Radiation resistance composites

The influence of radiation on the transport properties of different reverse osmosis composite membranes was smdied by Chmielewski and Harasimowicz [1]. Reverse osmosis membranes were irradiated with a Co source, with a linear accelerator, and were also immersed in a Cs high activity solution, reaching absorbed dose values around 40 kGy. The results of some tests with the irradiated membranes showed that aromatic polyamide composite membranes are highly radiation resistant. This allows these membranes to be used in radioactive solutions with an activity below 3.7 x lO Bq/m, which corresponds to absorbed dose values around 30 kGy. 

Radiation resistant ceramic matrix composites, Jones, 1997 [146]... 

Jones RH, Steiner D, Heinisch HL, Newsome GA, Kerch HM (1997) Review radiation resistant ceramic matrix composites. J Nucl Mater 245 87-107... 

DPA are excellent AO and HS in various rubbers and plastics, lubricating greases and oils [27], They have some antifatigue effect and provide no antiozonant protection [1], Their photostabilization activity is rather low. DPA may be used in radiation resistant polymer compositions for cable coatings in nuclear power plants [28]. Various 4,4 -disubstituted DPA contain a fert-alkyl (e.g. 1,1,3,3-tetramethylbutyl 9a, 1,1-dimethylethyl or their combinations), other alkyls or aralkylgroups (e.g. a,a-dimethylbenzyl, 9b) [1,3,24]. A tertiary amine 3-[(diphenylamino)methyl]-5-[(diphenylaminomethyl)thio]-l,3,4-thiadiazolidine-2 (14) was proposed as AO for rubbers [29],... 

Tris-4-nonylphenyl phosphite is an important additive useful as an antioxidant for rubber and in lubricating oil as for example in polyesters derived from neopentyl polyol (ref.33) in conjunction with a (Cg or Cg) dialkyidiphenylamine. It has found a use as an additive in radiation-resistant polypropene compositions (ref. 34). 

The family of PEN polymers exhibits a good radiation resistance and low flammability and toxic gas emission. The cyano group, because of its polarity, imparts good adhesion properties to glass fibers, therefore the polymers are suitable as a matrix for composite materials. 

R L Clough, K T Gillen and M Dole, Radiation resistance of polymers and composites , in The Effects of Ionizing Radiations on Polymeric Materials, eds A A Collyer and D W Clegg, Amsterdam, Elsevier, 1990. 

The principal criteria for the formulations were mechanical and thermal stability, homogeneity, radiation resistance, high containment capacity, low volume, corrosion resistance, low leachability, easy fabrication (mastered technology), and flexibility with regard to the composition of waste to be conditioned. 

The CVI SiC/SiC composites are also promising for nuclear applications because of the radiation resistance of the p phase of SiC, their excellent high-temperature fracture, creep, corrosion and thermal shock resistances. Studies on the P phase properties suggest that CVI SiC/SiC composites have the potential for excellent radiation stability [5]. Furthermore, because of excellent thermal fatigue resistance, start-up and shut-down cycles and coolant loss scenarii should not induce significant stmctural damage [5]. The CVI SiC/SiC are also considered for applications as stmctural materials in fusion power reactors, because of their low neutron-induced activation characteristics coupled with excellent mechanical properties at high temperature [6-8]. 

The commonly used synthetic fiber reinforcements are aramid, Nomex , nylon, and Kevlar fibers [19]. The research and development in the fields of synthetic fiber reinforced composites led to the development of aramid fibers. Further research led to the invention of meta and /> r -aramids [20]. Para and meta refer to the positions of the carboxylic and amine groups on the monomer ring. Nomex [21] was produced in the early 1960s and its excellent thermal, chemical, and radiation resistance [22, 23] led to extensive use in defensive clothing, insulation, and as a substitute for asbestos [24]. Additional researches with this /weta-aramid (Nomex) led to the fiber recognized as Kevlar [25]. Kevlar is a / ara-aramid fiber [26]. It was produced and trademarked by DuPont and became commercially accessible in 1973. In the last two decades, the worldwide production and use of aramids has been growing steadily. 

---