CR-39

• CR-39
• PADC
• Polydiethylenglykoldiallylbiscarbonat

Synthetic homopolymer, thermoset

Fixed

1.32 g/cm3 ( 25 ° C)

Polyallyldiglycolcarbonat ( PADC ) is a polymer which is used, inter alia, for the production of spectacle lenses and is also known under the designation CR-39.

Production

The thermosetting resin is provided by the addition of an initiator (often: diisopropyl peroxydicarbonate, IPP) to the monomer Diallyldiglycolcarbonat (ADC), followed by heating and hot polymerization.

The structural formula in the infobox with " m" and " n" gekennzeichntenen units represent different polymer chains are cross-linked spatially by the diisopropylperoxydicarbonate. This structure leads to behavior of the thermosetting resin.

History and Use

The Columbia Southern Chemical Company sought in 1940 as part of a project to synthetic resins, as different products based on natural materials were scarce by the 2nd World War. Sample 39 of 180 promised favorable properties, thus increasing the abbreviation CR -39 for " Columbia Resin # 39 " returned. The first applications were mild, self-healing fuel tanks ( glass fiber reinforced), sight tube and lenses for searchlight in war airplanes. From 1947 onwards, eyeglass lenses made ​​therefrom. Later plates for welding screens, crane cabin windows and goggles were crafted.

Use as a particle detector

CR -39 can be used as nuclear track detector ( SSNTD german, solid state nuclear track detector or, more precisely PNTD, plastic nuclear track detector). An incident particles of ionizing radiation enters the detector, forming a latent particle track, along the formed by the ionization radicals. If the irradiated CR -39 with typically 70 ° C hotter, 5-7 molar sodium hydroxide etched, so burn the points at which radicals occur faster than the surrounding material. Subsequently, the number of holes per unit area thus formed is determined by using a microscope. In connection with a so-called converter of LiF or PE can be determined as well as the neutron fluence by measuring the fluence of charged recoil particles.