Influence of halloysite nanotubes on physical and mechanical properties of cellulose fibres reinforced vinyl ester composites

Natural fibres are generally added to polymer matrix composites to produce materials with the desirable mechanical properties of higher specific strength and higher specific modulus while at the same time to maintain a low density and low cost. The physical and mechanical properties of polymer composites can be enhanced through the addition of nanofillers such as halloysite nanotubes. This article describes the fabrication of vinyl ester eco-composites and eco-nanocomposites and characterizes these samples in terms of water absorption, mechanical and thermal properties. Weight gain test and Fourier transform infrared analysis indicated that 5% halloysite nanotube addition gave favourable reduction in the water absorption and increased the fibre–matrix adhesion leading to improved strength properties in the eco-nanocomposites. However, halloysite nanotube addition resulted in reduced toughness but improved thermal stability

Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

Micromechanical analysis of hybrid composites reinforced with unidirectional natural fibres, silica microparticles and maleic anhydride

The work describes the analytical and experimental characterisation of a class of polymeric composites made from epoxy matrix reinforced with unidirectional natural sisal and banana fibres with silica microparticles and maleic anhydride fabricated by manual moulding. The analytical models, ROM rule of mixtures and Halpin-Tsai approach, have been used in conjunction with a Design of Experiments (DOE) analysis from tensile tests carried out on 24 different composites architectures. The following experimental factors were analyzed in this work: type of fibres (sisal and banana fibres), volume fraction of fibres (30% and 50%) and modified matrix phase by adding silica microparticles (0%wt, 20%wt and 33%wt) and maleic anhydride (0%wt and 2%wt). The ROM approach has shown a general good agreement with the experimental data for composites manufactured with 30%vol of natural fibres, which can be attributed to the strong adhesion found between the phases. On the opposite, the semi empirical model proposed by Halpin and Tsai has shown greater fidelity with composites manufactured from 50%vol of natural fibres, which exhibit a weak interfacial bonding. The addition of microsilica and maleic anhydride in the system did not enhance the adhesion between the phases as expected

Mechanical Properties of Cellulose Fibre Reinforced Vinyl-Ester Composites in Wet Conditions

The effect of prolonged water absorption on the physical and mechanical properties has been investigated for vinyl-ester composites reinforced with natural fibres. The elastic modulus of these composites was measured and the data were validated with various mathematical models. The modelling results revealed that the experimental data matched the data predicted by the Cox–Krenchel model. Prolonged exposure of these composites to water absorption caused a reduction in elastic modulus and strength

A review on the characteristics of gomuti fibre and its composites with thermoset resins

Gomuti fibre is obtained from Arenga pinnata tree and is known with other names such as sugar-palm fibre, gomutu, ijuk, serat aren and black fibre. This article presents a review on the physical, mechanical, chemical and thermal properties of gomuti fibre in comparison with other common natural fibres. Furthermore, this article reviews the mechanical properties of gomuti fibre composites with thermoset polymer resins based on the existing published literature. It is observable that gomuti fibre has a close similarity to coir fibre in its physical and mechanical properties than the other natural fibres. It has the characteristics of lower density, strength and modulus, but higher elongation. The composites with gomuti fibre also exhibit properties similar to coir fibre composites