ANITA GROZDANOV, IGOR JORDANOV, MARIA E. ERRICO, GENNARO GENTILE, and MAURIZIO AVELLA

ABSTRACT

Over the last decades, due to the increased environmental awareness, numerous stud­ies for production of biocomposites based on natural fibers have been published and many comprehensive reviews have been published. Compared with conventional reinforcements, such as glass and carbon fibers, natural fibers which are renewable resources, offer several other advantages including a wide availability (based on different vegetable species), recyclability, low density and low costs, low abrasion and preserving mechanical properties. Application of cellulose fibers in composites is not only beneficial from an ecological point of view, lowering the environmental impact of the final product within the production, usage and disposal period, but it offers further technical and economical benefits. Especially, natural fiber-reinforced biocomposites have the potential to replace current materials used for automotive industrial applications. In order to obtain composites with the best mechanical prop­erties, most of the research activities in the last decades have been concentrated on the surface physical and chemical modifications of the fibers mainly to optimize their interfacial behavior.

In the first part of this work, besides the overview of the state-of-the-art descrip­tion regarding biocomposites, we will also present characterization results of the lab-scaled flax fiber reinforced biopolymer matrices (PLA) as well as compared with the same-industrially produced composites.

In the second part of the paper, biocomposites based on “self-reinforced cel­lulose” or “all-cellulose” composites prepared from cotton textile fabrics by partial fiber surface dissolution in lithium chloride dissolved in N, N-dimethylacetamide

will be presented. Two different parameters have been studied: (i) surface treatment medium (alkaline/enzyme/bleaching) and (ii) cotton textile preforms (knits, woven).

10.1 INTRODUCTION

Due to the excellent characteristics, such as lower weight/higher strength, fiber-re­inforced composite materials have found wider technical application.12 Composite materials maximize weight reduction (as they are typically 20% lighter than alu­minum) and are known to be more reliable than other traditional metallic materi­als, leading to reduced aircraft maintenance costs, and a lower number of inspec­tions during service. Additional benefits of composite technologies include added strength, noncorrosive materials with superior durability for a longer lifespan. How­ever, because of the remarkable increased environmental consciousness, the substi­tution of traditional synthetic polymer based composites reinforced with glass and carbon fibers with new biocomposites was considered of fundamental importance.

Compared to traditional composites, biocomposites are materials based on natu­ral fibers of different preforms and fabrics and biocompatible polymer matrices. The interest for using biocomposites has increased because they are lightweight, nontoxic, nonabrasive during processing, have low cost and are easy to recycle. Ac­tually, the first natural fiber composites were used more than 100 years ago. In 1896, for example, airplane seats and fuel tanks were made of natural fibers with a small content of polymeric binders. However, these attempts were without recognition of the composite principles and the importance of fibers as the reinforcing part of composites as well as with the importance of having biodegradable matrix. The use of natural fibers was suspended due to low cost and growing performance of techni­cal plastics and, moreover, synthetic fibers. A renaissance in the use of natural fibers as reinforcements in technical applications began during the late twentieth century.

The automotive and space market is growing in terms of quantity, quality and product variety. The key factor for future growth is fuel efficiency. A 25% reduction in vehicle weight is equivalent to a saving of 250 million barrels of crude oil and a reduction in CO2 emissions of 220 billion pounds per year.23 Over the last several years European, American and Japanese recycling regulations have encourage the use of biomass in automotive materials. Additionally, European Union legislation implemented in 2006 has mandated that 85% of a vehicle must be reused or recycled by 2015. Japan requires 95% of a vehicle to be recovered (which includes incinera­tion of some components) by 2015.4

So, in the last 2 to 3 decades, scientists and engineers have worked together to improve and to enhance the performance of natural fiber based biocomposites, as well as to find some other possible application for them. The aim of this review is to give the overview of the state-of-the-art potential of biocomposites and in particular, biocomposites realized with Flax fibers and PLA matrix, and cotton-based “All­cellulose,” composites from lab-scale up to the industrial products.