The Experts below are selected from a list of 1668 Experts worldwide ranked by ideXlab platform

Fritz Vollrath - One of the best experts on this subject based on the ideXlab platform.

  • Weaving our way towards a new generation of Fibre-optic chemical sensors based on spider Silk
    2016 IEEE 6th International Conference on Photonics (ICP), 2016
    Co-Authors: Desmond M. Chow, Fritz Vollrath, Luc Thevenaz, Isabelle Dicaire, Tom Gheysens
    Abstract:

    From the spider's perspective, Silk is not only a building material but also a safety net, a weapon and a sensory organ to detect the presence of preys on its web. Indeed, this primeval material has been shaped over hundreds of millions of years by spiders to create a myriad of Silk Fibre types with different level of toughness, elasticity, stickiness depending on its attributed function in the web. From a human perspective, scientists are currently working on harnessing all the extraordinary properties of this material for applications spiders would never thought of, from biocompatible tissue engineering (enhancement of skin regeneration and nerve guides) to biodegradable electronics and development of specialised textile and composites. However, the potential of using spider Silk Fibre for chemical sensing has been overlooked. In this communication, we will explore the potential of using spider Silk as a new type of Fibre optic chemical sensor in a fully bio-inspired approach.

  • can Silk become an effective reinforcing Fibre a property comparison with flax and glass reinforced composites
    Composites Science and Technology, 2014
    Co-Authors: Darshil U Shah, David Porter, Fritz Vollrath
    Abstract:

    Abstract With the growing interest in bio-based composites as alternatives to traditional glass Fibre reinforced composites (GFRPs), there has been a persistent rise in the commercial use of plant Fibre composites (PFRPs). In contrast, nature’s ‘wonder-Fibre’ Silk has had no commercial applications, and only limited scientific investigations, as a composite reinforcement. To produce Silk Fibre composites (SFRPs) with useful properties, three key recommendations from our critical literature review were followed: (i) a high-failure strain, low-processing temperature thermoset matrix was used to (a) maximise the reinforcing effect of low-stiffness, ductile Silk, and (b) facilitate impregnation and avoid Fibre degradation, (ii) high Fibre volume fractions were employed to ensure that Fibres carried a larger fraction of the load, and (iii) given the lack of studies investigating fracture energy dissipation mechanisms in SFRPs, interface modification was avoided due to its complex, sometimes detrimental, effects on toughness. In directly addressing the question, ‘is there a case for Silks as polymer reinforcements?’, we evaluated various mechanical properties of nonwoven and plain woven SFRPs against similar flax and glass composites. In all cases, woven composites performed better than nonwoven composites. While SFRPs were weak in terms of stiffness, their flexural and tensile strength was comparable to PFRPs, but much below that of GFRPs. Notably, the low density of SFRPs, like PFRPs, made them comparable to GFRPs in terms of specific flexural properties. Woven SFRPs exhibited much higher fracture strain capacities than both flax and glass composites, making SFRPs suitable for applications where high compliance is required. The Achilles’ heels of PFRPs have been their reportedly (i) inadequate interfacial properties, (ii) inferior impact properties, (iii) poor strength performance, and (iv) high moisture sensitivity. We found that SFRPs outperformed their flax counterparts in areas (i)–(iii), and were more comparable to, but not better than, GFRPs. While concerns such as cost and ‘sustainability’ of Silk are acknowledged, potential applications for SFRPs are discussed.

  • Silk cocoon (Bombyx mori): multi-layer structure and mechanical properties.
    Acta Biomaterialia, 2012
    Co-Authors: Fujia Chen, David Porter, Fritz Vollrath
    Abstract:

    Bombyx mori cocoon is a natural composite made of Silk Fibre with a distinctive multi-layer structure that provides mechanical protection for its biological functions. Here we investigate the components, structure and mechanical properties of cocoon layers, and quantify the contributions of the multi-layer structure to the mechanical properties of cocoon. A better understanding of the multi-layer mechanism of a natural composite could help the further design of biomimetic multiscale artificial materials.

  • spider Silk Fibre extrusion combined wide and small angle x ray microdiffraction experiments
    International Journal of Biological Macromolecules, 2001
    Co-Authors: Christian Riekel, Fritz Vollrath
    Abstract:

    Abstract The major and minor ampullate Silks from live Nephila senegalensis (Tetragnathidae) and the major ampullate Silk from Euprostenops spp. (Pisauridae) spiders were investigated in situ by X-ray diffraction during forced Silking. Wide- (WAXS) and small-angle (SAXS) scattering patterns were obtained at the same time. WAXS data show that the thread at the exit of the spigots already contains β-sheet poly(alanine) crystallites. SAXS data suggest the presence of microfibrils with an axial repeating period of approximately 8 nm for both Nephila and Euprostenops . Minor ampullate (MI) Nephila Silk, however, does not show this axial repeat which is probably due to a higher amount of crystal forming poly(alanine). A microfibrillar morphology, connected by a network of random polymer chains, can explain the presence of highly oriented crystallites, an oriented halo and a diffuse background in the WAXS patterns. At high reeling speeds, bound water is co-extruded with the Fibre. It can be squeezed out of the Fibre by friction at a needle. Under natural conditions it is the spider's tarsal claws which might serve to squeeze out the water to improve the mechanical properties of the thread during dragline production.

  • spider Silk Fibre extrusion combined wide and small angle x ray microdiffraction experiments
    International Journal of Biological Macromolecules, 2001
    Co-Authors: Christian Riekel, Fritz Vollrath
    Abstract:

    The major and minor ampullate Silks from live Nephila senegalensis (Tetragnathidae) and the major ampullate Silk from Euprostenops spp. (Pisauridae) spiders were investigated in situ by X-ray diffraction during forced Silking. Wide- (WAXS) and small-angle (SAXS) scattering patterns were obtained at the same time. WAXS data show that the thread at the exit of the spigots already contains beta-sheet poly(alanine) crystallites. SAXS data suggest the presence of microfibrils with an axial repeating period of approximately 8 nm for both Nephila and Euprostenops. Minor ampullate (MI) Nephila Silk, however, does not show this axial repeat which is probably due to a higher amount of crystal forming poly(alanine). A microfibrillar morphology, connected by a network of random polymer chains, can explain the presence of highly oriented crystallites, an oriented halo and a diffuse background in the WAXS patterns. At high reeling speeds, bound water is co-extruded with the Fibre. It can be squeezed out of the Fibre by friction at a needle. Under natural conditions it is the spider's tarsal claws which might serve to squeeze out the water to improve the mechanical properties of the thread during dragline production.

Kintak Lau - One of the best experts on this subject based on the ideXlab platform.

  • interfacial bonding and degumming effects on Silk Fibre polymer biocomposites
    Composites Part B-engineering, 2012
    Co-Authors: Hao Wang, Kintak Lau, Joong Hee Lee, David Hui
    Abstract:

    Abstract Silk Fibre has been popularly used for bio-medical engineering and surgically-operational applications for centuries because of its biocompatible and bioresorbable properties. Using Silk Fibre as reinforcement for bio-polymers could enhance the stiffness of scaffoldings and bone implants. However, raw Silk Fibre consists of Silk fibroin that is bound together by a hydrophilic glued-liked protein layer called “sericin”. Degumming is a surface modification process for sericin removal which allows a wide control of the Silk Fibre’s properties, making the Silk Fibre possible to be properly used for the development and production of novel bio-composites with specific mechanical and biodegradable properties. Some critical issues such as wettability, bonding efficiency and biodegradability at the Fibre/matrix interface are of interesting topics in the study of the degumming process. Therefore, it is a need to detailedly study the effect on different degumming processes to the properties of the Silk Fibre for real-life applications.

  • design of an impact resistant glass Fibre epoxy composites using short Silk Fibres
    Materials & Design, 2012
    Co-Authors: Kintak Lau
    Abstract:

    Abstract The prevailing utilisation of light and strong structural materials has led to an increasing demand to engineering industries on developing different types of advanced composites. Thus, the development of simple and low cost woven glass Fibre composites with an improvement on their tensile and impact properties is suggested. In this paper, the hybridization of a glass Fibre reinforced composite is achieved by using low cost short Silk Fibres as a medium to enhance its cross-ply strength. The comparison on the tensile and impact properties of the composite reinforced by the short Silk Fibre (with the content from 0.3 to 0.6 wt%) with a pristine glass Fibre composite sample was conducted. Fracture surfaces were analysed by using scanning electron microscopy (SEM). Experimental results indicated that the maximum Young’s modulus and ductility index (DI) of a Silk reinforced composite increased by 50% and 75%, respectively as compared with the pristine one. Furthermore, the visual examination on drop-weight test samples proved that the impact resistance of the Silk reinforced composite was better than that of the pristine sample as well. According to the results obtained, it was found that the addition of 0.4 wt% short Silk Fibre into glass Fibre composite was shown to be the advisable reinforcement content to achieve better tensile and impact strengths.

  • Thermal properties and structure conformation on Silkworm Silk Fibre
    2012
    Co-Authors: Hao Wang, Kintak Lau
    Abstract:

    Silkworm Silk Fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. Degumming is a surface modification process which allows a wide control of the Silk Fibre's properties, making the Fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, the thermal properties and secondary structure were investigated to study the effects of distilled boiling water degumming. It was found that the degumming time had a little effect on the thermal decomposition properties and secondary structure of the Silk Fibre.

  • Effect of degumming time on Silkworm Silk Fibre for biodegradable polymer composites
    Applied Surface Science, 2012
    Co-Authors: Hao Wang, Kintak Lau
    Abstract:

    Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm Fibre), animal-based Fibre is a kind of sustainable natural materials for making novel composites. Silkworm Silk Fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing Silk Fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to Silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the Silk Fibre's properties, making the Silk Fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah Silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah Silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah Silk are affected by the degumming time due to the change of the Fibre structure and fibroin alignment.

  • characteristics of a Silk Fibre reinforced biodegradable plastic
    Composites Part B-engineering, 2011
    Co-Authors: Kintak Lau, Hao Wang, Debes Bhattacharyya
    Abstract:

    Silk Fibre is one kind of well recognized animal Fibres for bio-medical engineering and surgical operation applications because of its biocompatible and bio-resorbable properties. Recently, the use of Silk Fibre as reinforcement for some bio-polymers to enhance the stiffnesses of scaffolds and bone fixators has been a hot research topic. However, their mechanical and biodegradable properties have not yet been fully understood by many researchers, scientists and bio-medical engineers although these properties would govern the usefulness of resultant products. In this paper, a study on the mechanical properties and bio-degradability of Silk Fibre reinforced Poly (lactic-acid) (PLA) composites is conducted. It has been found that the Young’s modulus and flexural modulus of the composites increased with the use of Silk Fibre reinforcement while their tensile and flexural strengths decreased. This phenomenon is attributed to the disruption of inter- and intra-molecular bonding on the Silk Fibre with PLA during the mixing process, and consequent reduction of the Silk Fibre strength. Moreover, bio-degradability tests showed that the hydrophilic properties of the Silk may alter the biodegradation properties of the composites compared to that of a pristine PLA sample.

K Prashantha - One of the best experts on this subject based on the ideXlab platform.

  • study on the morphological and biocompatible properties of chitosan grafted Silk Fibre reinforced pva films for tissue engineering applications
    International Journal of Biological Macromolecules, 2018
    Co-Authors: Sareen Sheik, G. K. Nagaraja, Rajesha K Nairy, Ashwini Prabhu, P D Rekha, K Prashantha
    Abstract:

    The current study delineates the preparation of novel chitosan grafted Silk Fibre reinforced Poly (vinyl alcohol) (PVA) composite films with desirable properties. Although Silk fibroin has been extensively used for various biomedical applications, its properties could be further re-tailored for its suitability in the field of regenerative medicine. Chitosan was successfully grafted over Silk, via acylation with succinic anhydride and thereby the Fibres were incised and used for the preparation of the films. The grafted Silk Fibre reinforced PVA films were subjected to FTIR studies, microscopic analysis by atomic force microscopy (AFM) and optical microscopy techniques, X-ray diffraction (XRD) analysis and further evaluated for in vitro biocompatibility studies. The composite films demonstrated improved surface roughness with increasing concentration of the Fibre and its dispersion in the polymer matrix was observed. Furthermore, in vitro biocompatibility and cellular behaviour such as adhesion and proliferation of mouse fibroblasts as well as astrocyte cells was studied and the results showed improved proliferative activity, when compared to the pristine PVA films. These results were further supported by the results confirmed by MTT assay demonstrating the films to be non-toxic. The efficiency and feasibility of the films to be used for tissue engineering, was further evaluated by haemocompatibility studies using human erythrocytes, thus making them a potential material to be used for biomedical applications.

Sareen Sheik - One of the best experts on this subject based on the ideXlab platform.

  • study on the morphological and biocompatible properties of chitosan grafted Silk Fibre reinforced pva films for tissue engineering applications
    International Journal of Biological Macromolecules, 2018
    Co-Authors: Sareen Sheik, G. K. Nagaraja, Rajesha K Nairy, Ashwini Prabhu, P D Rekha, K Prashantha
    Abstract:

    The current study delineates the preparation of novel chitosan grafted Silk Fibre reinforced Poly (vinyl alcohol) (PVA) composite films with desirable properties. Although Silk fibroin has been extensively used for various biomedical applications, its properties could be further re-tailored for its suitability in the field of regenerative medicine. Chitosan was successfully grafted over Silk, via acylation with succinic anhydride and thereby the Fibres were incised and used for the preparation of the films. The grafted Silk Fibre reinforced PVA films were subjected to FTIR studies, microscopic analysis by atomic force microscopy (AFM) and optical microscopy techniques, X-ray diffraction (XRD) analysis and further evaluated for in vitro biocompatibility studies. The composite films demonstrated improved surface roughness with increasing concentration of the Fibre and its dispersion in the polymer matrix was observed. Furthermore, in vitro biocompatibility and cellular behaviour such as adhesion and proliferation of mouse fibroblasts as well as astrocyte cells was studied and the results showed improved proliferative activity, when compared to the pristine PVA films. These results were further supported by the results confirmed by MTT assay demonstrating the films to be non-toxic. The efficiency and feasibility of the films to be used for tissue engineering, was further evaluated by haemocompatibility studies using human erythrocytes, thus making them a potential material to be used for biomedical applications.

  • Development and characterization study of Silk Fibre reinforced poly(vinyl alcohol) composites
    International Journal of Plastics Technology, 2017
    Co-Authors: Sareen Sheik, G. K. Nagaraja, Jagadish Naik, R. F. Bhajanthri
    Abstract:

    The current study aims to explore the use of a low cost technique to develop biodegradable composite films of poly(vinyl alcohol) (PVA) reinforced with Silk Fibre. The composite films were fabricated by varying the weight percentage of Silk Fibres and PVA, using the solution casting technique and evaluated for their mechanical and bio-degradable properties. The films were further subjected to characterization by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and atomic force microscopy techniques (AFM). The prepared film composites showed enhanced mechanical properties as compared to the pure PVA film. From the XRD studies, the composite films exhibited improved crystallinity, when compared to the pristine sample. The dispersion of Fibres in the matrix was revealed by SEM. The thermal properties of the film composites increased with the increasing concentration of Silk Fibre. Moreover, the soil burial experiments revealed that the degradation rate improved with the addition of Silk Fibre, thus making it suitable in the packaging sector, without causing any ecological damage owing to its disposable property.

Hao Wang - One of the best experts on this subject based on the ideXlab platform.

  • interfacial bonding and degumming effects on Silk Fibre polymer biocomposites
    Composites Part B-engineering, 2012
    Co-Authors: Hao Wang, Kintak Lau, Joong Hee Lee, David Hui
    Abstract:

    Abstract Silk Fibre has been popularly used for bio-medical engineering and surgically-operational applications for centuries because of its biocompatible and bioresorbable properties. Using Silk Fibre as reinforcement for bio-polymers could enhance the stiffness of scaffoldings and bone implants. However, raw Silk Fibre consists of Silk fibroin that is bound together by a hydrophilic glued-liked protein layer called “sericin”. Degumming is a surface modification process for sericin removal which allows a wide control of the Silk Fibre’s properties, making the Silk Fibre possible to be properly used for the development and production of novel bio-composites with specific mechanical and biodegradable properties. Some critical issues such as wettability, bonding efficiency and biodegradability at the Fibre/matrix interface are of interesting topics in the study of the degumming process. Therefore, it is a need to detailedly study the effect on different degumming processes to the properties of the Silk Fibre for real-life applications.

  • Thermal properties and structure conformation on Silkworm Silk Fibre
    2012
    Co-Authors: Hao Wang, Kintak Lau
    Abstract:

    Silkworm Silk Fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. Degumming is a surface modification process which allows a wide control of the Silk Fibre's properties, making the Fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, the thermal properties and secondary structure were investigated to study the effects of distilled boiling water degumming. It was found that the degumming time had a little effect on the thermal decomposition properties and secondary structure of the Silk Fibre.

  • Effect of degumming time on Silkworm Silk Fibre for biodegradable polymer composites
    Applied Surface Science, 2012
    Co-Authors: Hao Wang, Kintak Lau
    Abstract:

    Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm Fibre), animal-based Fibre is a kind of sustainable natural materials for making novel composites. Silkworm Silk Fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing Silk Fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to Silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the Silk Fibre's properties, making the Silk Fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah Silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah Silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah Silk are affected by the degumming time due to the change of the Fibre structure and fibroin alignment.

  • characteristics of a Silk Fibre reinforced biodegradable plastic
    Composites Part B-engineering, 2011
    Co-Authors: Kintak Lau, Hao Wang, Debes Bhattacharyya
    Abstract:

    Silk Fibre is one kind of well recognized animal Fibres for bio-medical engineering and surgical operation applications because of its biocompatible and bio-resorbable properties. Recently, the use of Silk Fibre as reinforcement for some bio-polymers to enhance the stiffnesses of scaffolds and bone fixators has been a hot research topic. However, their mechanical and biodegradable properties have not yet been fully understood by many researchers, scientists and bio-medical engineers although these properties would govern the usefulness of resultant products. In this paper, a study on the mechanical properties and bio-degradability of Silk Fibre reinforced Poly (lactic-acid) (PLA) composites is conducted. It has been found that the Young’s modulus and flexural modulus of the composites increased with the use of Silk Fibre reinforcement while their tensile and flexural strengths decreased. This phenomenon is attributed to the disruption of inter- and intra-molecular bonding on the Silk Fibre with PLA during the mixing process, and consequent reduction of the Silk Fibre strength. Moreover, bio-degradability tests showed that the hydrophilic properties of the Silk may alter the biodegradation properties of the composites compared to that of a pristine PLA sample.

  • Mechanical properties of an injected Silk Fibre reinforced PLA composite
    2011
    Co-Authors: Kintak Lau, Hao Wang, Debes Bhattacharyya
    Abstract:

    Chopped Silkworm Silk Fibres and Poly-lactic acid (PLA) were mixed to form a fully biodegradable thermoplastic composite. Injection moulding process was used to mix these constituents together at a controlled temperature range. The mechanical properties of the composite were examined through tensile and flexural property and Izod impact tests. It was found that the Young's and flexural moduli of the composite increased while their strengths and impact resistance decreased during the tests as compared with a PLA sample. Early Fibre fractures observed from micrographs explain the reasons of enhanced moduli and reduction of strengths.