Enhancing the Mechanical Toughness of Epoxy-Resin Composites Using Natural Silk Reinforcements

Yang, Kang; Wu, Su Jun; Guan, Juan; Shao, Zhengzhong; Ritchie, Robert O.

doi:10.1038/s41598-017-11919-1

Cited by 40 publications

(39 citation statements)

References 49 publications

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“…Here, we address this environmental constraint by developing epoxide LCM to prepare LCEs within oxygen‐rich environments via the photocationic (acidic) polymerization mechanism . Unlike radical polymerization in acrylate‐based LCEs, photocationic polymerization bypasses issues related to oxygen inhibition that may limit accessible form factors or constrict fabrication protocols.…”

Section: Introductionmentioning

confidence: 99%

Microstructured Photopolymerization of Liquid Crystalline Elastomers in Oxygen‐Rich Environments

McCracken

Tondiglia

Auguste

et al. 2019

Adv Funct Materials

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Liquid crystal elastomers (LCEs) are soft materials that undergo large anisotropic shape change in response to stimuli. Rational organization of the local director field can impart spatial control of the strain profile, enabling stretch-based deformation capable of nearly 20 J kg −1 of output force. LCEs are increasingly being considered in end-use applications in robotics, therapeutics, and optics. Here, a new synthetic approach is introduced to prepare LCEs composed of main chain mesogens via the cationic photopolymerization of the epoxy liquid crystal monomer (LCM). This examination details the optical, mechanical, and thermal properties of epoxide-based LCEs as a function of spacer length (3, 6, or 11 carbons). The oxygen insensitivity of the cationic photopolymerization of these monomers makes this approach particularly attractive for implementation with emerging additive manufacturing techniques. This contribution focuses on microstructuring LCEs via 2-photon direct laser writing (2P-DLW). A custom heated cell facilitated 2P-DLW of the aligned LCE epoxy resin melts to fabricate diverse geometric arrays. Enabled by the orthogonality of the reaction chemistry, hybrid and microstructured material compositions are prepared via the encapsulation of LCE epoxy micropatterns with free-radical polymerization of acrylate-based LCEs. The distinct thermomechanical response of the hybridized and microstructured LCE composites enables local and spatially controlled actuation.

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Section: Introductionmentioning

confidence: 99%

Microstructured Photopolymerization of Liquid Crystalline Elastomers in Oxygen‐Rich Environments

McCracken

Tondiglia

Auguste

et al. 2019

Adv Funct Materials

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“…The authors investigated the tensile, flexural, interlaminar shear, impact, dynamic and thermal properties of the silk/epoxy composites and reported a linear increase of almost all properties with increasing fiber content between 30 and 60%. The reported specific mechanical properties compared well with those of glass/epoxy composites [5]. Similarly, Shah et al [4] prepared nonwoven and woven silk/epoxy composites using vacuum assisted resin transfer molding (VARTM), with fiber volume fractions of 36 and 45%, respectively.…”

Section: Introductionmentioning

confidence: 71%

“…Yet, silk filaments exhibit higher mechanical performance than plant fibers and offer naturally continuous length. In addition to a considerably higher toughness, its lower density makes silk a potential reinforcement to produce composites with specific mechanical properties comparable to those reinforced with glass fibers, as suggested in recent studies [4][5]. For example, Yang et al [5] fabricated woven silk/epoxy composites using a wet lay-up process followed by vacuum bagging and hot pressing at high pressure levels, yielding laminates with fiber volume fractions as high as 70%.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to a considerably higher toughness, its lower density makes silk a potential reinforcement to produce composites with specific mechanical properties comparable to those reinforced with glass fibers, as suggested in recent studies [4][5]. For example, Yang et al [5] fabricated woven silk/epoxy composites using a wet lay-up process followed by vacuum bagging and hot pressing at high pressure levels, yielding laminates with fiber volume fractions as high as 70%. The authors investigated the tensile, flexural, interlaminar shear, impact, dynamic and thermal properties of the silk/epoxy composites and reported a linear increase of almost all properties with increasing fiber content between 30 and 60%.…”

Section: Introductionmentioning

confidence: 99%

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Manufacturing silk/epoxy composite laminates: Challenges and opportunities

Hamidi¹,

Yalcinkaya²,

Guloglu³

et al. 2019

AIP Conference Proceedings

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Application of natural fibers in polymer composites has been gaining popularity in several industries pursuing environmentally friendly products. Among the natural fibers with proven potential applications, silk fibers have recently received considerable attention from researchers. Silk fibers provide higher mechanical properties compared to other commonly used natural fibers such as sisal, jute, and hemp. Silk may also exhibit comparable specific mechanical properties to glass fibers. However, silk composite laminates are rarely used in commercial products due to a number of fabrication challenges. This paper investigates such challenges for silk/epoxy laminates, especially issues related to manufacturing and preform architecture. First, challenges arising from preform architecture (i.e., random and woven preforms) are presented. Unlike glass fibers for which random mats are easier to manipulate, handling random silk preform proves to be more challenging, particularly compared to woven silk fabrics. The random silk/epoxy laminates show higher thickness variation and lower compaction, yielding lower fiber content. Second, fabrication of laminates by vacuum bag/wet lay-up and vacuum assisted resin transfer molding (VARTM) processes are presented. VARTM is found to be more appropriate for silk/epoxy laminate fabrication, as it allows a uniform impregnation of the silk preform, yielding higher part quality and limited void formation. Moreover, applying 0.21 MPa (30 psi) external pressure to the VARTM laminates allows to increase the fiber content of both random and woven silk/epoxy laminates from ~17 and ~30% to ~21 and ~33%, respectively. In contrast, wetting of silk preform during wet lay-up process, which is operator dependent, is difficult to achieve; and the produced laminates have high void content. Furthermore, SEM images show a weak silk/epoxy adhesion in laminates fabricated without external pressure. Finally, the mechanical performance of these laminates is assessed. The woven silk/epoxy laminates fabricated by pressurized VARTM exhibits the highest improvement in the specific flexural strength and modulus over pristine epoxy with 30 and 65% increase, respectively.

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“…Consequently, much of the research is focused on high quality composite materials, which are biodegradable or able to be recycled. Natural fibers offer environmentally friendly solution having the advantages of low density, low cost, biodegradability, good thermal properties and low energy consumption during processing [5][6][7].…”

Section: Mechaniczne I Termiczne Właściwości Hybrydowych Kompozytów Nmentioning

confidence: 99%

Mechanical and thermal behavior of hybrid glass/jute fiber reinforced composites with epoxy/polyester resin

Manuneethi¹,

Karthikayan²,

Venkatachalam³

2019

Polimery

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The hybrid glass/jute fiber composites were fabricated by hand layup (HL) and vacuum assisted resin transfer molding (VARTM) method using epoxy and isophthalic polyester resins as matrices. The effects of fiber and matrix type as well as fabrication method on the tensile and flexural mechanical strength of resulting composites were investigated. The morphological fracture was analyzed based on scanning electron microscopy (SEM) images. Also, the curing characteristics of two matrix resins was studied by using differential scanning calorimetry (DSC). For glass fiber composite, the curing rate of polyester resin is faster at 100 °C than that of composite with epoxy matrix. Using VARTM process, the composite with high fiber volume fraction (V f) of 52% was obtained.

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Enhancing the Mechanical Toughness of Epoxy-Resin Composites Using Natural Silk Reinforcements

Cited by 40 publications

References 49 publications

Microstructured Photopolymerization of Liquid Crystalline Elastomers in Oxygen‐Rich Environments

Microstructured Photopolymerization of Liquid Crystalline Elastomers in Oxygen‐Rich Environments

Manufacturing silk/epoxy composite laminates: Challenges and opportunities

Mechanical and thermal behavior of hybrid glass/jute fiber reinforced composites with epoxy/polyester resin

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