epdm

Hypothesis:

 The employment of graphene oxide (GO) in polymer composites has garnered significant interest due to its potential applications in the aerospace construction, and electronics industries. This is due to the proven potential of graphene oxide to enhance the mechanical, functional, and electrical properties of polymer-based composite materials. Additionally, the surface properties of polymer composites are directly influenced by the structural and mechanical properties of these materials.

The mechanical and surface properties of ethylene propylene diene monomer (EPDM)/GO composites are investigated. graphene oxide , prepared in powder form, was mixed with EPDM at loading contents of 1, 3, and 5 phr using a two-roll mill. The main objective was to investigate the effect of graphene oxide loading content on the tear strength and surface roughness of EPDM/GO composites through surface and mechanical analyses.

Results indicate that the incorporation of graphene oxide in a loading content of 3 phr leads to a significant improvement in mechanical properties. More than 75% increase in tensile strength, 5% increase in the elongation-at-break, and more than 16% rise in the tear strength are achieved when 3 phr GO is loaded into the structure of EPDM. The incorporation of graphene oxide also results in a slight improvement in the modulus of the system. Based on the atomic force microscopy and tensile test results presented in this work, a direct relationship between surface behavior and mechanical properties of EPDM/GO composites is observed.

The performance of rice husk ash (RHA), obtained by burning rice husks, as a filler for natural rubber (NR)/ethylene–propylene–diene monomer (EPDM) blends was investigated. For comparison purposes, two commercial reinforcing fillers, silica and carbon black were also used. A fixed 75: 25 blend ratio (wt %) of NR and EPDM was prepared using a two stage conventional mixing procedure. Filler loading was varied from 0 to 60 parts per hundred of resin (phr) at 15 phr intervals. The results indicated that RHA offers processing advantages over silica and carbon black. The use of RHA as an additional filler provided almost no improvement in the tensile strength and abrasion resistance of the 75: 25 NR/EPDM blends. The ozone resistance of the blends was inferior to those obtained from the addition of RHA. However, RHA was better in resilience property than that of silica and carbon black. Scanning electron micrographs revealed that the dispersion of RHA filler in the rubber matrix is discontinuous, which in turn generates weak structure when compared with carbon black and silica. According to these observations, RHA could be used as a diluent filler for the 75: 25 NR/EPDM blend, while silica and carbon black can be used as a reinforcing filler.

The bis (indenyl) zirconium dichloride catalyst was synthesized by a modified method at room temperature. Terpolymerization of ethylene، propylene and diene monomers were carried out using this metallocene catalyst under different conditions of different feed ratios of monomers، co-catalyst/catalyst ratios and polymerization temperatures. Methylaluminoxane (MAO) was used as a co-catalyst. The highest activity of catalyst was obtained at total pressure 4 bar، co-catalyst/catalyst ratio [Al] / [Zr] =600، polymerization temperature 60°C and E/P=67:33 and momomer feed ratio of 1700 kgEPDM/molZrh. The activity of catalyst showed bell-shaped behaviors versus co-catalyst/catalyst ratio ([Al] / [Zr]) and polymerization temperatures. The viscosity-average molecular weight (Mv) of terpolymers increased with increasing total pressure at different feed ratios of monomers. However، the viscosity-average molecular weight of terpolymers decreased at higher co-catalyst/catalyst ratios ([Al] / [Zr]) and higher polymerization temperatures. The increases in propylene and diene monomers in the feed ratios decreased the catalyst activity and viscosity-average molecular weight of terpolymers. The ratio of maximum average rate of terpolymerization to an average rate of terpolymerization at the end of the polymerization (DI) for different terpolymerization conditions was relatively high; an indication of the decay kinetics for this type of metallocene catalyst. Increasing the co-catalyst/catalyst ratio up to [Al] / [Zr] = 500 increased the Et% and ENB% in the final obtained polymers. However، increasing the polymerization temperature، diene and propylene concentrations in the feed ratio decreased the Et% and increased the ENB% contents in the final obtained polymers. Tg of the final terpolymers was between -64 and -52°C. The study on microstructures of some polymer revealed block type of chain microstructures.

In order to achieve dramatic improvements in the performance of rubber materials، attempts were made to develop carbon nanotube (CNT) -reinforced rubber composites. The maleic anhydride (MAH) modification of EPDM is an interesting way of compatibilizing the EPDM rubber with CNT. Novel ternary nanocomposites were prepared based on EPDM/EPDM grafted maleic anhydride (EPDM-g-MAH) blend composition with various concentrations (0-7 phr) of multi-wall carbon nanotube (MWCNT) on a two-roll mill. The effect of EPDM-g-MAH as a compatibilizer and MWCNT concentration were investigated on cure characteristics، mechanical، morphological and rheological properties of nanocomposites. The microstructure of nanocomposites has been characterized using scanning electron microscopy (SEM). At the same time the rheological behavior has been evaluated by a rubber processing analyzer (RPA). It was found that the cure time (t90) and scorch time (t5) decreased while maximum torque (MH) and minimum torque (ML) of the compatibilized composites were increased with increasing MWCNT loading which was consistent with the swelling data. It is observed that by increasing MWCNT loading the swelling index in solvent was decreased. This can be related to good interactions between carbon nanotube and EPDM matrix in presence of EPDM-g-MAH compatibilizer. The fracture surface study indicated that compatibilizer facilitated a homogenous dispersion of MWCNTs inside the matrix. On the other hand، carbon nanotubes in matrix caused roughness of the fractured surface compared with uncompatibilized samples. The mechanical properties such as tensile strength and elongation-at-break of compatibilized EPDM/MWCNT were higher than those of uncompatibilized nanocomposites. In addition، due to increasing MWCNT content the rheological properties such as storage modulus (G'') increased with respect to angular frequency while the complex viscosity decreased.

In this research, we have investigated the effects of addition of different percentages of nanoclay to the ethylene propylene diene monomer (EPDM) and nitrile butadiene rubber (NBR) on the characteristics of these rubbers as seal material. Properties such as tensile strength, modulus at different extensions, elongation at break, compression set, hardness, permeability and abrasion resistance are tested to assess the effect of addition of the nanoclay. Results indicate that addition of nanoclay at certain compositions could slightly reduce the strength of the rubber, however more stable modulus at different strains are provided, the hardness of the rubber is preserved and slightly enhanced, the permeability is reduced in both rubbers, especially considerable decrease in EPDM is observed, which is desirable in diminishing the effect of explosive decompression. At the same time, the compression test shows that the nanoclay improves the performance of the rubbers under compression, which is essential in seal application. The X-ray diffraction tests clarify that the dispersion of the nanoclay in the NBR samples is of high quality. In the EPDM samples, the dispersion is in need of improvement.

A series of ethylene-propylene-2-ethylidenebicyclo [2.2.1] hept.5-ene terpolymers (EPDM) have been prepared using a VOCl3/Al2Et3Cl3 catalyst under various Al/V ratios and diene concentrations via solution polymerization and characterized by FTIR, Mooney viscosity (ML1+4,125oC), and thermal gravimetery analyzing. The polymerization yield was seen to increase with augmentation of the Al/V ratio and diene concentration and pass through a maximum of about 200 gr polymer/g V. On the other hand, Mooney viscosity decreases with an increase in the two latter parameters. Increasing solvent to monomer ratio increased polymerization yield while it decreased Mooney viscosity. Accordingly, an optimum amount of solvent to monomer ratio (4:1 in mass) was found. One advantage of these polymer systems is that all the measured Tg property remained constant around 232-240 K in the range of incorporated ethylene and diene concentration. It has been observed that when Al/V ratio decreases and diene concentration increases, there is an increment in ethylene incorporation (40-60%), and the results have been compared with the characteristics of two commercial EPDMs (Herlen 563, Vistalon 7500).