Polyurethane Elastomer Composites Research Articles

Mechanical Behaviors of Orthogonal Spiral Metal Skeleton–Polyurethane Elastomer Composites under Complex Loading Modes

Herein, a novel material design strategy is proposed: an interpenetrating composite composed of a woven orthogonal spiral metal skeleton and polyurethane (PU) elastomer. This interpenetrating composite combines rigidity and flexibility, exhibiting excellent elasticity and deformation recovery. The deformation behavior and mechanical properties of the composites under various loading conditions are investigated through experiments and numerical simulations. Different degrees of warping behaviors occur in composites with various structural parameters under uniaxial tension. Alternating rotations and double spiral arrangements can significantly limit the warping phenomenon, with a maximum reduction of 78%. The bending load capacity is regularly increased by increasing the wire diameter and decreasing the pitch. Increasing the number of loaded spiral wires enhances the bending load capacity of the composites. Uniaxial compression tests demonstrate that the composites have excellent load‐carrying capacity and strain recovery, with compressive strength 1.5 times that of pure PU. Cyclic compression tests further illustrate the excellent energy consumption capacity and stability of the composites. Overall, the introduction of orthogonal spiral skeletons into the composites demonstrates the potential to achieve enhanced load‐carrying capacity and large strain recovery simultaneously.

Improvement of Mechanical and Acoustic Characteristics of Halloysite Nanotube-Reinforced Polyurethane Elastomer Composites and Their Applications.

Polyurethane incorporated with nanofillers such as carbon nanotubes, basalt fibers, and clay nanoparticles has presented remarkable potential for improving the performance of the polymeric composites. In this study, the halloysite nanofiller-reinforced polyurethane elastomer composites were prepared via the semi-prepolymer method. The impact of different halloysites (halloysite nanotubes and halloysite nanoplates) in polyurethane composites was investigated. Scanning electron microscopy, X-ray diffraction, infrared spectroscopy, electronic universal tensile testing, and acoustic impedance tube testing were employed to characterize the morphology, composition, phase separation, mechanical properties, and sound insulation of the samples. The composite fabricated with 0.5 wt% of halloysite nanotubes introduced during quasi-prepolymer preparation exhibited the highest tensile strength (22.92 ± 0.84 MPa) and elongation at break (576.67 ± 17.99%) among all the prepared samples. Also, the incorporation of 2 wt% halloysite nanotubes into the polyurethane matrix resulted in the most significant overall improvements, particularly in terms of tensile strength (~44%), elongation at break (~40%), and sound insulation (~25%) within the low-frequency range of 50 to 1600 Hz. The attainment of these impressive mechanical and acoustic characteristics could be attributed to the unique lumen structure of the halloysite nanotubes, good dispersion of the halloysites in the polyurethane, and the interfacial bonding between the matrix and halloysite fillers.

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.

Sustainable Strategy for Algae Biomass Waste Management via Development of Novel Bio-Based Thermoplastic Polyurethane Elastomers Composites.

This work concerns the waste management method of algae biomass wastes (ABW). For this purpose, we prepared bio-based thermoplastic polyurethane elastomer (bio-TPU) composites. Algae biomass wastes are derived from algal oil extraction of Chlorella vulgaris and from biomass of Enteromorpha and Zostera marina. ABWs were used in the bio-TPUs composites as a filler in the quantity of 1, 5, 10, and 15 wt.%. The bio-based composites were prepared via the in situ method. Polymer matrix was synthesized from a bio-based polyester polyol, diisocyanate mixture (composed of partially bio-based and synthetic diisocyanates), and bio-based 1,3 propanediol. In this study, the chemical structure, morphology, thermal and mechanical properties of prepared composites were investigated. Based on the conducted research, it was determined that the type and the content of algae waste influence the properties of the bio-based polyurethane matrix. In general, the addition of algae biomass wastes led to obtain materials characterized by good mechanical properties and noticeable positive ecological impact by increasing the total amount of green components in prepared bio-TPU-based composites from 68.7% to 73.54%.

Thermally conductive and compliant polyurethane elastomer composites by constructing a tri-branched polymer network.

Most elastomers suffer from poor thermal conductivity, which limits their further applications in various fields, especially for electronic devices. A common method to enhance thermal conductivity is to introduce thermally conductive fillers into elastomers. Unfortunately, thermal conductivity and compliance are often correlated and coupled: large amounts of fillers are required to increase thermal conductivity while damaging the compliance dramatically. In this study, we report thermally conductive and compliant polyurethane elastomer composites by constructing a tri-branched polymer network. The resultant polyurethane elastomer composites exhibit excellent superhigh stretchability (2000%), low Young's modulus (640 kPa), and low thermal resistance (0.11 K cm2 W-1). Experimental rheology and a theoretical tube model are employed to study the nature of the high compliant tri-branched polymer network. Furthermore, the remarkable flexibility of our elastomer composite and heat dissipation act as thermal interface materials in the thermal management of flexible electronics. These findings advance our understanding on the rational design of the polymer frameworks of thermal composites, improving our ability to predict, design, and leverage their unique properties for future applications.

Performance development of polyurethane elastomer composites in different construction and curing environments

This study addresses the performance development law of polyurethane elastomer in different construction environments to promote its popularization and application. The ultra high molecular weight polyethylene (UHMWPE) micropowder/polyurethane elastomer composites were prepared. Different types of construction and curing environments during the actual application of materials were simulated. The mechanical strength, flexibility, energy absorption state and cushion property of polyurethane elastomer at different environment conditions and curing time were studied systematically. The interactive development law of each performance was analyzed. The environmental adaptability of polyurethane elastomer was clarified. The results show that after curing at normal room temperature for 7 days, the index values of various performances for polyurethane elastomer at this time reached 95 % of the final value. And the various indexes were as follows. Tensile strength was 12–12.5 MPa, and elongation at break was 590 %-600 %. Tear strength was 78–80 N/mm. Absorbed energy was 1.7–1.8 J. The minimum buffer factor was 8–8.2. The hygrothermal environment accelerated the development of mechanical properties, but the cold environment greatly reduced the performance growth rate. These two environments damaged some performances of the material. Among them, mechanical strength and toughness decreased 45–60 %. In the performance forming process, the three indexes of mechanical strength, flexibility and energy absorption state had interactive relationship.

Synthesis and research of basalt microfiber‐reinforced polyurethane elastomer composites

AbstractBasalt microfiber‐reinforced polyurethane elastomer composites (BMF/PUE) were prepared by semi‐prepolymer method in this study. The degree of microphase separation and quantitative analysis of H‐bonding formation in polyurethane were determined by infrared spectroscopy. The fiber surface and the morphology at the tensile fracture interface of the composite materials were observed by scanning electron microscopy. The mechanical properties of composite materials were further measured on an electronic universal testing machine. Dynamic thermomechanical analysis and acoustic impedance tube were used to study the damping and acoustic properties of composite materials, respectively. The results indicated that the composite material prepared by adding 6 g of basalt microfibers treated with 3 min' crushing had the best overall performance. Compared with the matrix, BMF/PUE showed good sound insulation performance with a much wider effective damping temperature range. On the basis of ensuring its excellent overall performance, the mechanical properties were increased by 50.4% in tensile strength, 28.1% in elongation at break, and 14.2% in tear strength.

Influence of nanocrystalline cellulose extracted from different precursors on properties of polyurethane elastomer composites

Nanocrystalline cellulose (CNC) produced from waste paper by direct acid hydrolysis without any alkali or bleaching treatment was used to reinforce polyurethane elastomer (PU). By comparison, traditional cellulosic sources such as microcrystalline cellulose and waste cotton were also used to extract CNC and prepare polyurethane nanocomposites. The result showed that CNC extracted from waste paper had the largest aspect ratio, crystallinity and thermal stability. Three kinds of CNC all built interactions with polyurethane matrix through hydrogen bonds and covalent bonds. Amongst, polyurethane nanocomposites with CNC extracted from waste paper had the largest thermodynamic properties and stiffness. Briefly, CNC extracted from waste paper was comparable with CNC isolated from traditional cellulosic sources and could be used for stronger reinforcement of PU with lower cost. This work realized recycling of waste paper with a simple method and prepared a thermally resistant PU with low cost.

In Situ Grafted Composite Nanoparticles-Reinforced Polyurethane Elastomer Composites with Excellent Continuous Anti-Impact Performance.

Polyurethane elastomer (PUE) has attracted much attention in impact energy absorption due to its impressive toughness and easy processability. However, the lack of continuous impact resistance limits its wider application. Here, an amino-siloxane (APTES) grafted WS2-coated MWCNTs (A-WS2@MWCNTs) filler was synthesized, and A-WS2@MWCNTs/PUE was prepared by using the filler. Mechanical tests and impact damage characterization of pure PUE and composite PUE were carried out systematically. Compared with pure PUE, the static compressive strength and dynamic yield stress of A-WS2@MWCNTs/PUE are increased by 144.2% and 331.7%, respectively. A-WS2@MWCNTs/PUE remains intact after 10 consecutive impacts, while the pure PUE appears serious damage after only a one-time impact. The improvement of mechanical properties of A-WS2@MWCNTs/PUE lies in the interfacial interaction and synergy of composite fillers. Microscopic morphology observation and damage analysis show that the composite nanofiller has suitable interfacial compatibility with the PUE matrix and can inhibit crack growth and expansion. Therefore, this experiment provides an experimental and theoretical basis for the preparation of PUE with excellent impact resistance, which will help PUE to be more widely used in the protection field.

Copper metal‐organic framework toward flame‐retardant enhancement of thermoplastic polyurethane elastomer composites based on ammonium polyphosphate

In this article, copper metal‐organic framework (MOF‐Cu) was synthesized and used as synergism with ammonium polyphosphate (APP) to prepare flame‐retardant thermoplastic polyurethane (TPU) composites. The synergistic flame‐retardant effects between MOF‐Cu and APP in TPU composites were studied by cone calorimeter (CCT), limiting oxygen index tests (LOI), vertical burning tests (UL‐94), smoke density test, etc. The results showed that MOF‐Cu had some flame‐retardant effects on TPU, and APP had good flame retardancy in TPU/APP composites. And, the flame retardancy of TPU/APP was further enhanced when MOF‐Cu was used as synergism with APP. It has been found that the peak heat release rate (pHRR) and total heat release (THR) values of TPU/Cu0.0625 sample were reduced by 26.0% and 1.3% compared with pure TPU, respectively. And the pHRR and THR values of TPU/APP sample were reduced by 70.3% and 15.8% compared with pure TPU. In the case of TPU/APP/Cu0.0625 sample, the pHRR and THR values were furtherly reduced by 19.2% and 63.4% compared with TPU/APP, because of the minor amount of MOF‐Cu. It has been found MOF‐Cu cannot suppress the smoke release and reduce the total smoke release (TSR) value. However, 0.125 wt% MOF‐Cu can make the TSR value of TPU/APP/Cu0.125 sample reduce to 227.8 m2/m2, which was 23.4% lower than that of TPU/APP. The good synergistic flame‐retardant effect between MOF‐Cu and APP was obtained by the catalyzing carbonization process to form the char residue layer with high graphitization and expansion degree.

Influence of nickel citrate in flame retardant thermoplastic polyurethane elastomer composites based on ammonium polyphosphate

Influence of nickel citrate in flame retardant thermoplastic polyurethane elastomer composites based on ammonium polyphosphate

Investigation of the rubber elasticity and properties of polyurethane elastomers with different silicon carbide contents

Silicon carbide (SiC) powder was added to a polyurethane elastomer (PUR) to produce the composites. PUR was synthesized by mixing polyether polyol (PETP, Mw = 6000 g/mol) and 4,4′diphenylmethane diisocyanate. The stress-strain curves were carried out to estimate the effect of SiC on rubber elastic behaviour of PUR composites. As SiC content increases, the rubber elasticity region is noticeably decreased which can clearly be seen in the stress-strain curve, this could be attributed to the distribution of the SiC particles in the PUR matrix which prevents the cross-linking chain mobility of PUR and therefore affects the deformation while stretching. Furthermore, the decrease in the elongation at break is also co-related to the SiC content which hindrance the molecular mobility of the PUR chain. Shore A and D hardness increase by increasing SiC content up to 88 Shore A and 37 Shore D at 30 wt.% SiC. This is mainly due to the addition of SiC particles which act as active fillers in PUR matrix. The tensile strength and Young’s modulus are slightly increased when SiC content was increased. These observations support that Sick particles act as reinforcement which is active fillers and affect the stiffness in the elastic deformation of PUR.

Effect of fiber volume fraction on the mechanical properties of randomly oriented glass fiber reinforced polyurethane elastomer with crosshead speeds

The effect of fiber length and fiber volume fraction at different crosshead speeds on the mechanical properties and toughness of randomly oriented glass fibers reinforced polyurethane elastomer composites were studied using standard simple tension test. The modulus of elasticity and the yield stress increase with increasing the fiber volume fraction, the fiber length and the crosshead speed. The percentage increase due to the increasing of fiber volume fraction for 10 mm fiber length is much higher than that for 5 mm fiber length, while the percentage increase due to increasing of the crosshead speed for 10 mm fiber length is lower than that for 5 mm. The toughness of the failed specimens decreases with increasing the fiber volume fraction, the crosshead speed and fiber length.

Dispersion of particulate in solvent cast magnetic thermoplastic polyurethane elastomer composites

Our research focuses on the processing of a thermoplastic magnetorheological elastomer (MRE) by solvent-casting a thermoplastic polyurethane (PU) elastomer with magnetic particulate for fused filament fabrication (FFF) applications. MREs are typically prepared by curing a thermoset silicone with magnetic particulate. Alternatively, thermoplastic MREs may be produced by the addition of magnetic particulate to a thermoplastic elastomer (TPE). FFF is a valuable manufacturing technique that allows for the creation of parts with inherent anisotropies. For the case of an MRE, FFF allows for the production of structures with tunable magnetic susceptibility along different axes. In these composites, the degree of particulate dispersion significantly affects the isotropy of material properties, which becomes increasingly important when small material volumes are used, such as in FFF. Incorporating solvent-casting as a method of producing polymer composites allows for greater control over the particulate addition method, leading to improved dispersion when compared to a polymer melt. For our purposes, composite films were produced in order to examine the effect of wet vs. dry addition of particulate on dispersion. The solvent used for casting was dimethylformamide (DMF). Preparation of polymer solutions included dissolution of PU in DMF to 20 w/v% followed by addition of the magnetic particulate. The particulates used were <150 µm iron powder and 2–4 µm magnetite powder. Composite solutions were made to concentrations of 20, 30, and 40 w/w% particulate to polymer by addition of either dry particulate or particulate pre-suspended in DMF. It was found that wet addition of particulate led to improvement in particulate agglomeration and magnetite particulate exhibited a significantly higher degree of agglomeration than iron.

Development of multifunctional polyurethane elastomer composites containing fullerene: Mechanical, damping, thermal, and flammability behaviors

Thermoplastic polyurethane (TPU) composites filled with fullerene in the range from 0.5 wt% to 2 wt% were fabricated using melt-compounding. Fullerene addition levels up to nearly twofold increase in tensile strength, percent elongation, and modulus of TPU. The mechanical properties are improved as modified C60 content decreases. Fullerene loadings also enhance thermal stability of TPU. Glass transition temperature decreases by the inclusion of C60 into TPU matrix. Composites exhibited the improvement for storage modulus and vibration-damping behavior. The UL-94 rating and limiting oxygen index value of TPU are also extended to higher values after C60 loadings. Adjuvant effect is observed on fire performance in which pristine C60 inclusions and higher concentrations of C60 exhibit better fire performance. Additions of C60 give identical melt flow index values with that of TPU. Modified C60 particles disperse more homogeneously than pristine ones into TPU matrix because of the improvement in interfacial interactions between fullerene and polyurethane elastomer.

Polyurethane elastomer composites reinforced with waste natural cellulosic fibers from office paper in thermal properties

Polyurethane elastomer (PUE) composites were synthesized with a low additive content of waste natural cellulosic fibers from office paper. A new technology combining prepolymer method with physical blending and modification was adopted. The results showed that cellulosic fibers were covalently bonded to polyurethane molecular chains and served as a cross-linking agent making the degree of phase separation decrease. Even so, the lowest additive content of cellulosic fibers (1 wt%) in this work could make polyurethane still hold a certain degree of phase separation. Besides, thermal stability of polyurethane was improved from 288 to around 300 °C even at the low cellulosic fibers content. PUE with 3% cellulosic fibers had the better interfacial compatibility between cellulosic fibers and polyurethane causing the greater thermal reinforcement. PUE with 4% and 5% cellulosic fibers had the worse interfacial compatibility generating the better damping capacity indicating that cellulosic fibers could improve damping performance of polyurethane, especially polyurethane with 5 wt% fibers. It meant that cellulosic fibers had a potential application in damping materials.

Investigation of Thermal and Mechanical Properties of Aramid Fiber Reinforced Thermoplastic Polyurethane Elastomer Composites

Along with the emergence of thermoplastic polyurethane materials with its elastomeric behavior, there has been an improvement in the production of composites with functional properties by adding additives as well as advantages such as high production rates and diversity. In this study, thermal and mechanical behaviors of thermoplastic polyurethane (TPU) elastomer reinforced with aramid fiber (Kevlar) fabrics with different layers were investigated. Particular emphasis has been placed on the optimization of parameters such as good distribution and impregnation of TPU elastomers used as reinforcements on Kevlar interfaces. Composite samples prepared in 1, 2 and 3 layers of Kevlar fabric by using hot pressing method which were heated at 180 °C under the pressure of 10 MPa for 20 minutes to obtain the final product. Optical, modulus of elasticity, tensile strength, % elongation and thermal conductivity values of TPU reinforced Kevlar composite materials with different layer ranges are compared. It is concluded that the high mechanical strength and the high thermal conductivity values are associated with the amount of thermoplastic polyurethane materials between the kevlar sheets in few layered composite structures. It is also seen that the mechanical strength strongly depends on pore volume, adhesion on fiber-matrix interfaces and matrix concentration on aramid fiber reinforced thermoplastic polyurethane composites.

CuMoO4@hexagonal boron nitride hybrid: an ecofriendly flame retardant for polyurethane elastomer

A novel flame retardant (CuMoO4@h-BN) was synthesized through the co-precipitation method, and its structure and morphology were systematically characterized. CuMoO4@h-BN was added to polyurethane elastomer (PUE) to investigate the effect of thermal, flame retardancy and smoke suppression properties on the PUE composites. The results showed that 2 wt% CuMoO4@h-BN increased the residual char yield of the PUE composite notably to 9.8%. CuMoO4@h-BN exhibited an excellent charring effect. Compared with pure PUE, 2 wt% CuMoO4@h-BN decreased the peak heat release rate, total heat release and smoke density of the PUE composite by 73.6, 52.4 and 28.2%, respectively. CuMoO4@h-BN performed well in flame retardancy and smoke suppression. It may be attributed mainly to the physical barrier effect of h-BN and catalytic carbonization effect of CuMoO4. It is expected that this simple and inexpensive treatment of PUE may help expand the fire safety applications of the material.

Synergistic effect of expandable graphite and α‐type zirconium phosphate on flame retardancy of polyurethane elastomer

ABSTRACTOrganically modified zirconium phosphate (OZrP) was prepared by cation exchange of natural counterions with hexadecyltri‐n‐butylphosphonium bromide. Subsequently, OZrP and expandable graphite (EG) were incorporated into polyurethane elastomer (PUE), and the thermal stability and flame retardancy of PUE composites were investigated. The thermogravimetric analysis indicated that partial substitution of EG with OZrP could improve both the thermal stability and char yield of PUE composites. The cone calorimetry and limiting oxygen index test showed that partial substitution of EG with OZrP could further enhance the flame retardancy of PUE composites and presented an excellent synergistic effect. Moreover, the char residue of PUE composites was analyzed by X‐ray photoelectron spectroscopy and laser Raman spectroscopy. Their results indicated that the synergistic effect of the physical barrier to prevent transmission of heat and mass between condensed and gas phases. Therefore, the further combustion of the nether material could be inhibited, which created better flame retardancy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45188.

The flame retardancy and smoke suppression effect of heptaheptamolybdate modified reduced graphene oxide/layered double hydroxide hybrids on polyurethane elastomer

A MgAl-layered double hydroxide loaded graphene hybrid (RGO-LDH) was prepared through the co-precipitation method, and then heptaheptamolybdate (Mo7O246−) modified RGO-LDH hybrid (RGO-LDH/Mo) was synthesized by the ion exchange method. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, Laser Raman spectroscopy (LRS) and Transmission electron microscop (TEM) micrograph results showed the RGO-LDH/Mo was synthesized successfully. RGO-LDH/Mo was added into the polyurethane elastomer (PUE) for improving the flame retardancy and smoke suppression properties. The results showed that the char yield of PUE with RGO-LDH/Mo was increased significantly compared with pure PUE. The peak heat release rate and the maximum smoke density of the PUE composites decreased drastically. The reasons were attributed to the physical barrier of graphene and LDH, and the metal oxide generated from LDH could restrain the diffusion of inflammable gas. Meanwhile, MoO3 formed in the decomposition process of RGO-LDH/Mo promoted the catalytic carbonization and smoke suppression effect.