Investigation of resin systems for improved ablative materials Final report, 19 Jun. 1964 - 31 Jul. 1965

Resin systems investigated for improving ablative materials for use with fluorine-containing liquid propellant system

Chemical research projects office: An overview and bibliography, 1975-1980

The activities of the Chemical Research Projects Office at Ames Research Center, Moffett Field, California are reported. The office conducts basic and applied research in the fields of polymer chemistry, computational chemistry, polymer physics, and physical and organic chemistry. It works to identify the chemical research and technology required for solutions to problems of national urgency, synchronous with the aeronautic and space effort. It conducts interdisciplinary research on chemical problems, mainly in areas of macromolecular science and fire research. The office also acts as liaison with the engineering community and assures that relevant technology is made available to other NASA centers, agencies, and industry. Recent accomplishments are listed in this report. Activities of the three research groups, Polymer Research, Aircraft Operating and Safety, and Engineering Testing, are summarized. A complete bibliography which lists all Chemical Research Projects Office publications, contracts, grants, patents, and presentations from 1975 to 1980 is included

Insoluble polyelectrolyte and ion-exchange hollow fiber impregnated therewith

The number of quaternary sites and ion exchange capacity of a polyquaternary, cross linked, insoluble copolymer of a vinyl pyridine and a dihalo organic compound is increased by about 15-35% by reaction of the polymer with an amine followed by quaternization, if required. The polymer forms spontaneously in the presence of a substrate such as within the pores of a hollow fiber. The improved resin impregnated fiber may be utilized to remove ions from waste or process steams

Triazolinediones as highly enabling synthetic tools

Triazolinediones (TADs) are unique reagents in organic synthesis that have also found wide applications in different research disciplines, in spite of their somewhat "exotic" reputation. In this review, we offer two case studies that demonstrate the possibilities of these versatile and reliable synthetic tools, namely, in the field of polymer science as well as in more recently emerging applications in the field of click chemistry. As the general use of triazolinediones has always been hampered by the limited commercial and synthetic availability of such reagents, we also offer a review of the available TAD reagents, together with a detailed discussion of their synthesis and reactivity. This review thus aims to serve as a practical guide for researchers that are interested in exploiting and further developing the exceptional click -like reactivity of triazolinediones in various applications

Synthesis and characterisation of branched polymers

HyperMacs and HyperBlocks are polymers with highly branched architectures. The building blocks for these materials, AB(_2) macromonomers, are synthesized by living anionic polymerization and are well-defined in terms of molecular weight and polydispersity. The nature of the coupling reaction used to generate the highly branched HyperMacs results in branched polymers with a distribution of molecular weights and architectures. Previously a strategy for the synthesis of polystyrene HyperMacs has been reported in which the extent of reaction was limited by an unknown factor. In this thesis the modifications made to the synthetic strategy are reported for the production of more highly branched polystyrene HyperMacs or 'super' HyperMacs. Other variations along this theme include the addition of a B3 core creating core HyperMacs. Modifications to the improved HyperMac synthesis enabled the construction of polybutadiene AB(_2) macromonomers, resulting in polybutadiene HyperMacs; as well as triblock copolymer AB(_2) macromonomers constructed from polystyrene and polyisoprene forming block copolymer HyperMacs termed HyperBlocks. Characterisation of the materials above involved techniques including rheology, thermal analysis including differential scanning caliorimetry, (DSC), and dynamic mechanical analysis, (DMA), x-ray scattering (small angle x-ray scattering, SAXS) and transition electron microscopy, (TEM).Melt rheology showed polystyrene HyperMacs to be thermorheologically simple and HyperMacs showed little evidence for relaxation by reptation. Their rheological behaviour agreed well with the Cayley tree model for hierarchical relaxation in tube models of branched polymers. HyperBlocks showed phase separated morphologies with two distinct glass transition temperatures for their constituents. However the highly branched architecture of HyperBlocks disrupts long-range order seen in the macromonomers, as observed by SAXS and TE

Ion-exchange hollow fibers

An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, crosslinked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution

Study on Rheological Behavior of the Composites of Recycled HDPE with Recycled Tire Rubber Particles

This study was mainly concerned with rheological properties of composites of recycled high density polyethylene (HDPE) with recycled tire rubber particles at shear rates from 1.167 to 116.7 s-1. The viscosity was investigated in terms of effects of shear rate, shear stress, temperature, concentration of recycled tire rubber particles and heating duration. The temperature was in the range from 160 to 250 °C and the rubber particle concentration was between 0 and 25%. The heat duration for the composites was up to 240 minutes before testing. The viscosities of composites were decreased with increase in shear rate and shear stress. The change was considerably noticeable when the shear rate was less than 7.5 s-1. Increasing the temperature could also decrease the viscosity of composites of recycled HDPE and recycled tire rubber particles. The effect of temperature was more obvious at lower shear rate. The higher viscosity due to increased content of recycled tire rubber particles was explained in terms of increased interaction between recycled HDPE and recycled tire rubber particles. There was little change in viscosity after recycled HDPE and the composites were held up to 240 minutes at 220 °C