Properties of melt processable PTFE/PEEK blends: The effect of reactive compatibilization using electron beam irradiated melt processable PTFE

For the first time, blends of melt processable polytetrafluoroethylene (MP PTFE) with polyetheretherketone (PEEK) in the MP PTFE/PEEK ratio of 100/0, 80/20, 50/50, 20/80, and 0/100 w/w were prepared and characterized. MP PTFE/PEEK blends are attractive materials due to the combination of low coefficient of friction and universal chemical resistance of MP PTFE with good wear resistance and mechanical strength of PEEK while maintaining high thermal stability of both. Miscibility, phase morphology, and mechanical properties of the new MP PTFE/PEEK blends were investigated. To improve their end‐use properties, an attempt of reactive compounding with the electron beam irradiated MP PTFE (e‐beam MP PTFE) was made. The reactive compounding was done in two steps, that is, the preparation of a masterbatch (MB) consisting of e‐beam MP PTFE/PEEK (50/50 w/w) and subsequent melt blending of MP PTFE/PEEK with varying concentrations of MB. The e‐beam irradiation of MP PTFE carried out in air atmosphere and at room temperature with a dose of 50 kGy results in its chain scission associated with formation of ? COF and ? COOH functional groups. Such modified MP PTFE can be used to compatibilize MP PTFE/PEEK blends. Reactive compatibilized blends exhibit improved phase morphology and mechanical properties. Especially for MP PTFE/PEEK 50/50 blends, a great improvement of almost 250% in strain at break, 40% in stress at break, and more than 600% in toughness was achieved. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Atom transfer radical polymerization of graft chains onto polyethylene film initiated at tribromomethyl unit introduced by electron beam irradiation

A novel process for graft polymerization onto a polyethylene (PE) film using atom transfer radical polymerization (ATRP) was examined. First, a PE film irradiated with an electron beam was treated with carbon tetrabromide, thereby introducing tribromomethyl groups. The number of tribromomethyl groups introduced onto the film could be controlled by adjusting the electron beam irradiation dose. Methyl methacrylate (MMA) was then graft‐polymerized by ATRP in the initiator‐introduced PE film in the presence of a copper catalyst. Based on FTIR spectra from the PMMA grafted films, the behavior of graft polymerization reactions on the film surface and inside the film are discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reactive polytetrafluoroethylene/polyamide 6 compounds. II. Study of the reactivity with respect to the functionality of the polytetrafluoroethylene component and analysis of the notched impact strength of the polytetrafluoroethylene/polyamide 6 compounds

The formation of block copolymers as a result of an in situ chemical reaction during the reactive extrusion of electron‐beam‐irradiated polytetrafluoroethylene (PTFE) and polyamide 6 (PA) was detected indirectly with differential scanning calorimetry and Fourier transform infrared. As expected, the content of the block copolymers in the compound increased as the irradiation dose was increased. The notched impact strength showed an increase in the PTFE/PA compounds produced with highly irradiated PTFE. This behavior is discussed in the context of the degree of dispersion of the PTFE phase (as reported in part I of this series) and the adhesion changed by the in situ reaction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1317–1324, 2005     

Reactive polytetrafluoroethylene/polyamide compounds. I. Characterization of the compound morphology with respect to the functionality of the polytetrafluoroethylene component by microscopic and differential scanning calorimetry studies

Compounds of electron‐beam‐irradiated polytetrafluoroethylene (PTFE) and polyamide (PA) were produced by reactive extrusion. During extrusion, both a breakdown process of the PTFE agglomerates and a chemical reaction between PTFE and PA took place. The morphology of the compounds was characterized with differential scanning calorimetry using fractionated crystallization, with atomic force microscopy and scanning electron microscopy, and with dynamic light scattering. The particle size of the dispersed PTFE phase decreased as the irradiation dose increased. A simple theoretical model of the breakdown process of PTFE agglomerates was made for the discussion of the development of the observed degree of dispersion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1308–1316, 2005     

Characterization of three‐dimensional braided polyethylene fiber–PMMA composites and influence of fiber surface treatment

Three‐dimensional (3D) braided polyethylene (PE) fiber‐reinforced poly(methyl methacrylate) (PMMA), denoted as PE_3D/PMMA, composites were prepared. Mechanical properties including flexural and impact properties, and wear resistance were tested and compared with those of the corresponding unidirectional PE fiber–PMMA (abbreviated to PE_L/PMMA) composites. Both untreated and chromic acid‐treated PE fibers were used to fabricate the 3D composites in an attempt to assess the effect of chromic acid treatment on the mechanical properties of the composites. Relative changes of mechanical properties caused by fiber surface treatment were compared between the PE_3D/PMMA and PE_L/PMMA composites. The treated and untreated PE fibers were observed by scanning electron microscopy (SEM) and analyzed by X‐ray photoelectron spectroscope (XPS). SEM observations found that micro‐pits were created and that deeper and wider grooves were noted on the surfaces of the PE fibers. XPS analysis revealed that more hydroxyl (? OH) and carboxyl (? COOH) groups were formed after surface treatment. The physical and chemical changes on the surfaces of the PE fibers were responsible for the variations of the mechanical properties of the PE/PMMA composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 949–956, 2006     

The Influence of the Irradiation Temperature on the Ratio of Chain Scission to Branching Reactions in Electron Beam Irradiated Polytetrafluoroethylene (PTFE)

Polytetrafluoroethylene (PTFE) films have been irradiated by electron beam in vacuum at various temperatures ranging from room temperature up to temperatures far above the melting temperature. Changes of the chemical structure have been analyzed by ¹⁹F solid‐state NMR and IR spectroscopy. The concentration of several structures generated by irradiation increases with increasing irradiation temperature up to the beginning of the thermal degradation. The molar ratio of >CF? branching points to ? CF₃ end groups changes with crossing of the melting temperature. The generation of >CF? branching points is accelerated if the PTFE is irradiated in the molten state, where branching reactions become more important.

     

Multi-featured epoxy composites filled with surface-modified PTFE powders treated by Na-naphthalenide system

This study aimed to produce new multi-featured epoxy composites that are advanced in terms of mechanical properties, wear and impact resistance, and glass transition and heat deflection temperatures. Epoxy composites filled with chemically surface-treated poly (tetrafluoroethylene) (PTFE) powders at various ratios were prepared to obtain these improved properties. The chemical treatment was carried out via a Na-naphthalenide system. After this treatment, the x-ray photoelectron spectroscopy results presented the existence of functional groups such as OH, carbonyl groups, and CC unsaturation points on the surface of the PTFE powders. On the PTFE surfaces, while the atomic ratios of carbon and oxygen were substantially increased, the fluorine ratio presented a significant decrease after the chemical treatment. However, the wear rates of the novel composites were highly advanced despite this large decrease in the fluorine ratio on the surface of the PTFE powders. Moreover, functional groups such as OH, carbonyl groups, and CC unsaturation points and spongelike or network structures on the PTFE surfaces provided the opportunity to obtain strong adhesion and interfacial bonding between the surface-modified PTFE powders and the matrix. Strength and modulus values showed substantial enhancement besides the IZOD impact resistance. All glass transition and heat deflection temperatures were also substantially improved.     

Synthesis of poly(acrylic acid)/sodium humate superabsorbent composite for agricultural use

A novel poly (acrylic acid)/sodium humate superabsorbent composite was synthesized by graft copolymerization reaction of acrylic acid (AA) on sodium humate micropowder using N,N′‐methylenebisacrylamide (MBA) as a crosslinker and potassium peroxydisulfate (KPS) as an initiator in aqueous solution. The effects on water absorbency of factors such as reaction temperature, initial monomer concentration, and degree of neutralization of AA, amount of crosslinker, initiator, and sodium humate were investigated. The superabsorbent composite was characterized by scanning electron microscopy, and the graft copolymerization reaction of AA on sodium humate micropowder was characterized by IR spectroscopy. Results obtained from this study show that the water absorbency of the superabsorbent composite synthesized under optimal conditions for synthesis with a sodium humate content of 5.3% exhibited absorption of 684 g H₂O/g sample in distilled water. Water‐retention in soil is enhanced by the use of the superabsorbent composite. The effect of superabsorbent composite on the growth of corn is reported. The superabsorbent composite may be of use as water management materials for agriculture purposes in desert and drought‐prone areas. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5137–5143, 2006     

Surface‐initiated atom transfer radical polymerization from Mg(OH)2 nanoparticles to prepare the well‐defined polymer‐Mg(OH)2 nanocomposites

Well‐defined polymer‐Mg(OH)₂ nanocomposites were prepared by atom transfer radical polymerization (ATRP). The ATRP initiators were covalently attached to the Mg(OH)₂ by esterification of 2‐chloropropionyl chloride with hydroxyl group. The amount of polymer grafted from Mg(OH)₂ can be controlled using a different catalyst system and adding a small amount of polar solvent. The well‐defined diblock copolymer, consisting of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) were synthesized. The products were characterized by nuclear magnetic resonance, Fourier transform infrared, differential scanning calorimetry, and thermal gravimetric analysis. The morphologies of PS/PMMA and PS/PMMA/Mg(OH)₂‐g‐PS‐b‐PMMA blends are compared by using a scanning electron microscope. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3680–3687, 2007     

Protein adsorption on PTFE surface modified by ArF excimer laser treatment

Poly (tetrafluoroethylene) (PTFE) is a material that causes only a few rejections in a living body but has low tissue affinity. A soft tissue implant material that not only has high biocompatibility but also excellent bondability has been developed by photo-chemically incorporating OH functional groups on the PTFE surface with ArF excimer laser irradiation. Protein adsorption on untreated and treated samples was evaluated by scanning electron microscopy (SEM) and attenuated total reflection Fourier-transform infrared (ATR–FT-IR) spectroscopy, with bovine serum albumin (ALB) and fibrin (FIB) solutions. It has been found that protein adsorption increases with the increase in the OH group density on the PTFE surface. The maximum adsorption of both ALB and FIB was found on the PTFE sample treated with a laser fluence of 20 mJ/cm² and a shot number of 2000, whose water contact angle was 28 degrees; the quantities of both ALB and FIB adsorbed increased by a factor 2 as compared with untreated sample.     

Radiation–chemical modification of PTFE in the presence of graphite

PTFE with a 15% addition of graphite was subjected to irradiation using an electron beam of 10 MeV energy with absorbed doses of 26, 52, 78, 104, and 156 kGy. The effect of electron‐beam irradiation on the mechanical, sclerometic, and tribological properties, the crystallinity degree, and the morphology of the polymer surface was examined. It was found that the modification through irradiation entailed a gradual increase in the degree of crystallinity, which had a direct influence on the mechanical properties. An increase in the hardness, Young's modulus, and compressive strength of the polymer irradiated with an electron beam was also demonstrated. The electron‐beam irradiation reduced the value of components of the work‐of‐indentation, showing the growing resistance to deformation. An analysis of the scratch test parameters showed a reduced depth of penetration of the indenter into the material, proportionally to the irradiation value, at relatively constant values of the scratch depth after scratching load removal. A stereometric analysis of the scratch traces on the material allowed to determine coefficients of the wear micromechanism, β, and resistance to wear, W_β. It was found that after irradiation (especially with a dose of 4 × 26 kGy), a significant quantity of the material showed traces of ploughing, which meant a positive effect on the wear mechanism. The value of the wear resistance coefficient W_β for PTFE subjected to the absorbed irradiation dose increased intensively, which portended a significant reduction of the tribological wear compared to the nonirradiated material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42348.     

Temperature effects on positive electron resists irradiated with electron beam and deep-UV light

The exposure characteristics of poly(methyl methacrylate) (PMMA) and poly(methyl isopropenyl ketone) (PMIPK) were studied with electron beam and deep-UV light irradiation at different temperatures (20–160°C). The sensitivities and γ(contrast) values for electron beam irradiation show small temprature effects, but those for deep-UV light irradiation revel relatively large temperature effects. The result in which γ (contrast) values for the electron beam irradiation as a whole are significantly larger than for the deep-UV light irradiation is related to the molecular weight dispersity of irradiated resists. The result in which γ(contrast) for PMMA is larger than that for PMIPK at given development conditions is also related to the molecular weight ratios of the original and irradiated resists. The thickness reduction and negative inversion (crosslinking) compete under a large dose of electron beam irradiation, but the latter is scarcely apparent under deep-UV irradiation. The PMMA sensitivity for deep-UV irradiation diminishes in O₂ gas flow compared with the irradiation in N₂ gas flow, but PMIPK sensitivity is not influenced by O₂. From these results, the different decomposition mechanisms are discussed.     

An aqueous process to graft 2‐hydroxyl ethyl methacrylate onto polyvinyl chloride through its functional group

A simple aqueous method has been discussed to graft 2‐hydroxyl ethyl methacrylate (HEMA) onto the surface of polyvinyl chloride through its functional group ( OH). This method involves the conversion of the  OH group of HEMA to  ONa using metallic sodium. The modified surface has been characterized using FT ATR‐IR and Scanning electron microscopic methods. The advantage of the method is the feasibility of using the intact double bond of HEMA for further reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 113–118, 1999     

Synthesis and properties of new water‐soluble copolymers based on methyl acrylic acid sucrose ester and methyl acrylic acid

The new series of copolymers were obtained based on free radical solution copolymerization by mixing self‐made methyl acrylic acid sucrose ester (MASE) and methyl acrylic acid (MAA) with different ratios. Copolymerization behavior and properties of the new copolymers was investigated with the reaction time, temperature, monomer ratios and characterized by Fourier transform infrared spectra (FT‐IR), carbon nuclear magnetic resonance (¹³C NMR), and intrinsic viscosity. The results indicated that sucrose was successfully grafted onto poly (methyl acrylic acid). Further, it was demonstrated that low temperature benefited the esterification of MASE. Importantly, the copolymers were founded to have good compatibility with polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE), and polyethylene (PE). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43627.     

The mechanical and tribological properties of PTFE filled with PTFE waste powders

Polytetrafluoroethylene (PTFE) composites filled with PTFE waste offer interesting combination of tribological properties and low cost. PTFE composites waste was mechanically cut and sieved into powders. PTFE composites filled with PTFE waste powders were prepared by compression molding. Friction and wear experiments were carried out in a reciprocating sliding tribotester at a reciprocating frequency of 1.0 Hz, a contact pressure of 5.5 MPa, and a relative humidity of (60 ± 5)%. PTFE materials slid against a 45 carbon steel track. Results showed that a PTFE composite (B) filled with 20 wt % PTFE waste exhibited a coefficient of steady‐state friction slightly higher than that of unfilled PTFE (A), while wear resistance over two orders of magnitude higher than that of unfilled PTFE (A). Another PTFE composite filled with PTFE waste and alumina nanoparticles exhibited the highest wear resistance among the three PTFE materials. This behavior originates from the effective reinforcement of PTFE waste as a filler. It was experimentally confirmed that the low cost recycling of PTFE waste without by‐products is feasible. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1035–1041, 2007     

静电纺光致变色PMMA纤维的制备与表征

使用静电纺丝的方法制备了一种含有硝基螺吡喃(SP)的具有光致变色特性的PMMA纤维。红外光谱(IR)的研究结果表明,SP可以通过络合反应与PMMA结合。通过扫描电镜(SEM)的观察可以看出,SP的加入对PMMA纤维的形态结构几乎没有影响。紫外可见光谱以及紫外光照后的颜色变化观察的结果表明,SP的加入使PMMA纤维具备了良好的光致变色性能。     

Grafting of butyl acrylate and methyl methacrylate on butyl rubber using electron beam radiation

Being nonpolar in nature, butyl rubber (IIR) has poor compatibility toward polar polymers and fillers. It can be improved by grafting polar substrates on the butyl elastomer. Radiation‐induced polymer processing is getting increasing interest, as it leads to new and improved polymers with desirable and interesting properties. In this investigation, electron beam radiation has been used to graft methyl methacrylate (MMA) and butyl acrylate (BA) on IIR. This process has several advantages over conventional grafting processes such as cationic polymerization (which needs very low temperature and stringent reaction conditions) and solution radical polymerization (which often needs solvent removal and recycling). The grafted polymers were characterized by using ¹H NMR, IR, TGA, and SEM analysis. The degree of grafting increases with a decrease in irradiation dose as well as with an increase in monomer concentration. It was observed that there was a decrease in intrinsic viscosity in irradiated IIR samples, indicating the chain scission. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1340–1346, 2006     

The influence of plasma treatment on the tribological properties of hybrid PTFE/cotton fabric/phenolic composites

In this study, the effects of air‐plasma and N₂‐plasma treatment on the hybrid polytetrafluoroethylene (PTFE)/cotton fabric and a phenolic resin were investigated in detail. The tribological properties of the untreated and plasma‐treated hybrid PTFE/cotton fabric/phenolic composites were investigated. The results indicated that air‐plasma‐treated hybrid PTFE/cotton fabric/phenolic composites exhibited better antiwear and friction reduction properties. The combination of scanning electron microscopy and Fourier transform infrared spectroscopy analysis illustrated that hybrid PTFE/cotton fabric/phenolic composites treated with air‐plasma possessed more integrated structure and more functional groups, which plausibly contributed to the better tribological properties of the hybrid PTFE/cotton fabric/phenolic composites treated with air‐plasma. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Preparation of compatible blends of poly(methyl methacrylate) used in dentistry with a reactive terpolymer containing maleic anhydride and their thermomechanical characterization

This study focuses on the preparation of compatible blends with the poly(methyl methacrylate) (PMMA) using a reactive terpolymer maleic anhydride–styrene–vinyl acetate (MA–St–VA). In the first series of experiments, binary blends of the PMMA and the MA–St–VA terpolymer have been prepared in tetrahydrofurane. The PMMA and the MA–St–VA terpolymer formed the compatible blends. The effects on thermomechanical properties of MA–St–VA terpolymer ratio in the blends were studied. The glass transition temperatures (T_g), thermal expansion coefficient (α), and other thermomechanical parameters for the blends have been established by TMA method and the compatibility of two polymers has been evaluated by these TMA parameters. The addition of MA–St–VA terpolymer to PMMA made a plasticizing effect on PMMA. This effect regularly changed with the increasing of the terpolymer in the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 363–367, 2006     

Natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) blends

The grafting of the methyl methacrylate (MMA) monomer onto natural rubber using potassium persulfate as an initiator was carried out by emulsion polymerization. The rubber macroradicals reacted with MMA to form graft copolymers. The morphology of grafted natural rubber (GNR) was determined by transmission electron microscopy and it was confirmed that the graft copolymerization was a surface‐controlled process. The effects of the initiator concentration, reaction temperature, monomer concentration, and reaction time on the monomer conversion and grafting efficiency were investigated. The grafting efficiency of the GNR was determined by a solvent‐extraction technique. The natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) (NR‐g‐MMA/PMMA) blends were prepared by a melt‐mixing system. The mechanical properties and the fracture behavior of GNR/PMMA blends were evaluated as a function of the graft copolymer composition and the blend ratio. The tensile strength, tear strength, and hardness increased with an increase in PMMA content. The tensile fracture surface examined by scanning electron microscopy disclosed that the graft copolymer acted as an interfacial agent and gave a good adhesion between the two phases of the compatibilized blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 428–439, 2001