Zinc Stearate Research Articles

Polyamide 6 is an Integral Component of the Protective Coating for Steel ST3

In this study, an attempt was made to use PA 6 as a component of an experimental composite anticorrosive coating that increases the adhesion of hydrophobic coatings (iron stearate and zinc stearate) to protect structural steel St3. The phosphating primer leads to the formation of a film of iron salts insoluble in water on the steel surface and adsorption of PA 6 on them. Hydrophobization of the surface formed in this case zinc stearate leads to the formation of a coating with high adhesion and anticorrosive properties. Tannin is a corrosion inhibitor. The advantage of the tannin primer is that its molecules are able to bind to the metal surface and the PA 6 macromolecules simultaneously, forming a strong coating on the metal. Zinc stearate gives the coating hydrophobic properties and additional protection of the metal from corrosion.

Microstructure evolution and soft magnetic properties of Fe-based nanocrystalline soft magnetic composites coated with lubricant

Here, the influence of zinc stearate on the microstructure and soft magnetic properties of the Finemet nanocrystalline soft magnetic composites (NSMCs) was systematically investigated. The results demonstrate that the core loss (Pcv) decreases and the effective permeability (μe) increases of the NSMCs with increasing zinc stearate from 0 wt% to 2.0 wt%, which can be attributed to the reduction of residual stress during compaction. Further increasing zinc stearate up to 3.0 wt%, the Pcv increases sharply, while the μe shows a decreasing trend. It can be considered that the addition of excess lubricant decomposes to CO2 during annealing, which deteriorates the magnetic properties. After annealing at 560 °C, a thin hybrid layer of only about 53.6 nm containing iron phosphate, ZnO, and SiO2 is formed in the NSMCs with 2.0 wt% zinc stearate, which exhibits excellent soft magnetic properties such as low Pcv of 174 kW/m3 and high μe of 66.7 at Bm = 0.1 T for 50 kHz. In addition, loss separation has been carried out and suggests that the addition of lubricant mainly affects hysteresis loss in the total energy loss of NSMCs.

Effects of lubricants and billet geometry on the extrusion of AA6063/5% SiCp composites

Lubricants are necessary for metal forming to avoid direct contact, adhesion, transfer, and scratches from materials and tools. It is also essential for increasing tool durability and reducing energy use. The work aims to study the effects of lubricants and billet geometry on the extrusion of AA6063/5% SiCp. The lubricants were used such as graphite, zinc stearate, and molybdenum disulphide. The friction factor has been determined by the lubricant effect and billet geometry. The simulation was done for the lubricated condition which was compared with experimental results. It was found that improved billet quality was obtained by the graphite-lubricated 12:8 configuration die profile. Also, the friction factor for the graphite-lubricated 12:8 configuration dies profile was 10.5% less compared to other configure profiles. Scanning electron microscopy was used to investigate the surface of the lubricated extruded component, and samples were examined utilizing energy-dispersive X-ray analyses.

Enhancing the Initial Whiteness and Long-Term Thermal Stability of Polyvinyl Chloride by Utilizing Layered Double Hydroxides with Low Surface Basicity

This study investigated the impact of surface basicity on the performance of layered double hydroxides (LDHs) as heat stabilizers for polyvinyl chloride (PVC). LDHs with varying surface basicity were synthesized and characterized using XRD, SEM, BET, and CO2-TPD. The LDHs were then combined with zinc stearate and dibenzoylmethane to create an environmentally friendly heat stabilizer and added to PVC. The resulting PVC composites were evaluated for thermal stability using the oven-aging method. The results showed that a lower Mg/Al molar ratio (2.0) improved the initial whiteness and long-term thermal stability of PVC composites compared to higher ratios (2.5, 3.0, and 3.5). Replacing Mg with Zn in the LDHs had a similar effect to that of reducing the Mg/Al ratio. Crosslinking the laminae of LDHs with 5% silane coupling agent KH-560 reduced the surface basicity of LDHs by 79%, increasing the chromaticity index, b*, and thermal stability time of PVC composites by 48% and 14%, respectively. A descriptive relationship was established between the structure and surface basicity of LDHs and the initial whiteness and long-term thermal stability of PVC composites.

Synthesis of Glycerol Carbonate from Ethylene Carbonate Using Zinc Stearate as a Catalyst: Operating Conditions and Kinetic Modeling.

With the advent of biodiesel as a substitute/additive for diesel, the production of glycerol has experienced an increase, as it is an unavoidable byproduct of the biodiesel process; therefore, novel products and processes based on this triol are being very actively researched. Glycerol carbonate emerges as an advanced humectant from glycerol and a monomer for diverse polycarbonates. Its production in high yields and amounts can be achieved through the solventless transcarbonation of glycerol with other organic carbonates driven by alkaline catalysts, standing out amongst the cyclic carbonates due to its reactivity. Here, we have studied the main operational variables that affect the transcarbonation reaction of glycerol and ethylene carbonate catalyzed by zinc stearate: catalyst concentration, reagent molar ratio, and temperature. Subsequently, an appropriate kinetic model was fitted to all data obtained at 80 °C and several catalyst concentrations as well as reagent molar ratios. Finally, the selected kinetic model was extended and validated by fitting it to data obtained at several temperatures, finding that the activation energy of this reaction with this catalyst is around 69.2 kJ·mol-1. The kinetic model suggests that the reaction is bimolecular and elemental and that the process is interfacial in essence, with the catalyst dispersed in a narrow space between polar (glycerol) and nonpolar (ethylene carbonate) phases.

Characterization of Natural Rubber, Styrene Butadiene Rubber, and Nitrile Butadiene Rubber Monomer Blend Composites Loaded with Zinc Stearate to Be Used in the Solid Tire Industry

Vulcanization is an important step in the manufacture of solid tires in which the crosslinking process occurs. In vulcanization, the materials commonly used as activators and coactivators are ZnO and stearic acid, respectively. In this research, ZnO and stearic acid were replaced with zinc stearate to improve the characteristics of vulcanized rubber. Zinc stearate was applied in four formulas with a composition of 5 to 9 phr. A formula that is often used in the rubber industry was used as a comparison, and ZnO and stearic acid of 5 phr and 2.5 phr, respectively, were applied. The rubber compound for solid tire production was developed using an open mill at a compounding temperature of 45 °C ± 5 °C. The vulcanization process of developing the rubber compound into vulcanized rubber was carried out at 150 °C for 20 min. Rubber compound test results showed that the use of zinc stearate at a ratio of 8 phr accelerated the curing time (t90) between 58.3% and 69%, the scorch time (ts2) between 22.4% and 95.5%, and the torque delta (Δs) between 17.67 and 24.21 kg-cm. In addition, the vulcanized rubber mechanical properties test results for the compression set parameter increased between 28.6% and 57.1%. Scan results with SEM–EDS showed that using ZS could improve the homogeneous distribution of the material in the vulcanized matrix of solid tire rubber.

Multi-technique structural analysis of zinc carboxylates (soaps).

A series of medium- and long-chain zinc carboxylates (zinc octanoate, zinc nonanoate, zinc decanoate, zinc undecanoate, zinc dodecanoate, zinc pivalate, zinc stearate, zinc palmitate, zinc oleate, and zinc azelate) was analyzed by ultra-high-field 67Zn NMR spectroscopy up to 35.2 T, as well as 13C NMR and FTIR spectroscopy. We also report the single-crystal X-ray diffraction structures of zinc nonanoate, zinc decanoate, and zinc oleate-the first long-chain carboxylate single-crystals to be reported for zinc. The NMR and X-ray diffraction data suggest that the carboxylates exist in three distinct geometric groups, based on structural and spectroscopic parameters. The ssNMR results presented here present a future for dynamic nuclear polarization (DNP)-NMR-based minimally invasive methods for testing artwork for the presence of zinc carboxylates.

Comparative investigation of the structural evolution of zinc stearate and calcium stearate in a polypropylene random copolymer upon heating and cooling

Zinc stearate (ZnSt2) and calcium stearate (CaSt2) are two kinds of extensively used additives in polymer industry. However, the selection principle of the two soaps in different polyolefins is still unclear. To establish the action mechanism of these soaps in polyolefins application, the understanding of the exact structures when they play roles is prerequisite. In this work, considering that these additives play their roles during the melt processing of polyolefin, in which the structure may be different with their as-received states, the structures and evolution behavior of the two soaps in a polyolefin melt upon heating and cooling were systematically explored. It was found that the two soaps exhibited different dispersed structures and evolution behavior in the polypropylene random copolymer (PPR). The ZnSt2 in PPR presented microcrystal at low temperatures and dissociated into ionic clusters during heating, and then gradually aggregated and recrystallized upon cooling; while the CaSt2 in PPR exhibited vitreous agglomerates with lamella ordered structure at low temperatures and transformed to diverse colloidal liquid crystal aggregates during heating, and then gradually reassembled to vitreous agglomerates in cooling process. At concentration closed to practical application (about 1000 ppm or less), ZnSt2 in molten PPR dispersed in form of ionic clusters like closed small molecules, whereas CaSt2 in PPR melt presented weakly ordered aggregates. These findings provided an important foundation for building up the well-defined relationship between the structure and performance of these soaps in polyolefins.

Formulating calcium carbonate masterbatches

Abstract The effects of filler content, filler particle size and surface coating, as well as the natures of the wax and metal stearate lubricants on the properties of calcium carbonate-filled linear low-density polyethylene compounds were investigated. The elongation at break decreased exponentially with filler loading irrespective of whether the filler was surface coated or not. The corresponding decline in the impact strength was more gradual but it dropped abruptly on reaching a filler loading of 70 wt%. The effect of shear rate on the apparent melt viscosity followed an empirically modified Carreau–Yasuda model which included the effect of filler content. It features the zero-shear viscosity and the flow consistency index as adjustable parameters. These characterize the viscosity trends at low- and high-shear rates, respectively. In the absence of additives, the melt viscosity at 60 wt% filler exceeded that of the neat polymer by a factor of three. Adding 3 wt% wax and 1.0 wt% zinc stearate returned the melt viscosity to levels just above that of the neat polymer. Calcium stearate and magnesium stearate were less effective at reducing the apparent melt viscosity but a blend of the latter with zinc stearate performed particularly well.

Indigenous Production of Porous 316L through Powder Metallurgy and Investigation of their Mechanical Properties

Nowadays, 316L stainless steel implant materials exhibit a promising position in the field of biomaterials application, especially in medical due to their higher strength compared to other ceramic base materials. Therefore, in this work, the production of 316L implant materials and examination of the mechanical characteristics were carried out. Powder Metallurgy process has been chosen to produce the implant materials due to its high advantages in demonstrating the high mechanical properties of the green sample. 316L stainless steel with zinc streate powder of three different compositions, i.e., the first of 99% 316L stainless steel and 1% zinc stearate, the second of 97% 316L stainless steel and 3% zinc streate, and the third of 95% 316L stainless steel and 5% zinc streate, were cold pressed individually at 600 MPa pressure using UTM and sintered the green samples at 1120 °C for 1 hour and 30 minutes. Sintering temperature and time were the same for all the specimens. We investigated the mechanical behaviour of 316L stainless steel implant materials of different compositions at the same temperature for the same duration of time. After that, the mechanical properties and densification of this material were investigated.

Characterization of Prepared Superhydrophobic Surfaces on AZ31 and AZ91 Alloys Etched with ZnCl2 and SnCl2

Superhydrophobic surfaces were prepared using a two-step method that involved the etching of AZ31 and AZ91 magnesium alloys and then modifying the etched alloys with stearic acid. Magnesium alloys etched with ZnCl2 and SnCl2 exhibited surfaces roughened with micro- and nanoscale hierarchical structures consisting of two chemically distinct regions (Zn/Zn(OH)2 or Sn/SnO2 and Mg(OH)2). An optimum etching time of ten minutes was chosen for both etchants. Superhydrophobic surfaces with the highest contact angle were prepared when stearic acid reacted with the etched alloys at 50 °C for 4 h. Stearic acid was bound as zinc stearate and magnesium stearate on Mg alloys etched with ZnCl2 and SnCl2 solutions, respectively. The superhydrophobic process on AZ31 alloys etched with ZnCl2 and SnCl2 improved the corrosion resistance in phosphate buffered saline (PBS) solution compared to bare AZ31 alloy, with the use of ZnCl2 etchant leading to better results. An improvement in the corrosion resistance of AZ91 alloy was observed when the stearic-acid-modified AZ91 alloy was etched with SnCl2. In contrast, the use of ZnCl2 etchant to pretreat AZ91 alloy resulted in a significant deterioration in corrosion properties compared to bare AZ91 alloy. The microstructure of the Mg alloy had an impact on the etching and modification process. On the basis of the findings, a characterization of the chemistry of etching magnesium alloys and the formation of superhydrophobic surfaces was proposed. Magnesium alloys were prepared with superhydrophobic surfaces, incorporating antibacterial metals, features which may increase their potential for use in medical applications.

Manufacturing Technology of Sliding Bearings from Ferro-Graphite Compositions

Introduction. The development of modern technology imposes increasingly stringent requirements on materials operating under conditions of high pressures, speeds, deformations and aggressive media. The use of powder metallurgy methods in the creation of new materials makes it possible to provide a rational combination of production technology, structural and performance characteristics. Powder steels used in mechanical engineering are of great interest among the materials obtained by powder metallurgy. The article explores the possibility of manufacturing porous bearings made of iron powder for fan motors of domestic air conditioners instead of porous bearings made of bronze graphite.Problem Statement. To ensure long-term operation of fan motors from metal powders, it is necessary to create porous bearings without alloying additives with the required mechanical properties. This requires a series of experimental work to determine the dependences of mechanical and technological properties on the sintering temperature, compacting pressure and the porosity of samples.Theoretical Part. As a theoretical description, the use of a mold with an additional draining gap, which provides high bearing density at low compacting pressure, is analyzed. The effect of compacting pressure on the strength of sliding bearings under mechanical deformations depending on the sintering temperature is also considered.Conclusions. It was established in the work that during the sintering of sliding bearings at a temperature of 800-1100°C, a significant charge carburization occurs due to the decomposition of zinc stearate in closed pores. As a result, a ferritepearlite structure is formed, due to which the bearings are well calibrated and have high wear resistance when paired with a steel shaft. Optimum sintering modes and compacting pressures were selected, which showed high reliability and durability of the products obtained from pure iron powder.

Effect of capsicum oleoresin and denatonium benzoate in polybutylene succinate on anti-gnawing, thermal and rheological properties

The purpose of this research is to prepare anti-gnawing bio-polymer composites and to investigate morphology, thermal and rheological properties. The non-lethal substances of denatonium benzoate (DB) mixed with zinc stearate (ZnSt) and capsicum oleoresin (CO) impregnated in silica (SiCO) were mixed with polybutylene succinate (PBS). DB gives the bitter taste and CO provides burning sensation to the rats. The concentration of DB/ZnSt is 2 wt% and concentration of SiCO is ranging from 12 to 24 wt%. The influence of the substances and concentration is analyzed by the analysis of variance (ANOVA) method. The substances and concentration are most significant with P-values less than 0.05. The specimens were examined gnawing test for 3 months. The best rat-proof sample is 12S, consisting of SiCO 12 wt%. SiCO presents better rat-proof property than DB. The incorporation of DB/ZnSt reduced rheological properties and thermal stability. The increase in SiCO concentration in PBS improved rheological properties and thermal properties. The PBS composites are good rat-preventing plastics.

Fabrication of Durable Superhydrophobic Stainless Steel Mesh with Nano/Micro Flower-Like Morphologies for Self-Cleaning and Efficient Oil/Water Separation

How to fabricate durable superhydrophobic materials for cyclic oil/water separation to solve oil-induced pollutions is still a problem. Herein, we fabricated a durable Superhydrophobic Stainless Steel Mesh (SH-SSM) with nano/micro flower-like sheets by self-assembly of zinc stearate for the cyclic separation of various oil/water mixtures. The SH-SSM exhibits durable superhydrophobicity against static or dynamic treatments. In virtue of durable superhydrophobicity of the SH-SSM, the dusts on surface of SH-SSM can be removed completely by running water immediately showing excellent self-cleaning performance. Moreover, the SH-SSM can be used to perform gravity-driven separation of heavy oil/water and light oil/water mixtures by utilizing its superhydrophobicity that oil phase penetrates the mesh and water phase is restricted. Separation efficiencies of the SH-SSM can reach 99.99%. After 20 cycles of separation, the separation efficiencies for are > 97.00% and > 98.25% for heavy oil/water and light oil/water mixtures, respectively. Flux values of dichloromethane, hexane and petroleum ether are 2.5 × 105 L m−2 h−1, 1.7 × 105 L m−2 h−1, and 1.8 × 105 L m−2 h−1, respectively. This study proposes a facial approach to prepare durable superhydrophobic and self-cleaning material for cyclic and fast separation of oil/water.

Superhydrophobic magnetic sorbent via surface modification of banded iron formation for oily water treatment

In the current study, a simple dry coating method was utilized to fabricate a super-hydrophobic super-magnetic powder (ZS@BIF) for oily water purification using zinc stearate (ZS) and banded iron formation (BIF). The produced composite was fully characterized as a magnetic sorbent for oily water treatment. The results of X-ray diffraction diffractometer (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and particle size analysis revealed the fabrication of homogenous hydrophobic-magnetic composite particles with core–shell structure. Contact angle and magnetic susceptibility results showed that 4 (BIF): 1 (Zs) was the ideal coverage ratio to render the core material superhydrophobic and preserve its ferromagnetic nature. The capability of the fabricated composite to sorb. n-butyl acetate, kerosene, and cyclohexane from oil–water system was evaluated. ZS@BIF composite showed a higher affinity to adsorb cyclohexane than n-butyl acetate and kerosene with a maximum adsorption capacity of about 22 g g−1 and 99.9% removal efficiency. Moreover, about 95% of the adsorbed oils could be successfully recovered (desorbed) by rotary evaporator and the regenerated ZS@BIF composite showed high recyclability over ten repeated cycles.

Improving the Processability of a One-Step Hydrophobic Coating for Hot-Dipped Galvanised Steel for Industrial Applications

Hydrophobicity on steel-based metallic surfaces provides an advantage in limiting corrosion and debris buildup on the surface, thereby, improving the substrate performance. An experimental investigation was conducted on the development of zinc stearate and silicon dioxide coatings on the surface of hot-dipped galvanised zinc-coated steel substrates, which could be used to induce superhydrophobicity. Under optimal formulation and processing conditions, a contact angle of 146° could be produced within a 120-min processing window. This represents a reduction in processing time of 67% over previous literature using similar chemistry. In addition, we proved that costly nano silicon dioxide can be replaced by lower cost micro silicon dioxide without decreasing the performance of the coating contact angle. Under standard accelerated exposure tests, the coating was shown to reduce oxide build up by a factor of 3 compared to uncoated galvanized steel.

Combined Use of Non-Invasive and Micro-Invasive Analytical Investigations to Understand the State of Conservation and the Causes of Degradation of I Tesori del Mare (1901) by Plinio Nomellini.

In this study, the investigation of the oil painting on canvas I Tesori del Mare made by Plinio Nomellini in 1901 is presented. The aim of the research was threefold: the examination of the state of conservation in view of the restoration treatment, together with the identification of the causes of degradation and the study of the artistic technique. During the years, the artwork underwent several cleaning and fixing interventions, resulting in a patchy appearance of the surface. Nevertheless, the presence of consistent liftings persists, while the protective coating shows uneven chromatic alteration, both requiring further analysis. Multispectral imaging allowed for better visualization of the figuration’s structure and the restored areas. The combined use of Raman spectroscopy, Fourier Transform Infrared spectroscopy in the Attenuated Total Reflection mode (FT-IR ATR), and Scanning Electron Microscopy coupled with an Energy Dispersive Spectroscopy (SEM/EDS) enabled better understanding of the stratigraphy through the identification of some pigments, the binder, and the aged varnish layer on the top. SEM/EDS highlighted the presence of zinc in both the ground layer and the paint layers. Furthermore, FT-IR ATR spectroscopy showed peaks related to metal soaps such as zinc stearate, which are known to cause severe delamination of the paint layers, explaining the recurring lifting issues. Eventually, the varnish layer was found to be acrylic resin, presumably mixed with varnishes applied in past restoration treatments.

Micro-spectroscopic study of late 19th-early 20th century tube paints

Many issues in the conservation of paintings from the early modern period are still unresolved due to lack of information on paints from the late 19th and early 20th centuries, in particular their production, formulations, and later degradation processes. The inconsistency of the names that paint manufacturers chose for their products furthermore compounds the challenges faced by conservators and chemists wishing to study them. This paper addresses a number of these issues through investigations of commercial tube oil paints from a paint box owned by the Norwegian painter Harriet Backer (1845–1932). Samples were analyzed using a multi-instrumental approach. Micro-attenuated total reflection Fourier transform infrared spectroscopy and micro-Raman spectroscopy – supported by micro-X-ray powder diffraction – allowed the identification of binders, pigments, and extenders. The data highlight the use of materials that were new at the time and not reported in the manufacturer’s catalog. Furthermore, zinc stearate has been detected for the first time. Its detection and the absence of any zinc-based pigments confirms that zinc stearate was already used as dispersing agent in paint formulations at that time.

Preparation and thermal stability of bio-based Na/Zn composite liquid stabilizers for poly(vinyl chloride)

In this work, the adduct of maleic anhydride and methyl eleostearate (MAME) and dimer fatty acid (DFA) were converted to the sodium and zinc salts (L-Zn-MAME, L-Na-MAME, L-Zn-DFA, and L-Na-DFA), respectively, which were subsequently turned into Na/Zn composite liquid stabilizers(LTS-Na/Zn-MAME and LTS-Na/Zn-DFA) by formula combination. Na salts, Zn salts and mixed Na/Zn salts from these fatty acid salts were used as thermal stabilizers for poly(vinyl chloride) (PVC). The chemical structures of MAME, DFA, and their liquid zinc and sodium salts were verified using Fourier transform infrared (FTIR) spectra. Thermal stability and mechanical properties of the sodium and zinc salts, and their Na/Zn composite liquid stabilizers derived from MAME and DFA for PVC were investigated using discoloration and dynamic mechanical analyses, TGA-FTIR-MS, thermal decomposition kinetics, and Congo red and tensile tests. Thermal stability of pure PVC is poor, but membrane thermal stability can be improved by integrating thermal stabilizers. Results show that L-Na-MAME has an outstanding synergistic effect with the commercial general calcium/zinc stearate composite heat stabilizer(CaSt2/ZnSt2). CaSt2/ZnSt2/LTS-Na-MAME, LTS-Na/Zn-MAME and CaSt2/LTS-Zn-DFA/LTS-Na-DFA also have a better heat-stabilizing impact on PVC than CaSt2/ZnSt2, especially LTS-Na/Zn-MAME can more effectively enhance the primary coloring of PVC. In comparison to blank PVC and PVC/CaSt2/ZnSt2, both PVC/LTS-Na/Zn-MAME and PVC/LTS-Na/Zn-DFA display a larger elongation at break and acceptable tensile strength. The new stabilizers can largely enhance the heat stability of PVC resins, endowing PVC products with good plasticization performance, and can fully or partially replace the general calcium zinc stearate composite heat stabilizer and other heat stabilization products.

Lignin modified PBAT composites with enhanced strength based on interfacial dynamic bonds

AbstractPoly(butylene adipate‐co‐terephthalate) (PBAT) is a type of synthetic biodegradable thermoplastic copolyester with comparable mechanical properties to polyethylene, but the application of PBAT is limited by factors such as high cost, short shelf life, poor weather and water resistance. In order to develop PBAT composites with high performance and low cost, lignin‐modified PBAT biocomposites with enhanced tensile strength were prepared via in‐situ construction of interfacial dynamic bonds. Zinc stearate and epoxy soybean oil were introduced as the interfacial modifiers to construct dynamic bonds between lignin and PBAT, so as to improve the interfacial compatibility. The results demonstrated that the lignin/PBAT biocomposite with interface modifiers reached the maximum tensile strength of 36.7 MPa and an elongation at break of 725.3% at the lignin content of 5 wt%, with the tensile strength achieved 5% improvement on the basis of pure PBAT (34.9 MPa and 717.6%). When the lignin content was increased to 10 wt%, the lignin/PBAT biocomposite with interfacial modifiers still maintained the tensile strength of 35.4 MPa and the elongation at break of 627.8%, which was 82% and 31% higher than that of the directly compounded sample without interfacial modifiers, respectively. Even when the content of lignin loading increased to 20 and 30 wt%, the mechanical properties of the composites were still significantly improved by adding modifiers. The hydrophobicity of the composite was also improved after in‐situ interfacial modification. The strategy demonstrated in this work provides an effective reference for the development of lignin/PBAT composites with high performance but low cost.