Chemical, physical, and mechanical characterization of isocyanate cross-linked amine-modified silica aerogels
Chemical, physical, and mechanical characterization of isocyanate cross-linked amine-modified silica aerogels
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DOI：
10.1021/cm0513841
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发表时间：
2006-01-24
影响因子：
8.6
通讯作者：
Leventis, N
中科院分区：
文献类型：
--
作者：
Katti, A;Shimpi, N;Leventis, N
我们描述了一种新的机械强轻质多孔复合材料，通过将胺改性二氧化硅气凝胶的骨架框架与聚脲包封而获得。共形聚合物涂层保留了二氧化硅框架的介孔结构，导热系数保持在0.041 +/- 0.001 W m(-1) K-1的低水平。通过对新型交联二氧化硅气凝胶在压缩、三点弯曲和动态力学分析（DMA）下的力学行为进行表征，确定了其承载应用的潜力。通过DMA确定了一次玻璃化转变温度为130℃。在室温下，结果表明，在压缩交联气凝胶的超泡沫行为，在小应变（< 4%）下线性弹性，然后表现出屈服行为（直到40%应变），随后是致密化和非弹性硬化。在室温下，压缩杨氏模量和泊松比分别为129 +/- 8 MPa和0。而极限破坏时的应变为77%，平均比压应力为3.89 × 10(5) N，单位为kg（-1）。比抗弯强度为2.16 × 10(4) N，单位为kg（-1）。研究了应变速率和低温对压缩性能的影响。
We describe a new mechanically strong lightweight porous composite material obtained by encapsulating the skeletal framework of amine-modified silica aerogels with polyurea. The conformal polymer coating preserves the mesoporous structure of the underlying silica framework and the thermal conductivity remains low at 0.041 +/- 0.001 W m(-1) K-1. The potential of the new cross-linked silica aerogels for load-carrying applications was determined through characterization of their mechanical behavior under compression, three-point bending, and dynamic mechanical analysis (DMA). A primary glass transition temperature of 130 degrees C was identified through DMA. At room temperature, results indicate a hyperfoam behavior where in compression cross-linked aerogels are linearly elastic under small strains ( < 4%) and then exhibit yield behavior (until 40% strain), followed by densification and inelastic hardening. At room temperature the compressive Young's modulus and the Poisson's ratio were determined to be 129 +/- 8 MPa and 0. 18, respectively, while the strain at ultimate failure is 77% and the average specific compressive stress at ultimate failure is 3.89 x 10(5) N in kg(-1). The specific flexural strength is 2.16 x 10(4) N in kg(-1). Effects on the compressive behavior of strain rate and low temperature were also evaluated.