Influence of the concentration of trimethylol propane triacrylate on the electron beam-induced surface modification of EPDM rubber

2000

J. Appl. Polym. Sci.

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Electron-beam-initiated grafting of trimethylolpropane triacrylate (TMPTA) onto the bulk ethylene propylene diene monomer (EPDM) was carried out with varying concentrations of TMPTA at a constant irradiation dose of 100 kGy and over a wide range of irradiation doses (0 -500 kGy) at a fixed concentration (10%) of TMPTA. The rubber was also modified in the bulk by tripropylene glycol diacrylate (TPGDA, 10%) and tetramethylol methane tetraacrylate (TMMT, 10%) at an irradiation dose of 100 kGy. The modified rubbers were characterized by IR spectroscopy, crosslinking density measurements, and mechanical, dynamic mechanical, and electrical properties. The IR studies indicated increased peak absorbances at 1730, 1260, and 1019 cm Ϫ1 due to increased ͘CAO and COOOC concentrations up to certain levels of TMPTA and irradiation dose. These are accompanied by an increase in the crosslinking density. The tensile strength of the samples increases gradually with increasing both the concentration of the monomer and radiation dose up to a certain level. The values of the modulus also increase at the expense of the elongation at break. An increase in the number of double bonds from two in the case of the diacrylate to four in the case of the tetraacrylate also brings about an increase in the tensile strength and moduli values. The elongation at break, however, decreases. The DMTA measurements indicate changes in the glass transition temperature, T g , and tan ␦ max on modification. The T g shifts to a higher temperature with a simultaneous lowering of the tan ␦ max values as the TMPTA level is increased. A similar trend is observed when the irradiation dose is increased and the nature of the monomer changes from di-to tetraacrylate. The dielectric loss tangent registers an increase on modification by irradiation of TMPTA while the permittivity is decreased. All the results could be explained on the basis of the structural modification and crosslinking density.

Section: Structural Aspects: Ir Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure-property relationship of electron-beam-modified EPDM rubber

Majumder

2000

J. Appl. Polym. Sci.

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“…The surface energy increases from 44.8 mJ/m 2 (E 0/100 ) to 53.8 mJ/m 2 (E 10/100 ) for the surface-modified samples. 15 As the TMPTA level is increased, the crosslinking of EPDM increases, which is clear from the plot of gel content versus concentration (Fig. 4).…”

Section: Influence Of Concentration Of Tmpta On the Permeability Behamentioning

confidence: 76%

“…The introduction of polar groups on the surface such as ϾCAO and -C-O-C-is also reflected from the XPS studies. 15 It shows that the C1s core peak for the E 0/0 sample appears at a 284.9 eV binding energy, but as the TMPTA level increases, there is a progressive shift of the C1s core peak as well as the other constituent peaks due to the formation of C-O and CAO, to higher binding energies. This shift is maximum in the case of the E 10/100 sample, where an additional peak is also observed at 292.0 eV which may be ascribed to the O ʈ OCOCOOO groups.…”

Section: Influence Of Concentration Of Tmpta On the Permeability Behamentioning

confidence: 92%

Barrier properties of electron-beam-modified EPDM rubber

Majumder

Majali

et al. 2000

J. Appl. Polym. Sci.

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EPDM rubber was surface-and bulk-modified with varying concentrations of trimethylol propane triacrylate (TMPTA) in the presence of a constant electron-beam irradiation dose of 100 kGy and over a wide range of irradiation doses from 0 to 200 kGy at a fixed TMPTA concentration (10%). The permeation rate and absorption of three homologous nonpolar solvents, namely, n-hexane, n-heptane, and n-octane, along with an aromatic solvent, toluene, and a polar solvent, trichloroethylene, through unirradiated, unmodified control, and modified rubber membranes (Ϸ150 m) were studied. It was found that both the permeation rate and absorption decrease progressively with increase in the TMPTA concentration up to 10% for both the surface-and bulk-modified rubbers. With increase in the radiation dose, there also is an initial drop in the values up to 50 kGy for the control and surface-modified rubbers and up to about 100 kGy for the bulk-modified one. The control rubber shows the highest absorption and permeation for all the solvents except trichloroethylene, followed by the bulk-modified rubber membrane. Trichloroethylene is, however, absorbed and permeated most by the surface-modified sample. The observations are explained in terms of the structural modifications of the rubber, crosslinking, changes in the relevant thermodynamic properties such as surface energy, the penetrant size, and the transport mechanism of the penetrants. The influence of temperature on the permeability characteristics of the control and modified rubbers was also studied.

“…The use of polyfunctional monomers, such as multifunctional acrylates and allylic reactive molecules, in blends with the base polymer, is very effective in achieving the crosslinking at a reduced radical dose level to meet the optimum properties without much deterioration of the base polymer 11, 12. Bhowmick et al13 carried out surface modification of ethylene propylene diene monomer (EPDM) rubber in the presence of an acrylate monomer, trimethylol propane triacrylate (TMPTA). The influence of electron beam radiation on polymers was reported by several authors 14–17…”

Section: Introductionmentioning

confidence: 99%

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

Ray

J of Applied Polymer Sci

2001

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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.