Phosphonic acid functionalized siloxane crosslinked with 3‐glycidoxyproyltrimethoxysilane grafted polybenzimidazole high temperature proton exchange membranes

Phosphonic acid functionalized siloxane crosslinked with 3‐glycidoxypropyltrimethoxysilane (GPTMS) grafted polybenzimidazole (PBI) membranes are prepared by sol–gel process. The structure of the membranes is characterized by Fourier‐transform infrared spectroscopy and X‐ray diffraction spectroscopy. SEM images of the membranes show that the membranes are homogeneous and compact. The crosslinked membranes exhibit excellent thermal stability, chemical stability and mechanical property. The proton conductivity of the crosslinked membranes increases by an order of magnitude over range of 20 °C to 160 °C under anhydrous condition, which can reach 3.15 × 10^?2 S cm^?1 at 160 °C under anhydrous condition. The activation energy of proton conductivity for membranes decreases with increase of PBI, because the formation of hydrogen bond network between the phosphonic acid and the imidazole ring can enhance the continuity of hydrogen bond in the membrane. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44818.     

Influence of water addition on the structure of plasma-deposited allyl alcohol polymer films

One hundred and fifty nanometre thick polymer films made of allyl alcohol and H₂O addition were deposited onto aluminium substrates using the radio-frequency (rf) pulsed plasma mode. The structure–property relationships of polymer films were studied in dependence on the precursor ratio allyl alcohol-water. Both the regularity of structure and composition of such thin films in comparison to chemically polymerized allyl alcohol were investigated using by bulk-sensitive Fourier transform infrared spectroscopy (FTIR) in the spectral range of 4000–500 cm^?1 as well as surface-sensitive X-ray photoelectron spectroscopy (XPS). The intention of this work was to increase the yield in OH groups by addition of water to the allyl alcohol precursor. For an unambiguous identification of the functionality of the deposited films, the OH groups were labelled with trifluoroacetic anhydride and subsequently measured by XPS as well as quantitatively by FTIR. As expected, the O/C ratio grew with increasing water admixture by oxidation of both the plasma polymerized allyl alcohol layer to preferably aldehyde and/or carboxylic acid groups. In contrary, the concentration of OH groups in the deposited polymer film decreases dramatically with increasing admixture of water to the allyl alcohol plasma. It has been shown that the additional water has produced preferably higher oxidized C-O_x species with two or three C–O bonds. This fits also very well with the observation that almost no deuterium is introduced into the surface of plasma polymer if D₂O was added instead of H₂O.     

Preparation and Properties of Polyether Scale Inhibitor Containing Fluorescent Groups

Water soluble fluorescent monomer, 8-allyloxy-1,3,6-pyrenetrisulfonic acid trisodium salt (AP), was synthesized from 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt and allyl chloride. AP-tagged copolymer maleic anhydride (MA)–ammonium allyl polyethoxy sulfate (APES)-AP, which is a calcium phosphate inhibitor, was prepared and the structures of AP and MA-APES-AP were characterized by FTIR and ¹H-NMR. The influence of the mole ratio of MA:APES on a calcium phosphate inhibitor of MA-APES-AP was discussed. Fluorescent properties and scale inhibition performance of MA-APES-AP were also studied. The results indicate that monomer ratio has great impact on the performance of MA-APES-AP. Fluorescent intensity increases with the concentration of MA-APES-AP, with a correlation coefficient (r) of 0.9934 and MA-APES-AP limit of detection of 1.72 mg · L^?1. Calcium phosphate inhibition performance test results show that calcium phosphate inhibition of MA-APES-AP reaches 98.78 percent when the dosage is 12 mg · L^?1 at 80^°C.     

The effect of tunable modification parameters on the structure and properties of polypropylene with cyclotrimerization surface of isocyanates

The cyclotrimerization of methylene diphenyl 4,4‐diisocyanate (MDI) and 3‐isopropenyl‐α,α′‐dimethylbenzene isocyanate (TMI) was applied on the bead/membrane surfaces of a polypropylene (PP)‐bearing isocyanate group to synthesize a protective networked polymer. Chemical structures of these molecules were characterized through attenuated total reflectance–Fourier transform infrared spectroscopy. Results showed that the absorption peak of isocyanate group at 2255 cm^?1 became negligible after the reaction was completed. The absorption peaks of the isocyanurate groups appeared simultaneously at 1600 cm^?1 and at 1510–1560 cm^?1; this result indicated that the grafted isocyanates were almost consumed, thereby forming isocyanurates. Energy X‐ray dispersive spectroscopy revealed that oxygen content increased; indeed, isocyanurate was formed on the PP surface. Pure PP beads, PP‐g‐TMI, and cyclotrimerization products were also subjected to thermal property tests to investigate their corresponding thermal stabilities. Cyclotrimerization could result in the increase in PP‐grafted decomposition temperature, even slightly higher than pure PP. Rheological behavior in oscillatory flow was also evaluated; the storage modulus, loss modulus, and complex viscosity of cyclotrimerization products were higher than those of the PP‐grafted membranes. Surface morphology was further observed through field‐emission scanning electron microscopy and atomic force microscopy. The cyclotrimerization products contained blocks and exhibited a rough surface. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43327.     

Surface modification of polymethyl methacrylate intraocular lenses with the mixture of acrylic acid and acrylamide via plasma‐induced graft copolymerization

An approach is presented for the graft copolymerization of acrylic acid (AAc) and acrylamide (AAm) mixture onto the surfaces of polymethyl methacrylate intraocular lenses (PMMA IOLs) treated with an Argon gas plasma, followed by the exposure to the oxygen atmosphere. In this case, peroxides formed by the plasma treatment are likely to be responsible for initiating the graft copolymerization. The amount of peroxides on the surface of PMMA IOLs was determined using 1,1‐diphenyl‐2‐picrylhydrazyl, and the maximum amount was found with the plasma treatment at 30 W for 20 s under 5 mTorr pressure. The surfaces of the grafted PMMA IOLs were characterized using Fourier transform infrared spectroscopy‐attenuated total reflectance (FTIR‐ATR), electron spectroscopy for chemical analysis, and contact angle meter. The FTIR‐ATR spectrum of PMMA‐g‐AAc‐AAm showed the characteristic band of PAAc at 1580 cm^?1 together with those of PAAm at 1670 and 1630 cm^?1, confirming that the copolymer of AAc and AAm was successfully grafted onto the surfaces of PMMA IOLs. The experimental data of O1s/C1s and N1s/C1s reasonably concurred with the calculated data, a strong indication that the pH value of the reaction medium at 3.77 could produce a graft with an equal molar ratio. Surface tension of the samples increased to 52 dyn/cm due to the graft of the hydrophilic monomers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2361–2366, 2002     

Studies of Bone-Bonding Ability and Antibacterial Properties of Ag<Superscript>+</Superscript>, Cu<Superscript>2+</Superscript> or Zn<Superscript>2+</Superscript> ions Doping within Hench’s Bioglass and Glass-Ceramic Derivatives

Derived Hench’s bioglasses with specific ionic dopants Ag⁺, Cu²⁺, or Zn²⁺ have been prepared. The bone-boding ability or bioactivity behavior for the prepared glasses and their glass-ceramic derivatives has been investigated after immersion in phosphate solution for two weeks. Collective Fourier transform infrared absorption spectra (FTIR) and scanning electron microscopic (SEM) studies were conducted in order to study the in-vitro bioactivity behavior. X-ray diffraction (XRD) analysis was carried out to identify the crystallized phases upon thermal heat treatment through a two-step regime. The glasses and their glass-ceramic derivatives were tested to study their antibacterial or antifungal efficiency responding to the doped metal ions. FTIR spectra revealed the generation of two split peaks at about 560 and 605 cm^?1, after immersion in (0.2 M) sodium phosphate solution (Na₃PO₄), signifying the formation of a crystalline calcium phosphate phase, leading to hydroxyapatite formation. SEM examinations show characteristic rounded or nodular microcrystals for hydroxyapatite which support the FTIR data. X-ray diffraction analysis indicated crystallization of the main soda-lime silicate phase (1Na₂O.2CaO.3SiO₂) besides a secondary silicon phosphate phase (SiO₂.P₂O₅) in the studied glass ceramics. The route of crystallization is discussed on the basis of the presence of 6% P₂O_5; which facilitates the formation of phase separation and voluminous bulk crystallization of the main soda-lime silicate phase. The introduction of dopants is identified to cause no changes in the precipitated phases, with only minor changes in the percent of the crystalline phases. Experimental data indicate that the glass-ceramic samples are effective in bioactivity and antimicrobial efficiency.     

Application of Fourier transform infrared spectroscopy to study the interactions of poly(acrylic acid) and mixtures of poly(acrylic acid) and polyacrylamide with bone powders and hydroxyapatites

Fourier transform infrared (FTIR) spectroscopy was used to study the interactions of aqueous solutions of poly(acrylic acid) (PAA) and mixtures of aqueous solutions of PAA and polyacrylamide (PAAm) with chemically and thermally treated bone powders (BPs) and two commercial hydroxyapatites (HAs). An analysis of the spectra of the precipitates that resulted from the mixtures of PAA and the chemically treated samples of BP revealed that the spectra exhibited three new bands at 1544, 1552, and 1661 cm^?1. The first band was attributed to the formation of calcium–polycarboxylate resulting from the interaction between the carboxylic acid groups of PAA and the calcium ions of BP. The appearance of the other two bands, in addition to the disappearance of the band corresponding to the absorption of the acid groups of PAA, provided strong evidence for the existence of other interactions between the carboxylic acid groups and the amide groups of the organic matrix of BP. On the other hand, the FTIR spectra of the samples that resulted from the mixture of PAA and thermally treated BP and the two commercial HAs showed only a new absorption band at 1544 cm^?1. The interactions of mixtures of the aqueous solutions of PAA and PAAm, adjusted at low or high pH values, with the different BPs and HAs were examined. The mixtures of the aqueous solutions of PAA and PAAm interacted with the different BPs and two HAs, resulting in the formation of ternary PAA–BP–PAAm and PAA–HA–PAAm complexes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Preparation and characterization of proton exchange membrane based on polyphosphoric acid modified by PVDF‐HFP

A polyphosphoric acid functionalized proton exchange membrane (PEM) was prepared by a ring opening reaction using the epoxycyclohexylethyltrimethoxysilane (EHTMS) and amino trimethylene phosphonic acid (ATMP) as raw materials and was modified by poly(vinylidene fluoride)–hexafluoro propylene (PVDF‐HFP). The structure of the membranes was characterized by Fourier transform infrared and scanning electron microscopy. The X‐ray photoelectron spectroscopy explores the content of the elements in the membrane related to the ion exchange capacity value. The membranes’ properties including water uptake, swelling ratio, proton conductivity, and hydrolysis stability were studied. Performance tests show that when ATMP/EHTMS = 1/5, conductivity of the PVDF‐HFP modified PEMs increased from 0.83 × 10^?4 S cm^?1 at 20 °C to 9.53 × 10^?3 S cm^?1 at 160 °C, the swelling ratio of membranes decreased from 2.71% to 2.13%. The results indicate that the introduction of F atoms is beneficial to increase the proton conductivity and the dimensional stability. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46737.     

Fluorescent‐tagged no phosphate and nitrogen free calcium phosphate scale inhibitor for cooling water systems

Allyloxy polyethoxy ether (APEO) and chloracetic acid were used to prepare allyloxy polyethoxy carboxylate (APEC). 8‐hydroxy‐1,3,6‐pyrenetrisulfonic acid trisodium salt was reacted with allyl chloride to produce fluorescent monomer 8‐allyloxy‐1,3,6‐pyrene trisulfonic acid trisodium salt (AP). APEC and AP were copolymerized with maleic anhydride (MA) to synthesize AP tagged no phosphate and nitrogen free calcium phosphate inhibitor MA‐APEC‐AP. Structures of AP, APEO, APEC, and MA‐APEC‐AP were carried out by FTIR and ¹H‐NMR. Different MA : APEC mole ratios were employed for the manufacture of MA‐APEC‐AP to study the effect of mole ratio on performance of MA‐APEC‐AP. Relationship between MA‐APEC‐AP's fluorescent intensity and its dosage was studied. MA‐APEC‐AP's calcium phosphate inhibition was compared with the down to date calcium phosphate inhibitor (MA)‐ammonium allylpolyethoxy sulphate (APES). The results indicate that capability of MA‐APEC‐AP is heavily depended on the mole ratio of MA : APEC. Correlation coefficient r of MA‐APEC‐AP's fluorescent intensity and its dosage is 0.9983, and detection limit of MA‐APEC‐AP is 2.03 mg L^?1. MA‐APEC‐AP can be used to accurately measure polymer consumption on line besides providing excellent calcium phosphate inhibition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Electrochemical polymerization of phenanthrene in mixed electrolytes of boron trifluoride diethyl etherate and concentrated sulfuric acid

A novel high‐quality polyphenanthrene (PPH) film with electrical conductivity of 10^?1 S cm^?1 was synthesized electrochemically by direct anodic oxidation of phenanthrene in boron trifluoride diethyl etherate containing 10% concentrated sulfuric acid (v/v). The oxidation onset potential of phenanthrene in this medium was measured to be only 0.91 V versus saturated calomel electrode (SCE), which was lower than that determined in acetonitrile + 0.1 mol L^?1 Bu₄NBF₄ (1.56 V versus SCE). As‐formed PPH films from this medium showed good electrochemical behavior and stability. De‐doped PPH films were thoroughly soluble in dimethylsulfoxide or CHCl₃. The structure and morphology of the polymer were investigated using UV‐visible and Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy. FTIR and ¹H NMR spectra showed that the PPH was grown via the coupling of the monomer mainly at the C₄, C₅, C₉ and C₁₀ positions. Fluorescence spectral studies indicated that PPH was a blue‐green light emitter. Copyright © 2007 Society of Chemical Industry     

Methacryloxyethyl phosphate‐grafted expanded polytetrafluoroethylene membranes for biomedical applications

Expanded polytetrafluoroethylene (ePTFE) membranes were modified by graft copolymerization with methacryloxyethyl phosphate (MOEP) in methanol and 2‐butanone (methyl ethyl ketone (MEK)) at ambient temperature using gamma irradiation. The effect of dose rate (0.46 and 4.6 kGy h^?1), monomer concentration (1–40 %) and solvent were studied and the modified membranes were characterized by weight increase, X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XPS was used to determine the % degree of surface coverage using the C? F (ePTFE membrane) and the C? C (MOEP graft copolymer) peaks. Grafting yield, as well as surface coverage, were found to increase with increasing monomer concentration and were significantly higher for samples grafted in MEK than in methanol solution. SEM images showed distinctly different surface morphologies for the membranes grafted in methanol (smooth) and MEK (globular), hence indicating phase separation of the homopolymer in MEK. We propose that in our system, the non‐solvent properties of MEK for the homopolymer play a more important role than solvent chain transfer reactions in determining grafting outcomes. Copyright © 2005 Society of Chemical Industry     

Determination of the SiH content of hydrogen silicone oil by a combination of the fourier transform near infrared,attenuated total reflectance–fourier transform infrared,and partial least squares regression models

To verify the feasibility of the determination of the Si?H content (HC) of hydrogen silicone oil (HS‐oil) with Fourier transform near infrared (FT‐NIR) spectroscopy and attenuated total reflectance (ATR)–Fourier transform infrared (FTIR) spectroscopy combined with the partial least squares regression (PLS‐R) model, HS‐oil samples were synthesized from concentrated hydrosilicone oil (HC = 1.4 wt %), octamethylcyclotetrasiloxane, and hexamethyldisiloxane or prepared by the dilution of concentrated hydrosilicone oil with octamethylcyclotetrasiloxane. The FT‐NIR PLS‐R model (8695–4000 cm^?1, two principal components) was developed from the FT‐NIR spectral data, and the coefficient of determination for cross‐validation (R²) and the coefficient of determination for external validation (r²) were 0.992 and 0.995, respectively. The ATR–FTIR PLS‐R model (2302–2040 cm^?1, one principal component) was developed from the ATR–FTIR spectral data; it produced an R² of 0.995 and an r² of 0.996. This study demonstrated that the combination of FT‐NIR and ATR–FTIR spectroscopy with the PLS‐R model were successfully used to determine the HC of the HS‐oil. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40694.     

Characterization of structure of comblike polymer by pyrolysis gas chromatography and Fourier transform infrared spectroscopy

The characterization of branching in comblike polymers using high‐resolution pyrolysis gas chromatography (HRPGC) and Fourier transform infrared spectroscopy (FTIR) is investigated. The branching type can be identified from characteristic peaks of monomer and a group of dimers in pyrograms derived from α‐ and β‐scission of branched atoms. By resolving the overlapping bands between 2800–3000 cm^?1, the relative absorbance of CH₂ can be used to calculate the average branch length L. This method is helpful in evaluating the property of drag‐reduction agents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 359–363, 2001     

Fast‐swelling oxidized starch phosphate–poly(acrylate/acrylamide/2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid) superabsorbent composite

A fast‐swelling superabsorbent composite was prepared by solution polymerization of acrylate, acrylamide, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid and oxidized starch phosphate. Ethanol, propyl alcohol, butyl alcohol, and sodium bicarbonate were used as foaming agents to produce fast‐swelling characteristics. The structure of the superabsorbent composite was characterized using Fourier transform infrared spectroscopy (FTIR). The influences of the amount of water, acrylamide, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid, oxidized starch phosphate, initiator, and trihydroxymethyl propane glycidol ether, as well as the neutralization degree of acrylic acid on the equilibrium swelling degree and swelling rate of the superabsorbent composite, were investigated. The equilibrium swelling degree of the superabsorbent composite prepared in a 0.9 wt% NaCl aqueous solution was 52 g g^?1, and the swelling rate reached 0.86 mL g^?1 s^?1. The swelling kinetics was also investigated, and the results indicate that swelling of the superabsorbent composites obeys Schott's pseudo second‐order kinetics model. POLYM. ENG. SCI., 56:1267–1274, 2016. © 2016 Society of Plastics Engineers     

Determination of the Si?H content of hydrogen silicone oil by a combination of the fourier transform near infrared,attenuated total reflectance–fourier transform infrared,and partial least squares regression models

To verify the feasibility of the determination of the Si? H content (HC) of hydrogen silicone oil (HS‐oil) with Fourier transform near infrared (FT‐NIR) spectroscopy and attenuated total reflectance (ATR)–Fourier transform infrared (FTIR) spectroscopy combined with the partial least squares regression (PLS‐R) model, HS‐oil samples were synthesized from concentrated hydrosilicone oil (HC = 1.4 wt %), octamethylcyclotetrasiloxane, and hexamethyldisiloxane or prepared by the dilution of concentrated hydrosilicone oil with octamethylcyclotetrasiloxane. The FT‐NIR PLS‐R model (8695–4000 cm^?1, two principal components) was developed from the FT‐NIR spectral data, and the coefficient of determination for cross‐validation (R²) and the coefficient of determination for external validation (r²) were 0.992 and 0.995, respectively. The ATR–FTIR PLS‐R model (2302–2040 cm^?1, one principal component) was developed from the ATR–FTIR spectral data; it produced an R² of 0.995 and an r² of 0.996. This study demonstrated that the combination of FT‐NIR and ATR–FTIR spectroscopy with the PLS‐R model were successfully used to determine the HC of the HS‐oil. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40694.     

Surface characterization of 8‐quinolinyl acrylate‐grafted poly(ethylene terephthalate) prepared by plasma glow discharge and it's antibacterial activity

Poly(ethylene terephthalate) (PET) film was exposed to oxygen plasma glow discharge to produce peroxides on its surface. These peroxides were then used as catalysts for the polymerization of 8‐quinolinyl acrylate (QA) to prepare the PET grafted with QA (PET‐Q). The surface‐modified PET was characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR) and X‐ray photoelectron spectroscopy (XPS). The introduction of QA to the PET surface was confirmed by observing the presence of nitrogen in the XPS survey scan and high‐resolution spectra. The amount of QA grafted on to the PET surface as measured by the gravimetric method was about 5.2 μg cm^?2. The antibacterial activity of the surface‐modified PET texture was investigated by using a shake‐flask and an inhibition zone test method. After 6 h of shaking, the PET grafted with QA showed the inhibition (91%) of the growth of the gram‐positive microorganism, S. aureus. Even after laundering ten times, an effectiveness of the inhibition was found. However, little inhibition was shown with the gram‐negative microorganism, K. pneumoniae. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 863–868, 2006     

Studies on the photodegradation of polarized UV‐exposed PMDA–ODA polyimide films

Polarized Fourier transform infrared (FTIR) and ultraviolet‐visible (UV‐VIS) spectroscopy were used to investigate the photodegradation direction of polarized UV (PUV)‐irradiated polyimide (PI) films based on pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA). PI films strongly absorb below 350 nm, resulting in a photochemical reaction of the PI. PUV irradiation of the PI film caused a decrease of all existing peaks and formation of new peaks at 3258, 1748, and 1710 cm^?1 in the IR, due to degradation of the PI molecules. The preferential degradation of PI molecules parallel to the PUV irradiation direction results in the predominant orientation of the remaining PI molecules perpendicular to the PUV irradiation direction. But rubbing of the PI films induced orientation of the PI molecules parallel to the rubbing direction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3072–3077, 2002     

Polybenzimidazole‐graft‐polyvinylphosphonic acid—proton conducting fuel cell membranes

A new method for the preparation of polybenzimidazole (PBI)‐based membranes, containing high concentrations of immobilized phosphonic acid groups, has been developed. The procedure used is carried out in two steps: (1) Synthesis of modified PBIs, containing 1,2‐dihydroxypropyl groups and preparation of films there from; (2) Introduction of vinylphosphonic acid (VPA) and initiator (cerium ammonium nitrate) in the film, subsequent grafting of VPA from the active sites of the PBI backbone. Membranes with different length of the grafted polyvinylphosphonic acid chains were prepared. The molar ratio grafted VPA units per PBI repeating unit reaches 7.8. Proton conductivity was measured at 120°C and relative humidity (RH) 20–100%. For the membrane with highest concentration of phosphonic acid groups the proton conductivity was 35 mS cm^?1 at 100% RH and 8 mS cm^?1 at 20% RH. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The characterization of short chain branching in polyethylene using fourier transform infrared spectroscopy

The characterization of short chain branching in polyethylene using transmission FTIR spectroscopy is investigated. Traditional methodologies, using the methyl deformation band for qualitative and quantitative analyses, have recognized shortcomings. The methyl and methylene rocking bands, which are more characteristic of short chain branch type, were found to be more useful. Methyl, ethyl, butyl, isobutyl, and hexyl branches are qualitatively and quantitatively characterized in LLDPE copolymers by FTIR spectroscopy. Methyl branches were characterized by an absorbance at 935 cm^?1, ethyl branches at 770 cm^?1, butyl branches at 893 cm^?1, isobutyl branches at 920 cm^?1, and hexyl branches at 888 cm^?1. Fourier self-deconvolution was used to resolve overlapping bands for ethyl, butyl, and isobutyl branches. Using calibrations derived for LLDPE copolymers from ¹³C NMR data, FTIR spectroscopy was also used to characterize LLDPE terpolymers and LDPE resins. The FTIR and NMR data are in qualitative and quantitative agreement. In some cases correction were made to the FTIR results using data obtained from the methyl deformation band. The FTIR technique is less costly and faster than NMR spectroscopy. © 1994 John Wiley & Sons, Inc.     

Effects of hot‐air aging and dynamic fatigue on the structure and dynamic viscoelastic properties of unfilled natural rubber vulcanizates

The effects of hot‐air aging and dynamic tensile fatigue on the network structure and dynamic viscoelastic properties of unfilled natural rubber (NR) vulcanizates were investigated with magnetic resonance crosslink density spectrometry, Fourier transform infrared spectroscopy/attenuated total reflection (FTIR–ATR), and dynamic mechanical analysis. The results showed that there was a carbonyl weak absorption peak at 1723 cm^?1 in the FTIR–ATR spectra of unfilled NR vulcanizates after hot‐air aging; The crosslink density decreased continuously as the aging time increased. The dynamic modulus of an aged specimen declined considerably, and the value of tan δ after 72 h of aging greatly increased. There was a large difference in the FTIR–ATR spectra of unfilled NR vulcanizates before and after tensile fatigue. The peaks at 1597, 1415, and 1015 cm^?1 increased concurrently with the tensile fatigue time. Initial analysis suggested that structures such as conjugated dienes appeared in the network structure. The modulus declined sharply, whereas the value of tan δ increased noticeably, after tensile fatigue. The effects of hot‐air aging and tensile fatigue on the crosslink density and FTIR–ATR spectra of unfilled NR vulcanizates were different, but both affected the viscoelastic properties dramatically. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008