Nanocomposites of Polymers and Inorganic Particles

The book covers all of the specific aspects of this topic, ranging from preparatory approaches, functionalization strategies of NPs and polymers, processing and integration of nanocomposites in additive manufacturing materials, and technological methodologies to obtain functional multiphase materials for advanced application

A study of free-form shape rationalization using biomimicry as inspiration

Bridging the gap between the material and geometrical aspects of a structure is critical in lightweight construction. Throughout the history of structural development, shape rationalization has been of prime focus for designers and architects, with biological forms being a major source of inspiration. In this work, an attempt is made to integrate different phases of design, construction, and fabrication under a single framework of parametric modeling with the help of visual programming. The idea is to offer a novel free-form shape rationalization process that can be realized with unidirectional materials. Taking inspiration from the growth of a plant, we established a relationship between form and force, which can be translated into different shapes using mathematical operators. Different prototypes of generated shapes were constructed using a combination of existing manufacturing processes to test the validity of the concept in both isotropic and anisotropic material domains. Moreover, for each material/manufacturing combination, generated geometrical shapes were compared with other equivalent and more conventional geometrical constructions, with compressive load-test results being the qualitative measure for each use case. Eventually, a 6-axis robot emulator was integrated with the setup, and corresponding adjustments were made such that a true free-form geometry could be visualized in a 3D space, thus closing the loop of digital fabrication

Effects of Animal Hair Fibre on Polyester Resin

The effect of animal hair fibre on polyester resin was examined. The animal hair fibre was obtained from the Hausa – specie she-goat from Abattoir in Awka, Anambra State, Nigeria. The animal hair was washed and dried at 39oC for 3 hours at constant weight. The percentages by weight of animal hair sample used were 3%, 6%, 9% and 12% (w/w). The percentage by weight of the hair fibre was cast into the polyester resin, cured with accelerator and catalyst, stirred and cast into the dumbbell shaped and Teflon mould. The composite cured in the mould at a room temperature for 24 hours after which it was heat treated in the oven at 80oC for one hour for dimensional stability of the composite. From the results, the tensile strength of the composite increased from 3% (16.6698MPa) – 9% (29.3033MPa) with a sharp decrease in 12% (20.4288MPa) volume ratio. The tensile strength of the control sample 0% (30.0991MPa) was higher than the reinforced composites. The Modulus of the composite increased from 3% (541.2377MPa) – 9% (598.1224MPa) with a sharp decrease in 12% (530.1571MPa) volume ratio. The control sample 0% has higher modulus (649.4003MPa) than the reinforced composites. The load at break of the sample increase gradually as fibre loading increases from 3% (709.1161 MPa) to 9% (1084.2570MPa) after which there was a decrease as fibre volume increase to 12% (893.0747MPa). Flexural strength peaked at 6% fibre load (83.1131MPa) while there was variation in the results of flexural modulus with 9% fiber load having the highest value (2329.6509 MPa). The control sample has the value of (75.2204 MPa) for flexural strength and (2231.6092 MPa) for flexural modulus. The hardness result of the sample decreased from 0% (22.0667HV) - 6% (17.6667HV) volume ratio but increased as the fibre load increased from 9% (23.1667HV) – 12% (25.7333HV). Keywords: Animal hair, Polyester resin, Composite, Fibre

Mechanical properties of woven natural fiber reinforced composites

Epoxy matrix composites reinforced with woven natural fiber were studied. Composites having fiber volume fraction greater than 55% were prepared by hand lay-up technique. For reinforcement, three different natural fibers were used, jute, flax and silk. The tensile and flexural properties were investigated and the influence of the orientation of fibers on the stiffness were analyzed. It was observed that the tensile and flexural strength of silk composites is almost equal to that of flax composite and 1.98 times that of jute composite. Moreover the stiffness of the silk composites isn't influenced by orientation of fibers. Morphological examinations were carried out using scanning electron microscopy (SEM). All specimens were coated with a thin layer gold alloy prior to SEM observations. A high voltage of 20 kV was used for making the micrographs. The SEM investigation was used to study the fracture surface of the tensile specimens of the composites samples. The results of this study indicate that using silk fiber as reinforcement could successfully develop a composite material in terms of high strength and stiffness to produce a bio-composites for light applications compared to conventional composites

A potential material for tissue engineering : silkworm silk/PLA biocomposite

Author name used in this publication: Hoi-Yan Cheung2007-2008 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Bioinspired Hard–Soft Interface Management for Superior Performance in Carbon Fibre Composites

Nature has evolved to create materials of unmatched performance governed by the interfacial interactions between hard and soft surfaces. Typically, in a carbon fibre composite, one polymer and one type of carbon fibre is used throughout a laminate. In this work, we use a carbon fibre surface modification approach to vary the fibre–matrix interface throughout the laminate to tailor the soft–hard interfaces. We demonstrate this effect using reclaimed carbon fibre materials in a thermoset polymer, then extend this concept to a thermoplastic polymer matrix–polypropylene. The thermoset specimens examined in this work consist of 5 carbon fibre plies, featuring 0, 1, 3 or 5 surface-modified layers located at the centre of the composite. The largest improvements in physical properties for these composites (yield strength, ultimate flexural strength, and tensile modulus) were found when only 1 modified layer of carbon fibre was placed directly within the centre of the composite. Subsequent investigations revealed that for a polypropylene matrix, where the surface chemistry is tailored specifically for polypropylene, improvements are also observed when mixed surface chemistries are used. This work shows that surface modification of reclaimed carbon fibres as non-woven mats can provide significant improvements in mechanical properties performance for structural composites when used in strategically advantageous locations throughout the composite

The Formation of All-Silk Composites and Time–Temperature Superposition

Extensive studies have been conducted on utilising natural fibres as reinforcement in composite production. All-polymer composites have attracted much attention because of their high strength, enhanced interfacial bonding and recyclability. Silks, as a group of natural animal fibres, possess superior properties, including biocompatibility, tunability and biodegradability. However, few review articles are found on all-silk composites, and they often lack comments on the tailoring of properties through controlling the volume fraction of the matrix. To better understand the fundamental basis of the formation of silk-based composites, this review will discuss the structure and properties of silk-based composites with a focus on employing the time–temperature superposition principle to reveal the corresponding kinetic requirements of the formation process. Additionally, a variety of applications derived from silk-based composites will be explored. The benefits and constraints of each application will be presented and discussed. This review paper will provide a useful overview of research on silk-based biomaterials