The gradient modulus intermediate layer between CF and epoxy by designing double “rigid-flexible” structure using CNTs and polyamide (PA) on the CF surface was firstly established, and the effects of ...modulus intermediate layer on interfacial and mechanical properties of CF composites were investigated. The constructing of double “rigid-flexible” structure on the CF surface can greatly increase the polar functional groups, roughness and wettability of the CF surface as well as the thickness of intermediate layer, which could balance the modulus of fiber and resin to achieve the best matching. The interfacial shear strength (IFSS), interlaminar shear strength (ILSS), flexural strength, and impact strength of CF composites increased by 75.6%, 44.1%, 41.3%, and 34.6%, respectively. In addition, the interfacial failure behaviors and strengthening mechanisms of composites have been studied. This novel design and method built a multistage gradient modulus intermediate layer of composite with strong physicochemical interaction and good wettability, which has greatly potential for high-performance composite.
Display omitted
Display omitted
•A new growth method of TiO2 NWs on different CF surfaces was proposed.•Supercritical water is an availably medium to improve reaction efficiency.•Introducing HMTA or PEI on CF could ...increase significantly the adhesion strength between CF and TiO2 NWs and their interfacial shear strength with epoxy.•The tensile strength of carbon fiber does not decrease distinctly.
A novel amine-based functionalization method was developed to improve the interfacial adhesion between TiO2 NWs and CFs in supercritical water. The microstructure, morphology and mechanical properties of CFs were investigated. It was found that introducing hexamethylenetetramine (HMTA) dendrimers and branched polyethyleneimine (PEI) on CF could increase significantly the adhesion strength between CF and TiO2 NWs and their interfacial shear strength with epoxy resin, and the order is CF-PEI-TiO2 NWs>CF-HMTA-TiO2 NWs>CF-COOH-TiO2 NWs>CF-TiO2 NW. Meanwhile, the reinforcing mechanisms and interfacial failure modes have also been discussed. We believe that these effective methods may provide theoretical foundation for the preparation of high performance composite materials.
•Two natural polymers of chitosan and fulvic acid were successfully grafted with a synthetic monomer of acrylamide.•The amphoteric ternary copolymer flocculated three typical dyes effectively.•The ...water soluble flocculant had wide pH effectiveness scope and flocculation window.•Flocculation mechanism was combination of charge neutralization and bridging effect.
The flocculant made from natural polymers gained prominence in recent years due to its eco-friendliness and low cost. In this study, two natural polymers of chitosan and fulvic acid were successfully grafted with a synthetic monomer of acrylamide as a new type of flocculant. The prepared chitosan-acrylamide-fulvic acid (CAMFA) exhibited an excellent capacity to remove three typical dyes, the color removal ratios were 97.0%, 91.6%, and 38.2%, respectively, at the dosage of 283mg/L for 100mg/L of acid blue 113, reactive black 5 and methyl orange. The main flocculation mechanisms were charge neutralization and bridging effect. CAMFA showed nice flocculation performance with solubility in pure water, high removal efficiency, broad pH effectiveness scope, and a wide flocculation window. The ternary copolymer based on natural polymers is a promising candidate as a flocculant from the perspective of effectiveness, operation simplicity and cost.
A simple and green method to functionalize carbon fiber (CF) with hydroxyl-terminated hyperbranched polymer (HTHBP) synthesized directly through one-pot condensation polycondensation between ...isophorone diisocyanate (IPDI) and tris (hydroxymethyl) aminomethane (TOAM) was reported. The covalent grafting of HTHBP on the CF surface can greatly increase the polar functional groups, roughness and wettability of CF surface, thereby resulting to significant enhancement of interfacial properties of composites. After grafting, the interlaminar shear strength (ILSS), interfacial shear strength (IFSS) and impact strength of CFs/epoxy composites increased from 58.6 to 81.8 MPa, 48.8 to 87.8 MPa and 55.7 to 76.9 kJ·m−2, respectively. Furthermore, this surface functionalization process could remedy the single fiber tensile strength. The interfacial reinforcing mechanism was also revealed by analyzing interfacial microstructure. This research provided a thought that constructing a continuous gradient modulus interphase layer with strong physicochemical interaction and good wettability by a simple and green method, which could reinforce the interfacial performance and have a bright prospect application in high-performance composite.
Display omitted
•A hyperbranched structure with hydroxyl-terminated hyperbranched polymer was bonded on CF surface for the first time.•HTHBP was self-synthesized by a simple/green one-pot polycondensation between IPDI and TOAM and the maximum yield was 81%.•Non-toxic, inexpensive, and biodegradable TOAM was used as a novel raw material in synthesis of HTHBP.•HTHBP on interface region exhibited an excellent reinforcing efficiency (improving 79.9% in IFSS).
Abstract
Air quality issue such as particulate matter pollution (PM
2.5
and PM
10
) has become one of the biggest environmental problem in China. As one of the most important industrial base and ...economic core regions of China, Northeast China is facing serious air pollution problems in recent years, which has a profound impact on the health of local residents and atmospheric environment in some part of East Asia. Therefore, it is urgent to understand temporal-spatial characteristics of particles and analyze the causality factors. The results demonstrated that variation trend of particles was almost similar, the annual, monthly and daily distribution had their own characteristics. Particles decreased gradually from south to north, from west to east. Correlation analysis showed that wind speed was the most important factor affecting particles, and temperature, air pressure and relative humidity were key factors in some seasons. Path analysis showed that there was complex unidirectional causal relationship between particles and individual or combined effects, and NO
2
and CO were key factors affecting PM
2.5
. The hot and cold areas changed little with the seasons. All the above results suggests that planning the industrial layout, adjusting industrial structure, joint prevention and control were necessary measure to reduce particles concentration.
Protic ionic liquids (PILs) hybrid was applied as a lubricant additive with various functions in water-ethylene glycol solution (WG). The anticorrosion performance of the hybrid was evaluated by ...means of cast iron chips test and electrochemical measurement. It improves the anticorrosion effect of WG on cast iron. Meanwhile, the tribology experiment shows that the hybrid reinforces antifriction and antiwear properties of WG. Combining SEM/EDAX and XPS analyses of the worn surface with contact angle test, we concluded that the prepared hybrid has prominent anticorrosion and lubrication effects due to coexistence of an adsorption layer constructed by PILs and a tribofilm comprising FeS2.
•(PILs) hybrid was applied as an multifunctional additive with various functions in water-glycol solution (WG)lubricant.•The hybrid significantly improves the anticorrosion and lubricating properties of WG fluid.•The lubrication mechanism is attributed to an adsorption layer constructed by PILs and a tribofilm comprising FeS2.
Graphene oxide/carbon nanotubes reinforced high-performance polymer matrix composites featuring lightweight, electrical and thermal properties, are highly required, yet their development still ...remains a huge challenge. Here, a novel approach for a flexible and high strong (graphene oxide/carbon nanotube) aerogel/polystyrene (GOCA/PS) nanocomposite was developed by in-situ polymerization and hot-pressing method using prefabricated GO/CNT aerogel as the interconnected three-dimensional (3D) reinforcement skeleton. Aerogel plays the role of nano-rivets in composite to improve mechanical strength, and the enhancement mechanism was investigated. The results indicate that GO/CNT exhibits excellent dispersion in the polystyrene matrix. In compared with pure PS, the tensile, flexural, compressive, and impact strength of GOCA/PS composite with about 1.0 wt%, a 7:3 mass ratio of GO to CNT, were increased by shifted from 7.35 to 12.83 MPa (about 74.5%), 18.13–29.60 MPa (about 63.2%), 33.15 to 74.44 kJ/m2 (about 124.5%), and 2.09–6.53 MPa (about 211.94%), respectively. Moreover, the microhardness, elastic, flexural and compressive modulus also increased to maximum at a 7:3 mass ratio of GO to CNT. The approach may provide an effective approach to the design and investigation of reinforced composites.
•3D large-scale graphene oxide/carbon nanotube aerogel (GOCA) was prepared.•Large-scale GOCA/PS nanocomposite sheets were prepared via in-situ polymerization and hot-pressing.•GOCA/PS nanocomposite was greatly enhanced by 3D GOCA when the mass ratio of GO to CNTs in aerogel was 7:3.•The enhancement mechanism was explained.
Whereas the technical feasibility of solar water heaters (SWHs) has long been established, the economic feasibility of SWHs in regional China remains to be examined. This paper constructs cost models ...to calculate costs per unit energy saving of SWHs in 27 Chinese provincial capital cities. The cost effectiveness of SWHs is examined at the national level. At a micro level, we analyze the financial attractiveness of consumers’ investment in SWHs. A panel data model is employed to evaluate the effectiveness of a subsidy program in rural China. The results show that SWH costs, ranging from 0.305 to 0.744 CNY/kWh, are much lower than those of other major renewable energies across China. This finding indicates that the diffusion of SWHs is a cost-effective way to reach China’s renewable energy target. For consumers, incentive programs for SWHs are needed to improve the financial attractiveness of the devices in China. Existing subsidy policies for rural China have failed to significantly enhance the deployment of SWHs. The causes of the failure are examined and a new incentive program is suggested for rural areas of the country.
•We examine the economic feasibility of solar water heaters in 27 Chinese cities.•We evaluate policy effectiveness of solar water heaters (SWHs) using panel data.•Diffusion of SWHs is cost effective in fulfilling China’s renewable energy target.•Financial attractiveness of SWHs is limited without incentive programs.•The existing subsidy policy is proved to be a failure and a new program is suggested.
Abstract In order to improve the interfacial connection of hydroxyapatite (HAP) to poly- l -lactic acid (PLLA), γ-methacryloxypropyl-trimethoxysilane (γ-MPS) was used as a coupling agent to modify ...the surface of nano-HAP (NHAP) particles. The FTIR and XPS results showed γ-MPS was successfully bonded on the surface of NHAP. Silane modified nano-HAP (MNHAP) and PLLA were fabricated to nano-composite scaffold by a thermally induced phase separation method. The characterization of the composite scaffold showed that the scaffold had a nano-fibrous PLLA network (fiber size 100–800 nm), an interconnective microporous structure (1–8 μm) and high porosity (>90%). MNHAP was homogeneously distributed in the scaffold, also partly set in the nano-PLLA fibers. As a result, the compressive modulus and the protein adsorption of PLLA/MNHAP (80:20, w/w) composite scaffold increased to 4.2-fold and 2.8-fold compared with those of a pure PLLA scaffold. Incorporating MNHAP into PLLA network also buffered the pH reduction and reduced the weight loss in vitro degradation significantly.
Graphene oxide/carbon nanotube aerogel (GOCA) with honeycomb three-dimensional framework is an ideal reinforcement material which can significantly improve the dispersion in the polymer matrix, and ...enhance the mechanical properties, thermal and electrical conductivity of the composites. In this work, large-size GOCA and GOCA/polystyrene (GOCA/PS) composite sheet were prepared via critical drying and in-situ polymerization, respectively, and the standard splines of mechanical properties were tested. The results indicated that the tensile, flexural, compressive, and impact strengths of GOCA/PS composites increased with the increase of GOCA content. When the GOCA content was 1.1 wt %, the above mechanical properties increased to the maximum, increased by 103.29%, 60.30%, 177.03%, and 611.38%, respectively. However, as the content of GOCA increased, the electrical conductivity and thermal conductivity showed an increasing trend. In addition, the synergistic enhancement mechanism between GO and CNTs has also been studied. We believe that the present method may provide an effective route for the design and investigation of reinforced composites.
•3D large-scale GOCA and GOCA/PS were prepared.•The mechanical properties, electrical conductivity and thermal conductivity of the GOCA/PS nanocomposites were remarkably improved.•The enhancement mechanism was explained.
PDF
