A comprehensive review of techniques for natural fibers as reinforcement in composites: Preparation, processing and characterization.

During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

The return of a forgotten polymer : Polycaprolactone in the 21st century

The increase in awareness of the damage caused by synthetic materials on the environment has led to the development of eco-friendly materials. The researchers have shown a lot of interest in developing such materials which can replace the synthetic materials. As a result, there is an increase in demand for commercial use of the natural fiber-based composites in recent years for various industrial sectors. Natural fibers are sustainable materials which are easily available in nature and have advantages like low-cost, lightweight, renewability, biodegradability and high specific properties. The sustainability of the natural fiber-based composite materials has led to upsurge its applications in various manufacturing sectors. In this paper, we have reviewed the different sources of natural fibers, their properties, modification of natural fibers, the effect of treatments on natural fibers, etc. We also summarize the major applications of natural fibers and their effective use as reinforcement for polymer composite materials.

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Natural Fibers as Sustainable and Renewable Resource for Development of Eco-friendly Composites: A Comprehensive Review

There is significant work published in recent years about natural fibres polymeric composites. Most of the studies are about the characterization of natural fibres and their comparison with conventional composites regarding mechanical behaviour and application performance. There are dozens of types of natural fibres with different properties influencing their use, or not, in specific industrial applications. The natural origin of these materials causes, in general, a wide range of variations in properties depending mainly on the harvesting location and conditions, making it difficult to select the appropriate fibre for a specific application. In this paper, a comprehensive review about the properties of natural fibres used as composite materials reinforcement is presented, aiming to map where each type of fibre is positioned in several properties. Recent published work on emergent types of fibres is also reviewed. A bibliometric study regarding applications of natural fibres composites is presented. A prospective analysis about the future trends of natural fibres applications and the required developments to broaden their applications is also presented and discussed.

Natural Fibre Composites and Their Applications: A Review

The field of regenerative medicine has tremendous potential for improved treatment outcomes and has been stimulated by advances made in bioengineering over the last few decades. The strategies of engineering tissues and assembling functional constructs that are capable of restoring, retaining, and revitalizing lost tissues and organs have impacted the whole spectrum of medicine and health care. Techniques to combine biomimetic materials, cells, and bioactive molecules play a decisive role in promoting the regeneration of damaged tissues or as therapeutic systems. Hydrogels have been used as one of the most common tissue engineering scaffolds over the past two decades due to their ability to maintain a distinct 3D structure, to provide mechanical support for the cells in the engineered tissues, and to simulate the native extracellular matrix. The high water content of hydrogels can provide an ideal environment for cell survival, and structure which mimics the native tissues. Hydrogel systems have been serving as a supportive matrix for cell immobilization and growth factor delivery. This review outlines a brief description of the properties, structure, synthesis and fabrication methods, applications, and future perspectives of smart hydrogels in tissue engineering.

Smart Hydrogels in Tissue Engineering and Regenerative Medicine.

There is a growing interest in the development of natural fiber-reinforced composites, most likely due to their wide availability, low cost, environment friendliness, and sustainability. The market...

Hydrophobic treatment of natural fibers and their composites—A review

The nervous system is a crucial component of the body and damages to this system, either by of injury or disease, can result in serious or potentially lethal consequences. Restoring the damaged nervous system is a great challenge due to the complex physiology system and limited regenerative capacity. Polymers, either synthetic or natural in origin, have been extensively evaluated as a solution for restoring functions in damaged neural tissues. Polymers offer a wide range of versatility, in particular regarding shape and mechanical characteristics, and their biocompatibility is unmatched by other biomaterials, such as metals and ceramics. Several studies have shown that polymers can be shaped into suitable support structures, including nerve conduits, scaffolds, and electrospun matrices, capable of improving the regeneration of damaged neural tissues. In general, natural polymers offer the advantage of better biocompatibility and bioactivity, while synthetic or non-natural polymers have better mechanical properties and structural stability. Often, combinations of the two allow for the development of polymeric conduits able to mimic the native physiological environment of healthy neural tissues and, consequently, regulate cell behaviour and support the regeneration of injured nervous tissues. Currently, most of neural tissue engineering applications are in pre-clinical study, in particular for use in the central nervous system, however collagen polymer conduits aimed at regeneration of peripheral nerves have already been successfully tested in clinical trials. This review highlights different types of natural and synthetic polymers used in neural tissue engineering and their advantages and disadvantages for neural regeneration.

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Current and novel polymeric biomaterials for neural tissue engineering

TiO2-based nanomaterials have attracted prodigious attention as a photocatalysts in numerous fields of applications. In this thematic issue, the mechanism behind the photocatalytic activity of nano-TiO2 as well as the critical properties have been reviewed in details. The synthesis routes and the variables that affect the size and crystallinity of nano-TiO2 have also been discussed in detail. Moreover, a newly emerged class of color TiO2, TiO2 in aerogel form, nanotubes form, doped and undoped form, and other forms of TiO2 have been discussed in details. Photocatalytic and photovoltaic applications and the type of nano-TiO2 that is more suitable for these applications have been discussed in this review.

Synthesis and applications of nano-TiO 2 : a review

Synthesis of nano-hydroxyapatite (nHA) from waste mussel shells using a rapid microwave method

Textile based sensors, an emerging class of wearable devices, are a potential platform for next generation, functionality and amenability for the human body incorporating sensing and control. The main purpose of this review is to provide an overview of textile based sensors, sensor substrates, and substrate pre-processing including surface modification of the base substrates. This review also summarizes various conducting polymers and inks, production methods of developing robust conductive fibres or textiles, and different factors affecting the durability and cleaning of conductive textiles. This manuscript also critically examines properties relating to acceptability and performance of textile based sensors which are subjected to wear and care during repeated use e.g. care, maintenance, and durability. This aspect (wear and care) of performance is often ignored during development. Wear and care effects on performance need to be understood and solutions found for extending the life cycle and performance of textile based sensors.

Azam Ali

Papers

Hydrophobic treatment of natural fibers and their composites—A review

Current and novel polymeric biomaterials for neural tissue engineering

Synthesis and applications of nano-TiO 2 : a review

Synthesis of nano-hydroxyapatite (nHA) from waste mussel shells using a rapid microwave method

Textile sensors for wearable applications: a comprehensive review