The Experts below are selected from a list of 9996 Experts worldwide ranked by ideXlab platform
Surendra P Shah - One of the best experts on this subject based on the ideXlab platform.
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self Healing Efficiency and crack closure of smart cementitious composite with crystalline admixture and structural polyurethane
Construction and Building Materials, 2020Co-Authors: Caihong Xue, Zhihui Sun, Surendra P ShahAbstract:Abstract The crack closure and self-Healing Efficiency of smart self-Healing cementitious composite can effectively reveal the mechanism of self-Healing performance recovery. This study focused on effects of crack Healing on crack closure and mechanical performance recovery of crack-healed cementitious composite, including flexural compressive behaviours. Meanwhile, several parameters were defined to quantify the Efficiency of mechanical performance recovery Efficiency for self-Healing cementitious composite. Furthermore, the interfaces between self-Healing products and crack surface were analyzed and compared to provide understanding insight to the self-Healing recovery. It is found that the bonding interface dominated the flexural strength recovery, and therefore autonomous self-Healing yielded the maximum self-Healing Efficiency. On the other hand, the stiffness damage recovery index under compression is found to be an effective parameter to evaluate the inner crack Healing, which slightly depends on the bonding interface. The related results indicate that the development of smart self-Healing cementitious composite should consider the bonding between self-Healing product and crack surface to improve the self-Healing recovery Efficiency for engineering application.
Guoqiang Li - One of the best experts on this subject based on the ideXlab platform.
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a self Healing particulate composite reinforced with strain hardened short shape memory polymer fibers
Polymer, 2013Co-Authors: Guoqiang Li, Pengfei ZhangAbstract:Abstract A particulate composite dispersed with thermoplastic particles and strain hardened short shape memory polymer fibers was prepared to evaluate its ability to repeatedly heal wide-opened cracks per the two-step close-then-heal (CTH) self-Healing scheme. A two-step coating approach was used to enhance the shape fixity and workability of the cold-drawn programmed short polyurethane fibers. The relationship between recovery-stress and recovery-strain was experimentally determined by partially constrained shape recovery test. Notched beam specimens were prepared and fracture-Healing was conducted up to five cycles. It is found that the composite was able to heal the wide-opened crack repeatedly with considerable Healing Efficiency. It is also found that the Healing Efficiency increases as the fiber length increases, but in a reduced increasing rate. The recovery stress-recovery strain of the strain hardened shape memory polymer fiber behaves nonlinearly. The coated fiber is more effective than the uncoated fiber in closing wide-opened cracks when the recovery strain is within a certain range.
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Effect of strain hardening of shape memory polymer fibers on Healing Efficiency of thermosetting polymer composites
Polymer, 2013Co-Authors: Guoqiang Li, Oludayo Ajisafe, Harper MengAbstract:Recently, shape memory polymer fibers (SMPFs) have been used in a biomimetic two-step (Close-Then-Heal) self-Healing system for Healing macroscopic cracks. The objective of this study was to investigate the effect of cold-drawing programming of SMPFs on the Healing Efficiency of conventional thermosetting polymer composites and the possibility of Healing wide-opened crack by localized heating. To achieve the objective, continuous SMPF strand reinforced conventional epoxy composite beam specimens, which were dispersed with thermoplastic particles, were prepared. The SMPF strands were cold-drawn to various pre-strain levels before casting the polymer matrix. Repeated fracture/Healing test was conducted by uniaxial tension. It is found that the composites were able to repeatedly heal macroscopic cracks. Strain-hardening by cold-drawing increased the Healing Efficiency considerably. It was demonstrated that Healing can be achieved by heating locally surrounding the cracked region. The mechanism for the enhanced recovery stress was due to cold-drawing induced molecular alignment and formation of some perfect crystals in the hard segment domain of the SMPF.
Anil N Netravali - One of the best experts on this subject based on the ideXlab platform.
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bacterial cellulose integrated irregularly shaped microcapsules enhance self Healing Efficiency and mechanical properties of green soy protein resins
Journal of Materials Science, 2021Co-Authors: Shanshan Shi, Anil N NetravaliAbstract:Soy protein isolate (SPI)-based self-Healing thermoset resins were prepared using either poly(DL-lactide-co-glycolide) porous microspheres (MSs) and spherical microcapsules (MCs) or elongated MCs containing a combination of ground bacterial cellulose (GBC) and SPI as the Healing agent. Spray emulsification, combined with solvent evaporation technique, was used to prepare MCs and MSs. The technique resulted in two MC morphologies: one primarily consisting of a mixture of porous MSs and spherical MCs and the other consisting of elongated MCs with aspect ratios as high as 50, depending on the surfactant and GBC amount used. While porous MSs made the resin stronger, they did not contribute to self-Healing since they could not retain the healant. Part of the GBC, added during MC preparation, got successfully encapsulated into MCs to form strong GBC/SPI composite healtant. Most of the remaining GBC stayed on MC surfaces and was seen to enhance the MC/resin interfacial adhesion which, in turn, contributed to increased self-Healing Efficiency. Overall results indicated that resins with 20 wt% elongated MCs exhibited self-Healing efficiencies of about 45% in strength and 59% in toughness. The results suggest that the integration of GBC in the healant could also work in other resin systems to enhance their self-Healing efficiencies.
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parametric study of protein encapsulated microcapsule formation and effect on self Healing Efficiency of green soy protein resin
Journal of Materials Science, 2017Co-Authors: Joo Ran Kim, Anil N NetravaliAbstract:Soy protein isolate-loaded poly (d,l-lactide-co-glycolide) (SPI-PLGA) microcapsules were prepared using a water-in-oil-in-water emulsification solvent evaporation technique. Effects of microencapsulation formulation parameters such as homogenization speed (1000 or 10,000 rpm) and PLGA and poly(vinyl alcohol) concentrations (1 or 5%) were investigated on size, size distribution, protein loading, encapsulation Efficiency, and morphology of the microcapsules as well as their self-Healing Efficiency. SPI-PLGA microcapsules produced using homogenization speed of 10,000 rpm had an average diameter of 0.76 µm and contained smaller size of subcapsules within themselves, whereas microcapsules produced using homogenization speed of 1000 rpm were larger with an average diameter of 9.1 µm and contained diverse size of subcapsules inside. The PVA concentration did not show any significant effect on the SPI-PLGA microcapsule size. However, at higher PVA concentration of 5%, the SPI-PLGA aggregation of microcapsules resulted because of the excess residual PVA outside the microcapsules. Higher PVA also resulted in better bonding of microcapsules with the SPI resin, resulting in higher self-Healing Efficiency. The self-Healing Efficiency for various formulations studied varied between 29 and 53%. The SPI-PLGA microcapsules prepared using 1% PLGA, 5% PVA, and homogenization speed of 10,000 rpm resulted in the highest self-Healing Efficiency of 53%.
Halit Yazici - One of the best experts on this subject based on the ideXlab platform.
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sodium silicate polyurethane microcapsules synthesized for enhancing self Healing ability of cementitious materials optimization of stirring speeds and evaluation of self Healing Efficiency
Journal of building engineering, 2021Co-Authors: Ahsanollah Beglarigale, Doga Eyice, Yoldas Seki, Caglar Yalcinkaya, Oguzhan Copuroglu, Halit YaziciAbstract:Abstract In this study, stirring speeds during the synthesizing process of the sodium silicate/polyurethane microcapsules were optimized. The yield values of microcapsules at different stirring rates were evaluated. Based on the yield values and shape of microcapsules, optimized microcapsules were obtained. The measurements of the shell thickness of microcapsules were performed on the fractured microcapsules by using scanning electron microscopy. The optimized microcapsules were further characterized by means of optical microscopy and nanoindentation. Load vs. displacement and modulus of elasticity vs. displacement characteristics of the microcapsules were obtained. The average modulus of elasticity was found to be 633 MPa. The self-Healing Efficiency of the optimized microcapsules was evaluated by means of compressive strength tests. The incorporation of microcapsules reduced the compressive strength of fiber-reinforced mortar by 12–22%. However, it was observed that the microcapsules enhanced the self-Healing capacity (recovery in compressive strength) of the mortar.
Caglar Yalcinkaya - One of the best experts on this subject based on the ideXlab platform.
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sodium silicate polyurethane microcapsules synthesized for enhancing self Healing ability of cementitious materials optimization of stirring speeds and evaluation of self Healing Efficiency
Journal of building engineering, 2021Co-Authors: Ahsanollah Beglarigale, Doga Eyice, Yoldas Seki, Caglar Yalcinkaya, Oguzhan Copuroglu, Halit YaziciAbstract:Abstract In this study, stirring speeds during the synthesizing process of the sodium silicate/polyurethane microcapsules were optimized. The yield values of microcapsules at different stirring rates were evaluated. Based on the yield values and shape of microcapsules, optimized microcapsules were obtained. The measurements of the shell thickness of microcapsules were performed on the fractured microcapsules by using scanning electron microscopy. The optimized microcapsules were further characterized by means of optical microscopy and nanoindentation. Load vs. displacement and modulus of elasticity vs. displacement characteristics of the microcapsules were obtained. The average modulus of elasticity was found to be 633 MPa. The self-Healing Efficiency of the optimized microcapsules was evaluated by means of compressive strength tests. The incorporation of microcapsules reduced the compressive strength of fiber-reinforced mortar by 12–22%. However, it was observed that the microcapsules enhanced the self-Healing capacity (recovery in compressive strength) of the mortar.
