Grafting Of Glycidyl Methacrylate Research Articles

Thermal graft copolymerization-induced adhesion improvement of a FR-4 ®/PETG ® laminate

The lamination of a glass fibre-reinforced and epoxy-based printed circuit board (PCB) substrate, FR-4 ®, to an amorphous thermoplastic copolyester of dimethyl terephthalate with ethylene glycol and 1,4-cyclohexanedimethanol, PETG ®, was studied. The lamination was achieved by the simultaneous surface graft copolymerization of glycidyl methacrylate (GMA) on the argon plasma-pretreated FR-4 ® substrate and PETG ® film at an elevated temperature. The plasma-treated surfaces and the delaminated surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The adhesion strength between the FR-4 ® substrate and the PETG ® film was assessed by the T-peel test method. The adhesion strength was affected by the plasma pretreatment time of the substrates, the lamination time, and the lamination temperature. The FR-4 ®/GMA/PETG ® assembly from the simultaneous graft copolymerization with GMA and lamination exhibited a significantly more rapid lamination rate and a higher adhesion strength than those of the FR-4 ®/epoxy/PETG ® assembly from the epoxy adhesive-induced lamination of the plasma-pretreated FR-4 ® and PETG ® films. The phenomena are consistent with the presence of covalently bonded GMA graft chains on the surfaces of plasma-pretreated PETG ® and FR-4 ® films in the former assembly. The FR-4 ®/GMA/PETG ® assembly failed by a combined cohesive and adhesional mechanism.

Reactive processing of polymers: Melt grafting of glycidyl methacrylate on ethylene propylene copolymer in the presence of a coagent

Glycidyl methacrylate (GMA) was grafted on ethylene-propylene copolymer during melt processing with peroxide initiation in the presence and absence of a more reactive comonomer (coagent), trimethylolpropane triacrylate (Tris). The characteristics of the grafting systems in terms of the grafting reaction yield and the nature and extent of the competing side reactions were examined. The homopolymers of GMA (Poly-GMA) and Tris (Poly-Tris) and the GMA-Tris copolymer (GMA-co-Tris) were synthesized and characterized. In the absence of the coagent, high levels of poly-GMA, which constituted the major competing reaction, was formed, giving rise to low GMA grafting levels. Further, this grafting system resulted in a high extent of gel formation and polymer crosslinking due to the high levels of peroxide needed to achieve optimum GMA grafting and a consequent large drop in the melt index (increased viscosity) of the polymer. In the presence of the coagent, however, the grafting system required much lower peroxide concentration, by almost an order of magnitude, to achieve the optimum grafting yield. The coagent-containing GMA-grafting system has also resulted in a drastic reduction in the extent of all competing reactions, and in particular, the GMA homopolymerization, leading to improved GMA grafting efficiency with no detectable gel or crosslinking. The mechanisms of the grafting reactions, in the presence and absence of Tris, are proposed.

Reactive compatibilization of polyolefin/PET blends by melt grafting with glycidyl methacrylate

The melt free radical grafting of glycidyl methacrylate (GMA) onto high-density polyethylene (HDPE) was carried out in Brabender internal mixer. The GMA content of the grafted HDPE (HDPE-g-GMA) was determined through FTIR by means of a calibration curve. The influence of reaction procedure, radical initiator concentration and addition of a co-monomer (styrene) on the grafting efficiency was examined. Blends of poly(ethylene terephthalate) (PET) with HDPE and HDPE-g-GMA (75/25 w/w) were prepared by melt mixing in internal mixer. The morphology of the blends was then analysed by SEM microscopy. PET/HDPE-g-GMA blends displayed improved phase dispersion and interfacial adhesion as compared to unfanctionalized PET/HDPE blend.

Thermal imidization of poly(amic acid) precursors on surface-modified poly(tetrafluoroethylene) films via graft copolymerization with glycidyl methacrylate

A novel method for preparing composites of polyimides (PI) laminated to poly(tetrafluoroethylene) (PTFE) films is reported. PI/PTFE composites were developed through thermal imidization of poly(amic acid) (PAA) precursors on surface-modified PTFE films. Surface modification of PTFE films was carried out via Ar plasma pretreatment of the films, followed by UV-induced graft copolymerization with glycidyl methacrylate (GMA). The surface composition and topography of the graft copolymerized PTFE films and the delaminated PI and PTFE surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. The adhesion strengths of the PI (imidized PAA) on the GMA graft copolymerized PTFE films were evaluated as a function of various thermal imidization schedules. The adhesion reliability of the PI/PTFE composites was tested by a series of hydrothermal cycles. The development of strong Tpeel adhesion strengths of about 8 N/cm with excellent reliability for the PI/PTFE composites was attributable to the synergistic effect of coupling the curing of the epoxide functional groups of the grafted GMA chains with the imidization process of the PAA and the fact that the GMA chains were covalently tethered onto the PTFE surface. The PI/PTFE composites delaminated via cohesive failure inside the PTFE substrates. The delaminated PI film with a covalently adhered 'rough' PTFE surface layer exhibited a water contact angle as high as 140°.

Reactivity of glycidyl methacrylate grafted cellulose film prepared by grafting under ultrasonic irradiation

Ultrasonic irradiation largely accelerated ceric salt initiated grafting of glycidyl methacrylate (GMA) on regenerated cellulose film (cellophane thickness = 20 μm) at 60°C in air. The grafting under ultrasonic irradiation was characterized by a higher percent of grafting and graft efficiency and a lower density of GMA-grafted chains in the surface layer of the grafted films compared to the unirradiated system, which was obtained by attenuated total reflectance IR measurements. The grafted films were subjected to amination with ethylenediamine (En) at 70°C for 3 h in N,N-dimethylformamide. The amount of epoxy groups in the grafted films, which participated in the reaction with En, reached about 50–60 mol % and was slightly lower for the grafted film prepared in the irradiated system than that prepared in the unirradiated one. Adsorption of cupric ions with the aminated samples was performed at pH 5.0 using Clark–Lubs buffer solution and cupric chloride. The adsorption was extremely retarded for the aminated sample prepared using the unirradiated sample compared to that prepared using the irradiated one. The retarded adsorption phenomenon is discussed in terms of a larger formation of crosslinked structures on the surface layer of the former sample during the amination. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2462–2469, 1999

Surface Graft Copolymerization Enhanced Lamination of Poly(tetrafluoroethylene) Film to Copper and Epoxy-Based Print Circuit Board (PCB)

Lamination of poly(tetrafluoroethylene) (PTFE) film to a copper foil or to an epoxy-based print circuit board (PCB) Substrate (FR4®) was carried out. Lamination was achieved during surface graft copolymerization of glycidyl methacrylate (GMA) on an Ar plasma pretreated PTFE film at elevated temperature and in the presence of an epoxy resin adhesive. The plasma pretreatment introduces peroxides which are thermally degraded into free radicals to initiate the graft polymerization of GMA on the PTFE surface. The graft copolymerization with concurrent lamination is carried out in the complete absence of a polymerization initiator or system degassing. The modified surfaces and interfaces are characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The adhesion strength between the PTFE film and copper or the FR4® substrate was assessed by the T-peel strength test method. The adhesion strength was affected by plasma pretreatment time, as well as the grafting and curing temperature. The PTFE/GMA-epoxy resin/Cu and PTFE/GMA-epoxy resin/FR4 assemblies exhibit significant higher interfacial adhesion strengths compared to those assemblies in which only epoxy resin or GMA was used. They also exhibit better interfacial adhesion reliability. The PTFE/GMA-epoxy resin/Cu and PTFE/GMA-epoxy resin/FR4® joints delaminated by cohesive failure inside the bulk of PTFE film. The results suggest that the enhanced adhesion between the graft-modified PTFE film and copper or FR4® surfaces is attributable to the formation of covalent bonds between the tethered GMA graft chains on PTFE and the network of epoxy resin.

Electrochemical properties of polyethylene membrane modified with sulfonic and phosphonic acid groups

Ion-exchange membranes modified with sulfonic (-SO3H) and phosphonic acid (-PO3H) groups were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto polyethylene (PE) films and sub-sequent sulfonation and phosphonation of poly(GMA) graft chains. The surface area, thickness and volume of grafted PE film increased with increasing grafting yield. The specific electrical resistance of PE membrane modified with the -PO3H and -SO3H groups decreased with increasing the ion-exchange capacity. The PE membrane modified with -PO3H group had a lower specific electrical resistance than that of PE membrane modified with -SO3H group.

Determination methods of the grafting yield in glycidyl methacrylate-grafted ethylene/propylene/diene rubber (EPDM-g-GMA): Correlation between FTIR and1H-NMR analysis

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

Immobilized metal ion affinity hollow-fibre membranes obtained by the direct grafting technique

An immobilized metal ion affinity hollow fibre was prepared by radiation-induced direct grafting of glycidylmethacrylate (GMA) on hydrophilized polyethylene membranes. The epoxy group was converted into an iminodiacetate by iminodiacetic acid treatment. The effect of the radiation dose, salt inhibitors, methanol and GMA concentration, on the grafting degree was studied. The degree of grafting was closely related to the GMA concentration. Salt inhibitors failed in the production of a differential effect on the grafting and homopolymerization processes. Between 30 and 35% of methanol, there is a maximum yield, and no grafting was obtained with a methanol concentration above 50%. Water flux dropped exponentially with the increase in the grafting degree. Scanning-electron microscopy showed that the graft branches are formed on the pores. The pectinesterase adsorption capacity of the membranes was of the same order as of the commercial chelating soft gels.

Surface graft copolymerization enhanced adhesion of an epoxy-based printed circuit board substrate (FR-4) to copper

The lamination of surface modified printed circuit board (PCB) substrate, FR-4(R), from argon plasma pretreatment and UV-induced graft copolymerization with glycidyl methacrylate (GMA), to copper foil was carried out at elevated temperature and in the presence of an epoxy adhesive. The structure and chemical composition of the graft copolymerized surfaces and interfaces of the glass fiber-reinforced and epoxy-based FR-4 substrates were studied by X-ray photoelectron spectroscopy (XPS). The effects of the plasma pretreatment time, the UV illumination time, as well as the curing temperature, on the adhesion strength between the FR-4 substrate and copper were investigated. The assemblies involving GMA graft copolymerized FR-4, or the FR-4-GMA/epoxy resin/Cu assemblies, exhibited a significantly higher interfacial adhesion strength and reliability, in comparison to those assemblies in which only epoxy adhesive alone was used. The enhanced adhesion in the assemblies involving GMA graft copolymerized substrate arises from the fact that the covalently tethered GMA graft chains on the FR-4 surface can become covalently incorporated into the epoxy resin, resulting in the toughening of the epoxy matrix and increased interaction with copper.

Adsorption of Pb2+, Cu2+ and Co2+ by polypropylene fabric and polyethylene hollow fiber modified by radiation-induced graft copolymerization

Cation-exchange adsorbents were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) fabric and polyethylene (PE) hollow fiber and subsequent phosphonation of epoxy groups of poly(GMA) graft chains. The adsorption characteristics of Pb2+, Cu2+ and Co2+ for the two cation-exchange adsorbents were studied. In the grafting of GMA onto PP fabric, the degree of grafting (%) increased with an increase in reaction time, reaction temperature, and pre-irradiation dose. The maximum grafting yield was observed around 60% GMA concentration. In 50, 130 and 250% GMA-grafted PP fabric, the content of phosphoric acid was 1.52, 3.40 and 4.50 mmol/g at 80 °C in the 85 % phosphoric acid aqueous solution for 24 h, respectively. The adsorption of Pb2+, Cu2+ and Co2+ by PP fabric adsorbent was enhanced with an increased phosphoric acid content The order of adsorption capacity of the PP fabric adsorbent was Pb2+>Co2+>Cu2+. In adsorption of Pb2+, Cu2+ and Co2+ by PE hollow fiber, the amount of Pb2+ adsorbed by the PE hollow fiber adsorbent containing 1.21 mmol/g of -PO3H wasca. 54.4 g per kg. The adsorption amount of Cu2+ and Co2+ in the same PE hollow fiber wasca. 21.0 g per kg andca. 32.1 g per kg, respectively. The order of adsorption of the PE hollow fiber adsorbent was Pb2+>Co2+>Cu2+.

Adsorption of Co2+ and Cs1+ by polyethylene membrane with iminodiacetic acid and sulfonic acid modified by radiation-induced graft copolymerization

Two modified hollow fiber membranes, the chelating hollow fiber membrane with iminodiacetic acid and the cation-exchange hollow fiber membrane with sulfonic acid group (SO3H), were prepared by radiation-induced grafting of glycidyl methacrylate onto polyethylene hollow fiber membrane and its subsequent iminodiacetation and sulfonation. The adsorption characteristics of Co2+ and Cs1+ for the 2 hollow fiber membranes were examined when the solutions of Co2+ and Cs1+ permeate across the 2 membranes, respectively. Without regard to the chelating membrane with iminodiacetic acid group and the cation-exchange membrane with sulfonic acid group (SO3H), 2 membranes were observed to adsorb Co2+ higher than Cs1+. The adsorption curves of Co2+ by IDA group-chelating fiber membrane in the presence of Na1+ and Ca2+ showed that the chelating hollow was found to have a very high selectivity for Co2+, even though there is a high concentration of Na1+ and Ca2+ in the inlet solution. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 999–1006, 1999

Styrene-assisted melt free radical grafting of glycidyl methacrylate onto an ethylene and propylene rubber

This article deals with the efficiency of using styrene (St) as a comonomer to promote the melt free radical grafting of glycidyl methacrylate (GMA) onto an ethylene and propylene rubber (EPR) in a batch mixer and a corotating self-wiping twin screw extruder. The addition of St to an EPR/GMA/peroxide system increases not only GMA's grafting yield but also its grafting rate. The time required for the EPR/GMA/peroxide system without St to reach a given amount of grafted GMA is at least 10 times that needed for the same system in the presence of an equimolar amount of St. For example, about 60 min are required for the EPR/GMA/dicumyl peroxide (composition: 100/3.0/0.3 by weight) to reach 1.5 phr (parts per hundred resin) GMA (i.e., 1.5 g grafted GMA per 100 g EPR). The same amount of grafted GMA is reached in < 3 min when 3.0 phr St is charged to the system. This significant reduction of reaction time is crucial for a successful free radical grafting of GMA on EPR in a corotating twin screw extruder, because the residence time in such a machine is typically on the order of 0.5–5 min. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 125–133, 1999

Adsorption of Pb2+ and Pd2+ on polyethylene membrane with amino group modified by radiation-induced graft copolymerization

Six chelating hollow fiber membranes were prepared by radiation-induced grafting of glycidyl methacrylate onto a polyethylene hollow fiber membrane and its subsequent amination. The adsorption characteristics of Pb2+ and Pd2+ for the chelating hollow fiber membranes were presented when the solution of Pb2+ and Pd2+ permeates across the chelating membrane, respectively. The degree of grafting for glycidyl methacrylate increases with increasing monomer concentration, reaction temperature, and preirradiation dose. The adsorption of Pd2+ by chelating hollow fiber membranes modified with five kinds of amines was in the following order: diethylene triamine > hexamethyl diamine > ethylene diamine > dimethyl amine > trimethyl amine. The chelating hollow fiber membrane modified with iminodiacetic acid adsorbed Pb2+ ions much more than Pd2+. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 643–650, 1999

Adhesion enhancement of thermally evaporated aluminum to surface graft copolymerized poly(tetrafluoroethylene) film

Surface modifications of Ar plasma-pretreated poly(tetrafluoroethylene) (PTFE) film via UV-induced graft copolymerization with glycidyl methacrylate (GMA) and 1-vinylimidazole (VIDz) were carried out to improve the adhesion with evaporated aluminum metal. The surface compositions of the graft copolymerized PTFE films were studied by X-ray photoelectron spectroscopy (XPS). The adhesion strength of the evaporated aluminum to the surface graft copolymerized PTFE film was affected by the type of monomer used for graft copolymerization, the graft concentration, the plasma post-treatment of the graft copolymerized PTFE surface prior to metallization, and the extent of thermal treatment after metallization. The optimum T-peel adhesion strengths of the Al/PTFE laminates were in excess of 10 and 5 N/cm, respectively, for the GMA and VIDz graft copolymerized PTFE films. These adhesion strengths are significantly higher than those obtained between the evaporated aluminum and the pristine or plasma-pretreated PTFE film. The mechanism of adhesion enhancement and the failure of the metal-polymer assembly were also investigated. It was observed that the failure occurred within the PTFE film. The strong adhesion between Al and PTFE arises from the charge-transfer interaction between the Al atom and the epoxide moiety of the grafted GMA polymer, as well as from the fact that the graft chains are covalently tethered on the PTFE film surface as a result of the grafting process.

Surface modification of polymers for adhesion enhancement

Surface modification of low-density polyethylene (LDPE) and polytetrafluoroethylene (PTFE) films via graft copolymerization with acrylic acid (AAc), Na salt of styrenesulfonic acid (NaSS), N,N-dimethylacrylamide (DMAA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), glycidyl methacrylate (GMA), acrylamide (AAm) and 3-dimethyl(methacryloylethyl) ammonium propanesulfonate (DMAPS) was carried out for adhesion improvements. The surface microstructure and composition of the modified film surfaces were studied by angle-resolved X-ray photoelectron spectroscopy (XPS). It was demonstrated that the graft-modified LDPE and PTFE films are capable of exhibiting adhesive-free adhesion or auto-adhesion. The GMA graft copolymerized PTFE surfaces adhere strongly to one another when brought into direct contact and cured (i) in the presence of an epoxy adhesive and (ii) in the presence of a diamine curing agent alone. It was further demonstrated that the ozone-pretreated LDPE films and the Ar plasma pretreated PTFE films readily undergo photografting or thermal grafting with concurrent lamination when lapped together in the presence of a small quantity of the monomer solution. The simultaneous graft copolymerization and lamination process can be carried out under atmospheric conditions and in the complete absence of an added initiator or system degassing. Copyright © 1999 John Wiley & Sons, Ltd.

Styrene-assisted free radical grafting of glycidyl methacrylate onto polyethylene in the melt

Glycidyl methacrylate (GMA) is a very useful monomer as it bears an epoxy group which is capable of reacting with various other functional groups. However, its melt free radical grafting reactivity onto a polymer backbone is low. In this study, we show that the use of styrene (St) as a comonomer greatly promotes both GMA's grafting yield and grafting rate onto polyethylene (PE). It is proposed that, in the presence of St, the dominant mechanism of the free radical grafting of GMA onto PE is that St reacts first with PE secondary macroradicals and the resulting styryl macroradicals then copolymerize with GMA leading to grafted GMA. We also show that the contribution of St is not related to an improved solubility of GMA in the molten PE. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2763–2774, 1998

Styrene-assisted melt free radical grafting of glycidyl methacrylate onto polypropylene

The free radical grafting reactivity of glycidyl methacrylate (GMA) onto polypropylene (PP) in the molten state is low. This article shows that adding styrene as a second monomer (or comonomer) increases both the rate and yield of GMA grafting and reduces PP chain scission. The proposed mechanism is that when St is added to the PP/GMA/peroxide grafting system, St reacts first with PP macroradicals to form stable styryl macroradicals. These latter then react (or copolymerize) with GMA to form GMA grafted PP. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1053–1063, 1998

Free Radical Grafting of Glycidyl Methacrylate onto PP in a Co-rotating Twin Screw Extruder

Abstract A typical free radical grafting system is composed of a polymer substrate, a vinyl bearing monomer and a free radical initiator (usually a peroxide). When the reaction is to be carried out in a co-rotating twin screw extruder, there are two main ways to feed the chemicals to the extruder: either they are fed together to the main hopper (one-pot feeding) or only the polymer is fed to the main hopper and the grafting monomer and the peroxide are injected downstream either just before or after the first kneading zone (sequential feeding). In this study, we investigate the influence of feeding mode on the free radical grafting. We use the free radical grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) as a model system. It is found that GMA's grafting yields are very close between the one-pot feeding and the sequential feeding just before the first kneading zone. However, those obtained with the sequential feeding just after the first kneading zone are much lower. This dramatic difference is closely related to the mixing environments GMA and the peroxide are subjected to. When GMA and the peroxide are injected before the kneading zone where the screw channel is fully filled, GMA and the peroxide are forced to mix with PP. When they are fed to the extruder just after the kneading zone, however, they simply drip on the highly viscous PP. As such, before the grafting takes place between PP and GMA, the peroxide may have started to decompose and GMA may have started to polymerize. It is recommended that low molecular weight ingredients be fed to the extruder through a fully filled zone.

Melt Grafting of Glycidyl Methacrylate onto Polyethylene

Abstract The melt grafting of Glycidyl Methacrylate (GMA) onto Polyethylene in the presence of free radical initiators was conducted in a co-rotating twin screw extruder. Reaction kinetic parameters for the overall grafting and homopolymerization reactions were estimated in a batch melt mixer. Residence time distribution (RTD) in the extruder was determined and mean residence time and Peclet number (Pe) were estimated for different sets of reaction conditions. A twin screw simulation program was used to predict the flow characteristics along the length of the extruder. A modular reactor model consisting of plug flow and “axial dispersion” reactor cells was constructed and with the kinetic and transport information and the actual melt temperatures, the overall GMA conversion was predicted. In most cases the predicted conversion agreed well with experimentally determined values.