NORMA-AUREA RANGEL-VAZQUEZ, ADRIAN BONILLA PETRICIOLET, and VIRGINIA HERNANDEZ MONTOYA

ABSTRACT

The development of natural fiber reinforced biodegradable polymer composites promotes the use of environmentally friendly materials. The use of green materials provides alternative way to solve the problems associated with agriculture residues. Agricultural crop residues such as oil palm, pineapple leaf, banana, and sugar palm produced in billions of tons around the world. They can be obtained in abundance, low cost, and they are also renewable sources of biomass.

Among this large amount of residues, only a small quantity of the residues was applied as household fuel or fertilizer and the rest, which is the major portion of the residues is burned in the field. As a result, it gives a negative effect on the environ­ment due to the air pollution. The vital alternative to solve this problem is to use the agriculture residues as reinforcement in the development of polymer composites. A viable solution is to use the entire residues as natural fibers and combine them with polymer matrix derived from petroleum or renewable resources to produce a useful product for our daily applications.

Lignocellulosic materials are renewable resources that can be directly or indi­rectly used for the production of biomolecules and commodity chemicals. However, some of these applications are limited by the close association that exists among the three main components of the plant cell wall, cellulose, hemicellulose and lig­nin. Therefore, it is only through a clear understanding of this chemistry that one

can identify the reasons why lignocellulosics are so resilient to biological processes such as enzymatic hydrolysis and fermentation.

Recently environmental problems caused by the conventional fuel based plastics have become public major concerns. Many countries applied various policies and managements to overcome these problems, for example, recycle reuse and reduce protocol. However, due to the enormous amount of packaging and household plas­tics used every day, such attempt was found to be far from succeeded. Other mod­ern strategy is to replace the conventional plastics with biodegradable plastics such as modified starches, polylactic acids, polyhydroxyalkanoates and such. However, their prices and applications have always been considerated.

Although manufacture of a true biocomposite would demand a matrix phase sourced largely from renewable resources, the current state of biopolymer technol­ogy usually dictates that synthetic thermoplastics or thermosetting materials, such as polyethylene (PE) and polypropylene (PP), are used in commercial biocomposite production. There is still a considerable need for the development of thermosetting materials from renewable resources.

Recent examples of such developments include the use of vegetable oils to build thermosetting resins, which can then be modified to form cross-linkable molecules such as epoxides, maleates, aldehydes and isocyanates.

In recent years, there have been significant breakthroughs in the photoinitiated crosslinking of bulk PE and industrial application of photocrosslinked polyethylene (XLPE) insulated wire and cable. The mechanism and crosslink microstructures of the photocrosslinking of LDPE and its model compounds, the crystalline morpho­logical structures, surface photo-oxidation and stabilization of the XLPE materials, and the photolytic products of benzophenone (BP) as a photoinitiator during the photocrosslinking processes.

Molecular modeling used to be restricted to a small number of scientists who had access to the necessary computer hardware and software. The reliability of the obtained results strongly improved throughout the last decades. During this period Theoretical Chemists developed new strategies to describe the reality and Compu­tational Chemists were able to implement and test models. Nowadays many Experi­mental Chemists, working either in organic or physical chemistry, can easily take advantage of modern commercial software for both research and teaching purposes.

Computational chemistry is a branch of chemistry that uses principles of com­puter science to assist in solving chemical problems. It uses the results of theoretical chemistry, incorporated into efficient computer programs, to calculate the structures and properties of molecules and solids

The analysis techniques used were, FTIR to study this effect and an option to justify the obtained results is using theoretical calculations by means of the com­putational chemistry tools. Using QSAR properties, we can obtain an estimate of the activity of a chemical from its molecular structure only. QSAR have been successfully applied to predict soil sorption coefficients of nonpolar and nonioniz — able organic compounds including many pesticides. Sorption of organic chemicals in soils or sediments is usually described by sorption coefficients. The molecular electrostatic potential (MESP) was calculated using AMBER/AM1 method. These methods give information about the proper region by which compounds have inter­molecular interactions between their units.

The electrostatic potential is the energy of interaction of a point positive charge (an electrophile) with the nuclei and electrons of a molecule. Negative electrostatic potentials indicate areas that are prone to electrophilic attack. The electrostatic po­tential can be mapped onto the electron density by using color to represent the value of the potential. The resulting model simultaneously displays molecular size and shape and electrostatic potential value. Colors toward red indicate negative values of the electrostatic potential, while colors toward blue indicate positive values of the potential.

15.1 INTRODUCTION