Physical Properties of Polyurethanes Produced from Polyols from Seed Oils: II. Foams

Rigid polyurethane (PU) foams were prepared using three North American seed oil starting materials. Polyol with terminal primary hydroxyl groups synthesized from canola oil by ozonolysis and hydrogenation based technology, commercially available soybean based polyol and crude castor oil were reacted with aromatic diphenylmethane diisocyanate to prepare the foams. Their physical and thermal properties were studied and compared using dynamic mechanical analysis and thermogravimetric analysis techniques, and their cellular structures were investigated by scanning electron microscope. The chemical diversity of the starting materials allowed the evaluation of the effect of dangling chain on the properties of the foams. The reactivity of soybean oil-derived polyols and of unrefined crude castor oil were found to be lower than that of the canola based polyol as shown by their processing parameters (cream, rising and gel times) and FTIR. Canola-PU foam demonstrated better compressive properties than Soybean-PU foam but less than Castor-PU foam. The differences in performance were found to be related to the differences in the number and position of OH-groups and dangling chains in the starting materials, and to the differences in cellular structure.     

Production of Polyols from Canola Oil and their Chemical Identification and Physical Properties

The feasibility of a method based on ozonolysis and hydrogenation reactions for the production of polyols from unsaturated canola oil has been demonstrated. Polyol products with primary alcohol functional groups at position nine of each fatty acid ester in the original triacylglycerol have been produced from canola oil. Short straight-chain alcohols were also produced and were removed by wiped-blade molecular distillation. The pure components of the polyol, i.e. mono-ol, diol and triol were separated by flash chromatography, and identified by Fourier-transform infrared (FTIR), ¹H-nuclear magnetic resonance (NMR), ¹³C-NMR as well as mass spectrometry. Polyol identification was facilitated by the use of a simple high-performance liquid chromatography (HPLC) method to determine the composition of the polyol mixture, which can be exploited as a quality-control mechanism in designing novel polyol feedstocks. Basic correlations were established between the molecular diversity of the polyols and their physicochemical properties, such as hydroxyl number, acidity number, and viscosity. It has been found that the produced polyols are suitable for processing methods employing polyols for the production of polyurethanes and can be manipulated to create polyurethanes with desirable properties.     

Primary Hydroxyl Content of Soybean Polyols

Polyurethanes are obtained by reacting polyols with polyisocyanates. The primary hydroxyl content is a very important characteristic of polyols because it affects their reactivity. Typically primary hydroxyls are approximately threefold more reactive than the secondary hydroxyls when reacting with aromatic isocyanates. This paper presents a simple and convenient kinetic method for determining the primary hydroxyl content in soybean polyols, based on the difference in reactivity of primary and secondary hydroxyls with phenyl isocyanate (PI). The reaction kinetics were studied by following the disappearance of the NCO band at 2260 cm⁻¹ with time in the infrared spectra. The reaction of PI with soybean polyols was carried out in a toluene:dimethylformamide (9:1, v/v) mixture. The relative error of the method is in the range of ±5%. The method is characterized by simplicity and good reproducibility, and it can be applied to all soybean polyols irrespective of their structure.     

Modified Castor Oil Based Polyurethane Elastomers for One-Shot Process

Studies have been carried out on polyurethane elastomers based on modified castor oil in combination with different molecular weights of polyethylene glycol and polymeric methylene diphenyl-4,4′-diisocyanate (PMDI). The resulting polymers were cast into molds and the moldings were characterized by scanning electron microscopy and thermogravimetric analysis. Mechanical properties such as tensile strength, elongation at break, hardness, abrasion resistance, and compression set were measured. There is an increase in the flexibility of polyurethanes with increase in molecular weight of PEGs added to modified castor oil.     

Novel Segmented Thermoplastic Polyurethanes Elastomers Based on Tetrahydrofuran Ethylene Oxide Copolyethers as High Energetic Propellant Binders

Novel thermoplastic polyurethane (TPU) elastomers based on copolyether (tetrahydrofuran ethylene oxide) as soft segments, isophorone diisocyanate and 1,4‐butanediol as hard segments were synthesized for the purpose of using as propellant binders. In order to increase the miscibility of thermoplastic polyurethane elastomers with nitrate ester, polyethylene glycol (PEG) is incorporated in the co‐polyether (tetrahydrofuran ethylene oxide) as soft segment. When the molecular weight and content of polyethylene glycol are controlled to 4000 and 6% of soft segments, respectively, the properties of thermoplastic polyurethane elastomers are most perfect. If plasticizing ratio of nitrate ester to thermoplastic polyurethane elastomers exceeds 4 no crystallinities are determined at room temperature. The propellant samples were prepared by a conventional absorption‐rolling extrusion process and the mechanical and combustion properties evaluated afterwards. The maximum impulse reaches up to 265∼270 s which is a little bit higher than that of a HTPB propellant. The measured results reveal a promising TPE propellant candidate which shows good processing temperature (<393 K) and excellent mechanical properties. An attracting feature which can be pointed out is that the burning rate pressure exponent reaches as low as 0.36 without the addition of burning rate catalysts. This enables an easy control of propellant combustion.     

New T-Shape Polyurethanes: Synthesis,Thermal and Mechanical Properties

A series of new T-shaped polyurethanes were prepared from various diisocyanates and 2,5-dihydroxybenzelidene aniline (azomethine bisphenol). The latter compound was synthesized by the reaction of 2,5-dihydroxy-benzaldehyde with aniline. The structures of azomethine bisphenol and T-shaped polyurethane were confirmed by FT-IR, ¹H-NMR, ¹³C-NMR Spectroscopy and elemental analysis (CHN). The mechanical properties were characterized by tensile strength, tear strength and shore hardness. Thermal properties were also studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mechanical and thermal studies showed that the synthesized polyurethanes possess good mechanical and thermal properties.     

Viscoelastic Properties of a Biological Hydrogel Produced from Soybean Oil

Hydrogels formed from biopolymers or natural sources have special advantages because they may have biodegradable and biocompatible properties. The viscoelastic properties of a newly developed biological hydrogel made from epoxidized soybean oil (ESO) were investigated. The material called HPESO is a hydrolytic product of polymerized ESO (PESO). HPESO exhibited viscoelastic solid or gel behavior above 2% (wt. %) concentration at room temperature and viscous liquid behavior at 55 °C. The thermal assembly disassembly reassembly function of the HPESO hydrogel was completely reversible. The viscoelastic properties of HPESO were dependent on concentration. Analysis of modulus and concentration dependence and stress relaxation measurement indicated that HPESO was a physical gel where the cross-linkers between the molecules were physical junctions. HPESO hydrogel also exhibited fast initial recovery of its viscoelastic properties after being subjected to mechanical shear disruption. The function and behavior of the HPESO hydrogel suggest that this biomaterial may be suitable for applications in drug delivery and scaffolds of bioengineering and tissue engineering. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Influence of Nanogels on Mechanical, Dynamic Mechanical, and Thermal Properties of Elastomers

Use of sulfur crosslinked nanogels to improve various properties of virgin elastomers was investigated for the first time. Natural rubber (NR) and styrene butadiene rubber (SBR) nanogels were prepared by prevulcanization of the respective rubber lattices. These nanogels were characterized by dynamic light scattering, atomic force microscopy (AFM), solvent swelling, mechanical, and dynamic mechanical property measurements. Intermixing of gel and matrix at various ratios was carried out. Addition of NR gels greatly improved the green strength of SBR, whereas presence of SBR nanogels induced greater thermal stability in NR. For example, addition of 16 phr of NR gel increased the maximum tensile stress value of neat SBR by more than 48%. Noticeable increase in glass transition temperature of the gel filled systems was also observed. Morphology of these gel filled elastomers was studied by a combination of energy dispersive X-ray mapping, transmission electron microscopy, and AFM techniques. Particulate filler composite reinforcement models were used to understand the reinforcement mechanism of these nanogels. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

From Castor Oil-Based Multifunctional Polyols to Waterborne Polyurethanes: Synthesis and Properties

A novel castor oil-based multifunctional polyol (CM) is fabricated through mild thiol-ene photo induced reactions using castor oil (CO) and 1-thioglycerol (MPD) as building blocks. The effect of the reaction time, molar ratio of thiol to carbon–carbon double bond, and the loadings of photo-initiator are optimized. The resulting CM is combined with CO and employed as cross-linkers to prepare castor oil-based water-borne polyurethane emulsion with desirable mechanical properties and water resistance. Owing to the incorporation of CM cross-linker with high hydroxyl value of 371 mg KOH/g (which is 2.27 times higher than that of the CO), the prepared castor oil-based waterborne polyurethane (CMWPU) possesses compacted 3D network structure with high cross-linking degree, leading to improved glass transition temperature (45 °C), tensile strength (10.8 MPa), water contact angle (87.4°), and decreased water absorption rate (16.12%) with 20% CM additions. Overall, this work illustrates the feasibility of introducing bio renewable CM combined with CO to develop castor oil-based WPU employing a sustainable development strategy.     

Thermoplastic Polyamide Elastomers: Synthesis,Structures/Properties,and Applications

Thermoplastic polyamide elastomers (TPAEs) have emerged as important thermoplastic elastomer materials with significant potentials owing to their excellent low-temperature flexibility, easy processability, lightweight, good thermal stability and mechanical properties, etc. Over the last few decades, TPAEs have rapidly developed into a large variety of kinds of TPAEs. Striking advancements have been achieved in this research field. Unfortunately, there is not yet a review to summarize the progress. The present paper summarizes the major advancements dealing with TPAEs, in which synthesis, structures/properties as well as applications are introduced in detail. Moreover, current challenges and main developmental directions dealing with TPAEs are also presented. This review may motivate more interest in TPAEs, further facilitating their all-side research and more large-scale applications.     

Waterborne Polyurethane-Acrylate Containing Different Polyether Polyols: Preparation and Properties

The waterborne polyurethane–acrylate (PUA) was prepared based on isophorone diisocyanate, polyether polyol, dimethylol propionic acid, hydroxyethyl methyl acrylate, butyl acrylate (BA) and styrene (St). Fourier transform infrared spectrometry (FT-IR), Ultraviolet-visible spectrophotometry (UV-Vis) and Differential scanning calorimetry (DSC) were employed to investigate the structures, optical transparency and thermal properties. Some physical properties of the aqueous dispersions such as viscosity, particle size and surface tension were measured. Some mechanical performances and solvent resistance of films were investigated. When the ratio of the BA/St was 30/70, the films had excellent water and alkali resistances. The obtained PUA composites have great potential application such as coatings, leather finishing, adhesives, sealants, plastic coatings and wood finishes.     

Thermal and Mechanical Properties of Polyurethanes Derived from Mono- and Disaccharides

Thermal and mechanical properties of polyurethane (PU) sheets pre-pared from the glucose/fructose/sucrose–polyethylene glycol (PEG)–diphenylmethane diisocyanate (MDI) system were examined by differential scanning calorimetry, thermogravimetry, dynamic mechanical analysis and tensile tests. The saccharide content was varied at a constant NCO: OH ratio of 1·0. The glass transition temperature (T_g) increased with increasing saccharide content. The incorporation of saccharides into the PU structure results in a higher crosslinking density and a higher content of hard segments. The thermal decomposition was dependent on the saccharide content, an increase leading to a lower thermal decomposition temperature (T_d). The dissociation of saccharide OH groups and NCO groups is a major part of the thermal decomposition of these PUs. Dynamic mechanical analysis revealed two kinds of relaxation: the high temperature relaxation corresponds to main chain motion and the other is a local mode relaxation due to non-reacted isocyanate groups. The tensile stress and Young’s modulus increased with the saccharide content. © of SCI.     

Synthesis and Comparative Physico-chemical Study of Polyester Polyols Based Polyurethanes of Bisphenol-A and Bisphenol-C Epoxy Resins

Polyester polyols of epoxy resins of bisphenol-A and bisphenol-C were synthesized by reacting corresponding 0.02 mol epoxy resin, and 0.04 mol ricinoleic acid by using 1,4-dioxane (30 ml) as a solvent and 0.5 g triethyl amine as a catalyst at reflux temperature for 4–5 hr. Polyurethanes have been synthesized by reacting 0.0029 mol of polyester polyols with 0.004 mol toluene diisocyanate at room temperature and their films were cast from solutions. The formation of polyester polyols and their polyurethanes are supported by IR spectral data (1732.9–1730.0 cm^?1 ester and urethane and 3440.8–3419.6 cm^?1 OH and NH str). The densities of polyurethane of bisphenol-A (PU-A) and polyurethane of bisphenol-C (PU-C) were determined by a floatation method. The observed densities of PU-A and PU-C are 1.2190 and 1.2308 g/cm³, respectively. Slightly high density of PU-C is due to structural dissimilarity of two bisphenols. The tensile strength, electric strength, and volume resistivity of PU-A and PU-C are 34.7, 18.7 MPa; 80.7, 44.4 kv/mm; and 1.7 × 10¹⁵, 2.2 × 10¹⁵ ohm cm, respectively. PU-A and PU-C are thermally stable up to about 182–187°C and followed three step degradation. Incorporation of cyclohexyl cardo group in polyurethane chain did not impart any change in thermal properties but it caused drastic reduction in tensile and electric strength due to rigid nature of PU-C chains. PU-C has excellent chemical resistance over PU-A. Both polyurethanes possess good resistance against water, 10% each of aqueous acids (HCl, HNO₃, and H₂SO₄), alkalis (NaOH and KOH) and NaCl. Good thermo-mechanical, excellent electrical properties, and good chemical resistance of polyurethanes signify their usefulness in coating and adhesive, electrical and electronic industries.     

Sensory and Physico‐Chemical Properties of Cold Press‐Produced Tomato (Lycopersicon esculentum L.) Seed Oils

In this study, roasted and unroasted (control) tomato seeds were cold pressed and the seeds, oils, and seed presscakes (meals) were analyzed. Some physicochemical properties, total phenolic content and antioxidant capacity, thermal properties, mineral contents, fatty acids, sterols and tocopherols compositions, volatile compounds and sensory evaluation of the tomato seed oils were determined. The tomato seeds contained 3.3 % of ash, 17.3 % of oil and 27.2 % of protein. The cold press oil recovery rate was 7.2 and 10.28 % for control and roasted seeds, respectively. There were eight sensory terms defining the oils together with 34 different aromatic compounds quantified. The volatile compounds furfural, hexanal, benzaldehyde and 2‐isobutylthiazole were found with the highest frequency in the samples. Roasted, green and tomato were defined as characteristic sensory terms for tomato seeds oils. Fifteen different minerals, melting and crystallization temperatures and enthalpies of the oil samples were also quantified. This study provides important data for the tomato seed oils, and proves that pre‐roasted tomato seed oils are high quality, nutritious and aromatics oils with higher levels of consumer acceptability.     

Waterborne polyurethane/inorganic hybrid composites: preparation,morphology and properties

Abstract

A series of waterborne polyurethane/inorganic (WPU/TiO₂) hybrid composites were synthesised by a sol–gel process on the basis of isophorone diisocyanate, polyether polyol (GE-210), dimethylolpropionic acid, tetrabutyl titanate (TBT) and 3-glycidyloxypropyl trimethoxysilane as a coupling agent. The physical properties of the WPU and WPU/TiO₂ dispersions and hybrids were measured. Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy and X-ray diffraction were used to assess the fracture surface morphology and the dispersions of the WPU/TiO₂ hybrids. The scanning electron microscopy, transmission electron microscopy and atomic force microscopy results showed that the TiO₂ particles were dispersed homogeneously in the WPU matrix in nanoscale. The prepared hybrids showed good thermal stability and mechanical properties in comparison with pure WPU and showed tunable transparence with the TBT fraction in the film. Through suitable adjustment of TBT content, some thin hybrids have potential applications, such as coatings, leather finishing, adhesives, sealants, plastic coatings and wood finishes.     

New path in the thermal cracking of triacylglycerols (canola and soybean oil)

Triacylglycerols (TGs) are naturally occurring oils abundant in many crops. A series of batch uncatalyzed thermal decomposition experiments were performed using canola and soybean oils to explore pathways of TG cracking. A detailed gas chromatographic protocol based on mass spectrometric identification and flame ionization quantification was applied to the organic liquid product generated upon cracking. Reaction conditions were identified that resulted in a novel organic liquid product (OLP) composition compared to previously reported work. Under these conditions (temperatures within a 420-440 °C range) a new route for TG thermolysis was discovered in which cracking reactions of original TG-bound fatty acids were nearly complete and led to the formation of 15-25 wt.% C₂-C₁₀ linear saturated monocarboxylic acids and ca. 30% linear alkanes. Less than 2 wt.% C₁₆-C₁₈ fatty acids which were originally present in the feedstocks as glycerol triesters were found in the OLP. These reactions appear to be kinetically controlled due to abundant hydrogen formation. This route provides a significant enrichment of low-MW compounds in the OLP (65-70 wt.% being <C₁₁) and thus may be considered as a new option for the production of replacement products for petroleum-based fuels and chemicals.     

Development of Functional Polyurethane–ZnO Hybrid Nanocomposite Coatings from Thevetia peruviana Seed Oil

The present article reports eco‐friendly multi‐functional polyurethane–ZnO hybrid nanocomposite coatings obtained from Thevetia peruviana seed oil (TPSO). Initially, the polyols were prepared by treating TPSO with glycerol and the formation was supported by Fourier transform infrared (FT‐IR) and ¹H‐NMR studies. In the next stage, siloxane functionalized ZnO nanoparticles were added to the polyol mixture in different weight percentages (0, 1 and 2 %) and then treated with excess 4,4′‐diisocyanatodicyclohexylmethane (H₁₂MDI) in order to synthesize isocyanate terminated polyurethane nanocomposites. The polyurethane hybrids were then casted as thin films and cured under atmospheric moisture. After complete curing they were characterized by using FT‐IR, ¹H‐NMR, ¹³C‐NMR, X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and dynamic mechanical thermal analysis techniques. The hybrid nanocomposites showed superior thermo‐mechanical and anti‐corrosive properties compared to pristine polyurethane. Also, due to the presence of nano ZnO in the polyurethane matrix, the composite coatings are showing excellent resistance towards various bacterial and fungal stains.     

A Study on Structure and Mechanical Properties of Polyurethane/Organic-Montmorillonite Nanocomposites

The intercalated nanocomposites of polyurethane (PU) with organic-montmorillonite (OMMT) treated by cetryltrimethyl ammonium bromide was prepared. The interlayer spacing of PU/OMMT nanocomposites was 3–4 nm. The interface interaction of PU/OMMT nanocomposites was improved compared to that of PU/montmorillonite (MMT) composites. The orderly arrangement of the PU chains was hindered because of strong interface interaction between the silicate layers dispersed in the nanometer and PU chains. By adding 2 wt% OMMT to PU, tensile strength and tear strength of the PU/OMMT composites were increased from 10.5 MPa and 36.4 KN/m to 13.8 MPa and 42.2 KN/m, respectively. The tensile strength and tear strength increased with OMMT content firstly, reaching its maximum when the OMMT content was 8 wt%. After that, the tensile strength and tear strength decreased with the further increase of the OMMT content. Compared to that of PU, the elongation at break of the PU/OMMT nanocomposites increased, indicating that the stretch of PU/OMMT nanocomposites increased.     

Studies on interpentrating polymer networks of polyurethane and polybismaleimide. I. Polyurethane and bismaleimide-urethane copolymer

The interpenetrating polymer networks (IPNs) of polyurethane (PU) and the mixture of bismaleimide (BMI) and the 2-hydroxylethyl methacrylate (HEMA)-terminated PU prepolymer (HPU) were prepared by using a simultaneous polymerization technique. The effects of the PU molecular weight and the amounts of the PU on the mechanical properties, thermal stability, and dynamic mechanical properties are discussed. The IPNs exhibited superior ultimate tensile strength as the polyol of PU and HPU in the IPNs is based on poly(tetramethylene oxide) (PTMO) glycol of molecular weight 1000 (PTMO1000). Izod impact property of the IPNs indicated that the PU(PTMO1000)/BMI-HPU(PTMO1000) IPNs had much more significant improvement than that of the PU(PTM02000)/BMI-HPU(PTMO2000) IPNs. Better thermal stability was shown by the IPNs as compared with the components of the networks, i.e. PU or BMI-HPU copolymers. The dynamic mechanical analysis (DMA) indicates that these IPNs show various shifts in the loss moduli(E) at the high and low temperature transition peaks for various molecular weight of the polyol employed in the PU. Better compatibility between BMI and PU was found as the PU(PTMO1000) was employed.To whom all correspondence should be addressed.