Stabilization of Mechanical Pulp Against Color Reversion

摘要Arthur J.Ragoskas CTS-9414695这是一项关于巯基抗氧化剂光稳定机械浆的化学途径的研究。限制机械浆使用的主要因素是其易发生返色。所有类型的机械纸浆都会受到热或光引起的表面变色的影响。导致表面变色的过程还会导致木材纤维中碳水化合物和木质素成分的氧化降解。这一过程的公认机制包括木素中扩展的共轭结构的光激发；这通过分子内键断裂、通过分子间提取酚氢或通过产生单线态氧来启动自由基过程。虽然光变黄的机制已经得到了很大的关注，但抗氧化剂如何延缓这一过程还不是很清楚。在这项工作中，研究了硫醇基团抑制这些过程的机制。机械纸浆是一种比化学纸浆更有效的中间体。一般来说，化学纸浆只利用木材中的纤维素，而机械纸浆含有原始木材质量的85%，包括纤维素、半纤维素和木质素。然而，机械浆更难在化学上稳定，这限制了它在大多数纸制品中的使用。这就是这个项目要解决的问题。该奖项是无害环境化学品合成和加工特别倡议的一部分。

ABSTRACT Arthur J. Ragauskas CTS-9414695 This is a study of the chemical pathways by which mercapto-derived antioxidants photostabilize mechanical pulps. The principal factor limiting use of mechanical pulp is its tendency to undergo color reversion. All types of mechanical pulp suffer from surface discoloration induced thermally or photonically. The processes causing surface discoloration also cause oxidative degradation of the carbohydrate and lignin components of wood fibers. The accepted mechanism for this process involves photoexcitation of extended conjugated structures in lignin; this initiates a free-radical process either by intramolecular bond cleavage, by intermolecular abstraction of phenolic hydrogen, or by generation of singlet oxygen. Although the mechanisms of photoyellowing have received substantial attention, the ways in which antioxidants could retard this process are not well understood. In this work, the mechanisms by which thiol groups can inhibit these processes are examined. Mechanical pulp for papermaking is a more efficient intermediate than chemical pulp. Generally, chemical pulp uses only the cellulose in wood, while mechanical pulp contains 85% of the original wood mass including cellulose hemicellulose, and lignin. However, mechanical pulp is more difficult to stabilize chemically, and this limits its use for most paper products. This is the issue addressed in this project. This award is part of the Special Initiative in Environmentally Benign Chemical Synthesis and Processing.