禾草薄壁细胞分离、分析及其成膜机制的研究

Parenchymas are rich in agricultural waste stalks,accounting for ca. 1/4 of the whole tisue based on the weight. Most of them along with the stalks are laid aside or burnt,and even are troublesome to the production of pulp and cellulose, except for the part of uses in poultry feed and fertilizer. The objective of this study is to make parenchymas form film. Bagasse, corn-stalk, rice straw and wheat straw are selected for separation of parenchymas from them, with the means of physical treatment and/or chemical pulping delignification. Based on analyses of the cell morphology, chemical compostion and distribution in parenchymas, different films are made from the parenchymas after delignification and/or dissolution of hemicellulose to varying degrees, in order to reveal film-forming-responding to cellulose, hemicellose, and lignin in the cells. As for the parenchymas separated from the chemical pulps, they are treated by physical methods such as mechanical refining, ultrasonification, and homogenization etc., to get more flexible cells for best-formed film with compact surface-surface combination of the cells by hydrogen bonds. It is hoped that the mechanism of parenchymas-formed film will be cleared through investigation of the synergestic relationship between the properties of the films and the structural as well as chemical characteristics of the parenchymas delt with. Moreover, an ideal parenchyma-forming film technology will be established after comparative research on film-forming ways, also the resultant films will be evaluated for the performance in view of their utilization. It should be a significant foundation of the conversion of parenchymas to functionalization and high-valued products.

薄壁细胞在农作物废弃秸秆组织中其质量约占1/4，资源量巨大。目前为止，禾草薄壁细胞除了随一部分秸秆用于牲畜饲料和沤肥外，基本处于弃用甚至在纸浆及纤维素制品中属于"干扰"物质。项目以蔗渣、玉米秆、稻草和麦草为原料进行物理分离以及化学制浆脱木素后的筛分分离获取薄壁细胞；在全面分析测定薄壁细胞组织形态、化学组分构成及其在细胞壁中的分布的基础上，对原料薄壁细胞经不同程度脱木素和/或脱半纤维素后的膜制备，揭示纤维素、半纤维素和木素对成膜性态的响应关系；对制浆脱木素后的薄壁细胞经物理及化学的柔化处理，考察它们成膜的组织结构、表面特性和强度性能，研究薄壁细胞成膜的协同作用关系，揭示成膜机制，建立成膜薄壁细胞间最大表面接触而产生最大氢键结合的理想模式；探讨薄壁细胞理想制膜方式并优化建立相应的制膜工艺体系；从应用的角度系统评价薄壁细胞膜的相关性能，为薄壁细胞资源化、功能化、高值化的利用奠定基础。

禾草薄壁细胞分离、分析及其成膜机制的研究是基于农作物秸秆中占质量约1/4的薄壁细胞的巨大资源量的存在，而当其作为造纸原料应用时则成为一个重要的干扰物影响其整个过程乃至造纸产品的质量并拖累到草类制浆造纸工业的现实，将无用甚至干扰物质作为一种重要资源，利用薄壁细胞壁薄、柔顺、比表面大等的特点，将其从禾草原料中分离出来，并寄希望于制备成薄壁细胞膜，实现有附加价值的应用。. 对蔗髓用氧碱法、烧碱-蒽醌法和碱性亚硫酸盐法制浆，所获纸浆经筛选分别得到纤维和细小组分（主要为薄壁细胞和细（短）小纤维）。选定脱木素效率（卡伯值仅为5.2）、得率（11.3%）均不错的碱性亚硫酸盐浆细小组分经疏解后直接制膜，因介入的细（短）小纤维明显增大成形薄片的蓬松组织，在20g/m2定量以下完全形不成对气体的阻隔作用而达不到膜的要求。. 对稻、麦草经低温氧碱制浆，能从纸浆中筛选出来的细小组分得率均可达16%。将细小组分在大比例水中均匀悬浮、静置沉降、分层截取这样一种多级重复的处理，收集到的上层悬浮物为较纯的薄壁细胞。同时借助于纤维质量分析仪对薄壁细胞的快速判定，建立了细小组分分离薄壁细胞的工艺技术。继而用分离得到的薄壁细胞通过过滤成形法在优化工艺的基础上直接成膜，定量低至4g/m2就有较好的阻隔性。经疏解后的薄壁细胞破坏性小、比表面显著增加，柔化效果显著，使成膜在匀整性、强度，特别是气体阻隔性方面都得到明显改善。得到了符合预期的薄壁细胞膜。. 对禾草薄壁细胞分离、分析及其成膜机制的基础性研究，得到了大量的科学数据，让薄壁细胞转化成所期待的膜成为了现实。它不仅为薄壁细胞分离与成膜提供了理论依据，也为薄壁细胞膜未来的应用提供重要的科学依据。