Materials Literature
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Polymerizations of racemic- and meso-d,l-lactide were conducted at 120°C in xylylene or in bulk. Lead oxide (PbO), zinc stearate, antimony(III) 2-ethylhexanoate, and bismuth(III) 2-ethylhexanoate were used as initiators. With PbO and Zn stearate, bulk polymerizations were also conducted at 150°C. High yields (⩾90%) we…
Abstract A method for the synthesis of well‐defined poly(alkyl vinyl ether–2‐ethyl‐2‐oxazoline) diblock copolymers with hydrolytically stable block linkages has been developed. Monofunctional poly(alkyl vinyl ether) oligomers with nearly Poisson molecular weight distributions were prepared via a living cationic polyme…
High molecular weight, amorphous, partially substituted polyacetylenes (poly-RCOT) have been prepared using the ring-opening metathesis polymerization of substituted cyclooctetraenes. Spin-cast films of these polymers yielded unusually sharp, well-defined reversible electrochemistry for oxidative and reductive doping…
Abstract For the two groups of rubber modified thermoplastics (toughness by multiple crazing as in HIPS and ABS polymers or by multiple shearing as in high‐impact PA) the local processes of plastic deformation have been studied by different techniques of electron microscopy, including scanning, transmission and high v…
Using neutron diffraction, we have studied the crystal structure and magnetic ordering of the rare-earth and Cu moments in the layered perovskite systems ${\mathrm{NdBa}}_{2}$${\mathrm{Cu}}_{2}$${\mathrm{NbO}}_{8}$ (Nd 2:2:1:8) and ${\mathrm{PrBa}}_{2}$${\mathrm{Cu}}_{2}$${\mathrm{NbO}}_{8}$ (Pr 2:2:1:8). These are sy…
Abstract A method is described to impart flexibility and mechanical strength to conducting polyaniline by polymerizing aniline on fabrics and on cellulose papers. The study indicates that these conducting fabrics offer 16–18 dB of shielding effectiveness for the control of electromagnetic interference (EMI) up to a fr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnionic polymerization of monomers containing functional groups. 5. Anionic polymerizations of 2-, 3-, and 4-cyanostyreneTakashi Ishizone, Kenji Sugiyama, Akira Hirao, and Seiichi NakahamaCite this: Macromolecules 1993, 26, 12, 3009–3018Publication Date (Print):June 1, 1993P…
Solid-state alpha-track detectors using cellulose nitrate films were used to measure the radon exhalation rates from building materials. The radon flux emitted from the surface of the building material was measured by placing an inverted cup on the top of the building material. Cellulose nitrate film was placed within…
Abstract It has been found that dioctyl terephthalate (DOTP), a plasticizer for polyvinyl chloride (PVC), can be made from scrap terephthalate polyesters such as polyethylene terephthalate (PET) by a method known as degradative transesterification. It is recognized that this plasticizer is as good as plasticizer as co…
Two sets of cotton fabrics—one consisting of different types of fabric and the other of a fabric sampled sequentially during its normal processing stages—were investigated by DRIFT spectroscopy. The band assignments were consistent with previous work but, in general, the spectra could not be differentiated on visual e…
Ultraviolet optical absorptions of semiconducting copper phosphate glasses with batch compositions of 40%, 50%, and 55% CuO have been examined as a function of [Cu2+]/[Cutotal] in the glasses. The optical energy gap, Eopt, obtained from the fundamental absorption edge depends upon both glass composition and the ratio…
Abstract Racemic D , L ‐lactide and meso ‐ D , L ‐lactide were polymerized with four different initiators: Al(isopropoxide) 3 , AIEt 3 /neopentyl alcohol (1 : 1, mole ratio), AIEt 3 /(+)‐menthol (1 : 1, mole ratio) and methylaumoxane. Most polymerizations were conducted in xylene at 60, 90 and 120°C, but at 60°C the y…
A kinetic analysis of densification is presented for the case of isolated, identical pores separated by dense, polyerystal‐line material where the grain size is a variable (smaller to larger, relative to the pore size). The analysis includes the influence of both grain growth and mass transport rates on the driving po…
Abstract The objective of this study is to determine the energy dissipation processes in polymer‐matrix composites during impact of ballistic projectiles. These processes include heat, fiber deformation and breakage, matrix deformation and fracture, and interfacial delamination. In this study, experimental measurement…
Two crystals of monoclinic hen egg-white lysozyme were irradiated in a monochromatic synchrotron X-ray beam (λ = 1.488 Å), the first as a rapidly frozen crystal mounted at the end of a glass fiber at low temperature (120 K) and the second mounted in a capillary tube at ambient temperature (298 K). Comparison of oscill…
Abstract Four silane coupling agents, (1H,1H,2H,2H-polyfluoroalkyl)trimethoxysilanes ((1H,1H,2H,2H-henicosafluorododecyl)trimethoxysilane, C10F21C2H4Si(OCH3)3, (1H,1H,2H,2H-heptadecafluorodecyl)trimethoxysilane, C8F17C2H4Si(OCH3)3, (1H,1H,2H,2H-tridecafluorooctyl)trimethoxysilane, C6F13C2H4Si(OCH3)3, and (1H,1H,2H,2H-…
The corrosion resistance of stainless steel weld metal in the ranges of 17 to 28% chromium (Cr), 6 to 60% nickel (Ni), 0 to 9% molybdenum (Mo), and 0.0 to 0.37% nitrogen (N) was examined. Critical pitting temperatures were determined in ferric chloride (FeCl3). Passive film breakdown potentials were assessed from pote…
High‐temperature superconductors, ferroelectric materials , electrochromic films, and semiconductors are just some of the materials which can be produced from transition‐metal alkoxides using the sol–gel method. The method itself is outlined, the control of the various parameters, such as choice of precursor and mediu…
Abstract The orientation characteristics of extruded poly(ethylene terephthalate) (homopolymer) sheets are discussed with respect to: mode of extension (simultaneous versus sequential), strain rate, stretch ratio, and temperature. The nature of the stress–strain curve recorded during the process of extension, and its…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBroadband dielectric study on binary blends of bisphenol-A and tetramethylbisphenol-A polycarbonateG. Katana, F. Kremer, E. W. Fischer, and R. PlaetschkeCite this: Macromolecules 1993, 26, 12, 3075–3080Publication Date (Print):June 1, 1993Publication History Published online…