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The interfacial interactions between ultra‐high molecular weight polyethylene (UHMWPE) fiber and polymer determine the overall performance and service life of the fiber reinforced composite materials. In this article, polyaniline (PANI) layer is uniformly deposited on the surface of the UHMWPE fiber after plasma treatment to enhance the interfacial adhesion between UHMWPE fiber and rubber. At the same time, the PANI layer can also form a conductive path at the interface to monitor the damage of the composites in real time. Compared with the untreated UHMWPE fiber, the H pull‐out force of the PANI‐deposited UHMWPE fiber with rubber is increased by 67.9%, which is due to good mechanical interlocking and chemical bond between the fiber and the matrix. Moreover, the electrical resistance change during the fiber pull‐out process has a good correlation with the pull‐out force curve, which provides a new idea for in‐situ monitoring of the damage of composites. [ABSTRACT FROM AUTHOR]

In order to improve the interfacial adhesion between aramid fiber (AF) and rubber matrix, a simple and facile method of aramid nanofiber (ANF) coating is demonstrated in this article. Tannic acid (TA) and polyethyleneimine (PEI) are polymerized in an alkaline solution to form a thin TA/PEI (TP) layer that is deposited on the surface of AF to introduce functional groups such as hydroxyl and amino groups. Then, the ANF coating is utilized to construct nanostructures on the surface of AF to improve the interfacial adhesion between the fiber and the rubber. Through hydrogen bonding and/or π‐π stacking between the TP layer and the ANF, the ANF coating is firmly attached to the surface of AF. Compared with the untreated fiber, the interfacial adhesion of AF coated with ANF after 1, 3, 5, 7, 9 deposition cycles is increased by 27.8%, 29.1%, 31.5%, 43.1%, and 30.3%, and the mechanical properties of the fibers remain almost unchanged. This method shows its advantages of simple, facile, and time‐effective, which is of great significance for industrial applications. [ABSTRACT FROM AUTHOR]

Abstract: In this work, poly(l-lactide) (PLLA)/single-walled carbon nanotubes (SWNTs) fibers were first prepared at high drown ratio and low drown ratio, respectively. Then they subjected to tensile testing. It was found that the composite fibers obtained at low drown ratio showed no obvious enhancement of tensile strength and elongation at break, compared with the pure PLLA fibers obtained at the same low drown ratio. However, a significant property enhancement was observed for the composites fibers obtained at high drown ratio. Structure analysis of the as spun fibers before and after tensile testing suggests a possible stretching induced formation of brush-like hybrid structure in which the PLLA lamellae growing perpendicular to the SWNTs axis for fibers obtained at high drown ratio. This unique brush-like hybrid structure could largely enhance the interfacial interaction between PLLA and SWNTs, thus results in greatly improved tensile strength and elongation at break. [Copyright &y& Elsevier]

Fiber-reinforced rubber composites (FRRC) are widely used in tires, hoses, conveyor belts and other fields. Currently, the industry heavily relies on the resorcinol-formaldehyde-latex (RFL) system to enhance interfacial adhesion performance of FRRC; however, both resorcinol (R) and formaldehyde (F) pose significant risks to human health and the environment. Thus, some two-step RF-free dipping systems have been developed to replace RFL system. Nevertheless, these complex two-step systems face challenges during industrialization. In this study, we proposed a novel one-step eco-friendly dipping system (PCGL) for polyamide66 (PA66)fibers. By using the new system, a solid transition bridge between PA66 fiber and rubber matrix can be formed, due to the bonding between PA66 and isocyanate, the interaction among polyacrylic acid resin, isocyanate and epoxy, the catalytic effect of triethanolamine, as well as the co-crosslinking of styrene-butadiene-vinyl-pyridine latex and rubber. The interfacial adhesion performance of PA66 fiber/rubber composites treated by PCGL with optimized ratio of epoxy groups/isocyanate groups can reach more than 90% of RFL level, meeting industry requirements for high interfacial bonding performance, while maintaining strength and safety of composites. The mechanism of largely enhanced interfacial adhesion was revealed through the analysis of modulus transition and co-crosslinking at the composite interface. [Display omitted] • A novel one-step eco-friendly dipping system was developed for PA66 fibers. • The adhesion of this new dipping system reaches 90% of traditional RFL system. • It overcomes complex process and high cost of current two-step RF-free systems. • It shows equal interfacial adhesion with current two-step RF-free systems. • The mechanism of its high interfacial adhesion performance was revealed. [ABSTRACT FROM AUTHOR]

Abstract: In this article, a quantitative measurement of orientation functions for both the polymer matrix and the filler has been carried out, for the first time, in high-density polyethylene (HDPE)/inorganic whisker (SMCW) composite fibers, with aid of polarized Fourier transform infrared (FTIR) spectroscopy. A highly oriented structure was observed in the as-spun fibers, and the orientation functions of both polyethylene and the whisker decreased with the increase of whisker content. During tensile deformation of the fibers, the orientation functions were continuously enhanced as increasing of the strain for the matrix and the filler. However, a fast increase of orientation was found for pure polyethylene fiber and composite fibers with less whisker content, and a slow increase for composite fibers with higher whisker content. Very interestingly, a formation of hybrid shish-kebab structure with whisker acting as shish and polyethylene lamellae as kebab was observed in the as-spun fiber with low loading of whisker (less than 10wt.%), resulting in a strong interfacial interaction between polyethylene and whisker. As a result, the highest tensile strength was observed in this sample even it had a lower orientation compared with that of pure HDPE. For the composite fiber with 10 and 20wt.% whisker, no obvious formation of hybrid shish-kebab was observed, resulting in a poor interfacial interaction and subsequently, lower tensile strength. That result indicates that the tensile strength of the fibers depends not only on the orientations of the polyethylene and the whisker, more importantly, on the interfacial interaction between matrix and the filler. The change of orientations of the composite fibers by adding whisker and the formation of hybrid shish-kebab structure were discussed based on rheological measurement. [Copyright &y& Elsevier]

A plasma-assisted surface modification method was introduced to enhance the interfacial adhesion of rubber composites reinforced with ultra-high molecular weight polyethylene (UHMWPE) fibers. First various reactive monomers were grafted onto the fiber surface via a plasma-assisted radical polymerization reaction. Subsequently, the grafted fibers underwent RFL (resorcinol-formaldehyde-latex) dipping process to bolster their interfacial adhesion with rubber. Compared with the original UHMWPE fibers, the modified fiber-reinforced rubber composites showed an increase in H pull-out force by 105.3 %–165.7 N and peel strength by 145.2 % to 10.3 N/mm, reaching the level of general-purpose fabric-core conveyor belt (≥4.5 N/mm). After the modification, the dynamic fatigue life and aging stability of the fiber-reinforced rubber composites were significantly improved, thereby enhancing the service life and safety of the composites. The results show that this method greatly improves the chemical activity, hydrophilicity, and surface roughness of UHMWPE fibers with minimal damage, rendering it a promising choice for industrial applications. [Display omitted] • A new strategy for UHMWPE fiber modification applicable to rubber matrix was provided. • A rubber material that can be quickly vulcanized at low temperatures for use in textile core conveyor belts was prepared. • The H pull-out force between the modified UHMWPE fiber and rubber reached 165 N, which reached the application level. • The interfacial bonding mechanism and chemical reaction processes between modified fibers and rubber are elucidated. [ABSTRACT FROM AUTHOR]

This work simulates the real harsh service conditions of Fiber-reinforced polymer composites (FRPC), and the dynamic adhesion and failure mechanism of nylon 66 (PA66)-reinforced natural rubber (NR) composites under large deformation and wide temperature range are deeply studied by comprehensive analysis of the interfacial adhesion evolution, microstructure and failure damage location of the composites, interfacial heating rate, and modulus ratio of PA66/NR. The failure mechanism of PA66/NR composites is interfacial debonding at −20 °C, 25 °C and 80 °C, whereas that at 120 °C is matrix cracks. Interestingly, at −20 °C, the crack expansion at the interface is slow, and the samples show two-stage damage during fatigue, resulting in the highest fatigue life. At 80 °C, the interface heating rate and modulus ratio of the PA66/NR composites is the lowest, and thus the fatigue life is higher than that at 25 °C and 120 °C. Keywords: fiber reinforced polymer composites, fatigue life, failure mechanism. [Display omitted] • The test method for fatigue life under wide temperature range was established. • They show the highest fatigue life at −20 °C and the lowest one at 120 °C. • The failure location was studied by distribution of characteristic elements. • The fatigue failure mechanisms under wide temperature range were revealed. [ABSTRACT FROM AUTHOR]

• This article reviews the surface modification methods of aramid fiber and its composite materials. • Interfacial adhesion is important for aramid fiber reinforced composites. • The interfacial stress transfer mechanism of aramid fiber reinforced composites is still unclear. Aramid fiber (AF), which has excellent comprehensive properties such as low density, high specific strength, and high specific modulus, is widely used in composites reinforcement. AF-reinforced composites (AFRPs), which are very suitable for preparing advanced engineering materials, have drawn much attention due to their excellent properties. However, the smooth and chemically inert surface of the AF severely limits its applications. Various methods have been conducted to modify the surface of AF to improve the interfacial adhesion between fiber and matrix. The purpose of surface modification of AF is to improve the surface chemical activity and increase the surface roughness, which aims to achieve an excellent chemical bonding and mechanical interlocking between fiber and matrix. The major focus of this review is the surface and interface modification of AF. In this review, we briefly summarize the recent progress of different surface modification methods of AF and its reinforcement to polymers. Finally, some existing problems of AFRPs as well as future research prospects are discussed. [ABSTRACT FROM AUTHOR]

For fiber reinforced rubber composites, the interface is the most critical factor affecting the stress transfer efficiency and the ultimate reinforcing effect. In this study, we investigated the interfacial interaction of three kinds of fibrillar silicate (FS) filled natural rubber (NR) composites via a combination of quantitative nanomechanical technique of atomic force microscopy (AFM-QNM) and broadband dielectric spectroscopy (BDS) measurements. The force-deformation curves at nanoscale of these composites was revealed to quantitatively obtain the interfacial thickness and Young's modulus, and the Johnson−Kendall−Robert (JKR) contact model was used to fit the force-deformation curves to verify the reliability of the AFM-QNM results. The interfacial thickness of these composites with double-layer structure was further verified by High Resolution Transmission Electron Microscope (HRTEM) directly. The BDS results indicate that apart from the bulklike α -relaxation, a slower α inf -relaxation by 1−2 orders of magnitude than bulklike α -relaxation was observed in these nanocomposites attributed to restricted segmental relaxation of interfacial NR chains by FS, and the relaxation times of these composites agree well with the results of interfacial thickness and Young's modulus. An in-depth analysis of the interfacial interaction mechanism of these FS/NR composites was given. This study helps us to deep understand the interface of nanofiber reinforced composites, and it provides guidance for the interfacial design of high performance rubber composites. [ABSTRACT FROM AUTHOR]