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.     

Synthesis and properties of poly(amide-imide-urethane) thermoplastic elastomers

A new class of poly(amide-imide-urethane) thermoplastic elastomers based on two-step synthesis of 4,4′-methylene bis(4-phenylisocyanate) with different polyols (PPG and PTMG) and trimellitic anhydride was synthesized. Both resulting polymers showed semicrystalline structures and were readily soluble in polar solvents such as N-methyl-2-pyrrolidone and dimethyl formamide. The soluble poly(amide-imide-urethane)s afforded transparent, flexible, and tough films. Both new copolymers were then characterized by FTIR spectroscopy, universal tensile tester, simultaneous DTA/TGA (SDT), differential scanning calorimetry (DSC), and wide-angle X-ray diffraction studies, to determine their morphological structures, thermal stability, and mechanical properties. Compared to typical polyurethanes, these polymers exhibited better thermal stabilities due to the presence of imide groups. DSC and X-ray diffraction studies showed semicrystalline patterns for these polymers. Stress–strain properties revealed that these polymers have good extensibility like typical polyurethanes. © 1998 SCI.     

Thermal stability of polyurethanes based on vegetable oils

A series of polyurethanes from polyols derived from soybean, corn, safflower, sunflower, peanut, olive, canola, and castor oil were prepared, and their thermal stability in air and nitrogen assessed by thermogravimetric analysis, FTIR, and GC/MS. Oil‐based polyurethanes generally had better initial thermal stability (below 10% weight loss) in air than the polypropylene oxide‐based polyurethane, while the latter was more stable in nitrogen at the initial stage of degradation. If weight loss at a higher conversion is taken as the criterion of stability, then oil polyurethanes have better thermal stability both in air and in nitrogen. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1723–1734, 2000     

A new cyclic initiator system for the synthesis of novel star-shaped polyether-polyols (PEPOs) for fabrication of rigid cross-linked polyurethanes

Application of novel potassium salts (from mono- to penta-potassium) of 2,2,6,6-tetrakis(hydroxymethyl) cyclohexanol-activated 18C6 for propylene oxide polymerization is investigated. The novelty of the research concerns utilization of the cyclic-structured initiator with various substitution levels applied for anionic ROP of oxiranes. It results in the formation of bimodal macropentols (Scheme 1) with molar mass values in the range of M_n 2100–13200 g/mol and unsaturation, which depends on the initial concentration of monomer and alkoxide groups. The mechanism of the studied processes is discussed. The newly synthesized polyether-polyols (PEPOs) were used for the synthesis of new rigid polyurethanes (PURs) in one-step process. Thermogravimetric analysis (TGA) showed that the analyzed polyurethanes based on star-shaped polyols were characterized by two-stage thermal degradation and higher thermal stability in comparison to the linear polyols. The first stage of thermal decomposition of the tested PURs is related to the breaking of the urethane bonds in the rigid chains, while during the second stage, oligo-diol and oligo-pentol chains break down. A significant amount of solid degradation residue is advantageous in terms of the flame retardation of the obtained PUR, as this is usually associated with less products released during the degradation process. It was shown that the higher content of rigid segments in the PUR structure results in higher thermal resistance. The thermal behavior of the PURs was also investigated by differential scanning calorimetry (DSC).     

Preparation and characterization of novel polyurethanes containing 4,4′‐{oxy‐1,4‐diphenyl bis(nitromethylidine)}diphenol schiff base diol

Four novel segmented polyurethanes (PUs) based on4,4′‐{oxy‐1,4‐diphenyl bis(nitromethylidine)}diphenol (ODBNMD) diol with different diisocyanates such as 4,4′‐diphenylmethane diisocyanate, toluene 2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate have been prepared by solution method. The structures of ODBNMD and PUs have been confirmed by Fourier transform infrared (FTIR), nuclear magnetic resonance (¹H‐NMR and ¹³C‐NMR), UV‐visible, and fluorescence spectroscopies. The segmented PUs were further characterized by thermogravimetry (TGA), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction. FTIR confirmed hydrogen bonding interactions, whereas TGA and DSC suggested that introduction of aromatic/phenyl ring in the main chain considerably increased the thermal stability. POLYM. ENG. SCI., 54:24–32, 2014. © 2013 Society of Plastics Engineers     

Copolymers of Phenoxyethyl Methacrylate with Butyl Methacrylate: Synthesis,Characterization and Reactivity Ratios

Phenoxyethyl methacrylate (POEMA) and butyl methacrylate (BMA) were copolymerized by free-radical copolymerization using α,α′-azobisisobutyronitrile (AIBN) in 2-butanone solution at 333±1 K. Copolymers were characterized by FTIR, ¹H-NMR and ¹³C-NMR spectroscopic methods and by comparison of the spectra with the corresponding homopolymers. Thermogravimetric analysis of the copolymers was carried out in order to know their thermal stability. Copolymer composition was established by ¹H-NMR analysis. Monomer reactivity ratios (MRR) were computed using the classical Fineman – Ross (FR) and Kelen – Tüdos (KT) procedures. MRR were also estimated using a nonlinear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). The mean sequence lengths of the copolymers were estimated and suggest that random copolymers were obtained.     

Synthesis,thermal degradation and dielectric properties of poly[2-hydroxy,3-(1-naphthyloxy)propyl methacrylate]

2-Hydroxy-3-(1-naphthyloxy)propyl methacrylate (NOPMA) monomer was synthesized from reaction of 2-[(2-naphthyloxy)methyl]oxirane with methacrylic acid in the presence of pyridine. The polymerization of NOPMA was carried out by free radical polymerization method in the presence of AIBN at 60 °C. The structure of monomer and polymer was characterized by ¹H-NMR, ¹³C-NMR and FT-IR spectroscopy techniques. The glass transition temperature and average-molecular weights of poly(NOPMA) were measured using differential scanning calorimetry and gel permeation chromatography, respectively. The thermal degradation behavior of poly(NOPMA) has been investigated by FT-IR studies of the partially degraded polymer and thermogravimetry. The cold ring fractions (CRFs) were collected at two different temperatures, initially fraction-1 (CRF₁) is from room temperature to 320 °C, and the other fraction-2 (CRF₂) is from 320 to 500 °C. The volatile products of the degradation were trapped at ?195 °C (in liquid nitrogen). All the fractions were characterized by FT-IR, ¹H and ¹³C-NMR spectroscopic techniques, and the cold ring fractions (CRFs) were also characterized by GC–MS. For the degradation of polymer, the major compound between products of CRFs is α-naphthol. The GC–MS, FT-IR and NMR data showed that depolymerization corresponding to monomer was not prominent below 320 °C in the thermal degradation of poly(NOPMA). The mode of thermal degradation containing formation of the major products was identified. The dielectric permittivity (ε′), the loss factor (ε″) and conductivity (σ_ac) were measured using a dielectric analyzer in the frequency range of 50 Hz to 20 kHz.     

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.     

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.     

The Thermal Degradation of Waterborne Polyurethanes with Catalysts of Different Selectivity

The thermal stability of waterborne polyurethanes was measured by use of the thermogravimetric analysis. Waterborne polyurethanes (wbPUR) with catalysts of different selectivity were characterized using dynamic heating. In the dynamic method, heating rates with increments of 0.5, 1, 2, 5, and 10°C min^?1 were used in the range of 30–500°C, to achieve degradations of 0.025, 0.05, and 0.10, respectively. By using more selective catalysts, the resulting total time of decomposition was increased in all cases of degradation degrees for given initial temperature of waterborne polyurethanes. This paper shows how the dynamic method based on thermogravimetric analysis can be used to calculate the thermal stabilities of waterborne polyurethanes, using catalysts of different selectivity.     

A simple one‐step synthesis and polymerization of plant oil triglyceride iodo isocyanates

In this study, a novel and simple route for the synthesis of the iodine isocyanate (INCO) adduct of soybean oil triglycerides is described. Soybean oil iodo isocyanate (ISONCO) was synthesized by the reaction of iodine isocyanate and soybean oil at room temperature. ISONCO was then polymerized with polyols, such as, castor oil, pentamethylene glycol, and glycerol to give the corresponding polyurethanes and with polyamines, such as, ethylene diamine, hexamethylene diamine, and triethylene tetramine to give corresponding polyureas. The structures of the monomer and the polymers were determined by FTIR and ¹H‐NMR analyses. Thermal properties of the polymers were determined by DSC and TGA. Thermal degradation of the polyurethanes started at 150°C. Stability of the polyureas was higher than polyurethanes. Almost all polymers showed a T_g around ?50°C. The mechanical properties of the polymers were determined by tensile tests. Among the polymers synthesized, castor oil polyurethane showed the highest elongation at break and the lowest tensile strength of 140 KPa. The highest tensile strength of 900 KPa was observed in the pentamethylene glycol polyurethanes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Urethanes and polyurethanes based on oxypropylated cork: 1. Appraisal and reactivity of products

The reaction of various polyols derived from the oxypropylation of cork with aliphatic and aromatic mono‐ and diisocyanates was studied in solution at room temperature. In all instances, good second‐order kinetics were observed and the corresponding rate constant determined. The reactivity of the aromatic isocyanate was found to be much higher than that of aliphatic counterparts. The ensuing urethanes and polyurethanes were characterised by FTIR and ¹H NMR spectroscopy, DSC and sol/gel distribution. © 2001 Society of Chemical Industry     

Flame-retarding materials. II. Synthesis and flame-retarding properties of phosphorus-on-pendent and phosphorus-on-skeleton polyols and the corresponding polyurethanes

A phosphorus-on-skeleton compound was synthesized by reacting phenyl dichlorophosphate (PDCP) with 2-hydroxyethyl methacrylate (HEMA). This monomer was then copolymerized with other acrylic monomers to form a hydroxy-containing copolymer, which was then used as the polyol in the synthesis of a polyurethane. Phosphorus-on-pendent copolymers and phosphorus-free copolymers and their corresponding polyurethanes were also prepared for comparison with the phosphorus-on-skeleton material in terms of their flame-retardant properties. The flame retardancy and degradation mechanism of these copolymers and polyurethanes were analyzed with thermogravimetric analysis (TGA) and infrared spectroscopy. Although those phosphorus-on-skeleton copolymer polyols have less flame-retarding ability than that of the phosphorus-on-pendent copolymer polyol because of less phosphorus content, it was evident that the phosphorus-on-skeleton polyurethanes were more effective flame retardants than the phosphorus-on-pendent polyurethanes. This was attributed to the fact that the crosslinking arising from the phosphorus-on-skeleton copolymer polyols has a tremendous effect on the flame-retarding ability of the corresponding polyurethanes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 343–357, 2001     

Multiblock polyurethanes containing butadiene-co-acrylonitrile oligomers as soft segments

Summary Amorphous segmented polyurethanes (PUs) were prepared by a solution two-step synthesis from 2,4-toluenediisocyanate, 1,4-butanediol and ATBN, a telechelic butadiene-acrylonitrile oligomer. The composition was varied in the range 11–61% by wt of ATBN. The copolymers were characterized by elemental analysis, viscosity measurements and FTIR and¹H-NMR spectroscopy. Differential scanning calorimetry and dynamic mechanical thermal analysis showed the presence of two separate glass transitions for hard and soft segments, thus indicating a two phase behaviour of the investigated PUs. Evidence of interphase interactions was not found. The dynamic mechanical spectra suggested the occurrance of a phase inversion from a hard segment matrix to a soft segment continous phase when the ATBN content is 38% by wt or higher.     

Investigations on polyurethane ionomers. II. 3,4-dihydroxycinnamic acid-based anionomers

Polyurethanes of different compositions were synthesized by chain extending the prepolymer formed by the reaction of various polyols and diisocyanate with 3,4-dihydroxycinnamic acid. The polyurethanes were converted to their anionomers by treating with metal acetates. The polyurethanes were characterized using FTIR, FTNMR, TGA, and DSC analysis. The molecular weights of the polymers were determined using GPC. A detailed study of the effect of variation of molecular weight of the polyols and mol ratio of the various reactants on the glass transition temperature and molecular weight of the polyurethanes was made. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2105–2109, 1997     

Effects of the o‐aromatic ring in the molecular chain on the properties of polyester polyols

A series of liquid polyester polyols from adipic acid (AA), phthalic anhydride (PA), ethylene glycol, propanediol‐1,2, and trihydroxymethylpropane, varying in the molar ratio of PA to AA, were prepared. The effects of the o‐aromatic ring in the molecular chain, which came from PA, on the viscosity, glass‐transition temperature, and thermal degradation temperature of the polyester polyols were studied with viscometry, differential scanning calorimetry, and thermogravimetry. The intrinsic viscosity and glass‐transition temperature increased with the concentration of the o‐aromatic ring increasing. The temperature of the maximum thermal degradation rate for aliphatic polyester polyols was 434.20°C. Two steps of thermal degradation were found when there were o‐aromatic rings in the molecular chain. One thermal degradation temperature was 358.36–360.48°C, and the other was 412.85–427.18°C. Polyester polyols with o‐aromatic rings had higher stability at lower temperatures (<240.00°C). However, aliphatic polyester polyols had higher stability at higher temperatures (300.00–480.00°C). The activation energy and order of degradation were calculated from thermogravimetric curves. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1617–1624, 2002     

Synthesis and thermal dissociation of phenol- and naphthol-blocked diisocyanates

Phenol-, 2-naphthol-, and 1-nitroso-2-naphthol-blocked toluene diisocyanate (TDI) and isophorone diisocyanate (IPDI) adducts and their polymers with PPG-1000 were prepared and characterized by nitrogen estimation, IR, and ¹H-NMR spectroscopy. The absence of an IR absorption band at 2270 cm^?1 confirmed the completion of the reaction between the isocyanate and the blocking agents, whereas the presence of a band at 1075–1150 cm^?1 confirmed the formation of poly(ether urethanes). The deblocking temperatures were determined by the use of DSC and by the carbon dioxide evolution methods. The thermal stabilities of the 2-naphthol-blocked diisocyanates were less than the phenol-blocked diisocyanates. Dissociation temperature was also reduced by the nitroso group in the blocking agent. Mass spectral data confirmed the product analysis. The solubility of the adducts were determined in the different polyols. Adducts based on IPDI showed better solubility than did those based on TDI. © 1994 John Wiley & Sons, Inc.     

Synthesis,characterization, and properties of polyols from hydrogenated terpinene–maleic ester type epoxy resin

Three kinds of polyfunctional polyols with hydroxyl values of 180–320 mg/g were prepared by the reaction of hydrogenated terpinene–maleic ester type epoxy resin with secondary amines (diethylamine, N‐methylethanolamine, and diethanolamine), and the chemical structures were characterized by Fourier transform infrared spectroscopy and NMR spectroscopy. These polyols were used in place of commonly used polyols to prepare two‐component polyurethanes when reacted with polyisocyanates. The crosslinking reactions of the polyols with polyisocyanate could be catalyzed by the tertiary amine groups included in the polyols, and the reaction rate was affected by hydrochloric acid and the polarity of the solvents. The mechanical, water‐resistance, and chemical‐resistance properties of the crosslinked products of the polyols were evaluated by standard tests, and the thermal properties were examined by differential scanning calorimetry and thermogravimetric analysis. The results show that these epoxy–urethane polymers, with glass‐transition temperatures (T_g's) in the range ?5 to 37°C, had good thermally resistant properties, and the temperatures at 5% weight loss were in the range 235–280°C. All of the polymers formed transparent, strong, flexible films, with good chemical‐resistance properties and excellent impact strengths of greater than 50 cm, a flexibility of 0.5 mm, adhesions of 1–2, and pencil hardnesses of HB–2H. The larger OH functionality and OH value of the polyol resulted in higher T_g and pencil hardness values and better alcohol resistance and thermal stability in the crosslinked product of the polyol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Kinetics of Curing and Thermal Degradation of POSS Epoxy Resin/DDS System

Polyhedral oligomeric silsesquioxanes epoxy resin (POSSER) was prepared from 3-glycidypropyl-trimethoxysilane (GTMS) and tetramethylammonium hydroxide (TMAH) by hydrolytic condensation. POSSER was characterized using Fourier-transformed infrared spectroscopy (FTIR), ¹H-NMR, and liquid chromagraphy/mass spectrometry (LC/MS). The epoxy value of POSSER is 0.50 mol/100 g. The LC/MS analysis indicated that T₁₀ is the majority and contain some amount of T₈, besides, a trace T₉ also exists. The curing kinetics of POSSER with 4,4′-diaminodipheny sulfone (DDS) as a curing agent was investigated by means of differential scanning calorimetry (DSC). The curing reaction order n is 0.8841 and the activation energy Ea is 61.06 kJ/mol from dynamic DSC analysis. Thermal stability and kinetics of thermal degradation were also studied by thermal gravimetric analysis (TGA). TGA results indicated that the temperature of POSSE/DDS system 5% weight loss is approximately 377.0°C, which is higher by 12.6°C than that of pure POSSER, and the primary degradation reaction (300–465°C) followed first order kinetics; the activation energy of degradation reaction is 75.81 kJ/mol.     

Xylan derivatives: Benzyl ethers,synthesis, and characterization

The -2,3-bis(benzyl ether) of xylan, a natural polysaccharide, has been prepared by using a new benzylation method. This method was first tested on methyl-β-D -xylopyranoside, the monomer model of xylan. It implies the use of potassium hydroxyde, a crown ether as a catalyst, and benzyl bromide as a benzylating agent. Perbenzylated xylan is obtained with a good yield (80%) in a one-step reaction. It is soluble in most organic solvents. The ¹³C- and ¹H-NMR spectra of this polymer were assigned and are typical of a regular linear polymer. Differential thermal analysis and thermogravimetry indicate the temperature range at which this polymer can be processed at high temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 455–460, 1998