Three polymers, poly(4,4′-dinonyl-5,5′-bithiazole-2,2′-diyl-co-5-tert-butylphenylene-1,3-diyl) (PBBNBT), poly(4,4′-bis(p-dodecylphenyl)-2,2′-bithiazole-5,5′-diyl) (PDPBT), and poly(4,4′-dinonyl-2,2′-bithiazole-5,5′-diyl-co-ethynylene) (PENBT), have been synthesized. These polymers illustrate the ability to tune polymer properties around a specific chromophore, in this case the bithiazole ring system. Alterations of optical properties and solid-state morphology have been made while the electrochemical behavior characteristic of the bithiazoles, i.e., reversible reduction near -2.0 V and n-dopability resulting in conductivities around 10 2 S/cm, has been maintained. All three polymers have also been used as the emitting layer in polymer-based LEDs.
This paper presents the production method and the compressive mechanical response at low strains for a collection of polyethylene foams with high densities and cell sizes in the microcellular range. The materials were produced using a modified compression moulding technique that allows and independent control of density and cell size. The materials had a relative density between 0.27 and 0.92, an homogeneous and multistructured cellular structure with dense skin and foamed core and cell sizes in the range 30 to 100 microns. The Young´s modulus was reduced when density did. For relative densities higher than 0.7, the reduced Young's modulus of the foams was higher than that of the solid. In addition, it has been proved that variations in the cell size at constant density did not influence the Young's modulus. The advantages of using these materials for the production of plastic pipes have been analysed. A reduction of the weight of pipes loaded in compression of up to 42 % can be reached by using these foams in spite of the solid material from which the foam was produced.
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