Radiation‐induced graft copolymerization of MMA monomer onto UHMWPE: Adhesion improvement

Graft copolymerization of methyl methacrylate monomer onto ultra high molecular weight polyethylene (UHMWPE) and acid‐etched UHMWPE was conducted using preirradiation method in air in the presence of a Mohr salt and sulfuric acid to improve adhesion to the bone cement. The grafted samples were characterized by Fourier transform infrared (FTIR) spectroscopy, gravimetric method, goniometry, and interfacial bonding strength measurements. The FTIR results showed the presence of ether, carbonyl, and hydroxyl groups for grafted films. The gravimetric results showed that the chromic acid etching and graft copolymerization had a synergetic effect so, the irradiated, then chromic acid etched at room temperature and grafted sample (Rad etch25) had the highest grafting degree. The interfacial bonding strength between UHMWPE and poly methyl methacrylate bone cement was considerably improved by graft copolymerization and chromic acid etching. The surface morphology was studied by scanning electron microscopy. The substitution of polar groups into the backbone of UHMWPE by chromic acid etching and graft copolymerization changed its contact angles with water and methylene iodide and increased its surface energy, as evidenced by contact angle measurements. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Surface modification of ultra‐high‐molecular‐weight polyethylene. II. Effect on the physicomechanical and tribological properties of ultra‐high‐molecular‐weight polyethylene/poly(ethylene terephthalate) composites

We performed surface modification of ultra‐high‐molecular‐weight polyethylene (UHMWPE) through chromic acid etching, with the aim of improving the performance of its composites with poly(ethylene terephthalate) (PET) fibers. In this article, we report on the morphology and physicomechanical and tribological properties of modified UHMWPE/PET composites. Composites containing chemically modified UHMWPE had higher impact properties than those based on unmodified UHMWPE because of improved interfacial bonding between the polymer matrix and the fibers and better dispersion of the fibers within the modified UHMWPE matrix. Chemical modification of UHMWPE before the introduction of PET fibers resulted in composites exhibiting improved wear resistance compared to the base material and compared to unmodified UHMWPE/PET composites. On the basis of the morphological studies of worn samples, microploughing and fatigue failure associated with microcracking were identified as the principle wear mechanisms. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Surface attachment of horseradish peroxidase to nylon modified by plasma‐immersion ion implantation

The surface of polyamide (nylon 6) was modified by plasma‐immersion ion implantation (PIII) with nitrogen ions. Structural changes associated with carbonization, oxidation, and depolymerization were observed in the modified surface layer with Fourier transform infrared/attenuated total reflection (FTIR–ATR) spectroscopy, surface energy measurements, and X‐ray photoelectron spectroscopy (XPS). The enzyme activity of surface‐attached horseradish peroxidase was studied with a tetramethylbenzidine colorimetric activity assay. Compared to untreated controls, the PIII‐treated surface showed a higher level of the attached protein with increased longevity of bioactivity. Detection of the immobilized protein layer was made difficult by the presence of amide groups in nylon. Here we demonstrate the potential of combining FTIR–ATR spectroscopy with XPS measurements for this purpose. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120:2891–2903, 2011     

Preparation and characterization of grafting polyacrylamide from PET films by SI‐ATRP via water‐borne system

The grafted homopolymer and comb‐shaped copolymer of polyacrylamide were prepared by combining the self‐assembly of initiator and water‐borne surface‐initiated atom transfer radical polymerization (SI‐ATRP). The structures, composition, properties, and surface morphology of the modified PET films were characterized by FTIR/ATR, X‐ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by equable grafting polymer layer after grafted polyacrylamide (PAM). The amount of grafting polymer increased linearly with the polymerization time added. The GPC date show that the polymerization in the water‐borne medium at lower temperature (50°C) shows better “living” and control. After modified by comb‐shaped copolymer brushes, the modified PET film was completely covered with the second polymer layer (PAM) and water contact angle decreased to 13.6°. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Novel electron beam‐modified surface‐coated silica fillers: Physical and chemical characteristics

A novel process of surface modification of silica fillers has been performed by coating with an acrylate monomer, trimethylol propane triacrylate (TMPTA) and with a silane coupling agent, triethoxy vinyl silane (TEVS), followed by electron beam irradiation of these coated fillers. The surface‐modified fillers have been characterized by Fourier‐Transform Infrared Analysis (FTIR), Electron Spectroscopy for Chemical Analysis (ESCA), Contact angle measurements by dynamic wicking method, Scanning Electron Microscopy (SEM), Energy dispersive X‐ray spectroscopy (EDX), Transmission Electron Microscopy (TEM), Fractal studies, Thermogravimetric analysis (TGA), and X‐ray diffraction (XRD) studies. Presence of the acrylate and the silane coupling agent on the modified fillers is confirmed from the above studies. The contact angle measurements suggest a significant improvement in hydrophobicity of the treated fillers, which is supported by water flotation test. After irradiation and acrylate treatment an increase in filler aggregation is observed, which is not as significant in the case of silanized silica filler. However, XRD studies demonstrate that the entire modification process does not alter the bulk properties of the fillers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2255–2268, 2002     

Synthesis and characterization of nanosilica/waterborne polyurethane end‐capped by alkoxysilane via a sol‐gel process

A novel method was used to synthesis nanosilica/waterborne polyurethane (WPU) hybrids by in situ hydrolysis and condensation of tetraethyl orthosilicate (TEOS) and/or 3‐aminopropyltriethoxylsilane bonding at the end of the WPU molecular chain. The hybrid was characterized by scanning electron microscopy, energy dispersive spectroscopy (EDS), transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS). The results showed that the nanosilica/WPU hybrids with well‐dispersed nanosilica particles were synthesized, in which the particles had typical diameters of about 50 nm. In addition, XPS and FTIR analyses demonstrated that chemical interaction occurred between WPU and silica. The effects of TEOS on surface wettability, water resistance, mechanical strength, and thermal properties of the hybrid were also evaluated by contact angle measurements, water absorption tests, mechanical tests, and differential scanning calorimetry, respectively. An increase in advancing contact angles, water resistance, and tensile strength, as well as decrease in elongation at break and glass transition temperature, were obtained with the addition of TEOS. Water absorption decreased from 17.3 to 5.5%. The tensile strength increased to a maximum of 29.7 MPa, an increase of about 34%. Elongations at break of the hybrids decreased 191%. These results were attributed to the effects of the nanosilica and the chemical interaction between WPU and silica. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Surface modification and physical properties of various UHMWPE‐fiber‐reinforced modified epoxy composites

Two surface modification methods—plasma surface treatment and chemical agent treatment—were used to investigate their effects on the surface properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers. In the analyses, performed using electron spectroscopy for chemical analysis, changes in weight, and scanning electron microscope observations, demonstrated that the two fiber‐surface‐modified composites formed between UHMWPE fiber and epoxy matrix exhibited improved interfacial adhesion and slight improvements in tensile strengths, but notable decreases in elongation, relative to those properties of the composites reinforced with the untreated UHMWPE fibers. In addition, three kinds of epoxy resins—neat DGEBA, polyurethane‐crosslinked DGEBA, and BHHBP‐DGEBA—were used as resin matrices to examine the tensile and elongation properties of their UHMWPE fiber‐reinforced composites. From stress/strain measurements and scanning electron microscope observations, the resin matrix improved the tensile strength apparently, but did not affect the elongation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 655–665, 2007     

Surface modification of UHMWPE fibers by ozone treatment and UV grafting for adhesion improvement

In this study, the surface of ultra-high-molecular-weight-polyethylene (UHMWPE) fibers was modified by ozone pretreatment, followed by ultraviolet (UV) grafting, to enhance the interfacial properties of UHMWPE fibers/rubber composites. The fibers were first pretreated by ozone to introduce oxygen-functional groups. The graft polymerization of glycidyl methacrylate (GMA) onto the ozone-treated fibers was implemented by UV irradiation. The effects of time and GMA concentration on the grafting efficiency were investigated. The modified fibers were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). The XPS and FTIR results revealed that GMA was successfully grafted onto the fibers with epoxy groups. SEM images confirmed that a continuous layer of poly-(GMA) (PGMA) was grafted onto the fibers. The interfacial adhesion force of UHMWPE fibers with rubber matrix was characterized by H pullout testing, which showed that the maximum force the fibers/rubber composites increased by 79% over that of the untreated fibers.     

Synthesis and properties of polyurethane modified with an aminoethylaminopropyl‐substituted polydimethylsiloxane. II. Waterborne polyurethanes

A series of polyurethane (PU) emulsions modified with aminosilicone were synthesized, based on 2,4‐toluene diisocyanate (TDI), poly(tetramethylene oxide) (PTMO), and dimethylolpropionic acid (DMPA) as a prepolymer which was chain‐extended with aminoethylaminopropyl polydimethylsiloxane (AEAPS) in an aqueous emulsion. Their chemical compositions, structures, bulk and surface properties, and emulsion morphologies were investigated using Fourier transform infrared spectrum analysis (FTIR), tensile and surface contact angle measurements, electron spectroscopy for chemical analysis (ESCA), water swellablity, an emulsion stability test, and transmission electron microscopy (TEM). It was shown that the PU emulsions were stable and the siloxane chains were enriched on the PU surface. The water resistance of the PU film increased but the bulk tensile properties of the PU film were not changed significantly with a small amount siloxane modification up to 6 wt %. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 295–301, 2001     

Time‐dependent changes of surface properties of polyether ether ketone caused by air plasma treatment

The effect of air plasma treatment on wetting and energy properties, surface composition and morphology of polyether ether ketone (PEEK) was investigated. The influence of the storage time on the surface properties of plasma‐treated polymer plate was also examined. The properties were determined by advancing and receding contact angle measurements, Fourier transform infrared spectroscopy supported by theoretical spectrum modelling, X‐ray photoelectron spectroscopy and optical profilometry. Three theoretical approaches were used in the determination of the apparent surface free energy of the untreated and plasma‐treated PEEK samples from the measured contact angles of probe liquids (water, formamide, diiodomethane): the contact angle hysteresis method, the Owens and Wendt approach and the Lifsthitz ? van der Waals acid–base approach. It was found that air plasma treatment of PEEK causes significant chemical and morphological changes of the polymer surface, which are reflected in the decrease of contact angles from 83.4° to 11.7° for water after 180 s plasma treatment. This is due to the formation of polar functional groups resulting in the increase of the surface hydrophilicity. After plasma treatment the apolar component of the surface free energy practically does not change, while the polar component increases significantly, especially for plates treated for 180 s, from 0 to 19.6 mJ m^?2. In addition, the modified PEEK surface is not stable during storage and it acquires more hydrophobic character. © 2016 Society of Chemical Industry     

Physico‐mechanical properties of nano‐polystyrene‐decorated graphene oxide–epoxy composites

Nano‐polystyrene (nPS)‐decorated graphene oxide (GO) hybrid nanostructures were successfully synthesized using stepwise microemulsion polymerization, and characterized using Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), field‐emission scanning electron microscopy and transmission electron microscopy. XRD and FTIR spectra revealed the existence of a strong interaction between nPS and GO, which implied that the polymer chains were successfully grafted onto the surface of the GO. The nPS‐decorated GO hybrid nanostructures were compounded with epoxy using a hand lay‐up technique, and the effect of the nPS‐decorated GO on the mechanical, thermal and surface morphological properties of the epoxy matrix was investigated using a universal tensile machine, Izod impact tester, thermogravimetric analysis and contact angle measurements with a goniometer. It was observed that in the epoxy matrix, GO improved the compatibility. © 2017 Society of Chemical Industry     

Tween 20‐modified poly(vinyl chloride) exhibits enhanced blood‐compatibility

Poly(vinyl chloride) (PVC) resin was modified by grafting the non‐ionic surfactant poly(oxyethylene 20 sorbitan) monolaurate (Tween^® 20) using isocyanate chemistry. PVC was aminated using ethylenediamine and coupled with hexamethylene diisocyanate. Tween 20 was then reacted with the polymer, resulting in the grafting of the surfactant. The polymer modification was confirmed using infrared and X‐ray photo‐electron spectroscopy. Films of modified polymer were cast from a solution of tetrahydrofuran. The surface of films prepared from the modified polymer showed increased hydrophilicity as evidenced by contact‐angle measurements. The solid/water free energy of the modified polymer surface was nearly a quarter of the energy of the bare PVC surface. Static platelet adhesion studies using platelet‐rich plasma demonstrated significantly reduced adhesion onto a modified PVC surface compared with unmodified PVC. Data obtained demonstrate that modification of polymers with Tween 20 may be an interesting way of imparting protein‐ and cell‐repelling characteristics to them, thereby improving their blood‐compatibility. Copyright © 2005 Society of Chemical Industry     

Surface modification of fique fibers. Effect on their physico‐mechanical properties

A study has been performed to assess the possibilities of fique fibers (a Colombian native fiber) as reinforcement for polymeric matrices. The fique fibers were treated using different chemical surface treatments. The effect produced on the physico‐mechanical properties of fique fibers have been investigated. The applied surface treatments have been mercerization, and/or chemical agents such as maleic anhydride and acrylic acid, and also silanization. In order to analyze the chemical changes in the treated fibers, Fourier Transform infrared, FTIR, spectroscopy was used along with two related techniques: Attenuated Total Reflection (ATR) and Coupled Microscopy. Additionally, physical and mechanical properties of untreated and treated fique fibers have been studied. A wettability study using contact angle measurements has also been performed for surface free energy determination. The thermal stability of the fibers has been investigated by thermogravimetrycal analysis.     

Blending polypropylene with glycidyl methacrylate‐containing polymer to improve adhesion to elastomers

BACKGROUND: Polypropylene (PP) is one of the most widely used polyolefins but gets restricted in surface applications due to its non‐polar nature. Surface properties of films made of PP were modified to improve their adhesion to elastomeric polymers such as thermoplastic polyurethanes (TPU), especially to Pebax^® [poly(ether‐block‐amide)]. RESULTS: Surface modification of PP was brought about by blending it with glycidyl methacrylate (GMA)‐containing polymer to increase its surface energy. Films of modified PP were analyzed to determine the blending efficiency and characterized using contact angle measurements, differential scanning calorimetry, X‐ray photoelectron spectroscopy and scanning electron microscopy. Molecular dynamics simulations were done to determine surface and bulk properties of PP blended with GMA. The computational results correlated very well with the experimental data and revealed that the changes in the surface energy can be linked to the position of the functional group within the sample. T‐Peel tests indicated a 2.4 times increase in adhesion to Pebax^® and only 1.7 times increase in adhesion to TPU compared to unmodified PP. CONCLUSION: The surface energy and enhanced adhesion proved that PP was successfully modified and its surface made more polar. Copyright © 2008 Society of Chemical Industry     

Surface modification studies of Kapton® HN polyimide films

Surface imide hydrolysis of Kapton HN polyimide films in a 1 M KOH aqueous solution was studied using dynamic contact angle measurements, X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS). The surface energy of Kapton HN increased quickly upon KOH treatment due to the formation of polar polyamate. Prolonged treatment led to a jump in surface energy that we ascribe to the onset of etching causing increased surface roughness. Potassium depth profiles of treated Kapton HN samples measured by XPS and TOF‐SIMS demonstrated that during the first 10 minutes of 1 M KOH treatment the modification depth increased rapidly. Thereafter the thickness of the modified layer no longer increased. For Kapton H films, however, the development of etching was much slower and a steady increase in modification depth was observed even after long treatment times. The different behaviours between Kapton HN and Kapton H films in alkali solutions are analysed and discussed. Copyright © 2003 Society of Chemical Industry     

Surface‐initiated ring‐opening polymerization of ϵ‐caprolactone from the surface of PP film

This article presents the ring‐opening polymerization of ε‐caprolactone (ε‐CL) from PP film modified with an initiator layer composed of ? OSn(Oct) groups. This method consists of two steps: (1) Sn(Oct)₂ exchanged with the hydroxyl groups on the surface of PP film, forming the ? OSn(Oct) groups bonded on the surface; (2) surface‐initiated ring‐opening polymerization of ε‐CL with the ? OSn(Oct) groups. The initiator layer is characterized by attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR), contact angles, and X‐ray photoelectron spectroscopy (XPS). The growth of PCL chains from the initiator layer through ring‐opening polymerization is successfully achieved. ATR‐FTIR, XPS, and scanning electron microscope (SEM) are also used to characterize the grafted film. XPS results reveal that the PCL chains cover the surface of PP film after 4 h. The SEM images reveal that the PCL chain clusters grow into regular spheroidal particles, which can be changed into other different morphology by treated with different solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Controlling the surface wettability of poly(sulfone) films by UV‐assisted treatment: benefits in relation to plasma treatment

Hydrophilic and superhydrophilic surfaces of poly(sulfone) (PSU) thin films were prepared by UV irradiation in the presence of O₂ or acrylic acid (AA) vapor. Treated surfaces were then investigated by water contact angle measurements, Fourier transformed IR spectroscopy in attenuated total reflectance mode (FTIR‐ATR), X‐ray photoelectron spectroscopy (XPS), near‐edge X‐ray absorption fine structure (NEXAFS) and AFM. Water contact angle values of treated PSU films using either O₂ or AA vapor as the reactive atmosphere reached about 6° after more than 120 min of irradiation. FTIR‐ATR, XPS and NEXAFS analysis showed incorporation of oxygenated groups onto the surface that led to its hydrophilic characteristics. In addition, when AA vapor was used as the reactive atmosphere, a photopolymerization process of poly(acrylic acid) onto the surface of the PSU was observed. AFM analysis showed a very low level of roughness after the treatments. A comparison of UV‐assisted surface modifications of PSU films with traditional plasma treatments showed excellent qualitative agreement between the two techniques. Our results show that UV‐assisted treatments in the presence of AA vapor or O₂ are efficient ways of controlling the surface wettability and functionalities grafted on the surface of PSU films. This treatment can be considered as a permanent dry grafting method that resists aging and uses a simple experimental setup. © 2012 Society of Chemical Industry     

Surface modification of polysulfone membranes by low‐temperature plasma–graft poly(ethylene glycol) onto polysulfone membranes

A novel and general method of modifying hydrophobic polysulfone (PSF) to produce highly hydrophilic surfaces was developed. This method is the low‐temperature plasma technique. Graft polymer‐modified surfaces were characterized with the help of Fourier transform infrared attenuated total reflection (FTIR–ATR) and X‐ray photoelectron spectroscopy (XPS). Study results demonstrated that poly(ethylene glycol) (PEG) could be grafted onto the PSF membrane surface by low‐temperature plasma. The hydrophilic character of the modified surfaces was increased in comparison with that of the parent membrane. The contact angle for a modified PSF membrane was reduced apparently. We analyzed the effectiveness of this approach as a function of plasma operating variables including plasma treatment power and treatment time. Hence, plasma‐induced graft polymer modification of membranes can be used to adjust membrane performance by simultaneously controlling the surface hydrophilicity and hemocompatibility. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 979–985, 2000     

Solid‐state compaction and drawing of nascent reactor powders of ultra‐high‐molecular‐weight polyethylene

The continuous production of ultra‐high‐molecular‐weight polyethylene (UHMWPE) filaments was studied by the direct roll forming of nascent reactor powders followed by subsequent multistage orientation drawing below their melting points. The UHMWPE reactor powders used in this study were prepared by the polymerization of ethylene in the presence of soluble magnesium complexes, and they exhibited high yield even at low reaction temperatures. The unique, microporous powder morphology contributed to the successful compaction of the UHMWPE powders into coherent tapes below their melting temperatures. The small‐angle X‐ray scattering study of the compacted tapes revealed that folded‐chain crystals with a relatively long‐range order were formed during the compaction and were transformed into extended‐chain crystals as the draw ratio increased. Our results also reveal that the drawability and tensile and thermal properties of the filaments depended sensitively on both the polymerization and solid‐state processing conditions. The fiber drawn to a total draw ratio of 90 in the study had a tensile strength of 2.5 GPa and a tensile modulus of 130 GPa. Finally, the solid‐state drawn UHMWPE filaments were treated with O₂ plasma, and the enhancement of the interfacial shear strength by the surface treatment is presented. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 718–730, 2005     

Surface modification of microfibrillated cellulose for epoxy composite applications

Microfibrillated cellulose (MFC) possessing a ‘web-like’ morphology was successfully modified with three different coupling agents: 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and a titanate coupling agent (Lica 38). The surface modification was confirmed using infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), and contact angle measurements. These modifications changed the surface character of MFC from hydrophilic to hydrophobic. The untreated and treated MFC were successfully incorporated into an epoxy resin system using acetone as the solvent. Better and stronger adhesion between the microfibrils and the epoxy polymer matrix was observed for the treated fibers, which resulted in better mechanical properties of the composite materials.