Fracture and toughening mechanisms of silica- and core–shell rubber-toughened epoxy at ambient and low temperature

Tsang, Wing Lam; Taylor, A. C.

doi:10.1007/s10853-019-03893-y

Cited by 54 publications

(22 citation statements)

References 43 publications

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“…Tsang et al based their study of an anhydride-cured DGEBA on a combination of silica nanoparticles and a core shell rubber Type II [ 38 ]. Fracture behavior at −80 °C, −40 °C and ambient temperature was tested.…”

Section: Epoxy Resins Modified With Silica Nanoparticlesmentioning

confidence: 99%

Nanosilica-Toughened Epoxy Resins

Sprenger

2020

Polymers

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Surface-modified silica nanoparticles are available as concentrates in epoxy resins in industrial quantities for nearly 20 years. Meanwhile, they are used in many epoxy resin formulations for various applications like fiber-reinforced composites, adhesives or electronic components; even in space vehicles like satellites. Some of the drawbacks of “classic” epoxy toughening using elastomers as a second phase, like lower modulus or a loss in strength can be compensated by using nanosilica together with such tougheners. Apparently, there exists a synergy as toughness and fatigue performance are increased significantly. This work intends to provide an overview regarding the possibilities of nanotoughening with silica, the industrial applications of such epoxy resin formulations and the most recent research results.

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Section: Epoxy Resins Modified With Silica Nanoparticlesmentioning

confidence: 99%

Nanosilica-Toughened Epoxy Resins

Sprenger

2020

Polymers

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“…However, conventional studies on CSR nanoparticle/epoxy composite polymers have mainly considered the mechanical properties at room temperature. A number of studies have characterized the properties of the CSR/epoxy at cryogenic temperatures (at 77 K under LN 2 ambient conditions) [ 38 , 39 ] and low temperatures (from −109 to 20 °C) [ 40 , 41 , 42 ], but these studies are rare. Nevertheless, this temperature range is only a partial intersection of the operating temperature range required for the automotive industry, which presents insufficient information for structural adhesive manufacturing.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Characterization of Core-Shell Rubber/Epoxy Polymers for Automotive Structural Adhesives as a Function of Operating Temperature

2021

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Automotive structural adhesives must show a steady toughness performance in the temperature range of −40 °C to 80 °C, considering their actual usage environments. Core-shell rubber (CSR) nanoparticles are known to enhance the toughness of epoxy systems. In this study, a CSR, pre-dispersed, diglycidyl epoxy of bisphenol A (DGEBA) mixture at 35 wt % (KDAD-7101, Kukdo Chemical, Seoul, Korea) was used as a toughener for an automotive structural epoxy adhesive system. A simple, single-component, epoxy system of DGEBA/dicyandiamide with a latent accelerator was adopted, where the CSR content of the system was controlled from 0 to 50 phr by the CSR mixture. To determine the curing conditions, we studied the curing behavior of the system by differential scanning calorimetry (DSC). Modulus variations of the cured bulk epoxies were studied using a dynamic mechanical analyzer (DMA) in the dual cantilever mode. The flexural modulus of the cured epoxies at various temperatures (−40, −10, 20, 50, and 80 °C) showed the same tendency as the DMA results, and as the flexural strength, except at 0 phr. On the other hand, the strain at break exhibited the opposite tendency to the flexural modulus. To study the adhesion behavior, we performed single-lap joint (SLJ) and impact wedge-peel (IWP) tests. As the CSR content increased, the strength of the SLJ and dynamic resistance to the cleavage of the IWP improved. In particular, the SLJ showed excellent strength at low temperatures (32.74 MPa at 50 phr @ −40 °C (i.e., an 190% improvement compared to 17.2 MPa at 0 phr @ −40 °C)), and the IWP showed excellent energy absorption at high temperatures (21.73 J at 50 phr @ 80 °C (i.e., a 976% improvement compared to 2.07 J at 0 phr @ 80 °C)). The results were discussed in relation to the changes in the properties of the bulk epoxy depending on the temperature and CSR content. The morphology of the fracture surface was also provided, which offered useful information for composition studies using the CSR/epoxy system.

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“…liquid rubbers and CSIMPs) could endanger signi cant improvement in the toughness of epoxy resin through various mechanisms such as deboning, cavitation, and crazing [6,8]. Nonetheless, incorporation of such IMPs in epoxy formulation could result in deterioration of other desired properties of the host polymer (such as modulus, stiffness, and tensile strength) [9]. On the other hand, rigid IMPs not only could enhance the toughness of epoxy resin by crack pinning, crack de ection and de ection/bifurcation effect of growing crack, but also could boost stiffness and modulus of the host polymer [10].…”

Section: Introductionmentioning

confidence: 99%

Synergistic effects of multiwalled carbon nanotubes and core-shell particles on the toughness and physico-mechanical properties of epoxy resin: a systematic study

Gharieh

Dorraji

2021

Preprint

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Here, core-shell impact modifier particles (CSIMPs) and multiwalled carbon nanotubes (MWCNs) were used as reinforcing agents for improving toughness and tensile properties of epoxy resin. For this purpose, emulsion polymerization technique was exploited to fabricate poly(butyl acrylate-allyl methacrylate) core- poly(methyl methacrylate-glycidyl methacrylate) shell impact modifier particles with average particle size of 407 nm. It was revealed that using a combination of the prepared CSIMPs and MWCNTs could significantly enhance toughness and tensile properties of epoxy resin. Also, it was observed that the dominant factors in enhancing the fracture toughness of the ternary composites are crack deflection/arresting as well as enlarged plastic deformation around the growing crack tip induced by the combination of rigid and soft particles. The Response Surface Methodology (RSM) with central composite design (CCD) was utilized to study the effects of the amounts of core-shell particles and multiwalled carbon nanotubes on the toughness and tensile properties of epoxy resin. The proposed quadratic models were in accordance with the experimental results with correlation coefficient more than 98%. The optimum condition for maximum toughness, elastic modulus, and tensile strength were 3 % wt. MWCNT and 1.03 % wt. CSIMPs. The sample fabricated in optimal condition indicated toughness, elastic modulus, and tensile strength equal to 2.2 MPa. m1/2, 3014.5 MPa and 40.6 MPa, respectively.

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Fracture and toughening mechanisms of silica- and core–shell rubber-toughened epoxy at ambient and low temperature

Cited by 54 publications

References 43 publications

Nanosilica-Toughened Epoxy Resins

Nanosilica-Toughened Epoxy Resins

Mechanical Characterization of Core-Shell Rubber/Epoxy Polymers for Automotive Structural Adhesives as a Function of Operating Temperature

Synergistic effects of multiwalled carbon nanotubes and core-shell particles on the toughness and physico-mechanical properties of epoxy resin: a systematic study

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