield Stress Enhancement in Polyethylene–Glassy Diblock Copolymers
复制标题
聚乙烯-玻璃态二嵌段共聚物的屈服应力增强
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
R. Register
中科院分区：
文献类型：
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作者：
W. Mulhearn;R. Register
线性聚乙烯(PE)的低应变力学性能可以通过将一小段具有较高玻璃化转变温度(Tg)的聚合物加入到以PE为主的嵌段共聚物中而得到显著改变。特别是，当加入相对较小比例的玻璃块时，屈服应力和拉伸模数可以急剧增加，特别是当与促进PE块高结晶度和晶体厚度的热历史相结合时。例如，在PE两嵌段共聚物中加入15wt%的氢化聚降冰片烯(Tg=115°C)，以∼1°C/分钟的速度从熔体冷却，相对于相同热历史处理的PE均聚物值，屈服应力(从∼30到∼60 Mpa)和拉伸模量值(从∼1.5到∼3.5 Gpa)翻了一番。这些性能增强与晶片间无定形层的组成和玻璃块在晶片中的空间分布密切相关。
The low-strain mechanical properties of linear polyethylene (PE) can be substantially altered by the incorporation of a short block of a polymer with a high glass transition temperature (Tg) into a majority-PE block copolymer. In particular, the yield stress and the tensile modulus can be sharply increased with the addition of a relatively small fraction of glassy block, especially when combined with a thermal history that promotes high crystallinity and crystal thickness of the PE block. For example, the incorporation of 15 wt % of a hydrogenated poly(norbornyl norbornene) block (Tg = 115 °C) into a PE diblock copolymer, cooled from the melt at ∼1 °C/min, doubles the yield stress (from ∼30 to ∼60 MPa) and tensile modulus (from ∼1.5 to ∼3.5 GPa) relative to the values for a PE homopolymer treated with the same thermal history. These property enhancements are closely associated with the composition of the amorphous layer between crystal lamellae and the spatial distribution of the glassy block within this ...