Electrical and photoelectrical measurements are made on thin films of β‐cobalt phthalocyanine particles in Schottky junction cells. The results of current density‐voltage characteristics in dark at constant temperature are interpreted in terms of a space charge limited mechanism dominated by an exponential distribution of trapping levels. An analysis of the results enables the determination of the Fermi temperature of the trap distribution. The dependence of the photovoltaic parameters on pigment loading and polymer binder are investigated. Typical polymeric binders used throughout this study are polyvinylacetate (PVA) and polycarbonate (MK). The results show that the polymer has a strong effect on photocurrent generation efficiency in phthalocyanine composite type photovoltaic cell; polymers having a polar group seem desirable for improving the performance.

No abstract

No abstract

Material systems capable of handling both the ballistic impact and blast waves are necessary for security forces. In this study, the high strain rate performance of monolithic and bonded ultra-high molecular weight polyethylene (UHMWPE) with high-temperature resistant basalt/polyetherimide (B/PEI) composite is presented. Individual composite laminates were fabricated using vacuum-assisted compression molding. Subsequently, cylindrical test coupons were cut using a high-pressure waterjet. A suitable adhesive grade was used for the bonding of two different composite types. The dynamic compression studies were conducted on a split-Hopkinson pressure bar (SHPB). For identical incident energies, the range of strain rates attained by monolithic UHMWPE, B/PEI and bonded composites differed significantly. Monolithic UHMWPE achieved the highest rates of loading, whereas higher stresses were recorded for the B/PEI composite. Yet, monolithic UHMWPE, owing to higher constant stress plastic flow, results in higher toughness. Bonded composites revealed hybrid properties with delamination of UHMWPE as the primary failure mode. High-speed imaging exposed severe deformation of UHMWPE during dynamic compression. SEM micrographs revealed fiber pull-out and deforming behavior of UHMWPE and brittle failure of B/PEI composite. B/PEI in a bonded composite system never failed under dynamic compression within the experimental range, thus providing a window of opportunity to tailor-make better ballistic and blast protection materials.

<p>Novel ring-disubstituted isobutyl phenylcyanoacrylates, RPhCH=C(CN)CO₂CH₂CH(CH₃)₂ (where R is 2,3-difluoro, 2,4-difluoro, 2,6-difluoro, 3,4-difluoro, 3,5-difluoro, 2-chloro-4-fluoro, 2-chloro-6-fluoro, 3-chloro-2-fluoro, 3-chloro-4-fluoro, 4-chloro-3-fluoro) were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and isobutyl cyanoacetate and characterized by CHN analysis, IR, ¹H and ¹³C NMR. The acrylates were copolymerized with styrene in solution with radical initiation (ABCN) at 70C. The compositions of the copolymers were calculated from nitrogen analysis.</p>

No abstract

No abstract

Novel difluoro and chlorofluoro ring-disubstituted isobutyl phenylcyanoacrylates, RPhCH=C(CN)CO2CH2CH(CH3)2 (where R is 2,3-difluoro, 2,4-difluoro, 2,6-difluoro, 3,4-difluoro, 3,5-difluoro, 2-chloro-4-fluoro, 2-chloro-6-fluoro, 3-chloro-2-fluoro, 3-chloro-4-fluoro, 4-chloro-3-fluoro) were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and isobutyl cyanoacetate and characterized by CHN analysis, IR, 1H and 13C NMR. The acrylates were copolymerized with styrene in solution with radical initiation at 70C. The compositions of the copolymers were calculated from nitrogen analysis.