Irradiation of polymer blends

Irradiation of polymer blends has been the focus for several teams. The polymers most often used 

A list of the systems discussed in this chapter is given in Table 11.9. 

1 Normal and Ultra-High Molecular Weight Polyethylenes, PE/UHMWPE 

Minkova [1987], and Minkova and Mihailov [1990] studied gamma-irradiation of blends of these two polymers, in air at RT, to doses up to 60 kGy. The blends of the two were prepared by passing their mixtures through a melt-flow indexer at 190°C, four times. The pure components were similarly treated. The melting temperatures for the first and 

Blend Sample size (mm) T (irrad.) Cover gas Source dose, kGy Additives Properties Ref. 

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Irradiation of polymer blends containing a polyolefin — Irradiation of polymer blends can be used to crosslink or degrade the desired component polymer, of to fixate the blend morphology [4],... 

A. SINGH, Irradiation of polymer blends containing a polyolefin , Rad. Phys. Chem., 60 (2001)453-459... 

Polymer blends could be irradiated for the same purpose as polymers. For example, polymer devices for medical applications have been sterilized by irradiation for many years. Irradiation could also be used to obtain a polymer material suitable to foam by modifying its structural parameters (macromolecular mass, branch content). " For such an application, even if the irradiation of polymer blends is more complex than the irradiation of a pure polymer, the main objectives are the same in both cases. Thus, the following part will consider only the specific applications of irradiated polymer blends. 

Ceramic membranes are quite important since microporous ceramics are the principal barrier in UFe separation. Similar devices are used for microfiltration membranes and to a lesser extent for ultrafiltration. Homogeneous films are transformed into microporous devices by irradiation followed by selective leaching of the radiation damaged tracks, by stretching (Cortex is one welldmown example), or by electrochemical attack on aluminum. A few membranes are made by selective leaching of one component from a solid, as in membranes derived from glass or by selective extraction of polymer blends. 

For mechanical test such as tensile test and flexural test, the impregnation of polymer-blend to the carbon fiber was carried out several soakings of the fiber in the polymer-blend dispersion consists of PTFE (98.2 wt%) and fluorinated-pitch (1.8 wt%). A sheet of chemical crosslinked pre-forming sample was prepared under the pressure at around 20 MPa and then heat-treated at 350 °C 5 °C for 30 minutes. Samples were irradiated by EB up to 1000 kGy at 335 °C 3 °C in nitrogen gas atmosphere. 

Rizzo et al. [1983] investigated changes in the physico-chemical properties caused by gamma irradiation of LDPE/PP blends (100 0, 75 25, 50 50, 25 75, and 0 100) (Table 11.9). On irradiation of the individual polymers with 1500 kGy dose, the gel fraction was obtained as 95% in LDPE and 65% in PP. On irradiation of the blends the gel fraction increased with the LDPE-content and dose. On irradiation under vacuum, the crosslinking reactions predominated in LDPE, as discussed in Section 11.3.1. In the case of PP, accumulation of unsaturation with increasing dose contributes to extensive crosslinking at the high dose used here (1500 kGy), as discussed in Section 11.3.2. 

Table 11.64. Improvement of flexural properties of polymer blends by addition of a crosslinking agent and gamma irradiation [Numata and Fujii, 1995]...

T uminescence emission from irradiated materials has been known for many years. The phenomenon has been studied primarily on inorganic systems but also with polymers. A review of this work has been published by Partridge (i). A clearer understanding of the processes involved has led in more recent years to the use of this technique as a tool to probe the structure of heterogeneous polymer systems (2,3). This chapter describes the technique and shows its utility for the analysis of polymer blends and block copolymers. 

Enhanced Electrical Conductivity of Polymer Blends by Irradiation... 

Another interest of irradiation in the field of the conductivity of polymer blends was shown by Faez etal. These authors incorporated EPDM to lANl in order to improve mechanical properties of the material. PANl was doped not with irradiation, but with dodecylbenzene sulfonic acid by reactive processing in an internal blender. To cross-link the EPDM, a phenolic resin and e-beam irradation (75 and 150 kGy) were compared. Contrary to the cross-linking by phenolic resin, the cross-linking by e-beam irradiation did not interfere with the presence of the acid necessary for doping PANl. Consequently, better mechanical properties were obtained. Moreover, irradiation-induced additional conductivity led to a slightly more conductive material. 

Sonnier, R., Massardier, V., Clerc, L., Lopez-Cuesta, J. M., Bei eret, A., Reactive compatibilization of polymer blends by gamma-irradiation Influence of the order of processing steps. Journal of Applied Polymer Science 2010, 115(3), 1710-1717. 

Explores the modification of polymer blends by irradiation techniques... 

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