Castor Oil-based Polyurethane Research Articles

Study on Castor Oil-based Cationic Waterborne Polyurethane and Its Application

The raw material for polyurethane synthesis is mainly polyols, while traditional polyols come from fossil resources. With the decrease of fossil resources, the synthesis of polyurethane by vegetable oil-based polyols has gradually gained more attention. Castor oil is a kind of plant oil-based polyols, which are the most suitable plant oil polyols because of its non-toxic, biodegradable and trihydroxy structure. Polyurethane synthesized with castor oil as a polyol has many special properties, such as good antibacterial properties, anti-UV properties, good biocompatibility and biodegradable properties. This paper explores the performance and application of castor oil-based cationic waterbased polyurethane (CWPU), which is helpful to promote its performance research and wider application.

Controlled-release fertilizers with an ultralow coating content

The controlled-release fertilizers with superior controlled-release performance and an extremely low coating content were fabricated using castor oil-based polyurethane coatings, followed by dual superhydrophobic modification.

Particleboard Composite Made from Pinus and Eucalyptus Residues and Polystyrene Waste Partially Replacing the Castor Oil-Based Polyurethane as Binder

Particleboard Composite Made from Pinus and Eucalyptus Residues and Polystyrene Waste Partially Replacing the Castor Oil-Based Polyurethane as Binder

High-performance castor oil-based polyurethane thermosets: Facile synthesis and properties

With the growing concern on the shortage of fossil resources and the environmental problems associated with their use, vegetable oils as renewable resources are important alternatives to fossil resources. Here, we used castor oil to synthesize 1-thioglycerol modified castor oil polyol with ultra-high hydroxyl value up to 463 mg KOH g−1 via a solvent-free thiol-olefin click reaction. The cross-linked polyurethanes were prepared from this polyol in a solvent-free and catalyst-free manner, and exhibited high tensile strength of ∼83 MPa and Tg of ∼124 °C, much higher than other reported vegetable oil-based polyurethanes. Besides, the obtained polyurethanes exhibited excellent coating and optical properties, much better than the polyurethane from the unmodified castor oil. This work provides a green and high-efficient method of synthesizing vegetable oil-based polyol with ultra-high hydroxyl value to construct high-performance polyurethanes, which will expand the application of vegetable oil-based polymers.

Preparation of SiO2-decorated GO sheets and their influences on the properties of castor oil-based polyurethane coating film

Graphene oxide (GO) acted as an inorganic filler has attracted great attention in the construction of polymer-based composite coating film. Nevertheless, the high surface area, obvious van der Waals forces, and abundant hydrophilic groups of GO result in its poor dispersion behavior and compatibility in hydrophobic polymer, which greatly limits its widespread practical application. To solve the above issue, we have prepared SiO2-decorated GO (GO-SiO2) nanoparticles using the sol-gel hydrolysis method. The FTIR, Raman spectra, XPS and SEM analysis displayed that GO-SiO2 nanoparticles were successfully constructed and the SiO2 nanoparticles are covalently grafted onto GO sheet surfaces. Moreover, the GO-SiO2 nanoparticles are further employed as inorganic fillers into the non-solvent UV-curable castor oil-based polyurethane acrylate (COPUA) systems for the preparation of composite coating films. Herein, the GO-SiO2 nanoparticles can be uniformly dispersed in hydrophobic COPUA-based coating precursor, and have favorable compatibility with COPUA resin. The incorporation of GO-SiO2 nanoparticles into the coating film matrix would slightly decrease the gel content of coating films (all gel contents are above 91.5 %) while improving the hydrophobic property of coating films. Furthermore, the thermal stability and mechanical performance of coating films have reasonably enhanced trends by the incorporation of GO-SiO2 nanoparticles. The prepared coating films display favorable acid, alkali, and solvent resistance, and the high content of GO-SiO2 nanoparticles is beneficial to aggrandize the anticorrosion performance of coating films. This work provides a universal approach to modify GO sheets and construct multifunctional modified GO/polyurethane composite film for coating application.

Properties of Luffa Cylindrica Mats Reinforced Castor Oil-Based Polyurethane Composite as an Alternative for Oriented Strand Board.

The main objective of this work was to produce and characterize a novel ecofriendly castor oil-based polyurethane (COPU) matrix composite reinforced by Luffa cylindrica mats, luffa for short, to be used as panels, as an alternative to oriented strand board (OSB). To do so, the mechanical behavior was evaluated by tree point flexural, perpendicular o surface tensile, screw pullout, and impact tests that were carried on the novel composite along with the neat matrix. Furthermore, the physical characteristics, the thermomechanical behavior, and the functional groups of the materials were observed by water absorption and thickness swelling tests along with dilatometry and Fourier transform infrared spectroscopy (FTIR). A comparison with commercialized OSB was also performed for control. The luffa/COPU composite was prepared by hand lay-up with 48 vol% of luffa mats incorporated as the maximum allowed by the mold under the available resources for manufacturing. The luffa fibers acted as a good reinforcement for the COPU matrix, where the flexural strength and modulus of elasticity were increased by more than 23 and 10 times, respectively, and the other mechanical properties more than doubled for the composites compared to the neat COPU resin. In general, the composite presented a lower performance compared to the commercial OSB, with the impact results being the exception. The water absorption and thickness swallowing results showed an already-expected behavior for the studied materials, where the better performance was found for the hydrophobic neat resin. The FTIR revealed that there was little interaction between luffa and COPU resin, which can be translated to a weak interface between these materials. However, the mechanical behavior, together with the other results presented by the luffa/COPU composite, confirm it is more than enough to be used as civil construction panels such as OSB.

Study of the Influence of Heat Treatment on OSB Panels Produced with Eucalyptus Wood in Different Layer Compositions

In view of the lack of studies aimed at producing and assessing the effects of heat treatment of Oriented Strand Board (OSB) panels, this paper evaluated the thermal degradation kinetics of the raw materials, and the physical and mechanical properties of the panels made with eucalyptus wood and castor oil-based polyurethane adhesive. The OSB panels were subjected to post-production heat treatment (at 175 and 200 °C), replacing the use of wood chemical preservatives. Furthermore, the quantity of materials varied in the face:core:face layers in the proportions of 25:50:25 and 30:40:30, aiming to evaluate the possibility of structural applications for the panels. The results were statistically analyzed and compared with the specifications and classifications for OSB indicated by the European Standard EN 300 and the literature. The application of heat treatment improved the physical properties by decreasing the interaction with water and did not reduce the mechanical properties below the recommended levels. The variation in layer proportions indicated that all of them can be adopted without compromising the panel’s physical-mechanical performance. All treatments are compatible with the EN 300 classification for OSB/4 (heavy duty load-bearing boards for use in humid conditions), presenting technical feasibility and excellent structural profile for civil construction applications.

Biobased Castor Oil-Based Polyurethane Foams Grafted with Octadecylsilane-Modified Diatomite for Use as Eco-Friendly and Low-Cost Sorbents for Crude Oil Clean-Up Applications.

Herein we report the synthesis and characterization of novel castor oil-based polyurethane (PU) foam functionalized with octadecyltrichlorosilane (C18)-modified diatomaceous earth (DE) particles, exhibiting superior hydrophobicity and oil adsorption, and poor water absorption, for use in effective clean-up of crude oil spillage in water bodies. High-performance and low-cost sorbents have a tremendous attraction in oil spill clean-up applications. Recent studies have focused on the use of castor oil as a significant polyol that can be used as a biodegradable and eco-friendly raw material for the synthesis of PU. However, biobased in-house synthesis of foam modified with C18-DE particles has not yet been reported. This study involves the synthesis of PU using castor oil, further modification of castor oil-based PU using C18 silane, characterization studies and elucidation of oil adsorption capacity. The FTIR analysis confirmed the fusion of C18 silane particles inside the PU skeleton by adding the new functional group, and the XRD study signified the inclusion of crystalline peaks in amorphous pristine PU foam owing to the silane cross-link structure. Thermogravimetric analysis indicated improvement in thermal stability and high residual content after chemical modification with alkyl chain moieties. The SEM and EDX analyses showed the surface's roughness and the incorporation of inorganic and organic elements into pristine PU foam. The contact angle analysis showed increased hydrophobicity of the modified PU foams treated with C18-DE particles. The oil absorption studies showed that the C18-DE-modified PU foam, in comparison with the unmodified one, exhibited a 2.91-fold increase in the oil adsorption capacity and a 3.44-fold decrease in the water absorbing nature. From these studies, it is understood that this novel foam can be considered as a potential candidate for cleaning up oil spillage on water bodies.

Controllable release fertilizer with low coating content enabled by superhydrophobic castor oil-based polyurethane nanocomposites prepared through a one-step synthetic strategy

Although the inherent degradability and sustainability of bio-based polymers make them promising coating candidates for controlled-release fertilizer (CRFs), large amounts of coating materials (coating content usually above 5%) and complex modification process are usually required to achieve controllable-release characteristics, which increases the production costs and therefore limits their application. In this study, superhydrophobic castor oil-based polyurethane/carbon black nanocomposites was developed through a one-step synthetic strategy to synthesize CRFs with low coating content by a three-layer rotating-drum coating method. The effect of the carbon black content and layer distribution on contact angles, physicochemical properties, microstructure, and release characteristics of the resulting coating material and CRFs was characterized and discussed. The contact angle of the polyurethane nanocomposites can reach up to 152.6°. In addition, the N release longevity of the coated urea fertilizer was extended to 30 days, definitely meeting the standards for CRFs using low coating content of 3 %. The coated fertilizers presented Super Case II transport mechanism. The mechanism underlying the controlled-release of this coated fertilizer was explored and discussed. The technique reported here offers a number of advantages, including low cost, easy performance, and excellent controllable-release performance, opening numerous opportunities for widely application of this environmentally-friendly, green CRF.

Influence of natural exposure on castor oil based polyurethane reinforced with waste tire rubber

Waste tire rubber (WTR) has been extensively generated worldwide due to mobility needs growth. About 1.5 billion units are generated annually, constantly discharged in the environment with a few reusability alternatives. Therefore, rubber recovery methods and these residues’ transformation into a cost-effective product have gained attention. Aiming to minimize the usage of fossil resources and contributes to a circular economy, it was analyzed the usage of WTR particles (5–20% by weight) in castor oil-based polyurethane foams under natural aging to promote a holistic view of all factors involved in the performance of the foams. Morphological, thermal, chemical, and mechanical properties were determined before and after exposure to open air to observe the impact of photo-oxidation and hydrolysis. The increase in viscosity of pre-polymer during the rubber loading produced greater density foams with smaller cell sizes than neat PU, in which the average cell size increased after the weathering. The rubber contributes to enhancing the compressive behavior in the non-exposed samples. After exposure, the results suggest that degradation may act to increase the crosslinking density even with the presented structural changes such as yellowing and voids. Regarding thermal stability, the rubber promotes a slight decay in the ability to resist a heat flow before and after weathering. Still, the char yield increased, showing a possibility of better fire retardancy for composites. FTIR and UV–vis showed chemical structure changes as Photo-Fries network rearrangement, Norrish I random chain scission, and Norrish II β-scission. Besides, UV–vis revealed the maximum absorbance in the UVB region, showing that the PU reinforced by WTR can be a promising material for civil coatings.

Surface modification of pyrophyllite for optimizing properties of castor oil-based polyurethane composite and its application in controlled-release fertilizer

The high cost and difficulty in sustainability have hindered the wide application of the general synthetic resins in the controlled-release fertilizers (CRF). Here, the degradable castor oil-based polyurethane (PU) was filled by the natural pyrophyllite (PY) powders, which were pre-modified with few amount (≤0.5 %) of NDZ-201 coupling agent though a simple and economic mechanochemical method. Furthermore, the composite materials of PU and the modified PY (MPY/PU) with enhanced comprehensive properties were prepared and applied in CRF. Moreover, the release behaviors of the coated fertilizers were investigated while tuning the addition amount of modifier or the filling amount of MPY, and it was confirmed that the release performance was highly depended on the hydrophobic and mechanical properties of the composite coating. As a result, the best optimized MPY/PU coating exhibited significantly superior performance to the pure PU materials, and the duration of 80 % nitrogen release was more than 40 days. This confirms that the MPY/PU composite is a promising coating material for the CRF granules.

Castor oil-based waterborne polyurethane/tunicate cellulose nanocrystals nanocomposites for wearable strain sensors

In this study, tunicate cellulose nanocrystals (TCNCs) were introduced into castor oil-based waterborne polyurethane (WPU) to prepare bio-based nanocomposites through a simple solution blending method. The effect of TCNCs content on the particle size and stability of the composite dispersions, as well as the thermophysical and mechanical properties of the composite films were studied and discussed. The unique structure and properties of TCNCs, such as high crystallinity, large aspect ratio and high modulus, not only greatly improved the storage stability of WPU, but also showed significant reinforcing/toughening effects and excellent compatibility to WPU. By drip-coating silver nanowires (AgNWs) on the surface of the composite films, the flexible strain sensors were fabricated, which showed excellent sensitivity in monitoring human movement.

Self-healing castor oil-based polyurethane networks featuring cyclodextrin–adamantane host–guest interactions

Self-healing castor oil-based polyurethane networks featuring cyclodextrin–adamantane host–guest interactions

Curcumin-based waterborne polyurethane-gelatin composite bioactive films for effective UV shielding and inhibition of oil oxidation

Introducing natural products to obtain ultraviolet (UV) shielding materials for inhibiting the photo-oxidation of oily foods is environmentally friendly food technology. Instead of traditional physical mixing, curcumin was introduced into castor oil-based waterborne polyurethane as a chain extender and compounded with gelatin for bioactive composite films. With the increase of curcumin-based waterborne polyurethane (CWP), the film with 10 wt% CWP achieved nearly complete ultraviolet shielding. The swelling index and water solubility were reduced by 800% and 12.93%, respectively. The tensile strength and elongation at break increased by 183% and 114%, respectively. In addition, CWP enhanced the antioxidant activity of curcumin in water system by 52.10% and reduced the oxidation degree of soybean oil by 62.03–87.84%. This work provides a new idea for compounding natural active small molecules with polymers. • Curcumin was introduced into the waterborne polyurethane as a chain extender. • CWP was compounded with gelatin to obtain antioxidant packaging film WGA. • A small amount of CWP can achieve high transparency and complete UV shielding. • Water resistance,mechanical properties and antioxidant activity were optimized. • WGA film could effectively inhibit the photo-oxidation process of soybean oil.

Biobased dynamic polymer networks derived from castor oil and anhydrous piperazine

The development of castor oil-based polyurethanes has been restricted significantly because they have poor mechanical properties and cannot be reprocessed or recycled owing to their soft backbone combined with irreversible crosslinked structures. Herein, we synthesized novel castor oil derived dynamic polymer networks (DPNs) based on reversible piperazine-urea bonds, which were obtained by reacting isocyanate group with inexpensive anhydrous piperazine . The six-membered heterocyclic bifunctional piperazine acted as structural modifier to adjust the network stiffness and crosslink density and thus the mechanical properties of the DPNs. Soft, tough and even hard DPNs could be obtained easily by changing the feed content of piperazine. The reversible piperazine-urea bonds imparted DPNs with excellent malleability, reprocessability, and recyclability. In addition, the DPNs showed excellent solvent resistance, thermal stability, and durability. This study provides an important guidance for the synthesis of vegetable oil derived polymer networks that integrate tunable mechanical properties, reprocessability, and recyclability. • Castor oil-derived dynamic polymer networks (DPNs) were synthesized by incorporating piperazine-urea bonds. • The mechanical properties of the DPNs were tailorable by changing the content of incorporated piperazine-urea bonds. • The DPNs showed excellent malleability, reprocessability, durability and thermal stability.

COMPARATIVE STUDY OF PARTICLEBOARDS WITH HEVEA BRASILIENSIS WASTE FROM DIFFERENT PRODUCTION AND MOISTURE CONFIGURATIONS

After the production cycle of latex, Hevea brasiliensistrees becomeresidual living plants for this activity, although their woody trunks are still potentially subject to industrial utilization. Bio-composites derived from rubberwood particles were manufactured using two different configurations as a strategy to examine the potential of this species with respect to mechanical behavior. Homogeneous panels were developed from particles at the saturation condition, and heterogeneous panels were obtained from dry particles conditioned at 12% moisture content. Both examples were heat-pressed and glued with castor oil-based polyurethane resin. Density, short-term water absorption and thickness swelling, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile were evaluated. Panels derived fromrubberwood particles proved to be viable according to the technical standards.

Comparative Study of Plywood Boards Produced with Castor Oil-Based Polyurethane and Phenol-Formaldehyde Using Pinus taeda L. Veneers Treated with Chromated Copper Arsenate

Plywood is widely used in civil construction. Due to the importance of preservation and gluing in bio-composites, this study compares the influence of a chemical treatment with CCA (chromated-copper-arsenate) on Pinus taeda L. wood veneers to produce two plywood types using phenol-formaldehyde (PF) and castor oil-based polyurethane (PU). Four different treatments were performed to analyze both varieties’ physical and mechanical properties. As a result, an improvement in the properties of the treated panels was observed. Lower moisture contents and better interactions caused by less thickness swelling and water absorption were identified in the PU-based plywoods. The treatment with CCA was efficient, improving these properties when they were compared to the reference panels. Most treatments evidenced increases in the modulus of elasticity and modulus of rupture for both adhesives when the CCA treatment was applied to the veneers. Comparing the resins, the PF showed the best values of modulus of elasticity. All treatments met the requirements defined by the Brazilian standard document for the glue line shear.

Particleboards manufactured from Tectona grandis wood waste with homogeneous and three-layer heterogeneous compositions for commercial purposes

Tectona grandis wood presents decent dimensional stability as well as highly suitable physical and mechanical properties. These characteristics have encouraged the intense usage of this species, which also includes the reuse of wood processing waste for panel production. Using teak wood waste, this study aims to manufacture and evaluate heat-pressed particleboards at 5 MPa and 100 °C, by being glued with castor oil-based polyurethane resin at proportions of 10% for the homogeneous boards and 12% for the heterogeneous solutions. Single-layer (homogeneous) boards were compared with three-layer particleboard specimens (heterogeneous) having the finer particles in the outer layers. The basic density, moisture content, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile, water absorption, and thickness swelling after 24 h were evaluated to support this comparative study. All the manufactured particleboards met the standardized requirements of performance, thus being very feasible for usage as non-structural boards. When the two different compositions were analyzed, a considerably better performance of the three-layered particleboards was identified when compared to the homogeneous panels.

Bio-based castor oil and lignin sulphonate: aqueous dispersions and shape-memory films

Aqueous polyurethane dispersions based on castor oil and lignin sulphonate (LS) were successfully synthesized in homogenous solution with nanoscale PU-lignin particle sizes as small as 35 nm. The particles size was found to be LS independent, while the dispersion viscosity increases dramatically with increasing the LS content. The increase in viscosity with increasing LS content was explained based on the chemical structure of LS. The LS is a water-soluble material and chemically reacted with diisocyanate to become a part of the dispersion particle (i.e., the nanoparticles is in fact a mixture or copolymer of castor oil-based polyurethane and lignin dispersed in water). The affinity of the PU-LS nanoparticle towards water could be increased with increasing the content of LS. Therefore, the PU-LS nanoparticle can adsorb thick water layer with increasing the LS content. According to this suggestion, the free water in the dispersion would significantly decrease and consequently the dispersion viscosity increases considerably. The cross-link density was also increase with increasing the LS content of the thin films obtained from dispersion cast. The PU-LS thin films obtained from dispersion cast showed an excellent shape-memory effect and the shape recovery was found to be strongly LS dependent. Furthermore, the supper critical CO2 solution was used successfully to create three-dimensional porous structure of PU-LS with cell size depends on LS content. The temporary folded shape of PU-LS with 5 wt.% LS changed to its permanent shape (plane stripe) within just 17 s once the sample was immersed in a water bath at the programing temperature.

Enhancement of the mechanical and acoustical properties of flexible polyurethane foam/waste seashell composites for industrial applications

The importance of this work is the use of waste seashells WSS (5, 10, 15, 20, 25, and 30 wt.%) as a bio-filler to enhance the mechanical and acoustical characteristics of flexible polyurethane foam (FPU). Petroleum-based polyol was partially replaced by 25% castor oil resulting in high renewable content. The WSS was characterized by X-ray photoelectron spectroscopy (XPS). The chemical structure and morphological features for castor oil-based flexible polyurethane waste seashells (CO-FPU-WSS) composites were detected using Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM) techniques, respectively. Besides, the mechanical, non-acoustical and acoustical properties were investigated. The results indicated that bio-based FPU composites possessed better compressive strength than neat FPU foam. In addition, FPU composites enhance the sound absorption below 500 Hz. A 6 cm air gap behind the sample shifted the absorption toward 400 Hz (0.85) for CO-FPU-WSS 25% composite with a broader band. Thus, the FPU foam composite is considered a promising candidate for sound absorption applications such as for the automotive and building industries.