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The antibacterial and barrier properties of natural rubber used as gloves are very important for the safety of medical staffs. In this research, the silver (Ag) particles were loaded on the surface of graphene oxide (GO) first modified by polydopamine (PDA). Then, the complex particles (Ag-PDA-GO) were introduced into the natural rubber (NR) latex, and the Ag-PDA-GO/NR film composites were obtained by the dipping method. Results showed that a fine dispersion of Ag-PDA-GO in NR film was obtained due to the isolation effect of Ag and PDA between GO sheets. Compared with those of pristine NR composite, when the GO content was only 0.2 phr, the tensile strength, tear strength and modulus at 100% and 300% strains of the composites increase by 66.7%, 128%, 37.7% and 30.7%, respectively, compared with the pure NR. The gas diffusion coefficient was reduced by 15.6% due to the strong interface interaction between GO and NR macromolecules. When the GO content was only 0.1 phr, the minimum inhibitory concentrations (MIC) of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were 16 and 32 μg/mL, respectively. These results are of great significance for improving the barrier and antibacterial properties of medical rubber products., (Copyright © 2021. Published by Elsevier B.V.)

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]

The migration and blooming of antioxidant molecules in the field of anti‐aging rubber is a challenge, where developing novel nanocarriers loaded with antioxidant molecules can solve the above problem. In this article, the surface thiol functionalized mesoporous silica nanorods loaded with antioxidant N‐(1,3‐dimethyl)butyl‐N′‐phenyl‐p‐phenylenediamine (MSN‐SH‐4020) was synthesized to avoid the blooming of antioxidants and then to improve the anti‐aging performance of styrene‐butadiene rubber (SBR). The migration of antioxidant molecules could be limited by encapsulating antioxidant in the pore of mesoporous silica nanorods, and the contend of antioxidant in the SBR reaches up to 1.33 wt%. The sustained release of antioxidant molecules from the pore increases the effective time of action of the antioxidant. After 168 hours of thermal oxidative aging test at 100°C, styrene‐butadiene rubber with 10 wt % surface thiol functionalized mesoporous silica nanorods loaded with 4020 (MSN‐SH‐4020) shows preservation of mechanical properties without blooming. This approach is highly perspective in many applications, such as long‐life sealing rubber and conveyor belts. [ABSTRACT FROM AUTHOR]

Eucommia ulmoides, also known as the industrially and medicinally important hardy rubber tree, is the sole species of Eucommiaceae. Nevertheless, its dioecious property hinders sex recognition by traditional morphological observation at very early developmental stages, thus inhibiting breeding and economic cropping. In this study, double-digest restriction site-associated DNA sequencing (ddRAD-seq) was applied to screen sex-linked molecular markers for sex identification and investigation of the sex determination system in 20 male and female E. ulmoides individual plants, respectively. In consequence, five candidate male-specific loci but no female-specific loci were predicated among the 183,752 male and 147,122 female catalogue loci by bioinformatics analysis. Subsequent PCR (polymerase chain reaction) amplification and Sanger sequencing examinations were performed on another 24 individuals, 12 for each sex, from a separate population. One ideal sex-linked locus, MSL4, was identified among the five putative male-specific loci that were found using ddRAD data. MSL4 is 479 bp in length and highly conserved in all the male individuals, suggesting its feature of being stable and repeatable. Our results also indicated that the sex of E. ulmoides is likely determined genetically. In short, this study provides a consistent and reproducible ddRAD marker (MSL4) that is able to discriminate male from female seedlings in E. ulmoides, which will be valuable for rapid breeding practice and better commercial production of this economically important tree. [ABSTRACT FROM AUTHOR]

In this study, the surface of ultra-high-molecular-weight-polyethylene (UHMWPE) fibers was modified by ozone pretreatment, followed by ultraviolet (UV) grafting, to enhance the interfacial properties of UHMWPE fibers/rubber composites. The fibers were first pretreated by ozone to introduce oxygen-functional groups. The graft polymerization of glycidyl methacrylate (GMA) onto the ozone-treated fibers was implemented by UV irradiation. The effects of time and GMA concentration on the grafting efficiency were investigated. The modified fibers were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). The XPS and FTIR results revealed that GMA was successfully grafted onto the fibers with epoxy groups. SEM images confirmed that a continuous layer of poly-(GMA) (PGMA) was grafted onto the fibers. The interfacial adhesion force of UHMWPE fibers with rubber matrix was characterized by H pullout testing, which showed that the maximum force the fibers/rubber composites increased by 79% over that of the untreated fibers. [ABSTRACT FROM PUBLISHER]

Despite a large amount of work have been carried out to prepare polymer/graphene hybrid nanocomposites, preparing rubber composites filled with graphene oxide via layer-by-layer (LBL) electrostatic self-assembly has not yet been reported. In this work, free-standing conductive multilayer film of (PEI/XNBR/PEI/GO) 30 (30 is referred to the number of deposition cycles) was fabricated on glass substrate through alternative LBL self-assembly with graphene oxide (GO), carboxylic acrylonitrile butadiene rubber (XNBR) latex, and polyethyleneimine (PEI). During the self-assembly process, negatively charged carboxyl groups on XNBR latex and GO sheets can be electrostatically bound by positively charged amino groups from PEI molecules. After thermal treatment, XNBR latex particles in each layer are gradually mixed together and became a continuous rubber film layer, and partial ionic bonds among XNBR latex, PEI and GO sheets are changed into covalent amide bonds. The formation of the multilayer XNBR/graphene film with ordered arrangement of GO sheets and XNBR latex layers was demonstrated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The obtained XNBR/graphene film exhibited a significant improvement in mechanical properties, namely, 192% increase of the tensile strength and 215% increase of the elastic modulus. Besides, electrical conductivity of the prepared multilayer film reached 8.2E-03 S cm −1 after thermal reduced reaction. Hopefully, this prepared multilayer film may be potentially used as an elastomeric conductive material. [ABSTRACT FROM AUTHOR]

Nitrile rubber (NBR)/sliding graft copolymer (SGC) composites with significantly improved strength and damping property are successfully prepared. SGC is a novel kind of supramolecular material with sliding crosslink junctions. The micromorphology analyses of NBR/SGC composites indicate that the SGC phase with particle size less than 500 nm is fairly uniformly dispersed in the NBR matrix. As SGC content increases, the loss factors (tan δ) of NBR/SGC composites increase gradually. Specifically, the tan δ of NBR/SGC (100/40) is about 1.2 times higher than that of pristine NBR rubber. The tensile strength and elongation at break of NBR/SGC composites are unexpectedly improved after the addition of SGC. The significantly improved damping performance and tensile strength can be ascribed to the pulley effect of SGC and the strong interfacial hydrogen bonds between SGC and NBR. The high damping performance and good mechanical strength make the NBR/SGC composite a promising high‐performance damping material. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47188. [ABSTRACT FROM AUTHOR]

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]

We studied the effect of the microstructure of multiwalled carbon nanotubes (MWCNTs) on interfacial interaction in seven kinds of MWCNT/natural rubber (NR) composites. Unexpectedly, the degree of defects (I D /I G ) of MWCNTs was found to play a key role in the interfacial interaction of MWCNT/NR composites. The content of bound rubber (BR) of the composites almost linearly increased with the increase in the I D /I G of MWCNTs. Then we studied the interfacial interaction between MWCNTs with high degree of defects and NR. Interestingly, the BR of the composites consisted of loosely adsorbed BR (LBR) and tight BR (TBR). TBR occupied about half of the total BR, and cannot be removed by extraction in hot toluene for 48 h. Meanwhile, the mobilities of macromolecules in TBR were more restricted than those in LBR. We discussed in depth the molecular origin of the interfacial interaction between defected MWCNTs and NR, and then proposed that LBR was topologically confined by the steps-like structure of defected MWCNTs whereas TBR was principally chemically bonded to MWCNTs. This study provided new insight on the interfacial interaction between MWCNTs and NR and thus provides guidance for the preparation of high-performance elastomer composites with strong interfacial interaction. [ABSTRACT FROM AUTHOR]

The reaction mechanism and the interfacial modulus gradient of the interfacial transition layer between the environmentally friendly dipping system (PAL) and the rubber have not been fully studied. In order to better understand the chemical structures and nano-mechanical properties of the interface between the dip layer and the rubber, we used advanced atomic force microscope (AFM) and nanoscale Fourier transform infrared spectroscopy (nano-FTIR) to perform detailed analysis in this article. The characterization of interfacial nano-mechanical properties and chemical structures is very significant for the illustration of interfacial adhesion mechanism. AFM can effectively characterize the detailed interfacial modulus gradient and the thickness of interface, while nano-FTIR can comprehensively measure the interfacial chemical structures and the distribution of chemical bonds. The results suggest that the thickness of the interface between the PAL dip layer and the rubber matrix is 175 nm, and the crosslinking density of the interfacial layer is high, which explains that the failure location of fiber/rubber composites after pull-out tests occurs on the side of the rubber matrix. Similarly, the microstructure of resorcinol-formaldehyde-latex (RFL) system was also characterized, and the preparation of RFL usually requires carcinogenic and toxic substances such as formaldehyde and resorcinol. [Display omitted] • The reaction mechanism and interfacial modulus gradient of the PAL and the rubber have been fully studied. • Nano-FTIR can measure the interfacial chemical structures and the distribution of chemical bonds. • The thickness of the interfacial transition layer between the PAL and the rubber is about 175 nm. [ABSTRACT FROM AUTHOR]

To strengthen the interfacial adhesion between aramid fiber and rubber, inspired by mussel adhesion protein and mimicking adhesive molecule, a new environmentally friendly dipping system was developed. Specifically, water-soluble pyrogallic acid and polyethyleneimine are reacted to form a network structure, which is then mixed with rubber latex to prepare the dipping solution. We use blocked isocyanate and epoxy aqueous solution to activate the fiber, and then conduct the dipping treatment. The H pull-out force between modified aramid fiber and rubber reached 147 N, achieving the level of traditional resorcinol-formaldehyde-latex dipping system (154 N), while avoiding the utilization of harmful resorcinol and formaldehyde. In addition, we employed atomic force microscope for the first time to quantitatively characterize the modulus of the transition layer between the fiber and rubber. Results from this research provide new insights into the interfacial design of aramid fiber/rubber composites and will facilitate the development of aramid fiber/rubber composites. [Display omitted] • An environmentally friendly dipping system for aramid fiber was demonstrated. • The H pull-out force between modified aramid fiber and rubber reached 147 N. • We quantitatively characterize the modulus of the transition layer. [ABSTRACT FROM AUTHOR]

In this work, the thermo-oxidative aging performance of antioxidant N-isopropyl- N ′-phenyl- p -phenylenediamine (4010NA)/silica (SiO 2)/natural rubber (NR) composite was evaluated by the variations of mechanical properties and chemical structure after aging at 100 °C. Compared with 4010NA/carbon black (CB)/NR composite, there existed significant synergistic effects between 4010NA and SiO 2 on improving the thermo-oxidative stability of NR material. Then, by combining the results of experiments and molecular simulations, the synergistic stabilization mechanism in 4010NA/SiO 2 /NR composite could be attributed to the following comprehensive effects. Firstly, the incorporation of silica was capable of improving oxygen (O 2) barrier ability of NR and inhibiting the migration of 4010NA. Secondly, antioxidant 4010NA could be prior to terminate peroxy radicals, and its addition enabled 4010NA/SiO 2 /NR composite to be of an appropriately high cross-linking density due to a vulcanization accelerated effect. As a result, 4010NA/SiO 2 /NR composite exhibited more preeminent mechanical properties than 4010NA/NR and 4010NA/CB/NR composites during the thermo-oxidative aging process. This means that the combination of 4010NA and SiO 2 can be exploited to prepare high performance NR composite with a facile operation. Furthermore, molecular simulation, as a theoretical method, may contribute to our understanding about structure-properties relationship for NR composite in depth. Unlabelled Image • The anti-oxidation mechanism of 4010NA for NR was quantitatively elucidated from reaction energy. • The strong interactions between 4010NA and SiO 2 /NR including hydrogen bond enabled 4010NA to have low migration capacity. • The influence of SiO 2 on O 2 permeability in NR was illustrated according to free volume results. • The synergistic stabilization effects of 4010NA with SiO 2 greatly enhanced the mechanical properties of NR after aging. [ABSTRACT FROM AUTHOR]