Ali Ayoub

An Overview on the Technology of Cross-Linking of Starch for Nonfood Applications

For commercial success, bioplastics have to possess adequate physical properties. But the same properties of biopolymers — such as starch — that make them environmentally attractive feedstocks can affect their performance as materials. Despite the attractive properties of plant-based plastics, there have been few commercial applications due to their property drawbacks (e.g., high cost, brittleness, and lower impact resistance). Many biopolymers, such as starch, are often hydrophilic and some are even soluble in hot water. These properties have to be managed and controlled through the development of adequate formulations and processing. The primary challenge is to develop fast reactions that can be transformed into viable processes and integrated into existing process lines with economically viable formulations that are friendly to the environment. Cross-linking of starches is the most common method used in polysaccharide chemistry. This article briefly reviews some of the most promising chemistries available for the cross-linking of biodegradable starch materials and their applications.

A Review of Water-Resistant Hemicellulose-Based Materials: Processing and Applications

Hemicelluloses, due to their hydrophilic nature, may tend to be overlooked as a component in water-resistant product applications. However, their domains of use can be greatly expanded by chemical derivatization. Research in which hydrophobic derivatives of hemicelluloses or combinations of hemicelluloses with hydrophobic materials are used with to prepare films and composites is considered herein. Isolation methods that have been used to separate hemicellulose from biomass are also reviewed. Finally, the most useful pathways to change the hydrophilic character of hemicelluloses to hydrophobic are reviewed. In this way, the water resistance can be increased and applications of targeted water-resistant hemicellulose developed. Several applications of these materials are discussed.

Methods for facilitating microbial growth on pulp mill waste streams and characterization of the biodegradation potential of cultured microbes.

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high quality paper. Black liquor is a pulping waste generated by the kraft process that has potential for downstream bioconversion. However, the recalcitrant nature of the lignocellulose resources, its chemical derivatives that constitute the majority of available organic carbon within black liquor, and its basic pH present challenges to microbial biodegradation of this waste material. Methods for the collection and modification of black liquor for microbial growth are aimed at utilization of this pulp waste to convert the lignin, organic acids, and polysaccharide degradation byproducts into valuable chemicals. The lignocellulose extraction techniques presented provide a reproducible method for preparation of lignocellulose growth substrates for understanding metabolic capacities of cultured microorganisms. Use of gas chromatography-mass spectrometry enables the identification and quantification of the fermentation products resulting from the growth of microorganisms on pulping waste. These methods when used together can facilitate the determination of the metabolic activity of microorganisms with potential to produce fermentation products that would provide greater value to the pulping system and reduce effluent waste, thereby increasing potential paper milling profits and offering additional uses for black liquor.

Polysaccharides and lignin based hydrogels with potential pharmaceutical use as a drug delivery system produced by a reactive extrusion process

Currently, there is very strong interest to replace synthetic polymers with biological macromolecules of natural source for applications that interact with humans or the environment. This research describes the development of drug delivery hydrogels from natural polymers, starch, lignin and hemicelluloses by means of reactive extrusion. The hydrogels show a strong swelling ability dependent on pH which may be used to control diffusion rates of water and small molecules in and out of the gel. Also the hydrogels degradation rates were studied in a physiological solution (pH 7.4) for 15days. The results indicated that for all three macromolecules, lower molecular weight and higher level of plasticizer both increase the rate of weight loss of the hydrogels. The degradation was extremely reduced when the polymers were extruded in the presence of a catalyst. Finally the dynamic mechanical analysis revealed that the degradation of the hydrogels induce a significant reduction in the compressive modulus. This study demonstrates the characteristics and potential of natural polymers as a drug release system.

Recent Advances in Cationic and Anionic Polysaccharides Fibers

This chapter will discuss the recent advances on the cationic and anionic polysaccharides fiber and the effect on the paper properties.

Polysaccharide-based Fibers and Composites

This chapter gives a general introduction to the book and describes briefly the context for which the editors established its contents. The characteristics of polysaccharides during fiber processing and several technical challenges are presented alongside opportunities for processing polysaccharide fibers with desired properties. This book is not the first survey dealing with the interest of polysaccharides fibers or materials derived from renewable resources since several monographs have been published in recent years. The common denominator to many of these collective overviews is the biodegradable blends character of the ensuing material. We have attempted to gather in the present volume what we feel is a more comprehensive collection of monographs with the materials science elements as the predominant feature. Of course, the making blends based fiber issues remain essential here, but within the primary focus spelled out in the tittle.

The State of the Art: Introduction to Spinning

This chapter gives a general introduction to the book and describes briefly the context for which the editors established its contents. The characteristics of polysaccharides during fiber processing and several technical challenges are presented alongside opportunities for processing polysaccharide fibers with desired properties. This book is not the first survey dealing with the interest of polysaccharides fibers or materials derived from renewable resources since several monographs have been published in recent years. The common denominator to many of these collective overviews is the biodegradable blends character of the ensuing material. We have attempted to gather in the present volume what we feel is a more comprehensive collection of monographs with the materials science elements as the predominant feature. Of course, the making blends based fiber issues remain essential here, but within the primary focus spelled out in the tittle.