Thermal modification biological degradation

The hydrophilic character of wood, intrinsically connected with the structure of its three main macromolecular components, has been a longstanding source of problems, mostly arising from its lack of dimensional stability in moist environments. An additional major drawback is its susceptibility to photolytic and biological degradation. The interest of both scientists and technologists in modifying wood in order to overcome these drawbacks has called upon specific treatments like chemical, thermal, enzymatic or purely physical modifications. This chapter examines recent contributions to these issues, based on approaches which only involve the chemical modification of wood, carried out in bulk or at its surface. The other treatments have been aptly covered in a recent book [1] and a thorough review [2]. 

Polymer modifications are intended to impute different, typically desired properties to the new modified material-properties such as enhanced thermal stability multiphase physical responses biological resistance, compatibility or degradability impact response flexibility rigidity etc. 

The durability in use and reuse of the hydrocarbon polymers and their performance during recycling can be readily controlled. Since the catabolic enzymes cannot biodegrade polymers in the inhospitable hydrophobic environment at the polymer surface, oxidatively resistant hydrocarbon polymers are essentially non-degradable. As was seen in Chapter 9, extensive modification of the polymer surface is a prerequisite to biological attack. In particular, both thermal and photooxidation can be employed to provided a suitable surface environment for microbial colonization and the rate at which these processes occur can be controlled by the use of the appropriate antioxidants and stabilizers [7]. Photooxidation of the hydrocarbon polymers is particularly relevant to the control of litter, whereas thermal oxidation is a prerequisite for aerobic composting. 

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