A review of analytical models to describe pull-out behavior – Fiber/matrix adhesion

In this work, a 22 factorial design was used to study the effect of microfibrillated henequen cellulose fibers (HENCEL) and PLA-g-MA coupling agent contents on the tensile, flexural, and impact mechanical properties and the heat deflection temperature (HDT) of biodegradable PLA composites. The results show that the principal effects of HENCEL and MA are statistically significant for the tensile, flexural, HDT, and impact strength properties of PLA composites. Regarding the interactions between the principle effects, MA-HENCEL, there are differences with respect to the mechanical property; for example, for tensile and flexural mechanical properties, there is a synergistic effect between MA and HENCEL, whereas for HDT and impact strength there is not any. The micromechanical analysis shows an excellent agreement between the measured and the estimated values for both the composite tensile strength and the elastic modulus and only slight deviations were noticed for high microfibrillated cellulose fibers content. The morphological analysis via SEM indicated that the addition of PLA-g-MA improved the fiber-matrix adhesion because of the HENCEL unbounding and pull-out decreases from the PLA matrix. The use of appropriate values of matrix strength and stiffness and considering the improved fiber-matrix adhesion of the coupling agent yield a good agreement between experimental and estimated values.

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Quasi-Disk Type Microbond Pull-Out Test for Evaluating Fiber/Matrix Adhesion in Composites

Journal of Composite Materials ◽

10.1177/0021998309339636 ◽

2009 ◽

Vol 43 (16) ◽

pp. 1663-1677 ◽

Cited By ~ 7

Author(s):

Nak-Sam Choi ◽

Joo-Eon Park ◽

Soo-Keun Kang

Keyword(s):

Matrix Adhesion ◽

Pull Out ◽

Fiber Matrix

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Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154755 ◽

1989 ◽

Vol 47 ◽

pp. 556-557

Author(s):

K.L. More ◽

R.A. Lowden

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Chemical Vapor ◽

Chemical Vapor Infiltration ◽

Frictional Stress ◽

Fiber Reinforced ◽

Pull Out ◽

Carbon Coated ◽

Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

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Fiber-matrix bond strength by pull-out tests on slag-based geopolymer with embedded glass and carbon fibers

Journal of Adhesion Science and Technology ◽

10.1080/01694243.2020.1870322 ◽

2021 ◽

pp. 1-11

Author(s):

Lais Alves ◽

Nordine Leklou ◽

Pascal Casari ◽

Silvio de Barros

Keyword(s):

Bond Strength ◽

Carbon Fibers ◽

Pull Out ◽

Fiber Matrix

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Thermo-Mechanical and Morphological Properties of Polymer Composites Reinforced by Natural Fibers Derived from Wet Blue Leather Wastes: A Comparative Study

Polymers ◽

10.3390/polym13111837 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1837

Author(s):

Alessandro Nanni ◽

Mariafederica Parisi ◽

Martino Colonna ◽

Massimo Messori

Keyword(s):

Tensile Strength ◽

Polymer Matrix ◽

Thermoplastic Polyurethane ◽

Young Modulus ◽

Morphological Properties ◽

Poly Lactic Acid ◽

Matrix Adhesion ◽

The Poor ◽

Leather Wastes ◽

Fiber Matrix

The present work investigated the possibility to use wet blue (WB) leather wastes as natural reinforcing fibers within different polymer matrices. After their preparation and characterization, WB fibers were melt-mixed at 10 wt.% with poly(lactic acid) (PLA), polyamide 12 (PA12), thermoplastic elastomer (TPE), and thermoplastic polyurethane (TPU), and the obtained samples were subjected to rheological, thermal, thermo-mechanical, and viscoelastic analyses. In parallel, morphological properties such as fiber distribution and dispersion, fiber–matrix adhesion, and fiber exfoliation phenomena were analyzed through a scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) to evaluate the relationship between the compounding process, mechanical responses, and morphological parameters. The PLA-based composite exhibited the best results since the Young modulus (+18%), tensile strength (+1.5%), impact (+10%), and creep (+5%) resistance were simultaneously enhanced by the addition of WB fibers, which were well dispersed and distributed in and significantly branched and interlocked with the polymer matrix. PA12- and TPU-based formulations showed a positive behavior (around +47% of the Young modulus and +40% of creep resistance) even if the not-optimal fiber–matrix adhesion and/or the poor de-fibration of WB slightly lowered the tensile strength and elongation at break. Finally, the TPE-based sample exhibited the worst performance because of the poor affinity between hydrophilic WB fibers and the hydrophobic polymer matrix.

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Dynamic Single-Fiber Pull-Out of Polypropylene Fibers Produced with Different Mechanical and Surface Properties for Concrete Reinforcement

Materials ◽

10.3390/ma14040722 ◽

2021 ◽

Vol 14 (4) ◽

pp. 722

Author(s):

Enrico Wölfel ◽

Harald Brünig ◽

Iurie Curosu ◽

Viktor Mechtcherine ◽

Christina Scheffler

Keyword(s):

Tensile Strength ◽

Dynamic Loading ◽

Melt Spinning ◽

Structural Changes ◽

High Surface ◽

Single Fiber ◽

Scanning Calorimetry ◽

Matrix Interaction ◽

Pull Out ◽

Fiber Matrix

In strain-hardening cement-based composites (SHCC), polypropylene (PP) fibers are often used to provide ductility through micro crack-bridging, in particular when subjected to high loading rates. For the purposeful material design of SHCC, fundamental research is required to understand the failure mechanisms depending on the mechanical properties of the fibers and the fiber–matrix interaction. Hence, PP fibers with diameters between 10 and 30 µm, differing tensile strength levels and Young’s moduli, but also circular and trilobal cross-sections were produced using melt-spinning equipment. The structural changes induced by the drawing parameters during the spinning process and surface modification by sizing were assessed in single-fiber tensile experiments and differential scanning calorimetry (DSC) of the fiber material. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements were applied to determine the topographical and wetting properties of the fiber surface. The fiber–matrix interaction under quasi-static and dynamic loading was studied in single-fiber pull-out experiments (SFPO). The main findings of microscale characterization showed that increased fiber tensile strength in combination with enhanced mechanical interlocking caused by high surface roughness led to improved energy absorption under dynamic loading. Further enhancement could be observed in the change from a circular to a trilobal fiber cross-section.

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