PDF(Pubmed)
Abstract：
Pectin aerogels, with very low density (around 0.1 g cm-3) and high specific surface area (up to 600 m2 g-1), are excellent thermal insulation materials since their thermal conductivity is below that of air at ambient conditions (0.025 W m-1 K-1). However, due to their intrinsic hydrophilicity, pectin aerogels collapse when in contact with water vapor, losing superinsulating properties. In this work, first, pectin aerogels were made, and the influence of the different process parameters on the materials\' structure and properties were studied. All neat pectin aerogels had a low density (0.04-0.11 g cm-1), high specific surface area (308-567 m2 g-1), and very low thermal conductivity (0.015-0.023 W m-1 K-1). Then, pectin aerogels were hydrophobized via the chemical vapor deposition of methyltrimethoxysilane using different reaction durations (2 to 24 h). The influence of hydrophobization on material properties, especially on thermal conductivity, was recorded by conditioning in a climate chamber (25 °C, 80% relative humidity). Hydrophobization resulted in the increase in thermal conductivity compared to that of neat pectin aerogels. MTMS deposition for 16 h was efficient for hydrophobizing pectin aerogels in moist environment (contact angle 115°) and stabilizing material properties with no fluctuation in thermal conductivity (0.030 W m-1 K-1) and density for the testing period of 8 months.
摘要：
果胶气凝胶,具有非常低的密度（约0.1gcm-3）和高比表面积（高达600m2g-1），是出色的隔热材料，因为它们的热导率低于环境条件下的空气（0.025Wm-1K-1）。然而,由于它们固有的亲水性，果胶气凝胶与水蒸气接触时会崩溃，失去超绝缘性能。在这项工作中,首先,制成了果胶气凝胶，研究了不同工艺参数对材料结构和性能的影响。所有纯果胶气凝胶的密度都很低（0.04-0.11gcm-1），高比表面积（308-567m2g-1），和非常低的热导率（0.015-0.023Wm-1K-1）。然后，果胶气凝胶通过甲基三甲氧基硅烷的化学气相沉积使用不同的反应持续时间（2至24小时）进行疏水化。疏水化对材料性能的影响，特别是在导热性方面，通过在气候室中调节(25°C，80%相对湿度)。与纯果胶气凝胶相比，疏水化导致热导率增加。MTMS沉积16小时可有效地使果胶气凝胶在潮湿环境（接触角115°）中疏水，并稳定材料性能，在8个月的测试期内，热导率（0.030Wm-1K-1）和密度没有波动。
