Materials Chemistry and Physics 127 (2011) 305–309 Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys Structure and mechanical investigation of the effect of proton irradiation in Makrofol DE 7-2 polycarbonate M.H. Abdel-Salam a , S.A. Nouh b,∗ , Yasmine E. Radwan a , S.S. Fouad a a Physics Department, Faculty of Education, Ain Shams University, Cairo, Egypt b Physics Department, Faculty of Science, Ain Shams University, Cairo, Egypt article info Article history: Received 28 July 2010 Received in revised form 14 December 2010 Accepted 6 February 2011 Keywords: Proton irradiation X-ray diffraction FTIR Viscosity Mechanical properties Polymers abstract Makrofol-DE 7-2 polycarbonate is a class of polymeric solid state nuclear track detectors which has many applications in various radiation detection fields. In the present work, Makrofol samples were irradiated using different fluences (2.5 × 10 13 to 2.5 × 10 15 p cm -2 ) of 1 MeV protons at the University of Surrey Ion Beam Center, UK. The structural modifications in the proton irradiated Makrofol samples have been studied as a function of fluence using different characterization techniques such as X-ray diffraction, FTIR spectroscopy, intrinsic viscosity and mechanical properties. The results indicate that the carbonyl group (C O) is the most sensitive group towards proton irradiation, where it degraded under irradiation up to 2.5 × 10 15 p cm -2 . This degradation is also reported by FTIR spectroscopy and enhanced the degree of ordering in the degraded samples as revealed by XRD technique. Additionally, this degradation decreases the intrinsic viscosity from 0.68 to 0.41 at 35 ◦ C, indicating a decrease in the average molecular mass. Above 7.5 × 10 13 and up to 2.5 × 10 15 p cm -2 , the free radicals produced from scission are chemically active, can be used in chemical reactions that lead to the enhancement of the crosslinking process. Thus the proton irradiation in the fluence range 7.5 × 10 13 to 2.5 × 10 15 p cm -2 led to a more compact structure of Makrofol polymer resulted in an enhancement in its mechanical properties. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Proton irradiation is a useful technology to induce suitable mod- ifications of polymers. In particular, it is an important way to achieve some desired improvements that promise many appli- cations in a wide range of industrial fields. There are several applications of ion irradiated polymer such as microelectronics and biosensors production technologies [1]. Dramatic changes in the radiation-induced damage processes may occur if ion irradiations are performed, instead of classical-condition irradiations such as electron beams or gamma rays [1–3]. The reason is the very high value of the electronic stopping power of the ions which induces an unusual density of electron–hole pairs close to the ion path [1]. Also, proton irradiation may lead to many processes, such as the production of primary and secondary radicals, formation of double bonds and transformation of C–C bonds. These reactions depend on the proton dose as well as on the environmental conditions during and after irradiations [1,4]. Irradiation of nuclear track detectors with ionizing radiation has been found to cause surface damage and degradation of the ∗ Corresponding author. Tel.: +20 22677240; fax: +20 26822189. E-mail address: samirnouh90@hotmail.com (S.A. Nouh). amorphous nature. Molecular chain scission, intermolecular cross- linking, rearrangement of bonding, and formation of carbon-rich clusters are some structural deformations in the irradiated polymer that lead to changes in the physical properties of the material [5–7]. The effects of proton irradiation on polycarbonate have already been widely reported [8–16]. When Makrofol polycarbonate was irradiated with low linear energy transfer LET radiation such as gamma or electrons, the observed effect was only degradation of the polymer, while when irradiated with high LET such as heavy ions, Makrofol undergoes degradation at first and with increasing fluence the crosslinking of chains is achieved. It could be con- cluded that the behavior of Makrofol under proton irradiation is the same as that under heavy ions irradiation, this can be attributed to the high LET of protons compared with electrons or gamma-rays. Singh et al. [17] studied the effects of 80 MeV O 6+ ions irradiation on Makrofol-DE polycarbonate by different characterization tech- niques such as FTIR spectroscopy. They concluded that there was no significant variation in the absorbance bands and thermal sta- bility of Makrofol due to 80 MeV O 6+ ions irradiation at the fluence of 2.4 × 10 13 ions cm -2 . Hence, PC is radiation resistance up to this fluence. In the present study Makrofol DE 7-2 samples were irra- diated using 1 MeV protons with fluences between 2.5 × 10 13 and 2.5 × 10 15 p cm -2 aiming to investigate the modifications induced in its structural and mechanical behavior. 0254-0584/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.matchemphys.2011.02.017