Degree Of Grafting Research Articles

Epoxy/melamine polyphosphate modified silicon carbide composites: Thermal conductivity and flame retardancy analyses

Abstract Silicon carbide (SiC) was modified by melamine polyphosphate (MPP)-modified silicone to form SiC-MPP, then incorporated into epoxy resin (EP) for developing thermally resistant composites, which showed thermal conductivity and flame retardancy performance. The EP/SiC-MPP composites were prepared by blending and cured under 60°C for 2 h and 150°C for 8 h. The grafting degree of SiC-MPP was analyzed using Fourier transform Infrared, scanning electron microscope, and thermogravimetric measurements. The flame retardancy of the EP/SiC-MPP composites was studied by UL-94 vertical combustion and cone calorimetry test. The results showed that for EP/SiC-MPP containing 20 wt%, the UL-94 was case V1. Also compared to pure epoxy, the peak heat release rate (PHRR) of composites was reduced from 800 to 304 kW·m−2. The thermal conductivity of EP/SiC-M20 composites was 0.53 W·m−1·K−1, almost 2.5-fold higher than pure epoxy (0.21 W·m−1·K−1). The as-prepared EP/SiC-MPP composites exhibited enhanced flame retardancy and thermal conductivity. Based on analyses performed, these composites took credit-related applications.

Effects of Protein Functionality on Myofibril Protein-Saccharide Graft Reaction.

The myofibril protein (MP) isolate-saccharide graft reactions was prepared using the Maillard reaction with saccharides. The effects of various saccharides on protein functionality and quality of the Maillard reaction were investigated and compared with those of MP. The grafting degree of the MP isolate-saccharide graft reaction was significantly higher in the reducing sugar-treated groups (lactose, glucose, fructose, and palatinose). The browning intensity of the MP isolate-saccharide graft reaction with fructose, sucrose, and erythitol was higher than that observed in the control reaction (p<0.05). MP that reacted with reducing sugars (glucose, fructose, palatinose, and lactose) had fainter bands than MP that reacted with non-reducing sugars (sucrose, erythitol, trehalose, sorbitol, and xylitol). MPs conjugated with glucose exhibited higher protein solubility. The palatinose and lactose treatments were maximum in water binding capacity, though no significant difference in oil binding capacity among the saccharide treatments was observed. The emulsion stability of the MP isolate-saccharide graft reaction with palatinose and erythitol was higher than that of the control reaction. Therefore, reducing sugars have good protein functionality in the MP isolate-saccharides graft reaction.

Jatobá wood flour: An alternative for the production of ecological and sustainable PCL biocomposites

The industrial residue of Jatobá wood flour (JWF) was reused during production of biocomposites based on polycaprolactone (PCL), 50% by weight of JWF was added to PCL matrix. Initially, maleic anhydride-grafted polycaprolactone compatibilizer (PCL-g-MA) was synthesized and characterized using X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and degree of grafting. Afterwards, PCL/JWF and PCL/JWF/PCL-g-MA biocomposites were processed in an internal mixer and injection molded. From the gathered results, increase in torque and reduction in the melt flow index of PCL/JWF biocomposites were verified related to neat PCL. Upon addition of PCL-g-MA to PCL/JWF there was a lubricating effect with reduced torque and increased fluidity. PCL/JWF displayed increased elastic modulus, Shore D hardness, and heat deflection temperature (HDT) around 158.5%, 16% and 24.5%, respectively, related to PCL. Nevertheless, there was decline in tensile strength and impact strength, which were improved in PCL/JWF/PCL-g-MA, suggesting higher interaction among phases, providing greater stress transfer. An interesting finding was the nucleating effect of JWF in PCL matrix, as the increased degree of crystallinity and accelerated crystallization. Morphology of PCL/JWF evidenced several voids, but upon compatibilization with PCL-g-MA, the interfacial adhesion and wetness increased, improving the mechanical properties. JWF reusing presents great potential to produce sustainable biocomposites, reducing the final product costs.

Pineapple Fiber Hybrids Prepared by the Fusion of radiation-induced Graft Polymerization and Kabachnik-Fields three-component Reaction (RIGP-KF3CR)

ABSTRACT The fusion of multicomponent reactions and polymer chemistry allows the synthesis of polymeric materials that contain special classes of molecules that are otherwise difficult to produce. In this study, a locally available nonwoven fabric composed of pineapple fibers and polylactic acid (piñatex) was modified by radiation-induced graft polymerization (RIGP) of vanillin methacrylate, a lignin-derived monomer. RIGP yielded organic hybrids made from a natural, renewable, and biodegradable substrate, and surface aldehyde groups from vanillin. The grafted fabric was prepared by gamma pre-irradiation at 50 kGy, exhibiting an increasing degree of grafting with increasing reaction time and monomer concentration. Post-polymerization modification carried out using Kabachnik-Fields three-component reaction (KF3CR) enabled the immobilization of amine and phosphite moieties on the fabric. FTIR, SEM-EDS and XPS analysis of 8 amine and phosphite combinations showed the presence of the corresponding elements and functional groups, indicating successful surface functionalization through RIGP-KF3CR. All modified natural fibers-based fabrics displayed enhanced thermal stability without obvious radiation degradation effects. Synthesized natural fibers contain α-aminophosphonate pendants which may be useful in the selective adsorption and recovery of industry valuable metals.

Direct Observation and Semiquantitative Analysis of Hierarchical Structures in Graft-Type Polymer Electrolyte Membranes Using the AFM Technique.

The structural features of a polymer electrolyte membrane (PEM), consisting of polystyrene sulfonic acid (PSSA) grafted onto poly(ethylene-co-tetrafluoroethylene) (ETFE), can be characterized semiquantitatively by atomic force microscopy (AFM). The cross-sectional AFM phase images are converted to the binarized image by fitting two Gaussian functions. The domains correspond to hydrophilic PSSA domains and hydrophobic ETFE crystalline and amorphous regions, respectively, at lower and higher phase shift values. The area fraction of PSSA domains was consistent with the volume fraction determined by the grafting degree (GD). The dependence of the radius and interdomain distance of the PSSA domains on the GDs of PEMs shows discontinuous features at the threshold GD (39%). The former slightly increased from 10 to 12 nm and significantly increased to 17 nm at a GD greater than 39%; the latter decreased from 140 to 54 nm with increases in GDs up to 39% but inversely increased to 78 nm at a GD of 46%. This discontinuous change in radius and interdomain distance should be caused by the fusion of adjacent PSSA domains to form a larger size and spacing and thus less connectivity between each large domain, thereby lowering the conductivity at GD greater than 39%. We were able to demonstrate the existence of an ion-conducting hydrophilic path with a radius of approximately 10 nm. Even though it has received little attention in the past, it is expected to enable the design of electrolyte membrane functions in the future.

Synthesis of Amidoxime Adsorbent by Radiation-Induced Grafting of Acrylonitrile/Acrylic Acid on Polyethylene Film and Its Application in Pb Removal.

In the aquatic environment, heavy metals such as lead ions Pb (II) are of particular importance. These are due to Pb (II) being toxic at concentrations over 0.01 mg/L, when taken continuously over an extended length of time. Organs including the heart, gut, and kidneys are seriously harmed by Pb (II) intoxication. The neurological, reproductive, and bone systems are also affected. The removal of Pb (II) from aquatic environments is, therefore, crucial. Low density Polyethylene (LDPE) is grafted by radiation with Acrylonitrile and acrylic acid (PE-g-AN/AAc) for the adsorption of Pb (II). Factors that control the grafting process for optimum conditions, such as the effect of solvents, the air atmosphere, inhibitors, comonomer concentration, and composition and irradiation dose, are studied to obtain a high grafting yield without homopolymer formation and a higher water uptake. The results showed that the addition of 2.5% by wt% ferric chloride salt effectively inhibits homoploymerization of a mixture of 30% methanol and 70% H2O used as a solvent in nitrogen. The highest graft yield obtained was 320% at a 25 kGy radiation dose with an 80/20 monomer composition and 60% comonomer concentration. The resulting composite films were characterized by XRD to analyze the dispersion properties of the material, SEM for the surface morphology, FTIR analysis for the functional groups, TGA, DSC for the thermal stability and elongation, and tensile strength for the mechanical properties. The uptake of Pb (II) from lead nitrate aqueous solution by (PE-g-AN/AAc) was observed under different conditions of the degree of grafting, contact time, metal ion concentration, and pH. The results obtained suggest LDPE-g-p (AN/AAc) as a superabsorbent for the Pb (II) ion’s removal from an aqueous solution.

Graft Polymerization of Stearyl Methacrylate on PET Track-Etched Membranes for Oil-Water Separation.

In this article, results of PET track-etched membranes (PET TeMs) hydrophobized by photo-induced graft polymerization of stearyl methacrylate (SM) inside the pores were presented. The effects of monomer concentration, time of irradiation and the nature of the solvent on the degree of grafting and membrane morphology were investigated. The PET TeMs with pore diameters ranging from 350 nm (pore density of 1 × 108 pore/cm2) to 3.05 µm (pore density of 1 × 106 pore/cm2) were hydrophobized and tested for oil–water separation by using hexadecane–water and chloroform–water emulsions. Studies have shown high separation performance for membranes (up to 1100 mL/m2·s) with large pore diameters while achieving a high degree of purification.

Effects of Different Amounts of Corn Silk Polysaccharide on the Structure and Function of Peanut Protein Isolate Glycosylation Products.

Covalent complexes of peanut protein isolate (PPI) and corn silk polysaccharide (CSP) (PPI-CSP) were prepared using an ultrasonic-assisted moist heat method to improve the functional properties of peanut protein isolate. The properties of the complexes were affected by the level of corn silk polysaccharide. By increasing the polysaccharide addition, the grafting degree first increased, and then tended to be flat (the highest was 38.85%); the foaming, foam stability, and solubility were also significantly improved. In a neutral buffer, the solubility of the sample with a protein/polysaccharide ratio of 2:1 was 73.69%, which was 1.61 times higher than that of PPI. As compared with PPI, the complexes had higher thermal stability and lower surface hydrophobicity. High addition of CSP could made the secondary structure of PPI change from ordered α-helix to disordered β-sheet, β-turn, and random coil structure, and the complex conformation become more flexible and loose. The results of multiple light scattering showed that the composite solution exhibited high stability, which could be beneficial to industrial processing, storage, and transportation. Therefore, the functional properties of peanut protein isolate glycosylation products could be regulated by controlling the amount of polysaccharide added.

Preparation of high-solubility rice protein using an ultrasound-assisted glycation reaction

To date, the poor solubility of rice protein (RP) has limited its industrial application in food products. This study aimed to prepare high-solubility RP conjugates using ultrasound-assisted glycation between RP and dextran. The conditions of glycation, treatment at 82 °C for 22 min under 600 W ultrasonic power, were optimized using single-factor experiments and response surface analysis. The solubility of the conjugates reached 90.6 %. Compared with traditional wet-heating glycation, ultrasound-assisted treatment brought more high-molecular-weight components, higher degree of graft, and less contents of arginine and lysine, indicating that ultrasound accelerated the glycation reaction. Ultrasound also resulted in a looser and more flexible structure of RP, manifesting in a 10 % reduction in β-sheets and 10.6 % increase in random coils of conjugates. The analysis of fluorescence and surface hydrophobicity indicated that ultrasound increased the exposure of hydrophobic residues towards aqueous environment. Besides solubility, the foaming and emulsifying properties of RP were improved through conformational changes. In summary, ultrasound-assisted glycation was found to be an efficient and green method for preparing high-solubility RP conjugates.

Amidoxime-modified ultrathin polyethylene fibrous membrane for uranium extraction from seawater

The amidoxime-modified ultrathin polyethylene fibrous membrane (called as AFM) is prepared by a two-step graft polymerization method. The nano-sized particle structures are constructed on the AFM adsorbents surface after grafting. The adsorption behaviors of AFM adsorbent are studied by laboratory scale adsorption experiments. The adsorption results show that the adsorption of uranium by AFM is an endothermic spontaneous behavior without additional driving force. The AFM absorbent shows high specific surface area, good mechanical property and outstanding reusability of >12 cycles. Furthermore, the AFM adsorbent has a high uranium adsorption capacity of 147.38 mg/g in 8 ppm U-spiked simulated seawater for 96 h and 7.46 mg/g in natural seawater for 56 days. The results show that the degree of grafting (DG) and thickness of the membrane are the two key factors affecting the adsorption capacity. The adsorbent with thinner membrane thickness has a higher adsorption capacity at a moderate DG. This is because at moderate DG, the thinner the membrane is, the easier the adsorption sites are contacted by uranium ions. This work presents a novel membrane adsorbent with high uranium adsorption capacity and long service life, which shows significant application potential for uranium extraction from seawater.

In situ reactive coating of porous filtration membranes with functional polymer layers to integrate boron adsorber property

The state-of-the-art reverse osmosis membranes for seawater desalination have limited competence to efficiently remove boron. One promising approach for boron removal is to integrate membrane-based separation with selective adsorption of boron in pre- or posttreatment of seawater desalination; the porous support layer of established filtration membranes, constituting the largest part of total membrane volume shall be utilized for this function. Therefore, this study focuses on performing in situ modification of commercial polyethersulfone (PES) microfiltration membranes toward reactive coating the pore surface with a boron affinity polymer-based hydrogel. Modification is carried out in two steps: 1) adsorption of an amphiphilic copolymer which contains tertiary amine groups as co-initiator for surface-selective free radical generation; 2) grafting of a hydrogel layer by using a monomer solution comprising polyol-containing monomer as boron ligand, a cross-linker monomer, and the redox initiator ammonium persulfate (APS). The entire modification process is performed under flow-through conditions. Membranes with different pore sizes were modified; modification parameters, such as molar mass of macromolecular co-initiator as well as composition of reactive monomer solution, were systematically varied. It was found that using an “integrated” initiation system with low molecular weight co-initiator N,N,N′,N′-tetraethyl ethylenediamine (TEMED) added to the reactive solution, yielded significantly higher degree of grafting and therefore superior adsorber properties. Boron binding capacity of modified membranes was evaluated in terms of boron adsorption isotherms, adsorption kinetics, break-through behavior under filtration conditions and regeneration of the adsorber. The trade-off between permeance and boron binding capacity of modified membrane was studied in order to identify promising materials with competitive overall separation performance, i.e. high permeance at a specific filter cut-off in combination with high boron binding capacity.

Discovering the effect of solvents on poly(2-aminoethyl methacrylate) grafting onto chitosan for an in vitro skin model

The design of controlled grafting copolymers is critical in synthesizing effective artificial cellular matrices because of their regulatory role in cellular behavior. However, it is unclear whether poly(2-aminoethyl methacrylate) grafted onto chitosan generated by gamma-radiation-induced graft polymerization in different solvents can influence the physicochemical properties and biotech applicability of the copolymer. This work aims to demonstrate for the first time the effect of various solvents on the synthesis, properties, and biological performance of grafted chitosan using the simultaneous irradiation method. The results proved that the solvent is one of the critical factors affecting the properties of the modified polysaccharide. The degree of grafting showed a solvent-dependent profile. Hexane presented utmost importance concerning the degree of grafting. Ethyl acetate showed the best results in grafting extent and human dermal fibroblast growth. These findings indicate that proper solvent selection determines the possible copolymer use for in vitro engineered skin substitute models.

Molecular characteristics, mechanism of synthesis, adhesive properties of graft copolymer of chloroprene rubber with acrylic acid

AbstractSynthesized graft copolymers of chloroprene rubber with acrylic acid in a solution of a mixture of dimethylformamide and benzene, in the presence of potassium persulfate. The gravimetric method determined the orders of the reaction rate by the concentrations of acrylic acid (2.0) and potassium persulfate (1.2), the total activation energy of the process (24.4 kJ/mol). It was found that the degree of grafting increases up to 140% with an increase in the concentration of the monomer, initiator, temperature, and process time. The efficiency of grafting changes insignificantly with changes in synthesis conditions and has a high value (67%–91%) over a wide range of concentrations, temperatures, and times. With an increase in the concentration of acrylic acid and a process time of up to 8 h, the molecular weight of the grafted polyacrylic acid chains increases to 38,000. IR Fourier,1H, and13C NMR spectroscopic studies established the mechanism of graft copolymerization. Radical active centers are formed as a result of hydrogen abstraction from the rubber molecule after interaction with potassium persulfate. Copolymers synthesized at a mass ratio of rubber:acrylic acid from 1:0.5 to 1:2, have excellent adhesion to the surface of the skin and textile material.

Enhancing the durability and performance of radiation-induced grafted low-density polyethylene-based anion-exchange membranes by controlling irradiation conditions

This study presents a systematic analysis of the influence of irradiation conditions (absorbed dose, temperature, and atmosphere) on the physicochemical properties of radiation-induced grafted anion-exchange membranes (AEMs) based on low-density polyethylene (LDPE). Detailed characterization of the polymeric electrolytes shows striking effects of the irradiation conditions on the AEM properties. The LDPE films are irradiated both at room temperature (RT) and low temperature (LT, ∼ −10 °C). At each temperature, samples are irradiated in air as well as nitrogen. By lowering the sample temperature from RT to LT during irradiation in air it is possible to obtain a threefold increase in the degree of grafting (DoG). The higher DoG reflects in the OH− conductivity (σ) of the AEM irradiated at LT, which exhibits σ (T = 80 °C) = 215 mS cm−1, while the sample prepared at RT and air has σ (T = 80 °C) = 127 mS cm−1. Such high conductivity of the LT irradiated LDPE-AEM results in high-performance anion-exchange membrane fuel cell (AEMFC) with enhanced stability, as inferred from the time dependence of σ (T = 60 °C) measurements. The experimental results evidence that the control of both the irradiation temperature and the atmosphere diminishes the degradation effects caused by the radiation. Therefore, the present study advances the understanding of the role played by the irradiation process on the final properties of radiation-induced grafted LDPE-based AEMs and offers new possibilities to guide future developments for anion-exchange membranes.

The Influence of Pre-Irradiation and Simultaneous Grafting Methods on the Physicochemical Properties of Polyethylene-Based Anion-Exchange Membranes and Ionomers

Controlling the synthesis parameters during radiation-induced grafting (RIG) is a key feature to design anion-exchange membranes (AEMs) with enhanced properties that lead to high performances and stability. The present study provides a systematic investigation of the effect of RIG methods on physicochemical properties of LDPE-based AEMs with similar degree of grafting (DoG) and ion exchange capacity (IEC). The LDPE films were grafted with 4-vinylbenzyl chloride using two methods: i) pre-irradiation (PIM), using electron-beam (EB), and ii) simultaneous (SM), using gamma-ray (γ), both in air atmosphere and with different absorbed doses. The AEMs grafted by SM were irradiated with 20, 25, and 30 kGy, while the ones grafted by PIM were irradiated with doses of 30, 70, and 100 kGy. Samples grafted by the two different methods have the same molecular structure, but distinct physicochemical properties due to markedly differences in the degree of crosslinking. The studies have shown that grafting step directly influences the internal structure and morphology of AEMs. Multi-technique characterization demonstrated that RIG method determines the mechanical properties, water transport, and the distribution of ionic groups in AEMs. These characteristics have direct impact on fuel cell performance, anion-conductivity, and AEM stability.Figure 1 shows the polarization curves of anion-exchange membrane fuel cells (AEMFCs) operating at 80 °C with AEMs grafted by PIM and SM. Comparing AEMFCs performances containing AEMs with similar IECs from the two different grafting methods, it is possible to notice that AEMs synthesized by PIM, in general, promote better fuel cell performances than the corresponding ones prepared by SM. The main differences in the polarization curves are evidenced in the ohmic and the mass transport limiting regions. This result suggests that water management is enhanced in AEMs synthesized by PIM compared to the SM-AEMs. A membrane that allows rapid back diffusion of liquid water from the anode to the cathode, should reduce the current losses due to mass transport limitations.The gel content results confirmed the presence of more crosslinking in membranes synthesized by PIM than in the ones synthesized by the SM. As a consequence of that, enhanced mechanical properties were found for PIM-AEMs, indicating polymer backbone reinforcement due to high degree of crosslinking. Small-angle X-ray scattering measurements have confirmed that the microstructure of PIM and SM AEMs are different and this feature is directly related to ion conduction and water transportation.Figure 1. AEMFCs performances at 80 °C with LDPE-based AEMs grafted by the pre-irradiation method and by the simultaneous method. H2 anode gas flow=0.8 L min-1, O2 cathode gas flow=0.5 L min-1, both supplied unpressurized with optimal dewpoint temperatures ranging from 77 to 80 °C. AEMs are referred according to the grafting method and absorbed dose. 30 and 70-EB-PIM refer to the samples irradiated with 30 and 70 kGy, respectively, in the EB accelerator and grafted by the pre-irradiation method. 20 and 25-γ-SM refer to AEMs irradiated with 20 and 25 kGy, respectively, by γ-rays and grafted by the simultaneous method. Figure 1

Lactobacillus plantarum 21805 encapsulated by whey protein isolate and dextran conjugate for enhanced viability

Probiotics incorporated into food products are often insufficiently potent because of unfavorable interference during processing. This study addressed these issues by encapsulating Lactobacillus plantarum into whey protein isolate (WPI) and dextran (DX) conjugates using an encapsulator. The objective of this work is to investigate the effect of encapsulation using WPI and DX conjugates on the viability of Lactobacillus plantarum. The formation of the conjugates was confirmed with absorbance of the intermediate- and late-stage products, degree of grafting, browning index, and gel electrophoresis. Extending the heating time from 1 to 5 h increased the content of high molecular weight conjugates. These conjugates provided better protection of probiotics under processing stress conditions, gastrointestinal conditions, and storage. Furthermore, encapsulated L. plantarum exhibited a reduction of only 0.33 log CFU/mL after 90 d of storage at 4 °C. Thus, microencapsulation of probiotics can enhance the viability of functional food products and facilitate corresponding research.

Preparation and cesium adsorption behavior of Prussian blue-based polypropylene nonwoven fabric by surfactant-assisted aqueous preirradiation graft polymerization

In this research, we demonstrate the environmentally benign and efficient preparation of poly(acrylic acid)-grafted hydrophobic non-woven polypropylene fabric (PP-g-PAA) by pre-irradiation graft polymerization in the presence of surfactant and its further use in the fabrication of Prussian blue (PB)-immobilized adsorbent (PP-g-PAA-PB) for the decontamination of Cs+. The grafting degree and staining results revealed that incorporation of 0.5 wt% of the surfactant produced a uniform PP-g-PAA (with the grafting degree from 19% to 172%) even at the lower aqueous monomer concentrations ranging from 2 to 8 wt%. From the physicochemical analytical results, it was confirmed that the homogenous introduction of PAA and immobilization of crystalline PB only on the hydrophobic PP fibers while preserving the intrinsic porous structure of the PP fabric. Moreover, the PP-g-PAA-PB adsorbent exhibited the good adsorption capacity compared to that of powder-type commercial PB adsorbent, considering its one-seventh lower loading PB amount in the Cs+ adsorption test than that of commercial PB. Therefore, this radiation-induced graft polymerization strategy could offer a promising way for environmentally benign and efficient surface functionalization of various hydrophobic polymers for use in various environmental and biological applications.

Tuning Ice Nucleation by Mussel-Adhesive Inspired Polyelectrolytes: The Role of Hydrogen Bonding

Tuning Ice Nucleation by Mussel-Adhesive Inspired Polyelectrolytes: The Role of Hydrogen Bonding

Study on the mechanism of graft polymerization and sulfonation of proton exchange membranes for fuel cell

Poly (styrenesulfonic acid)-grafted poly(ethylene-co-tetrafluoroethylene) polymer electrolyte membrane (ETFE-PEM) applied for fuel cells was prepared by radiation induced-grafting using gamma-ray from 60Co source based on three steps (i) irradiation, (ii) polystyrene-graftedpoly(ethylene-alt-tetrafluoroethylene) (PS-g-ETFE), and (iii) sulfonation (ETFE-PEM). Mechanism of grafting and sulfonation of ETFE-PEM with grafting degree of 22% and sulfonation degree of 93% was revealed by solid 13C nuclear magnetic resonance (solid 13C NMR), Fourier transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM). The obtained results indicated that the styrene was grafted on the matrix of ETFE polymer by the π bond-breaking reaction which could be attributed to free radicals and formed the polystyrene chain at the surfaces of crystalline phases. The styrene migrated deep into the membrane due to the concentration gradient. The grafting reactions occurred at sites of C-H and C-F in the ETFE backbone but dominantly at the C-F sites while the sulfonation took place at the para position of polystyrene. The signatures related to side (secondary) reactions and by-products were not observed in the spectra indicating that the graft polymerization and sulfonation are well-controlled.

Investigation of chemical degradation and water states in the graft‐type polymer electrolyte membranes

AbstractChemical degradation in the presence of H2O2 aqueous solution and water states of poly(styrene sulfonic acid) (PSSA) grafted poly(ethylene‐co‐tetrafluoroethylene) polymer electrolyte membranes (ETFE‐PEMs) with grafting degree (GD) of 8.8%–21.1% are investigated using Fourier‐transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), and electrochemical impedance spectroscopy (EIS). The ETFE‐PEMs show the complete detachment at the α‐hydrogen atoms of the whole graft PSSA chains from the ETFE backbones, while their precursor polystyrene‐grafted ETFE films do not. This chemical degradation exhibits independently with GDs and takes place even at very low GD (&lt;10%). Water molecules of the membranes dried at 40°C are not completely de‐absorbed. The remains are partial non‐bonded water molecules, which are assumed to locate within the lamellar amorphous domains (constrained water molecules) of the crystalline phases. These constrained water molecules exist independently with the PSSA groups and do not detach together with them during the degradation. Note that the water molecules remained at 40°C show the additional contribution of 18%–19% to the total water uptake but do not contribute clearly to the conductance.