Dispersion of Single-Walled Carbon Nanotubes in a Non-Polar Polymer, Poly(4-methyl-1-pentene)

Abstract

Poly(4-methyl-1-pentene), PMP, a high melting polymer composed of hydrogen and carbon, has the potential to become an alternative to polyethylene (PE) as shielding material against Galactic Cosmic Radiation (GCR). PMP exhibits higher thermal stability than PE and is transparent in the UV/visible region of the electromagnetic spectrum. Single walled carbon nanotubes (SWNTs) were pretreated with a polar solvent, N, N-Dimethylformimide (DMF), and then dispersed in a halogenated hydrocarbon, cyclohexyl chloride, which also dissolved the non polar polymer, PMP. The composites were characterized via differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), microhardness measurements, and optical microscopy. DMA data revealed that the carbon nanotubes contributed to the enhancement of the high temperature alpha(c) relaxation which is thought to arise from motion around crystalline regions in the matrix. The storage modulus (60 Hz) increased from 2409 MPa in the neat PMP to 3716 MPa at -50 degrees C. The magnitude of the increase diminished near and above the glass transition region; the glassy matrix restricted motion of the crystalline regions. DSC data showed an increase in the percent crystallinity of the composite (75%) as compared to the neat polymer (68%). Low concentrations of nanotubes, when well dispersed, produced nanocomposites with varying degrees of transparency.

Polymer-Composite Materials for Radiation Protection

“…Clayton et al 25 studied the material properties of poly(4-methyl-1-pentene) (PMP) reinforced with 0.5 wt % loading of single-walled CNTs. They proposed the use of PMP, as an alternative to PE for use as a shielding material against GCR, because of its high performance material properties when compared to that of PE.…”

Modern Approaches to Polymer Materials Protecting from Ionizing Radiation

“…It was demonstrated that, in addition to radiation resistance, composite materials had higher mechanical strength and thermal stability, compared with a polymer without fillers 16,[41][42][43][44][45][46] . Relatively small amount of nanofiller is enough for improving properties of CNT-based polymer composites, which are featured by exceptionally high values of elastic modulus and tensile strength (of up to 1 TPa and tens or hundreds GPa respectively), and also thermal and electrical conductivity and high in-air oxidation resistance (>700 o C), without losing their elasticity 44,47,48 .…”

“…Using carbon nanotubes are suggested for improving radiation resistance and mechanical strengthen of water-containing polymers 66,67 (CNT). It was shown 66 that addition of CNT to polymethyl methacrylate matrix (PMMA) caused reduction in the depth of sample etching with high energy radiations (UV, ozone and electronic ray with the energy of 20keV), until it reached percolation barrier of the CNT network (at 0.5% wt of CNT) inside polymer matrix.…”

“…Matrix of poly(4-methyl-1-pentene) (PMP) with 0.5% wt of single-walled CNT (SWNT) has been suggested 67 as an alternative to polyethylene (PE) to be used as protective material against GCR, due to superb properties of this material compared with PE. As dynamic mechanical analysis (DMA) of non-filled PMP and a composite (PMP+) (PMP+0.5% wt of SWNT) showed, addition of SWNT improves viscoelastic properties of the composite, while elastic modulus and loss modulus turned to be higher than those of non-filled polymer.…”

Polyethylene/boron nitride composites for space radiation shielding

“…It has been paired with carbon nanotubes for improved modulus. 12 Polystyrene has slightly lower hydrogen content and has been paired with lead dimethacrylate, which can incorporate lead atoms directly into the polymer chains, 13 and with lead oxide particles.…”