Polyurethane Content Research Articles

Experiments and dimensional analysis of waste tire-based permeable pavements

This study investigates the stress–strain response of a novel high-porosity semi-bound soft–rigid permeable pavement blend prepared using rock- and tire-derived aggregates (RDA and TDA) bonded by a polyurethane (PUR) binder. A series of unconfined compression tests were performed on 36 mix designs (with different RDA and TDA proportions, PUR contents and curing durations) to identify the variables governing the stress–strain response. The greater the TDA content, the lower the mobilized strength (UCS) and stiffness (E50), both following an exponentially-decreasing trend. Meanwhile, an increase in PUR content (i.e. increase in the number of inter-particle bonds) and/or curing duration enhanced the UCS and E50. Unlike the UCS which often achieved a stabilized state at seven days of curing, the development of stiffness extended into higher curing durations. Applying the dimensional analysis concept, a practical modeling framework was proposed and validated (using an independent database) for the UCS and E50, allowing these parameters to be simulated as a function of the blend's basic properties – that is, RDA (or TDA) content and its mean particle size, PUR content, curing duration, and dry density. The proposed models can be used with confidence for preliminary design assessments and/or semi-bound soft–rigid optimization studies.

Efficient Softening and Toughening Strategies of Cellulose Nanofibril Nanocomposites Using Comb Polyurethane.

Cellulose nanofibrils (CNFs) have attracted attention as building blocks for sustainable materials owing to their high performance and the advantages of their abundant natural resources. Bioinspired CNF/polymer nanocomposites, consisting of a soft polymer phase and a high fraction (>50 wt %) of CNF reinforcement, have been focused on excellent mechanical properties, including Young's modulus, mechanical strength, and toughness, mimicking the energy dissipation system in nature. However, efficient softening and toughening with a small amount of the soft phase is still a challenge because a large amount of the polymer phase (nearly 50%) is still required to provide ductility and toughness. Here, we describe a topological strategy in the polymer phase for efficient toughening of bioinspired CNF nanocomposites with a water-soluble comb polyurethane (PU). The comb PU provided higher elongation at break and more efficient flexibility for the nanocomposite than the linear PU, even at a small content. Moreover, CNF nanocomposites with 30 wt % of PU content and tetrabutylammonium as bulky counterions showed enhanced toughness (180% higher) and strain at break (250% higher) when compared to pure CNF due to the promotion of slippage between nanofibrils. Scanning electron microscopy (SEM) images of the fracture surface for CNF/comb PU nanocomposites displayed the pull-out of mesoscale layers and nanofibrils, supporting that the comb topology promotes the slippage between fibrils. Furthermore, the rheological study revealed that the comb PU has an entanglement plateau modulus lower than linear PU by 1 order of magnitude, related to the loosened entanglements. Our study establishes an efficient softening and toughening strategy while using small amounts of polymer phase addition, promoting interfibrillar slippage with the loosely entangled comb PU phase.

Preparation and Properties of Bio-Based Polyurethane Controlled Release Urea Coating with Photosensitivity.

In order to improve the photodegradation ability of fertilizer coating material and realize the sustainability of fertilizers, in this study, the commercially available photosensitive iron stearate (FeSt3) was wet-ground into submicrometer FeSt3 (SFeSt3) particles and used in preparation of a SFeSt3-modified bio-based polyurethane (PU)-coated controlled release urea (PU-SFe-CRU). The results showed that after 1 month photodegradation, the coating material had significant yellowing, the oxygen content of SFeSt3-modified PU (PU-SFe) increased by 56.89%, and its structure became more porous and looser than PU. The thermal stability of PU-SFe decreased, and more intermediate products were produced after exposure to UV light. The germination experiment showed that PU-SFe before and after photodegradation (up to 60 mg/L) had no adverse effect on the seed germination and bud growth of rice. Additionally, PU-SFe had a significantly higher Cr adsorption capacity after photodegradation due to the increase of the oxygen-containing group and specific surface. This study provides a theoretical basis for the research and development of photodegradable environment-friendly controlled release urea.

Research on working performance of waterborne aliphatic polyurethane modified concrete

A waterborne polyurethane with relatively lower cost and higher solubility in water was adopted to improve the performance of ordinary concrete. The waterborne aliphatic polyurethane modified concrete (WPMC) was prepared by waterborne aliphatic polyurethane, cementitious materials, coarse and fine aggregates, polycarboxylate superplasticizer and foam stabilizer. Then, a series of experimental research and theoretical analysis were carried out to investigate the mechanical properties, durability and microstructure of WPMC. The appropriate content of waterborne polyurethane increased elastic modulus, compressive strength, splitting tensile strength and flexural strength of WPMC. A significant correlation was found between the splitting tensile strength or elastic modulus and compressive strength of WPMC. Furthermore, it could effectively improve the chloride penetration resistance and impermeability of concrete after the waterborne polyurethane was added. Also, the freezing and thawing resistance was enhanced. The improved formula was proposed to predict the capillary water absorption of concrete at any time. MIP and SEM test results showed that the microstructure of concrete was improved after adding waterborne aliphatic polyurethane. Finally, the PCA method was utilized to analyze the optimal polymer-cement ratio of WPMC. The conclusion was that 0.0044 was the better polymer-cement ratio. The findings demonstrate that it can improve the mechanical properties, durability and microstructure of the concrete after adding appropriate content of waterborne aliphatic polyurethane.

Study on preparation and performance of a thermosetting polyurethane modified asphalt binder for bridge deck pavements

With the rapid development of traffic volume and loading, sustainable pavement materials are developing to improve the longevity of orthotropic bridge deck pavement structures. This paper aims to develop a new flexible binder with improved mechanical characteristics for bridge deck applications. This research studied the preparation process, microstructural morphology, and mechanical properties of a newly developed thermosetting polyurethane modified asphalt binder (TPUA). The results showed that the viscosity of TPUA was greatly affected by the preparation temperature and the viscosity growth rate increased with the increase of preparation temperature. The curing time was determined by the change in the absorption peak of the infrared spectra of the NCO groups. When the content of the PU modifier exceeded 30 wt%, the polyurethane (PU) resin formed a continuous polymeric network in asphalt binder, and the PU had relatively good compatibility with the asphalt binder. TPUA still showed the characteristics of a viscoelastic material at medium and low temperatures. When the content of PU exceeded 30 wt%, TPUA gradually showed the characteristics of an elastic material at high temperature and had excellent high-temperature deformation resistance and elastic recovery properties. In addition, the TPUA binder showed improved low-temperature flexibility with the increase of PU. Overall, the mechanical properties of the asphalt binder were substantially enhanced with the incorporation of PU resin, generating a flexible binder with favorable application prospects.

Study Mullins effect of polyurethane reinforcement with halloysite nanotube by molecular dynamics simulation

Molecular dynamics simulation was applied to study the irreversible strain through loading and unloading cyclic tests of polyurethane (PU) reinforced with halloysite nanotube (HNT). The influences of the stretching cycle rate, different temperatures, the volume of halloysite nanotube and the density rate of the hard and soft domain of PU were studied on the permanent set. The results illustrate that the residual strain was increasing when the stretching loading is increasing, for example, with increasing strain load to 250% the residual strain increased to 55%. In contrast, the increasing volume fraction of HNT and hard part content of PU lead to lower residual strain. The recovery of the permanent set is achievable by increasing temperature from 1 K to 200 K residual strain is decreased to 52%. An Ogden constitutive and the theory of pseudo-elasticity were adopted to simulate this composite in the ABAQUS software. This model has proposed a reasonable prediction of plastic deformation.

Polyester fabric impregnated with carbon nanotubes directly to form a flexible heating fabric

In order to solve the problems of complex fabrication process, poor flexibility and high cost of heating element in electric heating clothing, a method of preparing flexible heating fabric by directly impregnating polyester fabric with carbon nanotube was proposed. According to the process flow of preparing flexible heating fabric, the process conditions of uniform loading carbon nanotubes on polyester fabric were determined, the flexible heating fabric was prepared under different process conditions, and the surface microstructure of the flexible heating fabric was observed and its heating performance was tested. The results show that the pretreatment process can reduce the resistance value of the flexible heating fabric. When the concentration of carbon nanotubes is 6wt% and the content of waterborne polyurethane is 35g/L, the flexible heating fabric can be prepared. By observing the surface micro-topography, it can be seen that the surface of the prepared flexible heating fabric is smooth, and a uniform conductive layer of carbon nanotubes is formed on the fabric. A 5V DC voltage was applied to the prepared flexible heating fabric, and the highest heating temperature was 46.8°C within 62 seconds after the electricity was turned on, which realized rapid electric heating and uniform heating, laying a foundation for the subsequent development of heating clothing.

Improving the mechanical performance of poroelastic road surface with low polyurethane content through surface activation

The poroelastic road surface (PERS) mixture with low polyurethane content (PERS-LPC) can reduce the construction cost of PERS pavement, which exhibits promising noise reduction capacity, whereas its mechanical performance needs to be further enhanced for real practice. This study aims to investigate the effectiveness of surface activations of crumb rubber and aggregate to improve the mechanical performance of PERS-LPC. Molecular dynamics (MD) simulations and indoor experiments have been conducted, including the indirect tension (IDT) test implemented on the dry-cured and freeze–thaw PERS-LPC specimens and Cantabro test performed on water-bathed specimens. The results showed that, the oxygen-containing groups, introduced by UV irradiation and KMnO4 soaking, enhanced surface polarity of crumb rubber and rubber-polyurethane bonding strength. The surface activity of basalt aggregate was increased by the inclusion of Portland cement but not by hydrated lime. The IDT strength of the dry-cured PERS-LPC mixture was improved by 10.3–17.5% with activated rubbers and by 35.6% with activated aggregates. The tension strength ratio (TSR) of the freeze–thaw mixture was increased only by 2% with activated rubber but up to 20.8% by the inclusion of 0.5 wt% cement. The Cantabro abrasion loss (CAL) of PERS-LPC specimens was reduced significantly from 20.1% to 11.6% with the soaked rubber and dropped dramatically to 7.9% after inclusion of 0.5 wt% cement. It was recommended to activate crumb rubber with UV irradiation for 24 h and mineral aggregate with 0.5 wt% cement in PERS-LPC mixture in terms of performance enhancement and operation convenience. The findings of this research were expected to support the mix design of an inexpensive and durable PERS-LPC mixture for noise reduction.

Dynamic Mechanical and Chemorheology Analysis for the Blended Epoxy System with Polyurethane Modified Resin

As the important matrix material, epoxy resin has been widely used in the composites for various fields. On account of the poor toughness of epoxy resin limiting their suitability for advanced applications, considerable interests have been conducted to modify the epoxy resin to meet the engineering requirements. In this study, the bio-based polyurethane (PU) modified resin was adopted to modify the pure bisphenol-A epoxy by blending method with various proportions. Aiming to illuminate the curing behavior, mechanical and thermal properties, the blended epoxy systems were characterized by viscosity-time analysis, dynamic mechanical analysis (DMA) at different frequencies and temperatures, mechanical tensile test, thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. The results indicated that the introduction of PU modified epoxy was found to significantly inhibit the viscosity growth rates especially when the content of PU modified epoxy resin is higher than 60%. Notwithstanding the dynamic modulus and Tg reduced with the increment of PU modified epoxy, remarkable increment on the elongation at break was found and the flexibility was greatly promoted with the introduction of PU modified epoxy. The proportion of PU modified epoxy in the blends should be put balance considerations to obtain optimal mechanical properties. TGA results and FTIR spectrum demonstrated that the addition of PU modified epoxy did not change the thermal decomposition mechanism and chemical reaction mechanism, but the addition of PU modified epoxy inhibits the curing reaction of epoxy resin by measured and calculated the damping temperature domain ΔT from 35.7°C to 48.9°C.

Effect of Stabilizers and Thermoplastic Polyurethane on the Properties of Three-Dimensional Printed Photochromic Wood Flour/Polylactic Acid Composites.

This study was aimed at investigating the photofatigue resistance and mechanical properties of photochromic wood-plastic composites using a stabilizer complex-AH (antioxidant 1010 and hindered amine light stabilizer HALS 770)-with different contents of thermoplastic polyurethane (TPU), which was prepared by the melt-blending extrusion process and three-dimensional (3D) printing. Photofatigue resistance, mechanical property, microtopography, and thermal analyses of 3D printed samples were performed. The results showed that the difference in surface color of composites improved by 26.7% with addition of AH after 10 days of accelerated aging, whereas the mechanical strength decreased. Upon adding TPU, composites' impact strength significantly increased by 25.48% and 87.87% with 10% and 20% addition, respectively. Meanwhile, the interface compatibilities between the components were enhanced. The differential scanning calorimetry and thermogravimetric analysis results indicated that 10% TPU could improve the thermal stability of composites.

A novel polyfunctional polyurethane acrylate prepolymer derived from bio-based polyols for UV-curable coatings applications

In recent decades, the sustainability, availability and low toxicity of biomass polyols have attracted more and more attention. Biomass polyols were used to prepare polyfunctional polyurethane acrylates, which can effectively improve the green performance of UV-curable coatings. Herein, a multifunctional polyurethane acrylate containing a variety of biomass was synthesized and characterized. Firstly, itaconic acid (IA), ricinoleic acid (RA) and oleic acid (OA) reacted with glycidyl methacrylate (GMA) respectively to obtain itaconic acid acrylate (IAG), ricinoleic acid acrylate (RAG) and oleic acid acrylate (OAG). Determination of the synthesis of IAG, RAG and OAG was conducted by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR). Then IAG, RAG, OAG and castor oil (CO) were mixed and reacted with isophorone diisocyanate (IPDI) to prepare polyurethane acrylate. The effects of IAG, RAG, OAG and CO on the thermal and mechanical properties of polymers were studied. The results showed that when the content of IAG was increased, the double bond conversion rate, the glass transition temperature, tensile strength, Young's modulus and gel content of polyurethane increased significantly. In addition, by adjusting the contents of IAG, RAG, OAG and CO, the thermal stability of polymers also showed regular changes. Among them, the thermal stability of polymers increased most with the increase of IAG content, followed by RAG, OAG and CO.

Effects of flexible and rigid parts of ε-caprolactone and tricyclodecanediol derived polyurethane on the polymer properties of epoxy resin

We report the synthesis of a novel polyurethane (PU) obtained from caprolactone (CL) and tricyclodecane diol (TCD-diol) and its reinforcing effect in the epoxy resin. Polycaprolactone (PCL)-TCD-polyol was synthesized by reacting TCD-diol with CL using tin(II)-2-ethylhexanoate. By changing the ratio of CL, PCL-TCD-polyol was synthesized with different molecular weights and chain lengths. Using PCL-TCD-polyol and polytetrahydrofuran (polyTHF) in a ratio of 1:1 with hexamethylene diisocyanate, polyurethane (PCL-TCD-PU) was prepared and used as a reinforcing agent with epoxy resin to improve the polymer properties. The mechanical and thermal properties of the epoxy cured specimens with and without the PCL-TCD-PU reinforcing agent were comparatively analyzed. The addition of PCL-TCD-PU with epoxy resin improved the tensile, impact, and flexural strengths, and it also had excellent physical properties that changed depending on the molecular weight and PU content of the TCD-polyol used in the PU. Furthermore, the fracture surface of the epoxy resin after the impact test had a specific pattern that was thoroughly analyzed by FE-SEM. Furthermore, thermomechanical analysis (TMA) showed that while increasing the PU content in the epoxy resin, the thermal expansion system is close to one, which clearly indicates that PCL-TCD-PU is expected to show excellent adhesive strength.

Design and Preparation of PU/EP Blend Resin Grafted by Hydrophilic Molecular Segments

Film-forming resins, as carriers of antifouling coatings, play an essential role in the functional performance of coatings. With the gradual promotion of coatings in the field of marine antifouling, the preparation of film-forming resins containing hydrophilic chain segments is urgently needed to give full play to the functional and time-sensitive performance of antifouling coatings. In this paper, the single-ended isocyanate group (NCO) polyurethane (PU) prepolymer with hydrophilic chain segments was prepared and grafted onto an epoxy resin (EP) molecular chain to obtain the PU/EP grafted blend. Successful preparation of the PU/EP grafted blends was confirmed by infrared spectrum analysis. Simultaneously, the grafted blend was cured, and its hydrophilicity and mechanical properties were also tested. The results demonstrate that the grafted method can effectively improve the hydrophilicity of the film-forming resin while maintaining its mechanical properties. It can be concluded from the hydrophilic and mechanical properties of the materials that the comprehensive properties of PU/EP grafted blends are the best when the PU content is between 40% and 50%. The hanging plate test showed that the antifouling effect of the antifouling coating prepared by hydrophilic modified PU/EP film-forming resin was better than that of the traditional antifouling coating under the experimental conditions.

Physical and Mechanical Properties of Natural Fiber Polyester Laminate Composites

The utilization of natural fibers as reinforcing composites has been widely used. Indonesia has natural fibers abundantly such as ijuk fiber (Arenga pinnata), sisal fiber (Agave Sisalana) and coconut fiber (Cocos Nucifera). Random orientation application of the fiber in composites affected to the lower properties. Therefore, the particular orientation of fibres wereapplied in manufacturing of composite by laminating the short fiber with Polyurethane (PU) adhesive. The size and moisture content (MC) of fiber were 14-15 cm and +10%, respectively. The resin content of PU was 5% by weight of the laminate sheet. The mixture of fibers and PU adhesive was cold pressed for 5 minutes with a thickness of 0.5-1 mm. The laminate sheet of PU-adhesive fibers then mixed with unsaturated polyester resin layer by layer. The fiber laminate composition of composite was varieted such as 1, 2 and 3 layers. The hand layup method was used in the manufacturing of the composite. The physical and mechanical testing like density, moisture content, water absorption, thickness swelling, flexural test (adapt to ASTM D 790 standard) and tensile test (adapt to ASTM D 638 standard) were carried out. In additionmorphological analyses were investigated on composite samples. The results research showed that the net density of polyester, ijuk fiber sheet, sisal fiber sheet, and coconut fiber sheet were 1.21, 0.9, 0.53 and 0.22 g/cm3. The range of composite density was 0.99-1.15 g/cm3. The single layer composite had lower thickness swelling and water absorption than those of the three layers composite. The highest tensile strength of three layers of sisal fiber composite was higher (33.84 MPa) than that of the three layers of coconut fiber composite (12.04 MPa). The flexural strength of double layers composite from fiber sisal was higher (63.16 MPa) than that of three layers coconut fiber composite (28.65 MPa).

Study on preparation and pavement performance of polyurethane modified asphalt based on in-situ synthesis method

In this study, based on the molecular structural analysis of traditional asphalt binder and polymer modifiers, hydroxyl-terminated polybutadiene (HTPB), which possesses a similar structure to asphalt binder and has a low polarity, were selected as soft segments for use as a polyurethane (PU) modifier. The PU was prepared in the asphalt binder based on an in-situ synthesis methodology, providing a new type of PU modified asphalt binder. The microstructure and molecular structure of the PU modified asphalt binder were analyzed by fluorescence microscopy and infrared spectroscopy. The high and low temperature performance, mechanical properties and water stability of PU modified asphalt binder were studied. Microstructure analysis shows that the PU can be formed in the asphalt binder, and has better compatibility compared with SBS. PU can gradually form a spatial network structure in the asphalt binder when its content exceeds 4 wt%. As the PU content increases, the modified asphalt binder exhibits better high-temperature deformation resistance and low-temperature cracking resistance. In particular, after the PU content exceeds 4 wt%, the low-temperature performance of the modified asphalt binder is better than that of 5 wt% SBS modified asphalt binder. In addition, following an increase in PU content, the adhesion and water stability of the modified asphalt binder and aggregate are significantly improved. This study will help provide guidance for the research and development of PU modified asphalt binder.

Improvements on performance of bio-asphalt modified by castor oil-based polyurethane: An efficient approach for bio-oil utilization

Bio-asphalt is a potential pave material in road engineering. In order to realize comprehensive utilization of a variety of bio-oils and improve the road performance of bio-asphalt, this study chose two different sources of bio-oil for effective utilization. First, vegetable oil was used to prepare mixed bio-asphalt through high-speed shearing. Polyurethane and castor oil were added to the bio-asphalt for modification to obtain castor oil-based polyurethane-modified bio-asphalt (CPBA). Based on the Box-Behnken Design, the penetration test and softening point test of the CPBA were carried out to evaluate its conventional performance. Temperature sweep, multiple stress creep recovery test, and bending beam rheometer test was conducted to evaluate its macroscopic rheological properties. Fourier transform infrared reflection (FTIR) was shown to reveal its modification mechanism. Scanning electron microscopy (SEM) was performed to observe its microscopic morphology and verify the effect of polyurethane modification. The results manifest that castor oil-based polyurethane can increase the high-temperature properties of bio-asphalt. However, when the amount of castor oil is too high, it will also weaken the high-temperature properties of CPBA. The high-temperature properties of CPBA depend on castor oil content, polyurethane content, and stress level. Vegetable oil and castor oil can improve the low-temperature properties of asphalt. Instead, the chemical reaction production of polyurethane or polyurethane and castor oil with asphalt negatively influences the low-temperature properties of asphalt. The optimal polyurethane content, castor oil content, and vegetable oil content determined using the response surface method were equal to 20.00%, 33.61%, 8.38%. FTIR results manifest that polyurethane can chemically react with castor oil but not with vegetable oil. Vegetable oil mainly plays a role in improving the compatibility of CPBA. SEM results also show that under the action of vegetable oil, the appearance and structure of the reaction products of polyurethane and castor oil have been greatly improved. The polyurethane application in bio-asphalt makes a variety of bio-oil used, improving bio-asphalt performance and availability.

Study on Properties of Bone Glue/Polyurethane Composite Modified Asphalt and Its Mixture

Composite modification technology is widely used in the materials field. To enhance the property of polyurethane modified asphalt and realize its application in road engineering, the bone glue/polyurethane composite modified asphalt (CMA) was prepared using bone glue, polyurethane, and neat asphalt in this research. The bone glue content ranges 5–10%, that of the polyurethane is 1–5%. The relationship between the modifier’s content and the conventional properties and rheological properties of CMA was revealed by response surface methodology (RSM). The CMA performance was further verified under the optimal content of the bone glue and polyurethane. The differences of properties of styrene–butadienestyrene (SBS) modified asphalt mixture, neat asphalt mixture, and bone glue/polyurethane CMA mixture were compared and analyzed by using the pavement performance test. The results showed that the CMA’s conventional properties and rheological properties are improved. The optimal bone glue content and polyurethane content determined by RSM are 6.848% and 2.759%, respectively. The low-temperature crack resistance and water stability of the CMA mixture are enhanced, better than neat asphalt mixture and SBS modified asphalt mixture. The CMA mixture’s dynamic stability is 85% of SBS modified asphalt mixture, but it is 2.4 times of neat asphalt mixture. The result indicated that the bone glue/polyurethane CMA mixture still has certain advantages of high-temperature stability. In this research, the composite modification of bone glue and polyurethane can significantly enhance the characteristic of asphalt and asphalt mixture and provide a new method for applying and promoting polyurethane modified asphalt in road engineering.

Polyurethane asphalt binder: a promising candidate for steel bridge deck-paving material

ABSTRACT To solve the problems of insufficient flexibility and low-temperature cracking resistance of epoxy asphalt binders in steel bridge deck-paving, a segmented linear polyurethane (PU) asphalt binder with thermoplasticity was synthesised via a chain extension reaction between a PU pre-polymer and chain extender in asphalt matrix. Successful synthesis was confirmed through Fourier transform infrared (FT-IR) spectroscopy. A series of tests were conducted to evaluate the properties of PU binders and determine an appropriate formulation. Asphalt binders with high PU contents (30–50%) perform significantly better than the base binder in terms of the high-temperature, low-temperature and mechanical properties. Further, the synthesised PU binder and other frequently used binders, e.g. epoxy and SBS-modified binders, in bridge deck asphalt pavements were compared. Results show that the synthesised PU binder has remarkably better flexibility and low-temperature property, but worse mechanical and high-temperature properties than an epoxy binder. However, the mechanical and high-temperature properties of the synthesised PU binder are substantially better than those of an SBS-modified binder. These results provide useful information for pavement engineers for selecting steel bridge deck-paving materials.

Investigation on the properties of new palm-oil-based polyurethane modified bitumen

Polyurethane-derived polymer synthesized by the reaction of 4.4′-diphenylmethane diisocyanate (MDI) with the new modified palm-oil-based polyol was used as an alternative additive to thermoplastic-elastomers, such as styrene–butadienestyrene (SBS), the most commonly used additive. The study aimed to investigate the effect of polyurethane (PU) modification on the rheological and chemical structure of base bitumen. The softening point, rotational viscosity, dynamic shear rheometer (DSR), multi-stress creep recovery (MSCR), bending beam rheometer (BBR), and Fourier transform infrared (FTIR) tests were conducted on the binders. The effects of curing time and temperature, isocyanate/hydroxyl (NCO/OH) molar ratio, and PU content were examined and the best modification conditions were determined. It was found that 24 h curing conditions at 85 °C were sufficient for the formation of PU bonds and these processes increased the rutting parameter of the binder by 256% compared to 1 h curing. At 50 °C and a frequency of 5 Hz, the binder with a 4:1 NCO/OH ratio had 63% more complex modulus than the binder with a 10:1 NCO/OH ratio. The 7 wt% PU modified binder had the same performance level as 4% SBS modification and 10 wt% PU modified binder was one degree higher. Moreover, above 60 °C, all the PU modified binders gave lower phase angles compared to the 4% SBS modified binder. 7 wt% PU modified binder showed similar elastic properties against cracks at low temperatures compared to the 4% SBS modified binder. The use of palm oil in the synthesis of PU presents an environmentally friendly and cost-effective solution compared to the use of petrochemical derivatives.

Analysis of Asphalt Concrete Wearing Course made with Asphalt Polyurethane Modifier

Modified asphalt is one of several solutions to road damage problems. The purpose of this study was to analyze the effect of adding polyurethane to the asphalt concrete wearing course (ACWC). The analysis method used is the Marshall Parameter analysis. Marshall specimens were prepared with modified polyurethane asphalt. The polyurethane content used is 1% to 4% by weight of asphalt with a range of 1%. The results showed that modified asphalt–polyurethane can improve ACWC performance in terms of stability, flow, VIM, VMA, VFA, and MQ. The best performing polyurethane content in this study was 2%, and usage of polyurethane levels above 3% is not recommended due to having MQ which does not meet the specification requirements.