Polyurethane Matrix Composites Research Articles

Influence of SWCNT on shielding and tensile properties of polyurethane nanocomposites

ABSTRACT The effect of single-walled carbon nanotubes (SWCNTs) as fillers in polyurethane matrix composites on the efficiency of attenuating electromagnetic waves in the X-band region (8–12 GHz) was studied in the current work. To meet the present-day challenges, the composites were tested using a tensile system. The inclusion of SWCNT in the polyurethane matrix proved the enhancement of electromagnetic interference shielding performance along with the improved mechanical properties. The composites were characterised by FTIR and FESEM. The dielectric properties were investigated in X-band frequencies. The shielding performance of the samples was found to be 28 dB for 1 wt% filler at 10 GHz. The effect of CNT on the mechanical performance of polyurethane composites was studied. The maximum tensile strength achieved was 2.87 MPa for 3 wt% CNT. The results showed that the synthesised sample materials found more shielding applications with favourable tensile properties.

Cactus-like ZnO decorated UHMWPE fibers to improve the strength and toughness of polyurethane matrix composites

Poor interfacial force is an important factor in preventing the development of fibers reinforced polymer composites. Fiber morphology design is an effective way to improve the interfacial property of composites. The development of nature has carried out the natural selection of survival of the fittest for organisms, and most of the surviving organisms have excellent structures and functions, which comes up with a new idea for the design of new reinforcement structure. Inspired by the cactus structure, we have prepared a new structural UHMWPE fiber reinforcement, which was characterized by a mass of cactus-like ZnO (C-ZnO) crystals decorated the UHMWPE fiber surface. The experimental results showed that the strength and toughness of C-ZnO UHMWPE fibers reinforced rigid polyurethane (RPU) composites were significantly improved. The satisfactory results were attributed to the cactus-like ZnO on the UHMWPE fiber surface, which could form a complex interfacial structure with the PRU matrix to increase the interface strength and the crack expansion paths.

Study on mechanical behaviors and failure mechanism of polyurethane matrix composites inspired by mussel chemistry and arthropod exoskeleton structures under dynamic impact

Polyurethane elastomer (PUE), an elastic polymer material of lightweight and unexceptionable mechanical properties, is widely used into the military protective structural materials to resist dynamic impact and absorb energy. However, the mechanical and thermal properties of PUE need to be enhanced due to failure damage caused by the thermal stress softening under high-speed impact. Inspired by the mussel chemistry and the exoskeleton structures of arthropods, catechol and polyethyleneimine were used to functionalize micro carbon fibers (MCFs) to enhance the mechanical and thermal properties of PUE composites. Compared with Pure PUE, the static compression modulus of PUE composite with a filler content of 2.0 wt.% was increased by 99.25%. The dynamic maximum strength and energy absorption were improved by 74.08% and 102.92%, respectively. Besides, the modified MCFs could significantly enhance the viscoelasticity and thermal conductivity characteristics of composites. The enhancement of impact resistance and energy absorption capability of the composites are mainly due to the synergistic effect of tough mussel adhesion proteins and enhancing MCFs. Thereinto, MCFs could provide incredible strength, and plenty of crosslinking networks based on phenol-amine chemistry were served as supporting structures to resist dynamic impact by effective energy dissipation. Therefore, this work can provide a way to prepare PUE composites with excellent thermal and mechanical performance, and it is beneficial to understand the deformation and failure mechanisms of PUE and other soft polymer materials under dynamic impact.

Investigation of the Mechanical Properties of Three-Dimensional Polyurethane Composites Reinforced with Warp-Knitted Spacer Fabrics

In this study, a novel composite having a unique three-dimensional structure was investigated. Warp-knitted spacer fabrics with glass fiber woven fabric were chosen as the reinforcement, while polyurethane foam was used as the matrix materials. The glass fiber woven fabric was pretreated with the warp-knitted spacer fabric first, and then a hand lay-up method was used to fabricate the three-dimensional polyurethane-based composites. The mechanical properties of the finished composites were determined. The influence of the fabric thickness, the surface structure of the fabric, and whether the woven fabric is laminated or not on the mechanical properties of the three-dimensional polyurethane composites were determined. The results show that the fabric thickness is positively related to the tensile and compressive properties and inversely related to the bending properties of the three-dimensional knitted/woven hybrid polyurethane matrix composites, provided that the surface structure is the same. The tensile and compressive strengths of the composites were higher when the glass fiber woven fabric was laminated with the spacer fabric than when the three-dimensional knitted/woven hybrid polyurethane matrix composites were not taken. Therefore, the knitted/woven fabric as reinforcement improved the tensile and compressive properties of the composites.

The Synergistic Effect of WS2 and SWNTs on Tribological Performance of Polyether MDI Polyurethane Elastomer under Dry and Wet Friction Conditions.

To adapt to the complex application of polyurethane bearings, it is feasible to improve the tribological performance of single polyurethane-based friction materials through the synergistic effect produced by multi-component-lubricating fillers. In this context, rather than using tungsten disulfide (WS2), which has demonstrated excellent self-lubricating performance as a lubricating oil additive, this paper proposes that WS2 and single-walled carbon nanotubes (SWNTs) can be designed for addition into a polyether 4,4′-diphenylmethane diisocyanate (MDI) polyurethane matrix as self-lubricating fillers so as to explore the synergistic effect of micro- and nano-lubricating fillers on the tribological performance of polyurethane matrix materials. Through a series of characterizations and tests, it was found that the dispersion of two-component-lubricating additives in a polyurethane matrix is improved when the ratio of WS2 to SWNTs is roughly 2:1. In this case, the tribological performance of polyurethane matrix composites is more satisfactory than at other ratios. In addition, compared with the blank sample, the tribological performance of the synergistically modified polyurethane composites under dry friction is more significantly improved with the increase in contact load, while there is no significant improvement under water lubrication. Aside from contributing to the idea of exploring the synergistic effect of WS2 and other micro or nanofillers, this method also opens up the possibility of practically applying WS2 in the field of friction.

Natural based polyurethane matrix composites reinforced with bamboo fiber waste for use as oriented strand board

Composites that use natural fibers as reinforcement have generated great interest in the industrial and scientific community due to the need for materials that present environmental responsibility and are economically viable. This work aimed to develop and establish a comparative analysis of the mechanical properties and physical characteristics between a castor oil based polyurethane resin composites reinforced with fibrous bamboo residue and a commercial Oriented Strand Board (OSB), in which where determined the technical issues of using these composites as OSB panels. Bamboo fibers used were obtained as a residue from a barbecue sticks industry. Composites were made with 20 and 40% volume fraction of continuous and aligned bamboo fiber. The density, moisture absorption, and mechanical strength of the composites were tested and compared with the commercial OSB. The composites not only presented mechanical performance superior to the commercial OSB, surpassing 1000 J/m, 85 MPa and 4.4 GPa for impact resistance, flexural strength, and flexural elastic modulus, respectively, but also fulfilled the standard requirements, while the commercial OSB, failed in most of the observed standards criteria. In addition, the developed materials contribute to a sustainable environment by using both bamboo waste and castor oil based polyurethane resin in a composite material.

The effects of cauliflower-like short carbon fibers on the mechanical properties of rigid polyurethane matrix composites

Stress concentration and weak interfacial strength affect the mechanical properties of short carbon fibers (CFs) reinforced polymer composites. In this work, the cauliflower-like short carbon fibers (CCFs) were prepared and the point was to illuminate the effects of fiber morphology on the mechanical properties of the CCFs/rigid polyurethane (RPU) composites. The results indicated that the surface structure of CCFs could increase the surface roughness of the fibers and the contact area between fibers and matrix, thereby promoting the formation of irregular interface. Compared with pure RPU and initial CFs/RPU composites, the strength and toughness of CCFs/RPU composites were simultaneously improved. The satisfactory performance was attributed to the special fibers structure, which played an anchoring role and consumed more energy during crack propagation.

The influence of ultraviolet radiation on the optical properties of glass fibre reinforcements for polyurethane matrix composites

AbstractPolyurethanes represent one of the most frequently used polymeric matrixes in composites. Although there have been many studies focused on the weather resistance of polyurethanes, this important property is unheeded during the reinforcing phase. In this article, the effects of ultraviolet (UV) radiation on the changes in optical properties of commercially available glass fibre reinforcements containing various polymeric binders used as compatibilising agents for the polymeric matrix in the final composite products were studied. The standardised experiments were performed using accelerated ageing equipment, q‐lab ultraviolet tester, in dry mode. Chemical modification of the binder in the form of polyesters or silanes by UV irradiation was studied using Fourier Transform–infrared spectroscopy. Changes in the optical properties caused by the degradation processes of polymeric components due to UV irradiation were evaluated based on colour changes in the examined samples using the yellowness index; statistical evaluation of the data obtained was conducted with an Anderson–Darling test of normality and an ANOVA test. It was demonstrated that both the amount of the binder and the glass fibre reinforcement's construction play a more important role than the chemical structure of the binder.

Biomimetic electrospun polyurethane matrix composites with tailor made properties for bone tissue engineering scaffolds

Abstract Bone tissue scaffolds require appropriate properties conducive for new tissue growth. In this study, we prepared a novel electrospun nanofiber scaffold using polyurethane (PU), rosemary (RM) oil and copper sulphate (CuSO 4 ) respectively. The properties of the developed membranes were established through scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), thermal gravimetric analysis (TGA), contact angle and mechanical testing. Further, blood compatibility and cytocompatibility assay were carried out to evaluate their biological responses. The developed composites rendered appropriate surface morphology with tailor made wettability and roughness. Composites with engineered physicochemical properties improved the blood and cytocompatible properties which can be potentially exploited for bone tissue engineering applications.

Preparation of rubber wood sawdust-based activated carbon and its use as a filler of polyurethane matrix composites for microwave absorption

Preparation of rubber wood sawdust-based activated carbon and its use as a filler of polyurethane matrix composites for microwave absorption

Preparation of rubber wood sawdust-based activated carbon and its use as a filler of polyurethane matrix composites for microwave absorption

Activated carbons were prepared from rubber wood sawdust by chemical activation using ZnCl2 as an activation agent at 500 °C for 60 minutes with ZnCl2/dried rubber wood sawdust mass ratios from 1.0 to 2.0. Flat polyurethane (PU) composites filled with the activated carbons were prepared by a chemical foaming method using different loading amounts of the activated carbons to investigate their complex permittivity and the microwave absorption properties for use in electromagnetic interference (EMI) shielding. It was found that the best activated carbon is obtained at a ratio of 1.5, which has the highest Brunauer-Emmett-Teller surface area and a micropore volume of 1301 m2/g and 0.37 cm3/g, respectively. With increasing activated carbon content, the dielectric constant (ɛ’) and the return loss increase in the frequency range of 1-3 GHz. The composite filled with 8 wt% activated carbon has a maximum dielectric constant of 3.0 and its return loss is above 10 dB at the global system mobile phone frequency of 1.8 GHz. Its EMI shielding efficiency is in the useful range of approximately 3 dB over a wide frequency range of 1-2.5 GHz. Compared with conventional materials such as polyethelene and polyester filled with metal additives, this composite is suitable for microwave absorption and is a potential candidate for EMI shielding applications.

The Preparation and Characterization of NiTi/CNT/Polyurethane Composite

The polyurethane matrix composites consisting of CNT and NiTi springs are prepared and the microstructure, mechanical property and damping property of the composites are investigated. It was found that the CNT and NiTi spring exhibit a good interfactial bonding with the matrix. The elastic modulus and tensile strength have been enhanced by the addition of CNT and NiTi spring. The NiTi spring is helpful to increase the recovery strain and enhance the energy absorption of the composites by the pseudoelastic deformation under the large deformation. The NiTi spring can not increase the damping property under low vibration amplitude because the pseudoelastity of the spring is not actuated when the deformation is small.

Wear behaviour of polyurethane composites with respect to the other mechanical properties

Two series of polyurethane matrix composites were prepared. As generally resistant to wear, the PUs can be used as matrices for wear protective and load-bearing composites. The objective of this study was to compare the mechanical properties of composites containing 5% vol. of selected ceramic particles, and unmodified PUs. The effect of various particles on physical and mechanical properties was studied. The results showed that the mechanical properties changed compared to reference materials: modulus improved in certain materials and in different temperatures, revealing the favourable influence of FA and SiO2 particles. In turn, Rm and wear resistance decreased with the type and shape of filler.

Platelet-reinforced polymer matrix composites by combined gel-casting and hot-pressing. Part II: Thermoplastic polyurethane matrix composites

A combined gel-casting and hot-pressing method was used to fabricate platelet-reinforced polymer matrix composites. Submicrometer thin alumina platelets were dispersed in a highly diluted polymer solution. A thermoplastic polyurethane elastomer was used as matrix for its high elasticity and excellent adhesion to the platelets. After dissolution of the polymer and casting, quick evaporation of the solvent triggered the formation of a polymer gel trapping the platelets in their well dispersed positions. The polymer–platelet gel densified during drying and the platelets were oriented horizontally due to the capillary forces and the large decrease in the thickness of the gel. The dried composites were hot-pressed to further improve the platelet orientation along the shear flow and close potential pores in the polymer. While the ultimate tensile strength of the composites gradually decreased with increasing platelet volume fractions, the increase in the elastic modulus and the stress necessary to deform the composite 10% was more than 100 and 18 times higher than the respective values of the pure polymer. The use of alumina platelets with an aspect ratio below the critical value allowed for the ductile platelet pull-out fracture mode. Since the polymer had to deform more to achieve identical deformation of the composite at higher platelet volume fraction, the strain at rupture steadily decreased. The incorporation of voids towards high platelet concentrations and the thereby triggered crack initiation and growth during straining lead to an additional decrease in the elasticity of composites with increasing platelet volume fractions. However, the extremely high extensibility of a polymer matrix allowed for the fabrication of composites that still deformed up to 162±19% at platelet volume fractions as high as 0.33. When compared to other platelet-reinforced elastomers, the achieved platelet volume fraction is much higher and the relative increase in elastic modulus and stress at low strains is therefore much larger at the expense of a decrease in the strain at rupture. The fabrication method and designing principles employed in this study are transferable to other types of polymers and platelets and potentially allow the creation of new composites with tailored properties.

Curing characteristics and mechanical properties of carbon fiber‐interlayered fabric composites based on a polyurethane matrix

AbstractPolyurethane matrix composites based on fiber‐interlayered carbon fabric laminates were prepared by compression molding to assess the feasibility of this approach, when using a highly reactive resin as matrix. The polyurethane matrix was prepared using the excess isocyanate to enhance the rigidity of the system through additional crosslinking. The fiber‐interlayered laminates consisted of different amount of short fibers between two carbon fabrics. Three composites containing, respectively, 12%, 18%, and 26% wt/wt total carbon fibers were produced for this study. Thermal and IR spectroscopic analysis were performed to select the most suitable thermal curing conditions for the matrix. The results showed that 70°C represents the minimum curing temperature required to carry out the reactions between polyol and isocyanate groups at an economical rate. In this condition, a multistep reaction occurs to consume the excess isocyanate. Mechanical strength of the composites was measured by three‐point bending tests, and the data were analyzed by the Weibull statistical method. Fiber content in the interlayer is a critical parameter in the manufacture of these types of composite materials. Composites with 13% and 21% wt/wt short fibers in the interlayers (giving a total carbon fiber content of 18% and 26% wt/wt) exhibit a wider cumulative distribution of strength data due to the restrictions that they impose on the flow of the resin, thereby resulting in an inhomogeneous distribution of resin throughout the samples. A composite with 12% total carbon content (7% wt/wt short fibers) exhibits a narrower cumulative distribution, denoting a greater reliability relative to the manufacturing method used in this study. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:132–145, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20094

Mechanical properties and erosion wear resistance of polyurethane matrix composites

In this paper, polyurethane matrix composites reinforced with aluminum oxide (Al 2O 3) particles were fabricated to improve the wear resistance of polyurethane (PUR) elastomer working in erosion conditions, the effects of Al 2O 3 content (0–64 wt%) and different silane coupling agents (i.e. A-1100 and A-187) on the mechanical properties and erosion wear resistances of the composites were investigated. Both the tensile strengths and the elongations at rupture of the composites were found to decrease with the content of Al 2O 3 particles; however, the hardness increased gradually. The composites treated with silane coupling agent A-1100 had higher tensile properties (tensile strength and elongation at rupture) than those treated with silane coupling agent A-187. Erosion tests were carried out on a self-made jet erosion machine. According to the results, the wear resistances of the two composites first increased until reaching a maximum, then decreased, with the increasing content of Al 2O 3 particles. The composites treated with silane coupling agent A-1100 had higher wear resistances than those treated with silane coupling agent A-187 due to the higher reaction activity of A-1100 with the matrix than A-187. The fracture surfaces and erosion area of the composites were analyzed with scanning electron microscope (SEM) and the erosion wear mechanism for the composites was discussed.

Failure of Spectra® Polyethylene Fiber-Reinforced Composites under Ballistic Impact Loading

Failure modes of Spectra polyethylene fiber-reinforced composites were examined under ballistic impact loading. Both woven fabric-reinforced laminates and angle-plied unidirectional fiber-reinforced laminates were found to exhibit sequential delamination, cut-out of a plug induced by through-the-thickness shear, and combined modes of shear and tensile failure offibers as obserxed in the cases of glass and graphite fiber composites. At low areal density, both laminates demonstrated similar ballistic limits. However, as areal density increased, differences in ballistic limit became more apparent, with angle-plied composite laminates showing higher values. When subjected to the repeated impact of a constant striking velocity below the ballistic limit, a progressive growth of local delamination was observed until gross failure of composites occurred. The use of lower striking velocity of the projectile led to the increase in cumulative numbers of impacts for full penetration defining an impact fatigue lifetime profile. The results of impact testing indicated that Spectra fiber-reinforced composites with vinyl ester resin matrix have a higher ballistic limit and longer impact fatigue life at a given striking velocity than the polyurethane matrix composites. Less effective absorption of impact energy by flexible polyurethane matrix composites was attributed to much more restrained pattern of delamination growth. Correlated with the results of dynamic mechanical analysis, these trends indicated that the stiffness of resin matrices plays an important role in controlling the ballistic impact resistance of Spectra fiber composites. Damping factor and resultant stress wave attenuation characteristics of materials seem to be less important parameters.