Determination methods of the grafting yield in glycidyl methacrylate‐grafted ethylene/propylene/diene rubber (EPDM‐g‐GMA): Correlation between FTIR and 1H‐NMR analysis

A normalized and universally applicable calibration function for the Fourier‐transformed infrared (FTIR) quantification of the glycidyl methacrylate (GMA) grafting yield in polymers of known compositions having ethylene block sequences was established. The ¹H nuclear magnetic resonance (¹H‐NMR) spectroscopy results achieved on different GMA‐grafted ethylene/propylene/diene rubber (EPDM‐g‐GMA) and ethylene/GMA copolymers were correlated to their FTIR data to calibrate the relative determination of the FTIR method. Both direct and indirect standardization approaches were followed and evaluated. The calibration deduced was used to investigate the free radical grafting reaction of GMA on EPDM rubber in the melt phase. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2616–2624, 1999     

Physical properties of water‐borne polyurethane blended with chitosan

Water‐borne polyurethanes based on 4,4‐diphenylmethane diisocyanate, poly(butylene adipate), and chain extender N‐methyldiethanolamine (MDEA) that provided tertiary amine groups were synthesized. The polyurethane–chitosan (PU/CS) blends can be dissolved in the acetic acid and cast into films. The mechanical properties including tensile strength and elongation, as well as the water absorption and thermal properties of the PU/CS films were evaluated. The tensile strength increased with the increased amount of chitosan, but the elongation decreased accordingly. The chitosan in the blends promoted the water absorption. Chitosan was more thermally‐stable than PU, as shown in the thermal gravity analysis. Chitosan also had higher crystallinity, as demonstrated by differential scanning calorimetry. The blends were partial compatible mixtures, based on the data obtained from a dynamic mechanical analysis. Biocompatibility test was conducted utilizing immortalized rat chondrocytes (IRC). After IRC were seeded onto the PU/CS films for 1.5 and 120 h, the number of cells was counted and the morphology of cells was observed by light microscopy and scanning electron microscopy. Blends containing 30% chitosan had more cells attached initially. However, the blends containing more than 70% chitosan appeared to promote the cell proliferation. IRC were round on PU/CS films with more PU, but spread when the chitosan content in blends was higher. Overall, PU/CS films with more chitosan had better mechanical properties as well as biocompatibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2683–2689, 2007     

Functional nano-fillers in waterborne polyurethane/acrylic composites and the thermal,mechanical, and dielectrical properties

Modification is mostly used to adjust and increase the performance of polymers by employing organic or inorganic fillers in composites. It is significant to investigate the functions of different fillers in polymer matrix. In this work, we prepared a series of composites by using polyurethane/acrylic dispersions as polymer matrix and nanofillers (cellulose nanocrystals, carbon nanotubes and aluminum oxide nanoparticles) as modifiers to study their micro-structure and applied performance. It is found that the different nanofillers can be dispersed in PUA homogenously, which are inclusive physically. Different nanofillers have a noticeable influence on the T_g for the acrylate copolymers and the T_g of the interphase between the acrylate and polyurethane. The CNTs significantly increases the elongation to 127.29%, and gives the highest dielectric response. We imply that the CNTs may be the most significant fillers to increase the mechanical and electrical properties.     

1H‐NMR investigation of the thermooxidation degradation of poly(oxymethylene) copolymers

The thermooxidative degradation of poly(oxymethylene) copolymer (CPOM‐Y) powder was studied in air in 150°C. The effect of the sequence distribution of degraded poly(oxymethylene) (POM) samples on the thermal decomposition behavior was investigated with ¹H‐NMR and gas chromatography/mass spectrometry. The results showed that the degradation process of CPOM‐Y could be divided into three stages with a gradually increasing degradation rate. The change in the sequence molar fractions agreed with the fact that the ethylene oxide (EO) units had higher thermal stability, and the degradation of POM was due to the decomposition of formal units. At the beginning, CPOM‐Y tended to split off formaldehyde, starting at the chain ends, some of which were not ended by EO units. In stage 2, the thermooxidation of POM occurred in the amorphous phase. In stage 3, no obvious rules for the changes in the sequence contents were obtained from NMR results, and this indicated further random chain scission and unzipping occurring heavily in the crystalline bulk. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 577–583, 2004     

Structure and composition of the surface of urethane/acrylic composite latex films

Polyurethane dispersions were prepared and urethane/acrylic composite latices were synthesized with polyurethane dispersions as the seed, and core‐shell emulsion polymerization. Fourier‐transform infrared spectroscopy coupled with attenuated total reflectance (FTIR‐ATR) analyses showed that the films obtained from the composite latices were rich in polyurethane component or segments at air‐facing and substrate‐facing surfaces, in comparison with their average composition. Moreover, the substrate‐facing surface contained even more polyurethane component or segments than the air‐facing surface. X‐ray photoelectron spectroscopy (XPS) detection also indicated that the polyurethane component or segments preferentially migrated to the surface layer of the films from the bulk, and that the films from blend latices displayed more polyurethane component or segments near the surface layer. Both FTIR‐ATR and XPS analyses suggested that some reorientation had happened in synthesizing the composite latices and/or after film formation. This structure and composition endow urethane/acrylic composite films with both surface properties (such as mar‐resistance, adhesion, wettability) from pure polyurethane, and film hardness from acrylic copolymers. © 2001 Society of Chemical Industry     

Mechanical and thermal properties of phenolic/glass fiber foam modified with phosphorus‐containing polyurethane prepolymer

Phenolic foam exhibits outstanding flame, smoke and toxicity properties, good insulation properties and low production costs. However, the brittleness and pulverization of phenolic foam have severely limited its application in many fields. In this study, a novel phosphorus‐containing polyurethane prepolymer (DOPU) modifier was firstly synthesized, and then the foaming formula and processing of toughening phenolic foam modified with DOPU and glass fiber were explored. The structure and reactive behavior of prepolymer and phenolic resin were investigated using Fourier transform infrared spectroscopy. The effects of DOPU and glass fiber on the apparent density, compressive strength, bending strength and water absorption were investigated. The results suggested that the apparent density, compressive strength and bending strength of modified phenolic foam tended to increase irregularly with increasing content of DOPU. The addition of DOPU led to lower water absorption of glass fiber‐filled foam. Thermal stability and flame retardancy were examined using thermogravimetric analysis and limiting oxygen index (LOI) tests. It was found that foam with 3% DOPU and 0.5% glass fiber added exhibited good thermal stability and high char yields. The LOI value of modified phenolic foams decreased with increasing DOPU content, but it still remained at 41.0% even if the amount of modifier loaded was 10 wt%. © 2012 Society of Chemical Industry     

Morphology,thermal properties,hydrophobicity and O2/N2 gas separation performance of 4,4′‐oxydiphthalic anhydride‐based polyimide/titania hybrids

Two 4,4′‐oxydiphthalic anhydride (ODPA)‐based polyimide (PI)/titania hybrid films with different morphologies were prepared through an in situ sol‐gel process. The precursor, poly(amic acid) (PAA), was synthesized using ODPA, diamine of 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane (BAPP) or 4,4′‐diaminodiphenyl ether (ODA) and a suitable amount of dimethylformamide solvent. A mixture of tetraethylorthotitanate (Ti(OEt)₄) and acetylacetone with molar ratio of 1:4 was then added to the PAA solution and mixed thoroughly. Following curing, PI/titania hybrid membranes with different crosslinkages and Ti(OEt)₄ contents were prepared. PI hybrids with the longer BAPP diamine present different morphologies and property changes related to the Ti(OEt)₄ content from those of hybrids with the shorter ODA diamine. The morphologies of the two ODPA‐based PI/titania hybrids were studied with reference to the disruption of imide ring formation. Different crosslinked structures produced were identified using Fourier transform infrared analysis from the frequency shift of the C?O band and relative absorbance intensities of bands of C?O group and imide ring (? N?). Thermal properties, O₂/N₂ gas separation performance, contact angle, storage modulus, glass transition temperature and decomposition temperature of the PI hybrids were all found to be functions of the Ti(OEt)₄ content, crosslinked structure and PI type. Copyright © 2012 Society of Chemical Industry     

Polyurethane‐acrylic hybrid emulsions with high acrylic/polyurethane ratios: Synthesis,characterization, and properties

Allyl polyoxyethylene ether (APEE) was used as coupling agent between polyurethane (PU) and acrylic polymer (AC) to synthesize stable waterborne polyurethane‐acrylic (PU‐AC) hybrid emulsions with high AC/PU weight ratio ranged from 45/55 to 70/30. The effect of the AC/PU weight ratio and the acrylate type including methyl methacrylate (MMA), butyl acrylate (BA) and mixture of them on the properties of the synthesized emulsions and resultant films were investigated. The research results showed that the colloidal particle of the emulsions behaved core‐shell structure, and the copolymers were not crosslinked. An increase in the AC/PU weight ratio led to an increase in the average particles size and the particle size distribution, but decrease in the viscosity of the emulsions. Meanwhile, the molecular weight distribution of the copolymers became wide, and the tensile stress, shore A hardness, storage modulus, glass transfer temperature, water resistance, and water contact angle of the resultant films increased, except that the films of PU‐BA were too soft to determine their mechanical properties. MMA and BA can provide the PU‐AC hybrid emulsions with very different properties, and which can be adjusted according to the special application. It was suggested that APEE can not only built up chemical bonds between PU and AC, but also increase the self‐emulsifying ability in the emulsion polymerization due to its hydrophilic ethylene oxide and carboxylic groups, resulting in that PU‐AC hybrid emulsions with high AC/PU ratio can be obtained by this method. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44488.     

Synthesis and properties of novel rosin‐based water‐borne polyurethane

A series of novel rosin‐based water‐borne polyurethanes (RWPUs) was prepared from fumaropimaric acid polyester polyol (FAPP) synthesised from rosin acid. Emulsions of the prepared RWPUs were investigated by transmission electron microscopy, and dried films of the emulsions were characterised by Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction and differential scanning calorimetry. Other properties including water absorption, tensile strength, elongation at break, and antibacterial activity of the RWPUs were also determined. The results suggest that RWPU prepared with 35 wt% FAPP has good potential for applications, with improved mechanical properties, thermal stability and water resistance. The RWPU showed excellent antimicrobial properties in killing both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus. Copyright © 2011 Society of Chemical Industry     

Synthesis and characterization of di‐polyester diamides

A series of di‐polyester diamides was synthesized via a nucleophilic ring opening polymerization process. FTIR investigations revealed the spectral characteristics evidencing the newly formed chemical bonds as well as the changes in the relative intensity of the characteristic peaks, due to the increasing side‐block lengths of the different members of the series. ¹H‐NMR analysis of the described materials confirmed the chemical structures seen by FTIR analysis. The side segment length of the different di‐polyester diamides was calculated from the integration ratios in the NMR spectra. The molecular weight results exhibited relatively small deviations from the stoichiometrically calculated values. All the members of the triblock series, with side blocks of up to 120 lactoyl units, were essentially amorphous and glassy at room temperature. The presence of two separate glass transitions indicated a segmented and microphase separated morphology. It was deducted that the amorphous nature of the relatively long poly(lactic acid) side blocks occurs due to the dominance of the hydrogen‐bonded central segment. Synthesis of a di‐polyester diamide containing a reduced number of hydrogen‐bond‐forming groups in the central segment yielded a partial side‐block crystallization. The di‐polyester diamide with 120 lactoyl unit‐long side blocks was eventually able to crystallize in solid state, following thermal treatment during thermal analysis. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Physical properties of water‐blown rigid polyurethane foams from vegetable oil‐based polyols

Fifty vegetable oil‐based polyols were characterized in terms of their hydroxyl number and their potential of replacing up to 50% of the petroleum‐based polyol in waterborne rigid polyurethane foam applications was evaluated. Polyurethane foams were prepared by reacting isocyanates with polyols containing 50% of vegetable oil‐based polyols and 50% of petroleum‐based polyol and their thermal conductivity, density, and compressive strength were determined. The vegetable oil‐based polyols included epoxidized soybean oil reacted with acetol, commercial soybean oil polyols (soyoils), polyols derived from epoxidized soybean oil and diglycerides, etc. Most of the foams made with polyols containing 50% of vegetable oil‐based polyols were inferior to foams made from 100% petroleum‐based polyol. However, foams made with polyols containing 50% hydroxy soybean oil, epoxidized soybean oil reacted with acetol, and oxidized epoxidized diglyceride of soybean oil not only had superior thermal conductivity, but also better density and compressive strength properties than had foams made from 100% petroleum polyol. Although the epoxidized soybean oil did not have any hydroxyl functional group to react with isocyanate, when used in 50 : 50 blend with the petroleum‐based polyol the resulting polyurethane foams had density versus compressive properties similar to polyurethane foams made from 100% petroleum‐based polyol. The density and compressive strength of foams were affected by the hydroxyl number of polyols, but the thermal conductivity of foams was not. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation and characterization of water‐blown polyurethane foams from liquefied cornstalk polyol

Polyurethane foams were prepared from the liquefied cornstalk polyol, which was obtained by the liquefaction of cornstalk in the presence of polyhydric alcohols using sulfuric acid as catalyst. The advisable liquefaction reaction conditions were selected by investigating their influences on the properties of liquefied cornstalk polyol, taking account of the requirement for the preparation of appropriate polyurethane foams. The influences of the contents of catalysts, water, surfactant, and isocyanate on the properties of polyurethane foams were also discussed, and feasible formulations for preparing cornstalk‐based polyurethane foams were proposed. The results indicated that the foams prepared from such liquefied cornstalk polyol exhibited excellent mechanical properties and thermal properties, and could be used as heat‐insulating materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

High‐performance waterborne coatings based on epoxy‐acrylic‐graft‐copolymer‐modified polyurethane dispersions

Polyurethane dispersions (PUDs) have been an active area of research since the early 1940s because of legislative restrictions on the use of organic solvents in conventional solvent‐based products and also because PUDs exhibit almost the same high performance levels as solvent‐borne polyurethanes. In the present study, properties of conventional waterborne PUDs are modified with epoxy‐acrylic graft copolymer blocks. The epoxy‐acrylic graft copolymers were first modified with ethylene diamine to give amine‐terminated blocks which in turn reacted with isocyanate‐terminated prepolymer (prepolymer mixing process) to give modified PUDs. Several experimental sets were prepared with varying compositions. The experimental sets were also prepared using conventional poly(ethylene glycol) blocks and ethylene diamine chain‐extenders. The physico‐chemical properties and film characteristics of the experimental sets show the dramatic improvement in important mechanical properties of PUDs due to grafting with epoxy‐acrylic copolymer blocks. Copyright © 2004 Society of Chemical Industry     

Thermal oxidative and photo‐oxidative degradation of polytetrahydrofuran studied using 1H NMR, 13C NMR and GPC

The products and mechanism of the thermal oxidative degradation at 180 °C and the photo‐oxidative degradation at 40 °C of polytetrahydrofuran have been investigated using ¹H NMR, ¹³C NMR and GPC. The NMR analysis was assisted by the use of DEPT ¹³C spectra, two‐dimensional NMR spectroscopy (COSY, HMQC and HMBC) and chemical shift simulation software. The NMR spectra of both thermally and photolytically degraded samples were similar showing that the degradation mechanisms were similar. GPC indicated that both chain scission, leading to lower molar mass products, and chain extension, leading to higher molar mass products, occurred initially. NMR analysis of the initial soluble degraded polymers showed that chain scission resulted in formate, aldehyde, propyl ether, butyl ether and propanoyl chain ends, and in‐chain ester groups were also formed. For longer periods of degradation, crosslinked gels were formed but these were not amenable to detailed structural characterisation by high‐resolution NMR to determine the crosslink mechanism. Copyright © 2004 Society of Chemical Industry     

Synthesis,thermal properties,and morphology of blocked polyurethane/epoxy full‐interpenetrating polymer network

Blocked polyurethane (PU)/epoxy full‐interpenetrating polymer network (full‐IPN) were synthesized from blocked NCO‐terminated PU prepolymer, with 4,4‐methylene diamine as a chain extender and epoxy prepolymer, with 4,4‐methylene diamine as a curing agent, using simultaneous polymerization (SIN) method. From FTIR spectra analysis it was found that the major reactions in the blocked PU/epoxy IPN system are the self‐polymerization of block PU/chain extender and the self‐polymerization of epoxy/curing agent. Meanwhile, from reaction mechanisms the copolymerization of IPN may have occurred at the same time. The weight loss by thermogravimetric analysis decreased with increasing epoxy and filler content. It was confirmed from scanning electron micrography (SEM) that when the blocked PU content increased, the microstructure of IPN became rougher. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 323–328, 2006     

In situ polymerization and characterization of polyester‐based polyurethane/nano‐silica composites

Polyester‐based polyurethane/nano‐silica composites were obtained via in situ polymerization and investigated by Fourier‐transform infrared spectroscopy (FTIR), or FTIR coupled with attenuated total reflectance (FTIR‐ATR), Transmission electron microscopy (TEM), atomic force microscopy (AFM), an Instron testing machine, dynamic mechanical analysis (DMA) and ultraviolet‐visible spectrophotometry (UV‐vis). FTIR analysis showed that in situ polymerization provoked some chemical reactions between polyester molecules and nano‐silica particles. FTIR‐ATR, TEM and AFM analyses showed that both surface and interface contained nano‐silica particles. Instron testing and DMA data showed that introducing nano‐silica particles into polyurethane enhanced the hardness, glass temperature and adhesion strength of polyurethane to the substrate, but also increased the resin viscosity. UV‐vis spectrophotometry showed that nano‐silica obtained by the fumed method did not shield UV radiation in polyurethane films. Copyright © 2003 Society of Chemical Industry     

Characterization of polyurethane resins by FTIR,TGA, and XRD

Fourier Transformed Infrared Spectroscopy, Thermogravimetric Analysis, and X‐ray Diffractometry have been used to investigate the rigid, semi rigid, and soft polyurethane (PU) forms, which were developed by the Group of Analytic Chemistry and Technology of Polymers ‐ USP ‐ São Carlos. The –NCO/–OH ratios were 0.6, 0.5, and 0.3% for rigid, semi rigid, and soft PUs, respectively, showing that different ratios cause differences in thermal behaviors and crystalline structures of the synthesized PU resins. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Radiation‐initiated graft polymerization of methylmethacrylate onto poly(tetrafluoroethylene): Characterization by 1H‐NMR

A broad‐line ¹H‐NMR study was carried out to examine the local structure of poly(methylmethacrylate) (PMMA) grafted onto Poly(tetrafluoroethylene) (PTFE). The NMR spectra were observed for three different samples with 1.0, 5.4, and 7.0 wt % PMMA over the temperature range from 150 to 380 K. With the help of selectively deuterated PMMA (PMMA‐d₅ and PMMA‐d₈)‐grafted samples, the NMR spectra were analyzed in terms of two components—a Gaussian (G) component, and a Lorentzian (L) component. Based on the second moments (〈ΔH²〉) analysis, the L and G components were attributed to the ¹H–¹H dipolar interactions within one CH₃ group and the interactions of CH₃ groups that are closely located in aggregated PMMA chains. Combining the results with the temperature dependence of 〈ΔH²〉 and the angular resolved XPS, the location and rotational motion of PMMA grafted onto PTFE are discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1386–1394, 1999     

Solid–solid phase‐change materials based on hyperbranched polyurethane for thermal energy storage

A hyperbranched polyol (HBP) was synthesized with poly(ethylene glycol) (PEG) as the core molecule and 2,2‐bis(hydroxymethyl) propionic acid as the chain extender. Then, a series of hyperbranched polyurethane phase‐change materials (HP‐PCMs) with different crosslinking densities was synthesized with isophorone diisocyanate and HBP as a molecular skeleton and PEG 6000 as a phase‐change ingredient. ¹H‐NMR, gel permeation chromatography, and Fourier transform infrared spectroscopy confirmed the successful synthesis of the HBP and HP‐PCMs. The polarization optical microscopy and wide‐angle X‐ray diffraction results show that the HP‐PCM exhibited good crystallization properties, but the crystallinity was lower than that of PEG 6000. The analysis results from differential scanning calorimetry indicated that the HP‐PCMs were typical solid–solid phase‐change materials with suitable phase‐transition temperatures. In addition, HP‐PCM‐3, with an appropriate degree of hyperbranched structure, possessed the highest thermal transition enthalpy of 123.5 J/g. Moreover, thermal cycling testing and thermogravimetric analysis showed that the HP‐PCMs exhibited good thermal reliability and stability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45014.     

Rectorite/thermoplastic polyurethane nanocomposites. II. Improvement of thermal and oil‐resistant properties

Organ‐rectorite/thermoplastic polyurethane (OREC/TPUR) nanocomposites were synthesized via melt intercalation. The dynamic mechanical properties by dynamic mechanical analysis (DMA), thermal and oil‐resistant properties were investigated. The results show that the storage modulus (E′), loss modulus (E″), and glass‐transition temperature (T_g) of the nanocomposites have an increase to some extent than those of pure TPUR. The thermal stability of nanocomposites was also studied in detail by thermal gravity analysis (TGA), which was higher than that of pristine TPUR matrix when the content of organic REC is at 2 wt %, and the decomposition temperature at 10% weight loss of OREC/TPUR is greatly increased up to 330°C from 315°C. Oil uptake of the composites is also significantly reduced in comparison with TPUR matrix, which is ascribed to the good barrier effect of nanosheets of OREC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1165–1169, 2005