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This paper evaluated the effect of a biobased polyurethane modifier on the moisture resistance of asphalt binder. Biomodifiers with high acid values have been implicated in moisture damage to asphalt. Here, castor oil with a relatively high acid value of 190 mg KOH·g−1 was used to produce biobased polyurethane. Biobased polyurethane was produced by combining castor oil, toluene diisocyanate (TDI), and diethylene glycol (DEG) at a molar ratio of 1∶2∶1. Asphalt binder was modified with 3%, 6%, or 9% of the biobased polyurethane (by weight of asphalt binder), and the moisture susceptibility of the modified asphalt was evaluated with a comprehensive laboratory experiment plan using the boiling water test, the indirect tensile strength test, the bitumen bond strength test, the water contact-angle moisture-susceptibility test, and the moisture-induced shear-thinning index test. Study results showed that the introduction of biobased polyurethane enhanced the bond between the aggregate and asphalt, thereby increasing the asphalt mixture's resistance to moisture damage. Consequently, the resistance of asphalt binders to cohesive failure and adhesive failure was enhanced in biobased polyurethane, as evidenced by respective increases of 19%, 40%, and 49% in tensile strength ratio for dosages of 3%, 6%, and 9% biobased polyurethane. Compared with neat asphalt, the asphalt blend containing 9% polyurethane had the highest bond-strength increases, 55.73% and 37.93%, for dry and wet conditions, respectively. This improvement is attributable to the phenol and amide components in biobased polyurethane, which increase the polarity of asphalt binder and increase the affinity of asphalt binder to siliceous aggregate. In addition, the moisture-induced shear-thinning index and the contact-angle moisture-susceptibility index showed that increased doses of biobased polyurethane resulted in increased resistance of asphalt to moisture damage. The study outcomes promote the sustainability of asphalt construction by introducing biobased polyurethane as a sustainable modifier for asphalt. [ABSTRACT FROM AUTHOR]

This work describes the flexural behavior of biocomposites composed of a polyurethane matrix derived from castor oil plants and coir fibers. A statistical design is performed to identify the effects of fiber alkaline treatment and aging on the flexural modulus and strength of the composites. Physical tests and failure analyses are carried out to better assess their mechanical performance. A second experiment at 100% relative humidity is performed on treated fiber composites to compare with those obtained by immersion in water. The flexural modulus of the composites is not significantly affected by the fiber alkali treatment, while the strength is reduced by 35.17% when treated fibers are considered. Increasing the exposure time of composites under both aging conditions progressively reduces their flexural properties. The aging process of biocomposites in an environment with 100% relative humidity takes twice as long to reduce to the same flexural properties as those aged in water. Highlights: Composites made with treated fibers showed higher apparent density and lower porosity.Water aging reduces flexural modulus and strength of biobased coir composites.The bending properties are strongly dominated by the properties of biobased polymer.100% relative humidity takes twice as long to reduce to the flexural properties as those aged in water.Untreated coir fibers achieve superior bending properties under moisture aging. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) synthesis based on poly(ethylene glycol) (PEG) with isosorbide (ISO) and pentamethylene diisocyanate (PDI), named (ISOPUs) was carried out targeting PUs from renewable sources. The cross‐linked ISOPUs were produced and the details of the curing kinetics were determined via Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). DSC scans displayed exotherms between 100 and 200°C, related to cross‐linking. ISO addition accelerated the curing and the maximum curing rate (Cmax), with 91°C and 0.2964 min−1 for the compound with 70% ISO. FTIR spectra confirmed the interaction between OH (ISO/PEG) and NCO (PDI) groups, with total NCO consumption (band at 2267 cm−1). Through the thermogravimetric analyses (TGA), the PU/70% ISO presented weight loss at 146°C due to the degradation of ISO. ISOPUs displayed a decreased activation energy (Ea) during curing over a range of 100 to 42 kJ/mol for 0 < α < 5%, as demonstrated using the Friedman model, and higher thermal stability as evidenced through TG analyses. Curing and degradation kinetics were modeled using Friedman (FR), Kissinger‐Akahira‐Sunose (KAS), and Ozawa‐Flynn‐Wall (OFW). Overall, ISO accelerated the curing rate and increased the degradation Ea, suggesting high thermal stability for PUs with intermediate ISO contents, that is, 30%–50%. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising alternative to petroleum-based polymers, however its high brittleness limits its practical applicability. In this study, two polyurethane elastomers (PUa and PUb) containing poly (ε-caprolactone) or poly(ε-caprolactone)/poly(butylene adipate) as soft segment and different hard segments content (38.16% for PUa and 53.12% for PUb) were synthesized and melt blended with PHBV in various proportions. The addition of 5–15 wt% PU elastomers to PHBV did not significantly change its thermal stability; however, the presence of PUs decreased the crystallization temperature of PHBV by up to 9 °C, and the crystallinity of PHBV decreased from 48.2% to 42.2 or 43.6% in the blends with 15% PUa or PUb, indicating the development of some interactions between PHBV and PUa/PUb. The addition of PUa to PHBV increased its elongation at break by up to 70%, a weaker effect being observed with PUb. Remarkably, a slight variation in the tensile strength and modulus, which remained close to those of neat PHBV, was concomitant with the increased ductility. The fatigue resistance of the selected blends was estimated by a DMA cyclic test under controlled force from − 20 to 70 °C, this test clearly differentiating the blends. [ABSTRACT FROM AUTHOR]

Bio-based polyurethanes are novel material with potential advantages for sustainable development, and their development play significant roles in promoting sustainability. Curcumin, a natural monomer, possesses high biological activity and features a symmetrical chemical structure with various functional groups such as phenolic hydroxyl, carbonyl and benzene ring. The presence of hydroxyl groups in the structure of curcumin provides essential conditions for its involvement in polyurethane synthesis. This review article provides an overview of the applications of curcumin as a chain extender, crosslinking agent and end-capper in polyurethanes, as well as its effects on the chemical structure, mechanical properties, and chemical stability of polyurethanes. Furthermore, the functional applications of curcumin-based polyurethanes in various fields such as medicine, food packaging, and coatings are discussed. Finally, considering the current research status and inherent properties of curcumin, the future prospects of curcumin-based polyurethanes are contemplated.

Polyurethane foams (PUFs) are a significant group of polymeric foam materials. Thanks to their outstanding mechanical, chemical, and physical properties, they are implemented successfully in a wide range of applications. Conventionally, PUFs are obtained in polyaddition reactions between polyols, diisoycyanate, and water to get a CO2 foaming agent. The toxicity of isocyanate has attracted considerable attention from both scientists and industry professionals to explore cleaner synthesis routes for polyurethanes excluding the use of isocyanate. The polyaddition of cyclic carbonates (CCs) and polyfunctional amines in the presence of an external blowing agent or by self-blowing appears to be the most promising route to substitute the conventional PUFs process and to produce isocyanate-free polyurethane foams (NIPUFs). Especially for polyhydroxyurethane foams (PHUFs), the use of a blowing agent is essential to regenerate the gas responsible for the creation of the cells that are the basis of the foam. In this review, we report on the use of different blowing agents, such as Poly(methylhydrogensiloxane) (PHMS) and liquid fluorohydrocarbons for the preparation of NIPUFs. Furthermore, the preparation of NIPUFs using the self-blowing technique to produce gas without external blowing agents is assessed. Finally, various biologically derived NIPUFs are presented, including self-blown NIPUFs and NIPUFs with an external blowing agent. [ABSTRACT FROM AUTHOR]

In this work, a facile and efficient strategy known as 'dynamic self-vulcanization of dual difunctional monomers' was reported to toughen poly(lactic acid) (PLA) with in-situ formed crosslinked bio-polyurethane (PCPUE) phase from plant oil-derived hydrogenated dimer diol (Pripol) and hexamethylene diisocyanate (HDI). By simply adjusting equivalent ratios (n NCO / n OH) of complementary functional groups between these two difunctional toughening monomers from 1.0 to 2.2 while fixing their total feeding content at 20 wt%, the notched impact strength (IS) and phase morphologies of PLA blends can be tailored in a broad range. When the ratio reached 1.6, the maximum IS value up to 87.1 kJ/m2 (about 28 times that of neat PLA) was achieved with an elongation-at-break of ~223 %. Based on the analysis on reaction mechanism and phase morphologies, the optimum interfacial compatibility between PLA and PCPUE phases in junction with the proper crosslinking density of rubbery PCPUE phase was considered to be responsible for such a remarkable improvement in impact toughness. [Display omitted] • Dynamic self-vulcanization system of dual monomers was developed to toughen PLA. • Plant oil-based flexible diol and HDI were used as precursors for bio-PU toughener. • Phase structure can be tuned by altering molar ratios of the dual monomers. • The maximum impact strength up to 87.1 kJ/m2 was achieved for the PLA/bio-PU blends. [ABSTRACT FROM AUTHOR]

• Biobased fertilizers offer 120-day nitrogen release at a 4 wt% coating ratio. • Biowaste-derived bionanocomposite can coat urea for well-tunable nitrogen release. • A mathematic model is built to design tailored slow-release porous materials. • This BCRF offers extended N-release, cost-efficiency, and tunability. Controlled-release fertilizers (CRFs) present a promising solution for alleviating food and nutrient scarcity. However, their development has been mainly hindered by both rapid and unsynchronized nutrient release and unsustainable coating materials. In this study, we address this issue by developing a new coating layer for CRFs using a programmable biopolyurethane nanocomposite. This nanocomposite is prepared from diphenylmethane diisocyanate (MDI)-functionalized bentonite nanoclay (BNT-MDI) and a biopolyol from biomass waste. The results show that the BNT-MDI-doped CRFs (BCRFs) exhibit an impressive nitrogen (N)-release longevity of approximately 120 days at a 4 wt% coating ratio, surpassing previous CRF formulations. In a 30-day snap bean cultivation study, BCRF significantly improved root length (1000 %), leaf length (257 %), leaf width (400 %), and plant height (1400 %) compared to the control. The superior performance of BCRF is attributed to the PU-nanoclay biocomposite film, with full nano-exfoliation, controllable porosity, and high crosslinking density. Furthermore, we introduce a new dynamic release mechanism and establish a quantitative relationship between the nanostructure, property, and release performance of BCRF by combining the multiplicative and diffusion models for porous materials. This study provides a theoretical framework and a straightforward methodology for designing programmable nanocomposite structures for future biobased CRFs. [ABSTRACT FROM AUTHOR]

A lignin-based PU coating was prepared for paper-based green packaging. Two representative diisocyanate were used to prepare the coatings. Due to the rigid aromatic, the physical properties of the TDI system reached the maximum below the lignin content of 40%. The HDI that contains flexible aliphatic chains alleviated the brittleness of coating, and it showed physical advantages when the lignin content was more than 50%. Owing to the high lignin content, the coating presented enhanced thermal stability. After coated with the lignin-based PU coatings, the dry tensile strength of coated paper was improved by 126%. Amazingly, the wet strength was increased from 0.31 to 12.6 MPa with an improvement nearly 40 times. Based on the coordination of lignin, Ag+ was introduced into the PU matrix, which imparted the coating with excellent antibacterial ability. The colony forming units of E. coli and S. aureus were both less than 1. However, no inhibition halo was observed, which indicated that the Ag was firmly anchored on the coating and the antibacterial ability is only available when the bacterial contact the coating surface. The lignin-based PU coating with favorable sustainability and properties shows great potential in paper-based green packaging fields. The prepared PU coating with high lignin content and firmly anchored Ag+ exhibits outstanding physical properties, thermal stability, and antibacterial property, which makes it an ideal candidate to be used in paper-based green packaging. [Display omitted] [ABSTRACT FROM AUTHOR]

Biobased thermosetting polymers have attracted interest owing to their renewable source materials, long service life, and properties comparable to those of petroleum-based materials. However, the fabrication of those that merge exquisite mechanical properties with fast self-healing performance has not been demonstrated to date. In this work, a biobased polyurethane coating was constructed using curcumin dioxime (CD), castor oil (CO), and isophorone diisocyanate (IPDI) to fulfill these features. The biobased CD monomer was prepared using curcumin and hydroxylamine hydrochloride and confirmed by nuclear magnetic resonance, flourier-transform infrared (FT-IR) spectra, and high-resolution mass spectrometry (HR-MS). To investigate the correlation between the mechanical properties and self-healing performance, a series of polyurethane coatings were fabricated by varying the ratio of CO to CD. The results showed that the crosslinking density (v e), glass transition temperature (T g), and Young modulus of these coatings increased with the decrease in the ratio of CO to CD, leading to tunable mechanical properties. In particular, the tensile strength and elongation of the COPU-4 coating were as high as 17.2 MPa and 295 %, respectively. The stress relaxation experiments revealed that these coatings exhibited low activation energy (E a), as low as 28.3 kJ/mol for COPU-5. Besides, all COPU-X coatings demonstrated self-healing efficiency higher than 71 % within 1 min at 90 °C, and some of them even reached >90 % after 8 min. The results demonstrate the promising tunable mechanical and excellent self-healing properties of these novel biobased polyurethane coatings and pave the way for the development of bioderived sustainable thermosetting polymers. [Display omitted] • A fully biobased CAN was fabricated using curcumin dioxime (CD) and castor oil (CO). • The CD/CO ratio was varied to investigate the relationship between mechanical properties and self-healing performance. • All the synthetic polyurethane coatings displayed impressive self-healing efficiency of >71 % in only 1 min at 90 °C. [ABSTRACT FROM AUTHOR]

This review article is based on the recent trends and development of biobased polyurethane (PU) adhesives from vegetable oil. A detail discussion has been reported about the PU adhesive starting from petroleum based to biobased source. Special attention has been given towards the utilization of castor oil based PU in adhesive technology, due to the wide range of castor oil among all vegetable oil. The appreciable adhesion, mechanical, thermal properties of vegetable oil based PU adhesives were compared with petroleum based PU adhesive, which were utilized to meet the specific application in adhesion industry. [ABSTRACT FROM AUTHOR]

Castor oil based transparent polyurethane elastomers were synthesized, which can be used as an advanced catheter material. The effect of NCO: OH ratio on the structural, optical, thermal and physicomechanical properties of polyurethanes (PU) has been studied. The optical properties of the PU was analysed by studying its percentage transmittance and haze. The results showed a high transparency of 90.7% for the PU with a NCO: OH ratio of 0.9:1. Differential scanning calorimetry (DSC) analysis revealed an increase in the glass transition temperature (Tg) of PU with increasing hard segment content whereas thermogravimetric analysis (TGA) shows an increase in the initial decomposition temperature of PU from 262 to 268°C upon increasing the NCO: OH ratio from 0.9 to 1.5. A similar trend of increment in the tensile properties of PU has been observed as a consequence of increasing the molar ratio of NCO: OH. In vitro cytotoxicity analysis of PU was studied using human embryonic kidney (HEK293) cell line that revealed the nontoxic character of PU. [ABSTRACT FROM AUTHOR]

In the current study, biobased polyurethane (PU) adhesives at three different stoichiometric ratios of hard (NCO) to soft segment (OH) (1.1:1, 1.3:1, 1.5:1) were prepared by reacting castor oil (CO) based polyol with partially biobased polyisocyanate (PBPI) in the presence of dibutyltin dilaurate (DBTDL) as catalyst. The synthesis of PU adhesive films such as CO-PU, CO-PU, and CO-PU was confirmed by Fourier transform infrared (FTIR) spectroscopy. The effect of stoichiometric ratios on the bonding strength of wood-to-wood substrate was studied using lap shear strength test. The change in lap shear strength of PU adhesive films subjected to acid and alkali solution was tested. The chemical resistance, surface properties and wetting energies of PU adhesive films were evaluated using scanning electron microscopy (SEM) analysis and contact angle measurement. Thermal stability and activation energy of the films were determined employing thermogravimetric analysis (TGA). The experimental result showed that CO-PU exhibited higher adhesive strength, where as CO-PU exhibited higher thermal stability. [ABSTRACT FROM AUTHOR]

In the present work, biobased polyurethane (BPU) polymers at different NCO: OH molar ratio were synthesized using castor oil based polyol and palm oil derived partially biobased aliphatic isocyanate (PBAI) with and without catalyst. The curing time of BPUs was studied employing attenuated Fourier transform infrared spectroscopy (AT-FTIR). The glass transition temperature (Tg) of the cured films of BPUs were evaluated using dynamic mechanical analysis (DMA) analysis. The higher glass transition temperature (Tg) was observed in biobased polyurethane with catalyst (BPUW) as compared with biobased polyurethane without catalyst (BPUWT). Cross linking densities of the BPUs were calculated by utilizing kinetic theory of rubber elasticity and found be higher in presence of catalyst. Further, the surface properties were studied using contact angle measurement. [ABSTRACT FROM AUTHOR]

High solids content polyurethane (PU) nanocomposites with enhanced thermal and mechanical properties were produced by incorporating of low fractions of cellulose nanocrystals (CNC) in a solvent-free process. This involved the use of a simple procedure to produce well dispersed and stable suspensions of CNC in biobased polyols, which were then used to produce PU-CNC nanocomposites. Transmission electron microscopy revealed that individual CNC particles were dispersed homogenously within the PU matrix. FTIR results suggested that CNC particles are covalently bonded to the PU molecular chains during polymerization. The thermal mechanical properties of the nanocomposites are significantly improved over pure PU as indicated by differential scanning calorimetry and dynamic mechanical analysis. Compared to pure PU, the PU nanocomposites made with the addition of only 0.5% of CNC had glass transition temperatures that were 6 °C higher, their Young's moduli were about 10% higher and their abrasion resistance was higher by about 25%. The optimal composition contains only 0.5% CNC (w/w) which indicates that there is good potential for utilization of low levels of CNC for reinforcement of PU composites made using biobased polyols. [ABSTRACT FROM AUTHOR]

In this study, novel bio-based polyurethanes that have characteristics of both thermosets and thermoplastics were prepared. The polyol functionalized by a high number of hydroxyl groups was synthesized and its application in polyurethanes, a well-known polymer in coating industry, was investigated. Sunflower oil was decorated for the first time with propargyl groups by ring-opening of epoxied groups using boron trifluoride diethyl etherate as catalyst. The polyol is obtained by photochemical thiol-yne coupling functionalization of propargylated oil in presence of mercaptoethanol in an economical, and environmental friendly procedure. The chemical structure of this sunflower based polyol and its intermediates were determined by 1 H NMR and FT-IR analysis. A series of polyurethanes containing various NCO/OH molar ratio were synthesized by a one-step procedure. The properties of the polyurethanes were studied by performing tensile testing, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). A facile and green method for the synthesis of bio-based polyurethanes and their application as a transparent coating made them exponentially advantageous. [ABSTRACT FROM AUTHOR]

A new biobased polyurethane formulation containing furan was synthesized and subsequently functionalized and de-functionalized via Diels-Alder and retro Diels-Alder reactions. Furan was inserted in the backbone polymer using 2,5-bis(hydroxymethyl)furan as chain extender. At the same time, another composition not containing furan was synthesized as reference. Both formulations were produced initially as films and then processed using electrospinning to obtain nanofibers membranes. The absence of catalysts, the high renewable content, the facile synthesis and spinnability of the polymer allow a quantitative and green production of versatile functionalizable platforms. The kinetic and efficiency of the functionalization were assessed using two different compounds: Fluorescein-5-maleimide and 3-Maleimidopropanoic acid. The high hydrophobicity of the membranes permits to perform the functionalization reactions in water, resulting in a process that minimally affects the membrane integrity which is, at the same time, environmental-friendly. Finally, the good biocompatibility opens the way for its use as biomedical tissue, widening the range of possible application of this material. [Display omitted] • Biobased polyurethane containing furan was successfully synthesized and, through electrospinning, membranes were obtained. • The membranes were functionalized with different maleimide-containing compounds using Diels-Alder cycloaddition (DA). • The kinetic of direct and retro DA were followed using UV–vis spectroscopy. [ABSTRACT FROM AUTHOR]

Biobased polyurethanes from soybean oil–derived polyols and polymeric diphenylmethane diisocyanate (pMDI) are prepared and their thermomechanical properties are studied and evaluated. The cross-linked biobased polyurethanes being prepared from soy phosphate ester polyols with hydroxyl contents ranging from 122 to 145 mg KOH/g and pMDI within 5 min of reaction time at 150°C in absence of any catalyst show cross-linking densities ranging from 1.8 × 103 to 3.0 × 103M/m3, whereas glass transition temperatures vary from approximately 69 to 82°C. The loss factor (tan δ) curves show single peaks for all these biobased polyurethanes, thus indicating a single-phase system. The storage moduli (G′) at 30°C range from 4 × 108 to 1.3 × 109 Pa. Upon postcure at 150°C, the thermomechanical properties can be optimized. Cross-link densities are improved significantly for hydroxyl content of 139 and 145 mg KOH/g at curing time of 24 h. Similarly, glass transition temperature (Tg) and storage moduli around and after Tg are increased. Meanwhile, tan δ intensities decrease as result of restricted chain mobility. Longer exposure time (∼24 h) induces thermal degradation, as evidenced by thermogravimetric analysis (TGA). The dynamic mechanical (DMA) analysis shows that postcure at 100°C for times exceeding 24 h also leads to improved properties. However, cross-linking densities are lower compared to postcure carried out at 150°C. [ABSTRACT FROM AUTHOR]

• Biobased self-healing PU coating with Zn micro-flakes were applied on AA7475. • E OCP values and current density/pH monitoring proved zinc was an anodic inhibitor. • Corrosion protection was better in the presence of 7.5 wt% Zn in the coating. • The self-healing and corrosion inhibition effects were confirmed by SVET/SIET, LEIS. AA7475 is a modern and competitive high strength alloy of relevance to the aerospace industry. In this work biobased organic polyurethane coatings were prepared from vegetable oils (crambe oil and castor oil) without (blank coating) and with incorporation of Zn micro-flakes to impart corrosion inhibition. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (FTIR-ATR) confirmed the incorporation of zinc in the polymeric matrix and atomic force microscopy (AFM) confirmed the coating homogeneity. The barrier properties of the coatings were studied by electrochemical impedance spectroscopy (EIS) and indicated better corrosion resistance for the sample with the highest content of Zn micro-flakes. Localized electrochemical techniques, namely the scanning vibrating electrode technique (SVET), pH micro-potentiometry (or scanning ion-selective electrode technique - SIET) and localized electrochemical impedance spectroscopy (LEIS) permitted to discriminate the details of the corrosion inhibition process. The results demonstrated that the Zn-containing coatings provide effective corrosion protection of the AA7475 and the protective ability improved significantly in the presence of 7.5 wt% Zn micro-flakes in the coating. [ABSTRACT FROM AUTHOR]

In this work, different thermoresponsive biobased polyurethane (PU) bionanocomposites with chitin nanocrystals (CHNCs) are prepared. The behavior of the biobased PU used as matrix differs from common polyurethanes, since hard segment is constituted by the macrodiol and soft segment by a biobased diisocyanate and chain extender. The effect of CHNC content on shape‐memory behavior is studied. It is observed that CHNCs tend to interact with diisocyanate/chain extender rich domain. In addition, an increase of the overall crystallinity of the material is also observed. Therefore, the addition of CHNCs contributes to the shape recovery of the bionanocomposites, as well as to shape fixity at high CHNC content. Finally, the cytotoxicity, hemocompatibility, and cell adhesion analysis reveals that the prepared bionanocomposites show potential to be used in biomedical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47430. Thermo‐activated shape‐memory response of a polyurethane bionanocomposite with a 3 wt% of chitin nanocrystals. [ABSTRACT FROM AUTHOR]