Positron lifetime reveals the nano level packing in complex polysaccharide-rich hydrolysate matrixes.
Positron lifetime reveals the nano level packing in complex polysaccharide-rich hydrolysate matrixes.
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正电子寿命揭示了富含复杂多糖的水解产物基质中的纳米级堆积。
DOI：
10.1021/ac300152g
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发表时间：
2012
影响因子：
7.4
通讯作者：
A. Albertsson
中科院分区：
文献类型：
--
作者：
U. Edlund;Yang Yu;Y. Z. Ryberg;R. Krause;A. Albertsson
正电子湮没寿命谱（帕尔斯）被用来量化的自由体积和分子堆积在水解产物和半纤维素为基础的屏障膜，来自木材加工操作过程中的工艺流。这些水解产物膜，包含相当份额的木质素与聚-和低聚-淀粉共存，具有非常低但可变的透氧性，但在阻隔性能以及分子量、支化度和单糖残基主链组成方面彼此不同。根据水解产物的帕尔斯测量，计算自由体积孔半径（r（h））、半径分布（n（r（h）、体积加权孔尺寸（（v））和孔体积分布（g（v（h），表明水解产物基质非常密集地填充有小孔。结果表明，水解产物的分子结构和组成，纳米级的分子堆积，并抑制氧通过膜的扩散的能力之间有明确的关系。
Positron annihilation lifetime spectroscopy (PALS) was used to quantify the free volume and molecular packing in hydrolysate and hemicellulose-based barriers films, derived from process streams during wood processing operations. These hydrolysate films, comprising a fair share of lignin coexisting with poly- and oligo-saccharides, have very low but variable oxygen permeability but differ among themselves with respect to barrier performance as well as molecular weight, degree of branching, and monosaccharide residue main chain composition. From PALS measurements on hydrolysates, the free volume hole radius (r(h)), radius distributions (n(r(h))), volume-weighted hole sizes ((v)), and hole volume distributions (g(v(h))) were calculated showing that the hydrolysate matrixes are very densely packed with small holes. The results show a clear relationship between hydrolysate molecular architecture and composition, the nanolevel molecular packing, and the ability of suppressing the diffusion of oxygen through the film.