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Functional Arg-Gly-Asp (RGD) tripeptide has a tremendous potential in clinical applications to accelerate the endothelialization of Magnesium (Mg) alloy vascular stent surface. The interaction mechanism of RGD on different surfaces of Mg and Mg alloy is important for promoting the development of Mg alloy vascular stent, yet still unclear. In the present work, first-principles calculation within density functional theory (DFT) was performed to investigate the interaction mechanism. The electron redistribution, effect of alloying elements and changes in the density of states of the adsorption systems were studied. The results revealed that RGD interacted with different surfaces of Mg (0001), Mg(112¯0) and Mg(101¯1) through ligand covalent bond; the pronounced localization of electrons of Mg(112¯0) and Mg(101¯1) surfaces promoted the adsorption of RGD tripeptide compared with that on the Mg(0001) surface; Zn/Y/Nd alloying elements improved the adsorption of RGD. Calculated results could provide insight for the interaction mechanism of biomolecule on the Mg and Mg-based alloy surfaces, and point out some directions for the future experimental efforts.

Proton exchange membranes (PEM) with high proton conductivity and water retention are critical to the commercial application of proton exchange membrane fuel cells (PEMFC). In this study, acid-base double-shell nanotubes with carboxylate inner shell and an imidazole outer shell (DSNT-A@B) are synthesized via continuous distillation-precipitation polymerization using halloysite nanotubes (HNTs) as seeds. Then, it is incorporated into sulfonated poly (ether ether ketone) matrix to prepare composite membranes. The carboxylic inner shell can increase the content of combined water, thereby giving the composite membrane higher water retention. The imidazole shell acts as basic shell to create acid-base pairs with the membrane and inner shell to promote proton conductivity following the Grotthuss mechanism. The results show that when the blending amount is 5 wt%, the proton conductivity of the composite membrane reaches 0.336 S/cm at 80 °C and 100% relative humidity (RH), which is twice as high as that of the original membrane. In particular, the water loss of SPEEK/DSNT-A@B-10 composite membrane is only 54.55% at 40 °C and 20% RH, which is 32.77% lower than the SPEEK membrane. Therefore, this DSNT-A@B/SPEEK composite membrane can be used as a potential candidate for high temperature and low humidity fuel cells.

The development of a proton exchange membrane (PEM) that can avoid rapid decay of proton conductivity under low humidity is of great significance for the practical application of PEMFC. In this study, acid–base core–shell microspheres (PCSMs-MA@TAC) with a carboxylic acid core and a triazine shell were synthesized by distillation-precipitation polymerization using cross-linked carboxylic acid microspheres (PMAA) as seeds. These PCSMs were then incorporated into a sulfonated poly(ether ether ketone) matrix to make hybrid membranes. Incorporation of PCSMs microspheres can not only strengthen the vehicle mechanism by increasing the water uptake of the membrane, but also the acid–base pairs formed at the SPEEK/PCSMs interface provide a new low-energy barrier pathway for proton hopping, thereby enhancing the proton conduction of the Grotthuss mechanism. The results show that when the content is 10 wt%, the proton conductivity of the SPEEK/PCSMs-MA@TAC composite membrane can reach 0.161 S cm−1 at 80°C and 100% RH, which is 19.3% higher than the SPEEK control membrane (0.135 S cm−1). In particular, even at 60% RH, the proton conductivity of the SPEEK/PCSMs-MA@TAC-10 composite membrane is still 67 mS cm−1, which is 3.16 times higher than that of the SPEEK membrane. Therefore, the SPEEK/PCSMs-MA@TAC composite membrane can maintain superior performance even under high temperature and low humidity conditions.

A facile Stevens rearrangement of the Weinreb amide and the subsequent key steps mediated by the carbonyl of the Weinreb amide led to the construction of azaspirocyclic skeletons of some typical alkaloids. And the formal total synthesis of (±)-cephalotaxine was completed

Sulfate-containing wastewater has a serious threat to the environment and human health. Microbial technology has great potential for the treatment of sulfate-containing wastewater. It was found that nano-photocatalysts could be used as extracellular electron donors to promote the growth and metabolic activity of non-photosynthetic microorganisms. However, nano-photocatalysts could also induce oxidative stress and damage cells. In this paper, the mechanism and regulation strategy of cadmium sulfide nanoparticles（CdS NPs）on the growth of sulfate reducing bacteria and the sulfate reduction process were investigated. The results shows that the sulfate reduction efficiency could be increased by 6.43% through CdS NPs under light conditions. However, the growth of C09 was seriously inhibited by 55.00% due to the oxidative stress induced by CdS NPs on cells. The biomass and sulfate reduction efficiency could be enhanced by 6.84% and 5.85%, respectively, through external addition of humic acid (HA). At the same time, the mechanism of the CdS NPs strengthening the sulfate reduction process by sulfate bacteria was also studied. Which can provide important theoretical guidance and technical support for the development of microbial technology combined with extracellular electron transfer (EET) for the treatment of sulfate-containing wastewater.

Bioleaching is intensively investigated for recovering valuable metals such as Li, Co, Ni and Cu. Nickel ion stress threatens the health of microorganisms when Ni

In this article, novel nanocomposite proton exchange membranes (PEMs) were prepared by embedding imino-containing phosphorylated silica nanoparticles into a sulfonated poly(arylene thioether sulfone) (SPTES) polymer matrix. SPTES was synthesized via condensation polymerization of 4,4′-thiobisbenzenethiol, 4,4′-difluorodiphenylsulfone, and disodium 3,3′-disulfonate-4,4′-difluorodiphenylsulfone. The imino-containing phosphorylated silica particles (Si-imP) were prepared by the Kabachnik–Fields reaction, which is confirmed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and energy dispersive spectroscopy. The results showed that the Si-imP were uniformly distributed in the composite membrane. The properties of the composite membranes, including thermal stability, water uptake, swelling ratio, oxidative stability, and proton conductivity, were thoroughly evaluated. Experimental results indicated that Si-imP may be effective reinforcement materials for SPTES membranes. It is noteworthy that an increase in proton conductivity from 0.138 S cm−1 of the SPTES control membrane to 0.173 S cm−1 of the composite membrane was achieved at the Si-imP content of 5 wt% under fully hydrated conditions at 80°C. This finding primarily stems from the fact that the Si-imP could be linked with the sulfonate ion clusters of SPTES to form more continuous ionic networks. These networks act as efficient proton-hopping pathways to enhanced proton conductivity. The nanocomposite membranes are demonstrated to be promising candidates as new polymeric electrolyte materials for PEM fuel cells operated at medium temperatures.

A new thermally conductive and electrically insulative polyimide were prepared by filling different amounts of hexagonal boron nitride (h-BN) particles, and the thermal conductivity of Polyimide (PI) composites were improved with the increasing h-BN content. Based on this, two methods were applied to improve thermal conductivity furtherly at limited filler loading in this paper. One is modifying the h-BN to improve interface interaction, another is fabricating a nano-micro hybrid filler with 2-D h-BN and 0-D nano-scale nanodiamond (ND) to build more effective conductive network. Both surface modification and hybrid system have a positive effect on thermal conductivity. The composites introducing 40 wt% hybrid filler (the weight ratio of ND/modified BN was 1/10) showed the highest thermal conductivity, being up to 0.98 W/(m K) (5.2 times that of PI). In addition, the composites exhibits excellent electrical insulation, thermal stability properties etc.

Anisotropic composite latex particles with heteromorphous bowl-like and popcorn-like shapes were fabricated by a general approach: seeded emulsion polymerization. The morphologies of polyvinylidene fluoride@poly(styrene-co-butyl acrylate-co-3-trimethoxysilyl propyl methacrylate) composite particles [PVDF@P(St-co-BA-co-MPS)] could be efficiently controlled by varying the feeding time of hydrophilic MPS. The deformation mechanism of bowl-like particles was largely attributed to the diverse rigidities of the P(St-co-BA-co-MPS) phase from the inhomogeneous cross-linking density formed through changes in the MPS feeding time. During the polymerization, the PVDF crystallization behaviors demonstrated an obvious transformation from unconfined to confined crystallization. Additionally, the chemical properties and morphologies of the particles’ surface greatly impacted the hydrophilic–hydrophobic character of the particle films. After the capping of the hydrophilic functional groups of the surface, the contact ang...

A series of self-catalytic phthalonitrile compounds with o-, m-, and p- amino groups, namely, 4-(2-aminophenoxy)phthalonitrile (2-NH2-CN), 4-(3-aminophenoxy)phthalonitrile (3-NH2-CN), and 4-(4-aminophenoxy)phthalonitrile (4-NH2-CN), were synthesized via a facile nucleophilic displacement of a nitro-substituent with 4-nitrophthalonitrile. The phthalonitrile resins were prepared by curing 2-NH2-CN, 3-NH2-CN, and 4-NH2-CN with 1,3-bis(3,4-dicyanophenoxy) benzene ( m-BDB). The structures of these compounds were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and wide-angle X-ray diffraction. Curing behaviors of 2-NH2-CN, 3-NH2-CN, and 4-NH2-CN with m-BDB were recorded by differential scanning calorimetry. The results show that the processabilities of m-BDB with 4-NH2-CN are superior to those with 2-NH2-CN and 3-NH2-CN due to higher self-catalytic efficiency and broader processing windows. Thermal stabilities were evaluated by thermogravimetric analysis, and the polymers with all these self-catalytic compounds exhibit excellent thermal and thermal-oxidative stabilities. Dynamic mechanical analysis reveals that these polymers have high storage modulus and high glass transition temperatures. The polymers of 4-NH2-CN show more outstanding processability, thermal stability, and dynamic mechanical properties than those of 2-NH2-CN and 3-NH2-CN and can be considered as a good candidate as a self-catalytic curing agent for high-temperature phthalonitrile polymers.

A novel pyridine-containing aromatic phthalonitrile monomer, 2,6-bis[4-(3,4-dicyanophenoxy)benzoyl]pyridine (BCBP) was synthesized from the nitro displacement of 4-nitrophthalonitrile by the phenoxide of 2,6-bis (4-hydroxybenzoyl)pyridine (BHBP). 4-(Aminophenoxy) phthalonitrile (APPH) was selected to promote the curing reaction, and the curing behavior has been investigated by differential scanning calorimetric (DSC), suggesting a wide processing window about 64 °C. Different curing additive concentrations resulted in polymers with different crosslinking degrees and subsequently influenced the performance of resins. The resulting BCBP polymer exhibited high glass transition temperatures exceeding 400 °C, outstanding thermo-oxidative stability with weight retention of 95% at 530 °C, indicating a significant improvement in thermal properties endowed by pyridine units. Additionally, it also showed a lower overall water absorption after submersion in boiling water for 50 hours. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3819–3825

Polyimide/multiwall carbon nanotube (PI/MWCNT) nanocomposite films with homogeneous MWCNTs dispersion were prepared via a solid state shearing pulverization (S3P) approach. Polyimide precursor, viz., poly(amic acid) (PAA), was synthesized from 4,4'-oxydianiline (ODA) and pyromellitic dianhydride (PMDA). Then, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) was mixed with the PAA powder and acid functionalized MWCNTs (acid-MWCNTs) by solid state shearing pulverization (S3P) approach. Finally, PI/MWCNT nanocomposite films were prepared by thermal imidization at elevated temperatures. Using such an approach not only the MWCNTs are well-dispersed but also the mechanical and thermal properties of PI are improved. The tensile strength of PI was enhanced by 74% and the elongation at break decreased to 10.35% with 5.0 wt% acid- MWCNT loading. And the glass transition temperature of PI was increased to 341 degrees C from 303 degrees C because of the strong interfacial bonding between PI and acid-MWCNTs. The solid state shearing pulverization (S3P) approach developed in this study provides a novel method to prepare various polymer composites with desired particle dispersion.

A new thermally conductive and electrically insulative polyimide were prepared by filling different amounts of hexagonal boron nitride (h-BN) particles, and the thermal conductivity of Polyimide (PI) composites were improved with the increasing h-BN content. Based on this, two methods were applied to improve thermal conductivity furtherly at limited filler loading in this paper. One is modifying the h-BN to improve interface interaction, another is fabricating a nano-micro hybrid filler with 2-D h-BN and 0-D nano-scale nanodiamond (ND) to build more effective conductive network. Both surface modification and hybrid system have a positive effect on thermal conductivity. The composites introducing 40 wt% hybrid filler (the weight ratio of ND/modified BN was 1/10) showed the highest thermal conductivity, being up to 0.98 W/(m K) (5.2 times that of PI). In addition, the composites exhibits excellent electrical insulation, thermal stability properties etc.

Hexagonal boron nitride microplatelets (h-BNMPs) or h-BN microplatelets/h-BN nanospheres (h-BNNSs) hybrids-filled polybutylene terephthalate (PBT)/polycarbonate (PC)/acrylonitrile butadiene styrene (ABS) blends with a mass proportion of 7 : 2 : 1 were prepared. The use of h-BNMPs resulted in composites with higher enhancement than h-BN hybrid fillers in terms of thermal conductivity. The addition of h-BN hybrids (h-BNMPs and h-BNNSs at the weight ratio of 8 : 2) achieved highest enhancement of mechanical properties, adding 6 wt% h-BN hybrids achieved a 39% increase in notched impact strength and a 4.9% increase in tensile strength. Moreover, not only did the incorporation of h-BN hybrids significantly enhance the mechanical performance of composites, but it remarkably improved the thermal conductivity of composites. Nevertheless, the doping of h-BNMPs resulted in the decrease of mechanical properties, although it availably contributed to the rise of thermal conductivity compared to the neat PBT/PC/ABS matrices.

The development of proton exchange membranes (PEMs) with high loading and stable electrolytes is currently critical and challenging for applications in new energy related devices such as proton exchange membrane fuel cells (PEMFC). In this study, a novel porous organic skeleton (Covalent triazine framework, recorded as CTFp) is synthesized as a material for immobilized guest molecules via a simple nucleophilic substitution reaction. The phosphoric acid molecule (H3PO4) is extruded into the CTFp porous organic framework by vacuum assisted method (VAM). Since the molecular size of H3PO4 is smaller than the window size of the micropores in CTFp, a high loading of H3PO4 is achieved. The large amounts of basic groups distributed in CTFp can form a strong electrostatic interaction with H3PO4, which ensures the low dynamic leakage of H3PO4. PEMs with high proton conductivity are developed by embedding phosphoric acid-loaded CTFp (H3PO4@CTFp) in a SPEEK matrix. The acid-base pair formed between H3PO4@CTFp network and SPEEK optimizes the interfacial interaction and enhances the dispersion of H3PO4@CTFp in the composite membrane. H3PO4 stored in CTFp provides rich proton hopping sites for proton transport. The hydrogen bond network formed by self-dissociation of high concentration H3PO4 molecules constructs a proton transfer channel with low energy barrier for proton transfer, thereby significantly enhancing the proton conductivity of the membrane. The results show that the proton conductivity of the composite membrane at 80 °C is 0.313 S/cm when the filler content is 15%. It is worth noting that the phosphoric acid leakage rate of H3PO4@CTFp is only 15.3% after the filler is immersed in water at 60 °C for 30 days. Therefore, the SPEEK/H3PO4@CTFp composite membranes are promising to develop new PEMs with low acid loss and high proton conductivity.

Core-shell structured polyacrylic (named CSSP) impact modifiers consisting of a rubbery poly(n-butyl acrylate) core and a rigid poly(methyl methacrylate) shell with a size of about 353 nm were prepared by seed emulsion polymerization. The CSSP modifiers with different core-shell weight ratios (90/10, 85/15, 80/20, 75/25, 70/30, 65/35 and 60/40) were used to modify the toughness of poly(butylene terephthalate) (PBT) by melt blending. It was found that the polymerization had a very high instantaneous conversion (> 95.7%) and overall conversion (99.7%). The morphology of the core-shell structure was confirmed by means of transmission electron microscopy. Scanning electron microscopy was used to observe the morphology of the fractured surfaces. Differential scanning calorimeter was used to study the crystallization behaviors of PBT/CSSP blends. The dynamic mechanical analyses of PBT/CSSP blends showed two merged transition peaks of PBT matrix, with the presence of CSSP core-shell structured modifier, that were responsible for the improvement of PBT toughness. The results indicated that the notch impact strength of PBT/CSSP blends with a core-shell weight ratio of 75/25 was almost 8.64 times greater than that of pure PBT, and the mechanical properties agreed well with the SEM observation.

We have developed an efficient and biological method for the covalent functionalization of nanodiamond (ND) biopolymers. ND-grafted-poly( l -lactic acid) (ND-g-PLLA) and ND-grafted-poly(e-caprolactone) (ND-g-PCL) were prepared by surface-initiated ring-opening polymerization. After homogenization of the surface by mixed acids and thionyl chlorides, the surface of ND was modified with 1,6-hexanediol to possess hydroxyl groups, which could be used as coinitiators to polymerize l -lactide or e-caprolactone to yield ND grafted with bio-polyesters. The FT-IR, Raman and NMR spectra revealed that the polyester chains were covalently attached to the ND and the weight gains as a result of the functionalized ND particles were determined by TGA analysis. The ND-g-PLLA and ND-g-PCL were both well dispersed in the organic solvents and the average diameters were measured. The TEM images demonstrate that the dispersion of pristine ND has been significantly improved after modification of ND with PLLA or PCL.

An improved toughness-stiffness balance was achieved in PBT matrix by adding poly(n-butyl acrylate)/poly(methyl methacrylate-co-glycidyl methacrylate) (PBMG) core-shell structured copolymer. A series of poly(n-butyl acrylate)/poly(methyl methacrylate-co-glycidyl methacrylate) (PBMG), core-shell structured modifiers with different contents of functional monomer (glycidyl methacrylate) were prepared, and the effects on mechanical properties of poly(butylene terephthalate) (PBT) blends were investigated. The morphology of the core-shell structure was confirmed by means of transmission electron microscopy. Scanning electron microscopy was used to observe the morphology of the fractured surfaces. The dynamic mechanical analyses of PBT/PBMG blends showed two merged transition peaks of the PBT matrix, with the presence of PBMG core-shell structured modifier, which were responsible for the improvement of PBT toughness.

Core–shell structured polyacrylic (named ACR) impact modifiers consisting of a rubbery poly(n-butyl acrylate) (BA) core and a rigid poly(methyl methacrylate) shell with a size of about 310 nm were prepared by seed emulsion polymerization. The ACR modifiers with different core–shell weight ratios (85:15; 80:20; 75:25; 70:30) were used to modify the toughness of poly(butylene terephthalate) (PBT) by melt blending. It was found that the polymerization had a very high instantaneous conversion (>90 %) and overall conversion (98 %). The ACR latexes had an obvious core–shell structure confirmed by transmission electron microscope. The mechanical properties of the PBT/ACR blends were evaluated, and scanning electron microscope (SEM) was used to observe the fractured morphology. Dynamic mechanical analysis and differential scanning calorimeter were used to study the molecular movement and crystallization behaviors of PBT/ACR blends. The results indicated that with an appropriate value of the core–shell weight ratio, poly(BA) could disperse well in the matrix and the brittle–ductile transition point could emerge. As a result, the notch impact strength of PBT/ACR blends with a core–shell weight ratio of 80:20 was 6.7 times greater than that of pure PBT, and the mechanical properties agreed well with the SEM observation.

Poly (methyl methacrylate)/boron nitride (PMMA/BN) composites were prepared by dispersing BN particles into methyl methacrylate monomer phase by bulk polymerization method. BN particles modified with silane coupling agent, γ-methacryloxypropyl trimethoxy silane, were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. Effects of modified BN particle content on thermal conductivity were investigated, and the experimental values were compared with those of theoretical and empirical models. With 16 wt% of BN particles, the thermal conductivity of the composite was 0.53 W/(m·K), 1.8 times higher than that of pure PMMA. The microstructures of the PMMA/BN composites were examined by scanning electron microscopy, energy-dispersive X-ray analysis, and transmission electron microscopy. Dynamic mechanical analysis and thermogravimetric analysis traces also corroborated the confinement of the polymer in an inorganic layer by exhibiting an increase in glass-transition temperatures and weight loss temperatures in the thermogram. Mechanical properties and electrical insulation property of the PMMA/BN composites were also determined. These results showed that PMMA/BN composites may offer new technology and business opportunities. POLYM. COMPOS., 36:1675–1684, 2015. © 2014 Society of Plastics Engineers

A novel high-temperature diphenyl sulfone-based phthalonitrile polymer is prepared from bis-[4-(3,4-dicyanophenoxy)phenyl]sulfone (BDS) monomer synthesized with high yield by a simple nucleophilic displacement of a nitro-substituent from 4-nitrophthalonitrile (NPN). The structure of BDS polymer is investigated by Fourier transform infrared spectroscopy and wide-angle X-ray diffraction. Curing behavior of BDS monomer with 1,3-bis(4-aminophenoxy)benzene (APB) is recorded by differential scanning calorimetry. The properties of BDS polymer are evaluated by thermogravimetric analysis, dynamic mechanical analysis, and tensile test. The results reveal that the BDS polymer exhibits excellent thermal and thermo-oxidative stabilities, high glass temperature ( Tg = 337°C), and outstanding mechanical properties (Young’s modulus: 4.02 GPa and tensile strength: 64.16 MPa). Additionally, the BDS polymer exhibits high flame retardance and low water uptake.

Polyimide/multiwall carbon nanotube (PI/MWCNT) nanocomposite films with homogeneous MWCNTs dispersion were prepared via a solid state shearing pulverization (S3P) approach. Polyimide precursor, viz., poly(amic acid) (PAA), was synthesized from 4,4'-oxydianiline (ODA) and pyromellitic dianhydride (PMDA). Then, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) was mixed with the PAA powder and acid functionalized MWCNTs (acid-MWCNTs) by solid state shearing pulverization (S3P) approach. Finally, PI/MWCNT nanocomposite films were prepared by thermal imidization at elevated temperatures. Using such an approach not only the MWCNTs are well-dispersed but also the mechanical and thermal properties of PI are improved. The tensile strength of PI was enhanced by 74% and the elongation at break decreased to 10.35% with 5.0 wt% acid- MWCNT loading. And the glass transition temperature of PI was increased to 341 degrees C from 303 degrees C because of the strong interfacial bonding between PI and acid-MWCNTs. The solid state shearing pulverization (S3P) approach developed in this study provides a novel method to prepare various polymer composites with desired particle dispersion.

Nanodiamonds have recently attracted great attention because of their outstanding hardness in combination with excellent wear resistance. Chemistry modification of the surface and incorporation into a material are required in many applications. In this report, Nanodiamond particles were firstly reduced and two different approaches were used to prepare carbon fiber grafted with nano-diamond. Nanodiamonds functionalized with hydroxyl and amino groups via chemical modification were successfully introduced into the functionalized carbon fiber surface by covalent bonds. The modification of the carbon fibers was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and Wide-angle X-ray diffraction (WAXD). BET surface area of the carbon fibers was increased by about 58% compared with the unmodified fibers.

Crystallization kinetics of MC nylon (PA6) and polyazomethine (PAM)/MC nylon (PAM/PA6) both have been isothermally and nonisothermally investigated by different scanning calorimetry (DSC). Two stages of crystallization are observed, including primary crystallization and secondary crystallization. The Avrami equation and Mo's modified method can describe the primary stage of isothermal and nonisothermal crystallization of PA6 and PAM/PA6 composite, respectively. In the isothermal crystallization process, the values of the Avrami exponent are obtained, which range from 1.70 to 3.28, indicating an average contribution of simultaneous occurrence of various types of nucleation and growth of crystallization. The equilibrium melting point of PA6 is enhanced with the addition of a small amount of rigid rod polymer chains (PAM). In the nonisothermal crystallization process, we obtain a convenient method to analyze the nonisothermal crystallization kinetics of PA6 and PAM/PA6 composites by using Mo's method combined with the Avrami and Ozawa equations. In the meanwhile, the activation energies are determined to be −306.62 and −414.81 KJ/mol for PA6 and PAM/PA6 (5 wt %) composite in nonisothermal crystallization process from the Kissinger method. Analyzing the crystallization half-time of isothermal and nonisothermal conditions, the over rate of crystallization is increased significantly in samples with a small content of PAM, which seems to result from the increased nucleation density due to the presence of PAM rigid rod chain polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2844–2855, 2004

The frictional properties of the composites reinforced with continuous steel fibers have been evaluated in LNBR modified phenolic resin based friction materials. The fiber orientations are introduced regarding the sliding direction, i.e. parallel (P) along the fiber direction, normal (N) and antiparallel (AP). The specific wear rates are increased if the sliding path is shifted from the P to the AP and N direction. The coefficient of friction is also dependent on the fiber alignment directions. The coefficients of these materials fall in the range of 0.49 to 0.54. The initial sliding interaction is plowing action if the turnplate temperature is below 250°C. Meanwhile, with the increase of the temperature, as ironed transfer film developed on the specimen, the interaction became adhesive and steady-state friction is established. The wear resistance of the composite is found to relate to the stability of the film.

In this paper, the corrosion behavior of Al 2 O 3 –SiO 2 , Al 2 O 3 –TiO 2 and Al 2 O 3 –SiO 2 –TiO 2 ceramic composite coatings in boiling 1 N HCl solution is investigated. It is shown that the addition of 3% SiO 2 to the base spraying powder of Al 2 O 3 increases porosity in the coatings and causes deterioration in their corrosion resistance. Adding 13% TiO 2 to Al 2 O 3 improves the anti-corrosion property of the ceramic coating due to a reduction in porosity. The connected porosity in the Al 2 O 3 -based ceramic composite coatings rises with the open porosity and is independent of the density of the coating.