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Highlights The interaction between fiber and polymer matrix is crucial for the properties of fiber‐reinforced composites. This paper explored the use of end‐capped waterborne polyurethanes (WPU) modified basalt fiber (BF) to reinforce the polypropylene (PP), aiming to improve interfacial interaction and mechanical properties. Furthermore, the effect of the ratio of soft and hard segments in the end‐capped WPU and the fiber content on the comprehensive properties of the composites have been thoroughly investigated. Three kinds of capped aqueous polyurethanes with different soft‐to‐hard segment ratios were prepared, corresponding to isocyanate indices (R) of 1.3, 1.4, and 1.5, respectively. The results indicated that the fracture section images of the composites confirmed the modification effect of BF and the good interfacial compatibility between end‐capped WPU modified BF (W‐BF) and PP. Moreover, the composite with R = 1.4 end‐capped WPU modified BF exhibited the optimum mechanical properties, fatigue properties and thermal deformation temperature. Specifically, the tensile strength, fatigue performance and heat distortion temperature achieved value of 47.7 MPa, 55,000 cycles and 142.5°C, which represent increases of 32.5%, 400%, and 10.9%, respectively, compared with the unmodified fiber‐reinforced composites, respectively. This efficient interface modification strategy will provide a novel method for high‐performance fiber reinforced composites. Waterborne polyurethanes improve the surface roughness of BF. Chemical and physical interaction between WPU and BF. WPU modification to enhance BF‐PP interfacial interaction. WPU and BF increase the tensile strength by 40%. Stronger interfacial interactions lead to higher thermal stability. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) nanoplatelets can be used to reinforce neat resin or the matrix phase of fiber composites for improved mechanical properties. Although the oxygen content levels in GO and reduced graphene oxide (rGO) strongly influence the interface with the polymer, experimental-based optimization of the oxygen content for enhanced composite properties is difficult and time-consuming. Fortunately, molecular dynamics (MD) simulation can be used to efficiently predict the interfacial properties of composite on the molecular level and provide physical insight into the effect of the oxygen content of rGO. In this study, MD is used to predict the elastic properties of rGO/epoxy interfaces and the corresponding interfacial shear strength (IFSS) for different oxygen content levels. The results indicate that increasing levels of oxygen in rGO results in interfaces with a reduced in-plane elastic modulus but a substantially higher IFSS. These results are important for the design of rGO/epoxy composites for specific engineering applications. [ABSTRACT FROM AUTHOR]

Remarkable mechanical reinforcement of chitosan films using graphene is extremely important to greatly widen the practical application of chitosan (CS) in many fields, but there still exist challenges to regulating graphene-CS interactions for both enhanced strength and toughness. In this work, we functionalized graphene oxide (GO) with carboxyl (G-COOH) and amino groups (G-NH2), and investigated the effects of interfacial interactions on the mechanical properties of graphene/CS composite films in detail. We found that the G-NH2/CS composites exhibited the most remarkable reinforcement in both tensile strength and toughness than the GO/CS and G-COOH/CS composites, even different from a theoretical prediction on graphene-CS interactions. Such remarkable reinforcement is mainly attributed to the moderate graphene-CS interaction, uniform dispersion, and high alignment of G-NH2 in CS films.

Covalent modification of multiwalled carbon nanotubes (MWCNTs) is an efficient way to improve the interfacial interaction and compatibility between MWCNTs and the matrix. In this article, MWNCTs were covalently modified by 4,4′‐difluorobenzophenone (DB) to allow temperature‐tolerant functional groups on the walls. These surface‐functionalized MWCNTs (MWCNTs‐DB) were then attached to poly(ether ether ketone) (PEEK) resins by in situ grafting polymerization, to prepare high‐strength PEEK nanocomposites. The addition of 1 wt% MWCNTs‐DB improved the tensile and flexural strength of the PEEK nanocomposite by 28% and 22%, respectively, compared with pristine PEEK. In particular, the optimal break at strain of the PEEK nanocomposites reaches 39%. The glass transition temperature of the PEEK nanocomposites increased from 148 to 153°C, indicating strong interfacial interactions between MWNCTs and PEEK. Furthermore, scanning electron microscopy images confirmed the amelioration of MWNCTs dispersion in PEEK resins achieved by in situ grafting polymerization. Our results demonstrate the potential of surface‐functionalized carbon nanotubes for use in high‐temperature applications and offer innovative protocols for designing and preparing high‐performance nanocomposites with enhanced mechanical properties, which could have applications in various fields such as aerospace, automotive, and biomedical engineering. [ABSTRACT FROM AUTHOR]

It has been proposed that rattan fiber (RA) as reinforcement can be a promising candidate for the fabrication of composites. In present research, composites were fabricated by reinforcing rattan fibers with poly(vinyl) alcohol (PVA) matrix. Its various properties (mechanical, thermal, and morphological properties) were evaluated and compared with that with neat PVA. Surface treatments of fibers were carried out to have a better compatibility with PVA matrix. The mechanical properties were found to increase at the early stage with the increase in treated rattan fiber content till optimum (24 wt%) fiber loading and thereafter declines. At 24 wt% (optimum) fiber loading the mechanical properties obtained were 48.722 MPa of tensile strength, 45.72 MPa of flexural strength, 1.57 GPa of young’s modulus and 5.89 kJ/m2 of impact strength. Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM) were used for analysis. The TGA inferred that the thermal stability of the composites increased as compared to neat PVA matrix. It was found that composites fabricated from 24 wt% fiber content shows superior mechanical properties as well as thermal properties as compared with other fabricated composites and can be used for making partition boards, light weight packaging boxes, and furniture.

Poly(arylene sulfide sulfone)/graphene nanoplate (PASS/GNP) composites with segregated structure based on continuous polymer fiber skeletons were fabricated by coating a thin conductive layer on the PASS fibers and then performing compression molding. The formation of a unique segregated conductive network endowed the PASS/GNP composites with high electrical conductivity and excellent electromagnetic interference (EMI) shielding effectiveness (SE), reaching 17.8 ​S/m and 30.1 ​dB, respectively, when the content of the GNPs in the conductive layer was 20 ​wt%. The PASS/GNP composites also exhibited outstanding mechanical properties, which was attributed to the continuous PASS fiber skeletons that could withstand large loads and the strong interfacial interaction between the conductive layers and the PASS fibers that could provide good stress transfer. This approach is suitable for most soluble polymers.

To improve the uniformity and the mechanical/wear performances of the aramid pulp (AP)/nitrile butadiene rubber (NBR) composites, two types of ionic liquids (ILs), that is, 1‐carboxymethyl‐3‐methylimidazolium chloride ([CmMIM]Cl) and 1‐allyl‐3‐vinylimidazolium chloride ([AVIM]Cl) were applied on the AP surface, respectively. The ILs partially disrupted the hydrogen‐bonds between the aramid chains to mitigate the fiber entanglement, and connected the AP to the rubber matrix by hydrogen‐bond interaction or the crosslinking reaction during the vulcanization. The test results showed that, the IL treatments effectively improved the tensile and tear strengths without obviously affecting the physical characteristics of the composites. The wear properties of the AP/NBR composites also improved due to the enhancements of the tear strength and the connection between the AP and NBR matrix. Compared to the [CmMIM]Cl, the [AVIM]Cl was more efficient to improve the properties attributed to its better compatibilization for the AP/NBR system. For example, the specific wear rate under 20‐N load of the composite with 15‐phr [AVIM]Cl‐AP was 1.1 × 10−7 mm3 N−1 mm−1, which was approximately 25% and 35% lower than that of the composites reinforced with 15‐phr [CmMIM]Cl‐AP and untreated AP, respectively. [ABSTRACT FROM AUTHOR]

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Plastic products play a significant role in fulfilling daily necessities, but the non-decomposable nature of plastic leads to inescapable environmental damage. Recycling plastic material is the most appropriate solution to avoid pollution and short product lifespan. The present study shows the recycling effect on carbon nanofiber (CNF) reinforced polypropylene (PP) nanocomposite to attain the purpose of reuse and sustainability. 30 wt% CNF melt-blended with polymer and PP-nanocomposites were fabricated using the injection molding technique. PP-CNF nanocomposites were recycled, and mechanical, thermal, and morphological properties were investigated. Three-point bending and tensile testing showed a low decrement of ~1% and ~5% in bending and tensile strength after recycling 30 wt% PP-CNF nanocomposites. Scanning electron microscopy (SEM) images show that the alignment of CNF was disturbed after recycling due to the decrement in the aspect ratio of CNF. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) showed that the crystallinity of PP increases with recycling. The lowering of interfacial interaction between CNF and PP after recycling was studied by a stress-controlled rheometer. The decrement in mechanical properties of PP-CNF nanocomposite is not significant due to CNF reinforcement; hence, it can be reused for the same or other structural applications. [ABSTRACT FROM AUTHOR]

The development of high‐performance green rubber materials with excellent comprehensive properties is very important for the environment and resources. Graphene has excellent electrical, mechanical, and thermal properties and is regarded as the most promising functional filler for rubber composites. In this work, a facile and efficient strategy was used to prepare graphene rubber materials with balanced integrated properties by chemical modification of graphene oxide (GO) with gelatin (Gel). Gel molecules as bridges could not only connect with GO by chemical bonds, but also physically entangle with natural rubber (NR) molecules. The optimized dispersibility of GO and the enhanced interfacial interaction between GO and NR together enable graphene rubber to exhibit excellent integrated properties, such as tensile strength of 29.7 MPa and heat build‐up of 1.9°C only at 1 phr of Gel‐rGO (G‐rGO) content. Additionally, finite element simulation was used to evaluate the temperature field distribution of graphene rubber tires, and the temperature of the NR/Gel‐rGO (NR/G‐rGO) tread was 17.3°C lower than that of NR/GO. This work will provide effective strategies for the preparation of high‐performance graphene rubber materials. [ABSTRACT FROM AUTHOR]

The nanofiber-matrix interaction remains one of the primary factors that governs the performance of transparent composites. Here, a novel porous and fish scale-like poly(L)-lactide (PLLA) ultrafine fiber was prepared by combining electrospinning and subsequent acetone treatment. Following embedding of the electrospun PLLA fibers into a poly(methyl methacrylate) (PMMA)-acetone solution, the porous and fish scale-like PLLA fibers were found to interlock with the PMMA matrix. The mechanical properties of composites reinforced with these fibers were improved in comparison with those of a pure PMMA resin, while the transmittance of the composite was maintained above 80% at a wavelength of 589 nm. Observation of the cross-sectional morphology of the prepared material and subsequent molecular dynamics analysis showed that the fibers can significantly enhance the interfacial compatibility between the PLLA fibers and the PMMA matrix. This novel fiber can therefore be considered to be an effective candidate for the reinforcement of transparent composites.

Developing the polymer-based thermal interface materials (TIMs) is one of the most promising approaches to address heat accumulation along with the functionalization, integration, and miniaturization of modern electronics, while it is still a great challenge to balance the thermal conductivity and mechanical properties. In this article, Fe ion-anchored graphene (FeG) is successfully fabricated by a facile in situ Fe reduction of graphene oxide (GO) approach, and then cellulose nanofibers (CNFs)/FeG composites are prepared by vacuum-assisted filtration. FeG exhibits excellent dispersion and exfoliation in CNFs/FeG composites, due to the strong interfacial interaction between CNFs and FeG, such as hydrogen bonds and "Fe–O" complex binding. Thus, CNFs/FeG composite has the largely improved thermal conductivity up to 30.2 W/mK at FeG content of 50 wt%, which is substantially increased by 1160% in comparison with that of pure CNFs. In addition, the mechanical performances of CNFs/FeG-50 are unexpectedly simultaneously enhanced to 244 MPa for tensile strength, 4.10% for elongation at break, and 9.5 GPa for Young's modulus, outperforming pure CNFs with increase of 137%, 33%, and 121%, respectively. This study provides a significant strategy for the design and construction of high thermal conductivity and high-performance polymeric TIMs in flexible and portable electronics. [ABSTRACT FROM AUTHOR]

We have developed a three-way evolved gas analysis-mass spectrometry technique combined with principal component analysis (EGA-MS-PCA) to probe the interfacial state between matrix and filler in poly(styrene-b-butadiene-b-styrene) (SBS) nanocomposites containing graphene nanoplatelets (GNPs). Although the peaks arising from the polystyrene and polybutadiene components present in the system were readily captured, the different patterns of peak intensities, which vary according to the applied temperature and GNP content, make interpretation of the data difficult. The data sets are thus subjected to mathematical decomposition based on principal component analysis (PCA) to selectively derive essential information. The EGA-MS-PCA process reveals that the inclusion of GNPs essentially works to restrict the decomposition of the polystyrene component in the SBS sample, mostly indicating the formation of a π–π stacking interaction between the SBS and GNPs. This observation, in turn, provides in-depth understanding that is likely to lead to stiffness of SBS by incorporation of GNPs.

In this article, the effect of the addition of graphene oxide (GO) and reduced graphene oxide (rGO) on the mechanical properties, thermal stability, and electrical conductivity of polyvinyl alcohol (PVA) has been investigated. Different weight percentages of nanofillers ranging from 0.5 to 5 wt% have been combined with PVA. The ultrasonic technique has been applied to disperse nanofillers in the PVA solution. The nanocomposite films have been prepared via solution casting technique and the dispersion of nanofillers into the PVA has been studied through optical microscopy. The microstructure, crystallization behavior, and interfacial interaction were characterized through X‐ray diffraction and Fourier transform infrared spectroscopy. Differential scanning calorimetry (DSC) and thermogravimetric analysis have been applied to study the thermal properties of the prepared nanocomposites. The DSC results revealed that the crystallization temperature and melting temperature were enhanced in the presence of GO nanofiller. Besides, the tensile strength at break was improved along with the addition of GO; however, elongation at break for PVA/GO and PVA/rGO was diminished. Moreover, all specimens showed insulating behavior and the only sample was electrically conducting, which contain a high amount of rGO (5 wt%). [ABSTRACT FROM AUTHOR]

[Display omitted] Previous studies have shown that the increase in Young's modulus of cement-based materials by h-BN (about 20%) is lower than that of graphene and graphene oxide (an increase of 35.8%−78.6%). In order to further improve the interfacial interaction between calcium silicate hydrate (CSH) and hBN nanostructures, a series of defective hBN nanostructures were inserted between CSH layers to form defective hBN-CSH layered nanostructures. The interfacial interaction and tensile properties of hBN-CSH layered nanostructures were investigated, in considering the effect of internal (defect sizes in hBN) and external field (strain rate and temperature). The results show that the failure strain and stress of CSH models are enhanced by 18.18% and 14.74% with the incorporation of pure hBN while an increase of 35.53% and 31.58% in failure strain and stress is achieved by incorporating defective hBN (R 3), attributed to high interfacial interaction. In addition, the tensile strain of defective hBN-CSH nanostructures (with a decrease of 33.49%) is more sensitive to temperature than that of free-defect hBN-CSH (with a decrease of 29.71%). Also, the tensile strain of defective hBN-CSH (R 3) nanostructure (with an increase of 6.49%) is more sensitive to strain rate than that of free-defect hBN-CSH (with an increase of 4.38%). By constructing different interface interactions, a parameterized scheme is provided for the optimization and regulation of the spatial structure of the cement matrix. [ABSTRACT FROM AUTHOR]

The effects of polymer blend components on the phase morphology, crystallization behavior and mechanical performance of materials processed by high speed thin‐wall injection molding (HSTWIM) and compression molding (CM) processes were investigated. High density polyethylene (HDPE) and polypropylene (PP) containing different ratios of rubber phase (0%, 18% and 21%) were selected to construct different blends. HSTWIM is shown to trigger the formation of a multilayered structure for these blends with oriented polymer crystals and epitaxial growth of HDPE crystals on PP. Such a layered structure is thought to provide a good template for morphological control of various functional polymer composites. Moreover, the addition of rubber in the multilayered structure with the rubber phase partially distributed between layers is observed. These issues are thought to be responsible for the much enhanced fracture energy compared with specimens from CM. The structural details and formation mechanism of these layered structures consisting of different compositions were investigated. Such a study could provide some guidelines for the preparation of high performance bio‐mimic materials or various functional polymer composites with alternating multilayered structure. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

3D robust network unsaturated polyester-glass fabric composites modified with varying amount VGCNF are prepared through combined hand lay-up techniques followed by a filtering membrane vacuum-assisted method. The electro-thermal-mechanical behaviors of the nanocomposites are studied. Critical nanofiller weight fraction is observed at which thermal and mechanical properties showed maximum enhancement. On the other hand, no such critical nanofiller weight fraction for maximum enhancement of electrical properties. However, minimum nanofiller weight fraction is required to form critical percolation threshold at which insulating changes to conductive. The addition of nanofiller results in crystallization, graphitization and structural distortion of the composite. The enhancement in tensile and flexural strengths of 56.17% and 53.26% are obtained respectively at the critical weight fraction of 2 wt% VGCNF. Similarly, enhancement in electrical conductivity of 9 order magnitude was obtained for UP/GF nanocomposite with 3 wt% VGCNF. The microscopy studies showed the random and uniform dispersion of nanofiller in the matrix along with mechanical interlocking between matrix and reinforcement which is solely by the new methodology adopted for the preparation of nanocomposite. [ABSTRACT FROM AUTHOR]

In this study, the graphene oxide nanosheets (GONs) with three lateral sizes (small area GO (SAGO):0.85 μm, medium area GO (MAGO):8.2 μm and large area GO (LAGO): 38 μm) were synthesized through modified Hummer's method, covalently functionalized by p-phenylenediamine (PPDA), introduced into a polyamine cured epoxy composite and characterized by experimental and theoretical approaches. The GONs size distribution was investigated by a scanning electron microscopy (SEM). The GONs-PPDA nanosheets were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA). The GONs-PPDA/epoxy composites were characterized by dynamic mechanical thermal analysis (DMTA), tensile test and electrochemical impedance spectroscopy. The fracture surface morphology and GONs-PPDA distribution in the epoxy matrix were studied by field emission-scanning electron microscopy (FE-SEM). Results revealed that incorporation of the GONs with lateral particle size less than 1000 nm into the epoxy matrix greatly improved the mechanical properties of the epoxy matrix. In addition, the anti-corrosion properties of the polymer composite was significantly improved after incorporation of medium sized GO-PPDA sheets, implying that the size control of GONs is an effective approach for obtaining a high performance epoxy composite with enhanced mechanical properties. The theoretical quantum mechanics (QM) results evidenced that diamine/epoxy affinity is due to their H-bonding interactions, and diamine bonding to the GO surface occurred via physical (i.e., H-bonding) and chemical (i.e., proton transfer) interactions. The QM computations also proved that increasing the number of diamine molecules bonded to the GO surface resulted in stronger epoxy binding to the GO surface, an observation further evidencing the improved physical and mechanical properties of epoxy composite filled by diamine-functionalized small-size GO nanosheets found in experiments. [ABSTRACT FROM AUTHOR]

In this work, the poly(butylene terephthalate) (PBT) nanocomposites containing modified nano-Sb2O3particles were dispersed by two different dispersing techniques, including high speed rotating to disperse (HSR) and high energy ball milling to disperse (HEBM). The dispersion, interfacial interaction and mechanical properties of nanocomposites were investigated. The results showed that the dispersion and compatibility of nanocomposites dispersed by HEBM were better than that of HSR. From the analysis of interfacial interactions between nano-Sb2O3particles and PBT matrix, the interfacial adhesion (B) and tensile strength of interfacial (σi) were decreased with the increase of nano-Sb2O3particles content. The value of parametersBandσiof HEBM nanocomposites was higher than that of HSR, which indicated that the nanocomposites dispersed by HEBM had stronger interfacial interaction than that of HSR. As a result, the nanocomposites dispersed by HEBM had better mechanical properties than that of HSR. [ABSTRACT FROM PUBLISHER]

The main goal of the present work was to enhance the interfacial interaction between natural rubber (NR) and microcrystalline cellulose (MCC) using maleated natural rubber (MNR) as compatibilizer. The effect of MNR loading on the cure, mechanical and thermal properties of NR/MCC composites was studied. The variation in the crosslink density, solvent uptake and morphological properties was also analyzed to explain the properties of NR/MCC composites. Significant improvement in the maximum rheometric torque, modulus and tensile strength was observed for NR composite containing 5 phr (parts per hundred of rubber) MCC along with 10 phr MNR in comparison to NR composite containing only 5 phr MCC. The tensile strength increased by 62.52% for NR/MCC composite in presence of 10 phr MNR as compatibilizer in comparison to NR-gum. Thermogravimetric analysis showed the enhancement in thermal stability of NR/MCC composite due to addition of MNR. A mechanism is suggested to describe the interaction of MNR with both NR and MCC. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel core-shell-structured carboxylated-styrene butadiene rubber (XSBR)-functionalized nanodiamond (ND-XSBR) was synthesized and characterized. Epoxy (EP) nanocomposites toughened by pristine ND and ND-XSBR were investigated and compared. The ND-XSBR-reinforced nanocomposite exhibited mechanical properties superior to those of the one filled by pristine ND. At a low-filler loading, the ND-XSBR exhibited an impressive toughening effect. The maximum flexural strength was shown when the filler loading was as low as 0.1 wt % for the EP/ND-XSBR nanocomposite. Furthermore, enhanced fracture toughness and fracture energy were shown by surface functionalization, representing enhanced compatibility between the ND-XSBR and EP matrix. The glass transition temperature ( Tg) and storage modulus of the nanocomposites were studied, and the EP/ND-XSBR0.1 nanocomposite exhibited the highest Tg owing to the stronger interfacial interaction. The EP/ND-XSBR0.2 exhibited higher storage modulus and Tg than the EP/ND0.2, because the higher interfacial interaction can restrict the molecular mobility of the EP by the functionalized ND-XSBR. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1890-1898 [ABSTRACT FROM AUTHOR]

The synthesis of poly(propylene carbonate) (PPC) consumes carbon dioxide, which forms a promising route to fix greenhouse gas. Developing the applications of PPC could enhance the recycle of carbon dioxide. However, PPC typically has low mechanical strength and thermal stability, and its glass transition temperature (T g ) is low as well, which restrict its use in practice. In this study, we have for the first time found that wool powder (WP) can be an efficient additive to modify PPC. By adding just 2.0wt% wool powder (WP) to PPC, the mechanical properties, glass transition temperature, and thermal decomposition temperature can be improved significantly. PPC containing 2.0wt% WP shows comparable tensile properties to commonly-used polymers such as poly(butylene succinate), polypropylene and high-density polyethylene. We further showed that PPC can form strong interfacial interaction with WP, responsible for the improvement in PPC mechanical properties. Addition of wool powder may offer a promising way to boost the applications of PPC. [ABSTRACT FROM AUTHOR]

Composites were prepared from poly(lactic acid) (PLA) and a natural CaSO4 filler to study the developed structure and the interaction of the components. The filler was characterized very thoroughly by several techniques and the results indicated that the filler contains a considerable amount of small particles with size much below the volume average size of 4.4 µm. The presence of these small particles did not result in inhomogeneity, considerable extent of aggregation was not observed in the composites. The filler was coated with stearic acid to modify interactions and optimum coverage corresponded to the amount estimated from the specific surface area of the filler. Mechanical properties changed only slightly with increasing amounts of the uncoated filler, but coating resulted in a drastic change of tensile properties and deformation behavior. Considerable plastic flow was observed around filler particles on the fracture surface of broken specimens. The quantitative estimation of interfacial interactions and their comparison to existing data proved that the interaction of PLA and CaSO4 corresponds to values observed in other mineral filled polymers. On the other hand, the reinforcing effect of the coated filler is extremely poor indicating almost zero interaction. Additional experiments proved that considerable amount of stearic acid dissolves in PLA and plasticizes the polymer. Stearic acid seems to desorb also from the surface of the filler, dissolve in the polymer and modify matrix properties.

Controlling the interfacial interaction is a prerequisite for the preparation of aluminum matrix composites reinforced by carbon nanotubes (CNTs) with high performance. In this paper, Cu-coated CNTs fabricated by the compound reduction method were applied to control the interfacial interaction between carbon nanotubes and aluminum matrix for improving the interfacial bonding and mechanical properties of aluminum matrix composites. The microstructure, interfacial structure, interfacial interaction, and mechanical properties of Cu-coated composite were studied in detail. The in-depth study results show that Cu nanoparticles act as a bridge connecting the carbon nanotubes and matrix and forming Al 2 Cu intermetallic, which is in favour for better dispersion of carbon nanotubes and interfacial bonding. In addition, Cu nanoparticles are preferentially deposited at the defects of carbon nanotubes to repair the defects and inhibit the formation of brittle Al 4 C 3 phases. As a result, Cu-coated composite displays the superior strength with yield strength and ultimate tensile strength of 203 MPa and 287 MPa, which are 45% and 38% higher than those of matrix (140 MPa and 207 MPa) and 8% and 12% higher than those of uncoated composite (188 MPa and 256 MPa), respectively. The introduction of Cu nanoparticles can significantly improve the interfacial bonding strength of Cu-coated composite, ensuring the effective transfer of load from the matrix to carbon nanotubes and exerting its strengthening and toughening effect. [ABSTRACT FROM AUTHOR]

The present work describes the development of high performance cellulose nanocrystals/carboxymethyl cellulose (CNC/CMC) films through a rational design of CNC surface chemistry. Considering the anionic surface nature of CMC, surface cationization of CNCs was performed in order to build strong interfacial bonding by electrostatic attraction and form uniform dispersion state by electrostatic repulsion. Nanocomposite films were fabricated by dispersing the CNCs and cationically modified CNCs (mCNCs) in CMC matrix through solution casting. The resultant CNC/CMC and mCNC/CMC films were then evaluated in terms of processability, mechanical properties and fracture surface morphology. Results showed that the reinforcing capacity of mCNCs was greatly dependent on its substitution degree. High substitution degree was favorable for obtaining mCNC/CMC film with uniform dispersion and superior mechanical properties. The observed distinctive reinforcing phenomena from CNCs and mCNCs in CMC matrix were interpreted in terms of dispersion state and interfacial bonding based on the fracture surface morphology. [ABSTRACT FROM AUTHOR]

The effects of particle sizes/distribution and contents on the processing, changes in microstructure and functional properties of wood polymer composites (WPCs) prepared from virgin high-density polyethylene (vHDPE) and sodium hydroxide (NaOH) treatedDaniella oliveriwood flour via compression molding have been explored. Findings from this study suggested that an appropriate choice of wood flour characteristics could improve the interactions between the wood flour and the vHDPE matrix by eliminating incomplete wetting, segregation, and agglomeration of wood flour particles during processing while enhancing mechanical and thermal properties of the composites. Properties of the WPCs were optimized when wood flour of particle sizes/distribution and contents of +210–300 µm and 35 wt%, respectively, were blended with vHDPE matrix. [ABSTRACT FROM PUBLISHER]

The interfacial interaction and the microstructure evolution play a vital role in the mechanical properties of thermoplastic polyurethane (TPU) based energetic composites. In this work, inspired by the strong adhesion of mussels, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) energetic crystals were coated with polydopamine (PDA) via in-situ polymerization of dopamine and then dispersed in TPU matrix. The core-shell structure of CL-20@PDA was confirmed by in-depth structural characterizations. The uniform and compact PDA shell gave rise to a high thermal stability with phase transition temperature of CL-20 crystals increased by 11.5 °C. Moreover, the PDA modification endowed the TPU based composites with excellent mechanical properties. A striking increase in mechanical properties and creep resistance was achieved with 6 h polymerization time of PDA. Compared with the PBX-Raw with untreated CL-20 crystals, the compressive and tensile strength after PDA coating increased by 115% and 57%, and the compressive and tensile fracture energy increased by 148% and 68%. The storage modulus at 25 °C was 40% higher than PBX-Raw. The enhancement effectivity could be ascribed to both interfacial interaction and the microstructure evolution of TPU binder. The theoretical simulations by molecular dynamics demonstrated the strong interfacial interaction mechanism between CL-20 and PDA. Moreover, the abundant hydrogen bonds between the hard segments of TPU and functional groups of PDA facilitated the formation of more hard microdomains which acted as physical crosslinking points to promote the phase separation. This work provides a potential method for the mechanical and thermal enhancement for TPU based energetic materials based on dopamine chemistry. Inspired by the strong chemical adhesion of mussels, the polymerization of dopamine was introduced to coat energetic crystals, which play a vital role in the interfacial interaction and the microstructure evolution of thermoplastic polyurethane (TPU) binder, resulted in mechanical and thermal enhancement for TPU based energetic materials. [Display omitted] • Core-shell structure was constructed through a novel, facile and general route via self-polymerization of dopamine. • CL-20@PDA composites exhibited 11.5 °C higher phase transition (ε.→γ) temperature than that of pure CL-20. • The mechanical enhancement was disclosed based on interfacial interaction and the microstructure evolution of TPU binder. • Theoretical simulations for the interfacial interaction showed good accordance with the experimental observations. [ABSTRACT FROM AUTHOR]

Styrene-butadiene-styrene tri-block copolymer/graphene (SBS/GE) nanocomposites were prepared by solution mixing and in situ reduction of graphene oxide using hydrazine hydrate. The dispersion state of graphene was examined by XRD and optical examination, which indicates that the graphene nanosheets are well exfoliated and dispersed in the SBS matrix. The interfacial interaction between graphene and SBS was investigated by sedimentation experiment in toluene. After dissolving of the SBS/GE nanocomposite, the graphene nanosheets do not separate from the solution, moreover, even after prolonged ultracentrifugation, a dark-colored supernatant with graphene suspension is still retained, suggesting that the graphene nanosheets are stabilized in the solution with the attached SBS molecules due to the existence of strong interfacial interaction. The well dispersion of graphene and the enhanced interfacial interaction lead to a remarkable improvement in the electrical conductivity and mechanical properties. A percolation threshold as low as 0.12 vol.% of graphene has been achieved because of the formation of a three dimensional conductive network. Meanwhile, with the incorporation of as low as 0.5 wt% of graphene, the tensile strength of the nanocomposite has already displayed a two-fold increase compared with that of pure SBS. [ABSTRACT FROM AUTHOR]

Abstract: Polymer/filler composites have been widely used in various areas. One of the keys to achieve the high performance of these composites is good interfacial interaction between polymer matrix and filler. As a relatively new approach, the possibility to enhance polymer/filler interfacial interaction via crystallization of polymer on the surface of fillers, i.e., interfacial crystallization, is summarized and discussed in this paper. Interfacial crystallization has attracted tremendous interest in the past several decades, and some unique hybrid crystalline structures have been observed, including hybrid shish–kebab and hybrid shish–calabash structures in which the filler served as the shish and crystalline polymer as the kebab/calabash. Thus, the manipulation of the interfacial crystallization architecture offers a potential highly effective route to achieve strong polymer/filler interaction. This review is based on the latest development of interfacial crystallization in polymer/filler composites and will be organized as follows. The structural/morphological features of various interfacial crystallization fashions are described first. Subsequently, various influences on the final structure/morphology of hybrid crystallization and the nucleation and/or growth mechanisms of crystallization behaviors at polymer/filler interface are reviewed. Then recent studies on interfacial crystallization induced interfacial enhancement ascertained by different research methodologies are addressed, including a comparative analysis to highlight the positive role of interfacial crystallization on the resultant mechanical reinforcement. Finally, a conclusion, including future perspectives, is presented. [Copyright &y& Elsevier]

Nanocomposite fibers were prepared from chitin whiskers (ChWs) as the reinforcing phase and poly(vinyl alcohol) (PVA) as the matrix. Colloidal suspensions of ChWs, obtained by acid hydrolysis of chitin from crab shell, were thoroughly mixed with aqueous PVA. The homogeneous PVA-ChW suspensions were gel-spun into a methanol coagulating bath. Wide-angle X-ray diffraction patterns evidenced the orientation of ChWs along the fiber axis. From differential scanning calorimetry, the crystallinity of the PVA component was found to increase with ChW loading due to the possible dragging of PVA chains adhering to ChWs during vertical extrusion. The non-isothermal crystallization peak of PVA was observed to shift to lower temperature with ChW loading indicating interfacial interactions between PVA and ChW. Further interaction between PVA and ChW was evidenced by the shifting of the Fourier transform infrared bands of PVA to lower wavenumber and the dynamic tan δ peak, corresponding to α-relaxation of PVA, shifting to higher temperature. The interaction of ChWs with the matrix PVA yielded a significant enhancement in the mechanical properties of the nanocomposites. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: To utilize the extreme reinforcing performance of chitin whiskers (ChWs), the current work was undertaken to fabricate nanocomposites embedded with highly uniaxial oriented ChWs into the matrix polymer. Fibers of poly(vinyl alcohol) (PVA)/ChWs were prepared by gel spinning and the fibers were subjected to a hot drawing to their maximal draw ratio. WAXD analysis revealed the very high orientation of ChWs in the PVA matrix. DSC measurements showed that, upon ChWs loadings, crystallinity of PVA increased and non-isothermal cooling crystallization peak of PVA shifted towards lower temperature, indicating the interaction of PVA with ChWs. Measurement of infrared dichroism suggested that the orientation of overall PVA chains increased with the increase in ChWs loading due to the possible dragging of PVA chains attached with ChWs during drawing, which resulted higher PVA crystallinity in the composites. The stress transfer in PVA/ChWs interface quantified by X-ray diffraction evidenced the strong adherence between the two. The stress transfer between PVA and ChWs interface, and higher PVA crystallinity induced by ChWs were reflected to the outstanding enhancement in mechanical- and anti-creep properties of nanocomposite fibers. [Copyright &y& Elsevier]

The mechanical properties of a composite are closely related to the interfacial adhesion between the fillers and matrix. In this paper, aiming at obtaining high performance high density polyethylene/sericite-tridymite-cristobalite (HDPE/STC) composite, two strategies have been employed. First, gamma ray irradiation is adopted to introduce some oxygen containing groups onto the molecular chain of HDPE in order to improve the poor interfacial interaction between hydrophobic matrix and hydrophilic fillers. On this basis, STC fillers are further treated with coupling agent in order to form stronger interfacial interactions. It is found that when STC are treated with a coupling agent which has amine terminal groups, enhanced interactions between oxygen-containing groups on the irradiated matrix (γ-HDPE) and amine groups on the pre-treated STC are formed and result in improved mechanical properties of the composites. Compared with HDPE/STC composite, the yield strength and notched izod impact strength of modified composite increase up to 30.1 MPa and 547 J/m from 26.4 MPa and 110 J/m, respectively. [ABSTRACT FROM AUTHOR]

A Gamma-ray irradiation was employed to modify high density polyethyelene (HDPE) in order to impart poor interfacial interaction between hydrophobic matrix and hydrophilic Sericite-Tridymite-Cristobalite (STC) filler. The STC filler was further treated with a silane coupling agent. The FTIR, SEM and rheological observations confirmed enhanced interactions between oxygen containing groups on the irradiated matrix (γ-HDPE) and NH2 groups of silane-treated filler (t-STC), resulting in improved mechanical properties of the composites (10 times in case of impact strength). The parameter of the theoretical model used characterizing interfacial interaction increased from 2.69 for HDPE/STC up to4 for irradiated and surface treated material. [ABSTRACT FROM AUTHOR]

In this work, the effect of composition, particle size and particle size ratio on the tensile properties of well-characterized hard/soft latex blends was investigated. Four blends of hard/soft latices, with varying particle sizes (either small or large), and volume fractions of 100/0, 80/20, 60/40, 50/50, 40/60, 20/80 and 0/100 were studied. The stress at break increased and the strain at break decreased as the amount of hard particles in the blend increased. A simple model, introduced by Pukanszky for filled polymers and polymer blends, proved to be a very useful tool for evaluating the tensile properties of the latex blends. Parameter B of the model could be related to the specific surface of the dispersed hard particles and the particle size ratio. Increasing the specific surface of the dispersed hard particles resulted in an increase in parameter B. The influence of particle size ratio on parameter B was shown to depend on the formation of aggregates. [ABSTRACT FROM AUTHOR]

To achieve synergistic reinforcing and cross-linking effect across interface between hydrophilic nanocellulose and hydrophobic rubber, active thiol groups were introduced at reducing end of CNF while retaining hydroxyl groups on the surface, thus forming a percolation network in nanocomposites. The nanocomposites were obtained by casting/evaporating a mixture of dispersed modified CNF and NR in latex form, in which covalent cross-links were formed between thiol groups and double bonds of NR via photochemically initiated thiol-ene reaction. Strong interfacial interaction between NR matrix and end-modified CNF was characterized by Fourier-transform infrared spectroscopy. The structural and mechanical properties of the nanocomposites were evaluated by scanning electron microscopy, dynamic mechanical analysis and tensile tests. Compared to neat NR, the nanocomposite reinforced with 10 wt% modified CNF showed significantly higher values of tensile strength (0.33 to 5.83 MPa), Young's modulus (0.48 to 45.25 MPa) and toughness (2.63 to 22.24 MJ m−3). [Display omitted] [ABSTRACT FROM AUTHOR]

Interfacial performance is quite significant for maintaining the structural performance of steel–concrete composite structures. Quantitative assessment on the interfacial effect is critical. For this reason, theoretical investigation on the interfacial interaction of steel–concrete composites was performed, with the symmetry of the model considered. Influence of interfacial slip on the mechanical properties of the composites was considered. Analytical solutions of the interfacial slip and strain were provided. The accuracy of the predictions from the improved analytical model was validated by comparing them against the results from experimental and numerical studies. The influence of design parameters of the composite members on the interfacial effect was discussed. The proposed analytical model was also employed to assess the effect of the bond developing at the interface between concrete and steel on the deformation exhibited by simple composite structural forms (e.g., beams). Through the analysis, the priority design parameters of the composite structures are determined for controlling the level of interfacial slip in order to achieve optimum bearing capacity. Different to commonly used energy methods, numerical methods and finite element methods, the study provides a simple and straightforward analytical solution for describing the interfacial interaction of composite structures for the first time, which can act as scientific instruction for the interfacial slip control of composite materials and structures. [ABSTRACT FROM AUTHOR]

Improving the interfacial interaction between rubber and silica nanoparticles, and simultaneously reducing free sulfur and preventing migration and volatilization of a rubber vulcanizing agent, commercial sulfur compound aliphatic ether polysulfide (VA-7) was chemically attached to the silica surface to obtain a functionalized nanoparticle (silica-s-VA7). Functional nanoparticles can not only effectively crosslink rubber without sulfur as a novel vulcanizator, but are also evenly dispersed in the rubber matrix and improve the dispersion of the remaining pristine silica as an interfacial compatibilizer. In addition, the thicker immobilized polymer layer and prominent crosslinking density of SBR nanocomposites simultaneously demonstrate that the novel vulcanizing agent silica-s-VA7 gives rise to significant improvement on the rubber–filler interfacial adhesion on account of the covalent linkages of organic and inorganic interfaces between elastomer and nanofillers. We envisage that this strategy may provide a new avenue to implement high-efficiency design for a multifunctional rubber-vulcanizing agent through an organic and inorganic hybridization mechanism. [ABSTRACT FROM AUTHOR]