Effects of montmorillonite on the electron beam irradiated alumina trihydrate added polyethylene and ethylene vinyl acetate nanocomposite

Abstract

This study aims at investigating the effects of montmorillonite (MMT) nanocomposite on the electron beam irradiated alumina trihydrate flame retardant added polyethylene and ethylene vinyl acetate blends (FRLE). The addition of MMT into FRLE blends has increased the limiting oxygen index (LOI%), which corresponds the improvement of flame resistivity, whereas increasing amount of MMT and irradiation dosage were found moderately influenced LOI% of the blends. However, incorporation of MMT has shown reinforcing effect to the FRLE, where the tensile strength for the samples subjected to 150 and 250 kGy irradiation have increased for 10.7 and 27%, respectively. In addition, increasing loading level of MMT and irradiation dosage caused inferior effects to the surface and volume resistivity of FRLE as high as four folds. This is due to the enhancement of transportability of MMT ionic in polymer matrix that caused the reduction of resistivity of FRLE. POLYM. COMPOS., 33:1883–1892, 2012. © 2012 Society of Plastics Engineers

Investigation of the interaction of copper(II) oxide and electron beam irradiation crosslinkable polyethylene

“…With reference to Table 1, all the samples failed immediately when the electron beam irradiation dose was increased to 50 kGy. This is due to the fact that low degree of crosslinking networks in the polymer matrix resulted in the failure to effectively support the polymer matrix in withstanding the static load under high temperature [19]. Further increment of irradiation dose up to 100 kGy delayed the failure time of pristine LDPE by 3-4 min.…”

“…The free hydrogen ions could extract the hydrogen atoms from another LDPE macromolecular chain to further release new free radicals and form hydrogen gas as illustrated in Reaction 2 [12,16]. The free radicals released could react together to form a 'bridge' (or crosslinking network) between two LDPE macromolecules [16,19] as shown in Reaction 3. The formation of crosslinking networks in the polymer matrix of all LDPE composites could help the LDPE matrix in resisting the attack of hot xylene [23].…”

“…This is because the total number of -C-H bonds available in the LDPE matrix has significantly reduced when the electron beam irradiation increased up to 250 kGy in all the copper(II) oxide added LDPE composites. This is due to the fact that free radicals generated at higher irradiation doses (>100 kGy) are mainly entrapped inside the already-crosslinked macromolecular chains of the LDPE matrix [19]. This could restrict the movement of the free radicals in the LDPE matrix and cause the formation of new crosslinking networks inside the already-crosslinked chains of the LDPE matrix [20] The formation of new crosslinking networks inside the already-crosslinked chains resulted in failure to provide significant increment in the size of crosslinking networks in the LDPE matrix.…”

“…This also indicates that the formation of crosslinking networks has been significantly induced when subjected to a higher irradiation dose of 250 kGy. The application of high-energy electron beam irradiation could induce the formation of free radicals in the polymer matrix, and thus increase the formation of crosslinking networks in the polymer matrix [19]. Besides, the increase of irradiation dose from 200 to 250 kGy has decreased the creep elongation of pristine LDPE from 141.9% to 132.1%.…”

“…The increase of irradiation dose could rapidly increase the degree of crosslinking in the LDPE matrix. Such crosslinked LDPE exhibited outstanding mechanical properties, such as high tensile strength and high elongation, and electrical properties [16,19,20].…”