Publications
208 results found
Bray DJ, Taylor AC, 2013, Quantifying the dispersion of nanoparticles in polymers, Handbook of Functional Nanomaterials, Pages: 433-460, ISBN: 9781629481685
The properties of polymers can be modified by the addition of nanoparticles. However, the degree of dispersion of nanoparticles can greatly affect the properties of such nanocomposites. If there is agglomeration of the nanoparticles, this can cause reductions in the strength or poor barrier performance. This chapter discusses the principal types of nanoparticles, and outlines some of the methods that may be used to disperse such particles into polymers. The high surface area and incompatibility of nanoparticles with polymers make achieving a homogeneous dispersion of nanoparticles in a polymer matrix difficult. Even if a good dispersion can be achieved initially, the nanoparticles may agglomerate during further processing, to leave a poor dispersion in the final nanocomposite. When agglomerates are formed, these can act as defects resulting in a reduction in the performance of the material rather than any enhancement. Hence it is critical that the degree of dispersion of the particles can be described quantitatively. This can be achieved using the Area Disorder parameter to give a quantitative classification, allowing an objective distinction to be made between good, random and poor dispersion. Challenges in ensuring an accurate interpretation of nanoparticle dispersion when these techniques are applied to real nanocomposite materials, introduced through the use of a limited number of small micrographs with finite resolution and by the use of many types of particle morphologies, can be addressed by careful analysis to give a robust assessment using the Area Disorder.
Jagannathan N, Bojja R, Manjunatha CM, et al., 2013, Fatigue behaviour of a hybrid particle modified fiberglass/epoxy composite under a helicopter spectrum load sequence, Advanced Composites Letters, Vol: 22, Pages: 52-56, ISSN: 0963-6935
The fatigue life of a glass fiber reinforced plastic (GFRP) hybrid composite containing 9 wt.% of rubber microparticles and 10 wt.% of silica nanoparticles in the epoxy matrix, under a standard helicopter rotor spectrum load sequence was determined and observed to be about three times higher than that of GFRP with unmodified epoxy matrix. The underlying mechanisms for the observed improvements in spectrum fatigue life of GFRP-hybrid composite are discussed.
Manjunatha CM, Jagannathan N, Padmalatha K, et al., 2012, The fatigue and fracture behavior of micron-rubber and nano-silica particles modified epoxy polymer, International Journal of Nanoscience, Vol: 11, Pages: 1240002-1-1240002-7, ISSN: 1793-5350
A thermosetting epoxy polymer was hybrid-modified by incorporating 9 wt.% of CTBN rubber microparticles and 10 wt.% of silica nanoparticles. The resin was poured into steel mould and cured to produce bulk epoxy polymer sheets from which fatigue test specimens were machined. The total fatigue life of the hybrid-modified epoxy polymer was determined by conducting constant amplitude fatigue tests with dog-bone shaped test specimens, at a stress ratio, R = σ min/σ max = 0.1, using a sinusoidal waveform at a frequency of 3 Hz. Further, the fatigue crack growth behavior of the hybrid-modified epoxy polymer, at a stress ratio, R = 0.1, was determined using a standard 50 mm wide compact tension specimen. The fatigue fracture surfaces were observed using a scanning electron microscope. The cyclic fracture toughness of the hybrid-modified epoxy polymer, estimated from the fracture surface analysis, correlated well with the reported values of the toughness; which was significantly greater than that of the neat epoxy polymer. The energy dissipating micromechanisms of, (i) rubber particle cavitation and plastic deformation of the surrounding material, and (ii) silica nanoparticle debonding followed by plastic void growth, were observed to be operative, resulting in an improved fracture toughness. The fatigue crack initiation and propagation lives were determined from the experimental data. The enhanced capability to withstand longer crack lengths, due to the improved toughness together with the retarded crack growth rate, were observed to enhance the total fatigue life of the hybrid-modified epoxy polymer. © 2012 World Scientific Publishing Company.
Chen J, Taylor AC, 2012, Epoxy modified with triblock copolymers: morphology, mechanical properties and fracture mechanisms, JOURNAL OF MATERIALS SCIENCE, Vol: 47, Pages: 4546-4560, ISSN: 0022-2461
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- Citations: 58
Bray DB, Gilmour SG, Guild FJ, et al., 2012, Quantifying nanoparticle dispersion by using the area disorder of Delaunay triangulation, Journal of the Royal Statistical Society Series C: Applied Statistics, Vol: 61, Pages: 253-275
Characterizing the quality of dispersion of nanocomposites presents a challenging statistical problem for which no direct method has been fully adopted. A high precision, statistically well-grounded measure is required which is suitable for dealing with a single small non-homogeneous particle pattern obtained from the material. Our approach uses the Delaunay network of particles to measure the area disorder ADDel, which can be further used to categorize a material sample into well or poorly dispersed. ADDel-analysis is applied to several micrographs of nanoparticle-modified materials and found to classify the type of dispersion reliably. Selected spatial point processes are employed to estimate expected imprecision in observed measurements.
Kinloch AJ, Hsieh TH, Sohn Lee J, et al., 2012, The mechanics and mechanisms of fracture of nano-modified polymers, Pages: 58-74
The present paper considers the general mechanical, fracture and cyclic-fatigue properties of four different epoxy polymers containing various concentrations of well-dispersed silica nanoparticles. Firstly, it was found that, for any given epoxy polymer, their Youngs modulus steadily increased as the volume fraction, vf, of the silica nanoparticles was increased. Modelling studies showed that the measured moduli of the different silica-nanoparticle filled epoxy-polymers lay between upper-bound values set by the Halpin-Tsai and the Nielsen no-slip models, and lower-bound values set by the Nielsen slip model; with the last model being the more accurate at relatively high values of vf. Secondly, the presence of silica nanoparticles always led to an increase in the toughness of the epoxy polymer. However, to what extent a given epoxy polymer could be so toughened was related to structure/property relationships which were governed by (a) the values of glass transition temperature, Tg, and molecular weight, M c, between cross-links of the epoxy polymer, and (b) the adhesion acting at the silica-nanoparticle/epoxy-polymer interface. Thirdly, the two toughening mechanisms which were operative in the epoxy polymers containing silica nanoparticles were identified to be (a) localised shear-bands initiated by the stress concentrations around the periphery of the silica nanoparticles, and (b) debonding of the silica nanoparticles followed by subsequent plastic void-growth of the epoxy polymer. Fourthly, for one formulation the cyclic-fatigue properties have been studied and a significant improvement was found to arise from the addition of the silica nanoparticles. Finally, the toughening mechanisms have been quantitatively modelled and there was good agreement between the experimentally measured values and the predicted values of the fracture energy, Gc, for all the epoxy polymers modified by the presence of silica nanoparticles. The modelling studies have emphasised the importa
Manjunatha CM, Jagannathan N, Padmalatha K, et al., 2011, Improved variable-amplitude fatigue behavior of a glass-fiber-reinforced hybrid-toughened epoxy composite, Journal of Reinforced Plastics and Composites, Vol: 30, Pages: 1783-1793, ISSN: 1530-7964
A thermosetting epoxy polymer was hybrid-modified by the addition of 9 wt.% of rubber microparticles and 10 wt.% of silica nanoparticles. The GFRP composite laminates employing the unmodified epoxy matrix (GFRP-neat), and the hybrid epoxy matrix (GFRP-hybrid), were produced by a resin-infusion technique. The experimental fatigue lives of both GFRP composites under three different variable-amplitude load sequences, namely (a) a three-step increasing block (IB), (b) a three-step decreasing block (DB), and (c) a random block (RB) load sequence derived from a three-step load block, were determined. The fatigue life of the GFRP-hybrid composite was higher than that of the GFRP-neat composite under all the three load sequence blocks investigated, by about × 2.6 to × 4.0 times. The matrix crack density and the stiffness reduction rate were both lower in the GFRP-hybrid composite compared to the GFRP-neat composite material. The suppressed matrix cracking and reduced delamination growth rates in the hybrid-modified epoxy matrix enhanced the fatigue life of the corresponding GFRP-hybrid composite. Using the constant-amplitude fatigue data generated at various stress ratios, the fatigue lives under these variable-amplitude load sequence blocks were predicted using empirical models. The predicted fatigue lives, although conservative, were in reasonably good agreement with the experimental results.
Hsieh TH, Kinloch AJ, Taylor AC, et al., 2011, The effect of carbon nanotubes on the fracture toughness and fatigue performance of a thermosetting epoxy polymer, JOURNAL OF MATERIALS SCIENCE, Vol: 46, Pages: 7525-7535, ISSN: 0022-2461
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- Citations: 191
Bray DJ, Gilmour SG, Guild FJ, et al., 2011, Quantifying nanoparticle dispersion: application of the Delaunay network for objective analysis of sample micrographs, JOURNAL OF MATERIALS SCIENCE, Vol: 46, Pages: 6437-6452, ISSN: 0022-2461
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- Citations: 24
Rossi G, Giannakopoulos I, Monticelli L, et al., 2011, A MARTINI Coarse-Grained Model of a Thermoset Polyester Coating, MACROMOLECULES, Vol: 44, Pages: 6198-6208, ISSN: 0024-9297
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- Citations: 63
Manjunatha CM, Jagannathan N, Padmalatha K, et al., 2011, The effect of micron-rubber and nano-silica particles on the fatigue crack growth behavior of an epoxy polymer, International Journal of Nanoscience, Vol: 10, Pages: 1095-1099, ISSN: 1793-5350
A thermosetting epoxy polymer was hybrid-modified by incorporating 9 wt.% of CTBN rubber micro particles and 10 wt.% of silica nano-particles. The unmodified and the hybrid-modified resins were poured into steel moulds and cured to produce bulk epoxy polymer sheets from which standard compact tension test specimens were machined. Fatigue crack growth tests were conducted using a 50 kN servo-hydraulic test machine, with the following test parameters: stress ratio, R = σmin/σmax = 0.1, sinusoidal waveform and frequency, ν = 3 Hz. The crack length was monitored by a compliance technique. The fracture surfaces were observed in a high resolution scanning electron microscope. The fatigue crack growth rate of the hybrid epoxy polymer was observed to be significantly lower than that of the unmodified epoxy polymer. The threshold stress intensity factor range, ΔKth, of the epoxy polymer was observed to increase by the addition of micron-rubber and nano-silica particles. The energy dissipating mechanisms viz, (i) cavitation of the rubber microparticles followed by plastic-deformation and void growth of the epoxy and, (ii) silica nanoparticle debonding followed by plastic-deformation and void growth of the epoxy, were observed to be operative and contribute for the reduced crack growth rate in the hybrid epoxy polymer.
Hsieh TH, Kinloch AJ, Masania K, et al., 2011, The toughness of epoxy polymers and fibre composites modified with rubber microparticles and silica nanoparticles (vol 45, pg 1193, 2010), JOURNAL OF MATERIALS SCIENCE, Vol: 46, Pages: 4092-4092, ISSN: 0022-2461
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- Citations: 7
Brooker RD, Guild FJ, Taylor AC, 2011, Quantifying the dispersion of carbon nanotubes in thermoplastic-toughened epoxy polymers, JOURNAL OF MATERIALS SCIENCE, Vol: 46, Pages: 3108-3118, ISSN: 0022-2461
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- Citations: 10
Hsieh TH, Kinloch AJ, Taylor AC, et al., 2011, The Effect of Silica Nanoparticles and Carbon Nanotubes on the Toughness of a Thermosetting Epoxy Polymer, JOURNAL OF APPLIED POLYMER SCIENCE, Vol: 119, Pages: 2135-2142, ISSN: 0021-8995
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- Citations: 52
Giannakopoulos G, Masania K, Taylor AC, 2011, Toughening of epoxy using core-shell particles, JOURNAL OF MATERIALS SCIENCE, Vol: 46, Pages: 327-338, ISSN: 0022-2461
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- Citations: 128
Taylor AC, Williams JG, 2011, Determining the Fracture Energy of Structural Adhesives from Wedge-Peel Tests, JOURNAL OF ADHESION, Vol: 87, Pages: 482-503, ISSN: 0021-8464
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- Citations: 5
Taylor AC, 2011, Adhesives with Nanoparticles, HANDBOOK OF ADHESION TECHNOLOGY, VOL 1 AND 2, Editors: DaSilva, Ochsner, Adams, Publisher: SPRINGER-VERLAG BERLIN, Pages: 1437-1460, ISBN: 978-3-642-01168-9
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- Citations: 9
Hsieh TH, Kinloch AJ, Masania K, et al., 2010, The mechanisms and mechanics of the toughening of epoxy polymers modified with silica nanoparticles, POLYMER, Vol: 51, Pages: 6284-6294, ISSN: 0032-3861
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- Citations: 353
Kinloch AJ, Hsieh TH, Masania K, et al., 2010, The Toughness of Epoxy Polymers Modified with Silica Nanoparticles, 18th European Conference on Fracture, Pages: 1-8
Manjunatha CM, Sprenger S, Taylor AC, et al., 2010, The Tensile Fatigue Behavior of a Glass-fiber Reinforced Plastic Composite Using a Hybrid-toughened Epoxy Matrix, Journal of Composite Materials, Vol: 44, Pages: 2095-2109, ISSN: 1530-793X
A thermosetting epoxy-polymer was modified by incorporating 9 wt% of carboxyl-terminated butadiene–acrylonitrile rubber microparticles and 10 wt% of silica nanoparticles. The tensile fatigue behavior at a stress ratio, R = 0.1 for both the neat-epoxy polymer (i.e., unmodified) and the hybrid-epoxy polymer was first investigated. The fatigue life of the hybrid-epoxy polymer was about six to ten times higher than that of the neat-epoxy polymer. Secondly, the neat- and the hybrid-epoxy resins were infused into a quasi-isotropic lay-up, E-glass fiber fabric via a ‘Resin Infusion under Flexible Tooling’ set-up to fabricate glass-fiber reinforced plastic (GFRP) composite panels. The tensile fatigue tests at a stress ratio, R = 0.1 were performed on both of these GFRP composites during which the matrix cracking and stiffness degradation were routinely monitored. The fatigue life of the GFRP composite increased by about six to ten times due to employing the hybrid-epoxy matrix, compared to employing the neat-epoxy matrix. Suppressed matrix cracking and a reduced crack propagation rate were observed in the hybrid-epoxy matrix, which resulted from the various toughening micromechanisms induced by the presence of both the rubber microparticles and silica nanoparticles. These factors were considered to contribute towards the enhanced fatigue life which was observed for the GFRP composite employing the hybrid-epoxy matrix.
Manjunatha CM, Taylor AC, Kinloch AJ, et al., 2010, The Tensile Fatigue Behavior of a GFRP Composite with Rubber Particle Modified Epoxy Matrix, Journal of Reinforced Plastics and Composites, Vol: 29, Pages: 2170-2183, ISSN: 1530-7964
A thermosetting epoxy polymer was modified by incorporating 9 wt% of a CTBN rubber microparticles. The stress-controlled CA tensile fatigue behavior at stress ratio, R = 0.1 for both the neat and the modified epoxy was investigated. The addition of rubber particles increased the epoxy fatigue life by a factor of about three to four times. The rubber particle cavitation and plastic deformation of the surrounding material was observed to contribute to the enhanced fatigue life of the epoxy polymer. Then, the neat and the rubber-modified epoxy resins were infused into a quasi-isotropic, lay-up E-glass fiber, non-crimp fabric in a RIFT set -up to fabricate GFRP composite panels. Further, the stress-controlled CA tensile fatigue tests at stress ratio, R = 0.1 were performed on both of these GFRP composites. Matrix cracking and stiffness degradation was continuously monitored during the fatigue tests. Similar to bulk epoxy fatigue behavior, the fatigue life of GFRP composites increased by a factor of about three times due to the presence of rubber particles in the epoxy matrix. The suppressed matrix cracking and the reduced crack propagation rates in the rubber-modified matrix contribute towards the enhanced fatigue life of GFRP composites employing a rubber-modified epoxy matrix.
Kinloch AJ, Johnsen BB, Sohn Lee J, et al., 2010, Tough Nanoparticle-Modified Polymers, 12th International Conference on Fracture (ICF 12), Publisher: International Congress on Fracture (ICF), Pages: 522-531
A crosslinked epoxy polymer has been modified by the addition ofnano-silica particles. The particles were introduced via a sol-gel technique which gave a very well dispersed phase of nano-silica particles which were about 20 nm in diameter. The glass transition temperature was unchanged by the addition of the nanoparticles, but both the modulus and toughness were increased. The fracture energy, GIc, increased from 100 J/m2 for the unmodified epoxy to 460 J/m2 for the epoxy with 20 wt. % of nano-silica. The microscopy studies showed evidence of debonding of the nanoparticles and subsequent plastic void growth of the epoxy polymer. A theoretical model of plastic void growth was used to confirm this mechanism. The cyclic-fatigue behaviour of the epoxy polymers has also been studied and the fatigue properties were clearly enhanced by the presence of the nano-silica particles. Indeed, it was found that the values of the strainenergy release rate at threshold, Gth, from the cyclic-fatigue tests increased steadily as the toughness, GIc, also increased, i.e. as the concentration of nanosilica particles was increased.
Guild FJ, Kinloch AJ, Taylor AC, 2010, Particle cavitation in rubber toughened epoxies: the role of particle size, Journal of Materials Science, Vol: 45, Pages: 3882-3894, ISSN: 1573-4803
Hsieh TH, Kinloch AJ, Masania K, et al., 2010, The toughness of epoxy polymers and fibre composites modified with rubber microparticles and silica nanoparticles, JOURNAL OF MATERIALS SCIENCE, Vol: 45, Pages: 1193-1210, ISSN: 0022-2461
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- Citations: 310
Hsieh TH, Kinloch A, Taylor A, et al., 2010, The effect of carbon nanotubes and nanosilica particles on the toughening performance of polymer-based nanocomposites, Pages: 725-728
Nano-fillers are considered good potential reinforcements for improving the mechanical and thermal properties of composites and adhesives. This study aims to investigate the toughening performance of an anhydride-cured thermosetting epoxy composite modified by various types of nano-reinforcements, including multi-walled carbon nanotubes (MWNTs) and nanosilica particles. The nanosilica particles were dispersed very well even at high concentrations. However, the MWNTs were agglomerated. The glass transition temperature of the nanocomposite was measured using differential scanning calorimetry, and all the measured values of each formulation were between 142 and 146°C. The Young's modulus was increased by the addition of the nanosilica particles, but the addition of up to 0.18 wt% of MWNTs had no significant effect. The toughening performance of the nanocomposites was examined using the single-edge notch-bend (SENB) test. The fracture toughness was increased from 0.69 MPam1/2 for the unmodified epoxy polymer to 1.03 MPam1/2 for the nanocomposite containing 0.18 wt% MWNTs and 6.0 wt% nanosilica; the fracture energy was also increase by 52% to 203 J/m1/2 for the same material in comparison with the neat polymer. The toughening mechanisms were explored by studying the fracture surfaces using field emission gun scanning electron microscopy, which showed pull-out of MWNTs. Besides, void growth due to interfacial debonding between the matrix and the MWNTs, plus subsequent plastic deformation of the matrix, can be observed around the MWNTs or in the core of entangled MWNT agglomerates.
Brooker RD, Kinloch AJ, Taylor AC, 2010, The Morphology and Fracture Properties of Thermoplastic-Toughened Epoxy Polymers, JOURNAL OF ADHESION, Vol: 86, Pages: 726-741, ISSN: 0021-8464
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- Citations: 74
Rouyre T, Taylor AC, Fu M, et al., 2010, Nano-and Micro-silica Modification of Epoxy Polymers, International Conference on Solid Dielectrics ICSD, Publisher: IEEE, ISSN: 1553-5282
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- Citations: 5
Zuo K, Blackman B, Willams G, et al., 2010, The Fracture and Fatigue Behaviour of Nano-modified SAN, 2nd International Conference on Advances in Product Development and Reliability (PDR), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 43-+, ISSN: 1022-6680
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- Citations: 1
Stephan S, Anthony K, Taylor AC, et al., 2009, SiO<inf>2</inf> nanoparticles in adhesive formulations ultra-tough and fatigue resistant, Adhaesion Kleben und Dichten, Pages: 8-11, ISSN: 0943-1454
Constantly growing demands are placed on adhesives in the aircraft, automotive, shipbuilding and wind turbine industries. At the same time, it is important that the costs of these adhesives do not rise. One solution to this problem could be structural adhesives which combine surface-modified SiO 2 nanoparticles with reactive liquid rubbers to produce a highly specialised property profile.
Manjunatha CM, Taylor AC, Kinloch AJ, et al., 2009, The tensile fatigue behaviour of a silica nanoparticle-modified glass fibre reinforced epoxy composite, Composites Science and Technology, Vol: 70, Pages: 193-199, ISSN: 0266-3538
An anhydride-cured thermosetting epoxy polymer was modified by incorporating 10 wt.% of well-dispersed silica nanoparticles. The stress-controlled tensile fatigue behaviour at a stress ratio of R = 0.1 was investigated for bulk specimens of the neat and the nanoparticle-modified epoxy. The addition of the silica nanoparticles increased the fatigue life by about three to four times. The neat and the nanoparticle-modified epoxy resins were used to fabricate glass fibre reinforced plastic (GFRP) composite laminates by resin infusion under flexible tooling (RIFT) technique. Tensile fatigue tests were performed on these composites, during which the matrix cracking and stiffness degradation was monitored. The fatigue life of the GFRP composite was increased by about three to four times due to the silica nanoparticles. Suppressed matrix cracking and reduced crack propagation rate in the nanoparticle-modified matrix were observed to contribute towards the enhanced fatigue life of the GFRP composite employing silica nanoparticle-modified epoxy matrix.
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