Materials Literature
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Photochemical dry etching and surface modification of polyethylene terephthalate (PET) was investigated with an incoherent excimer UV source, employing a dielectric barrier discharge in krypton chloride to provide intense narrow-band radiation at λ=222 nm (KrCl*). The roughness of the exposed PET was measured with a s…
Crystalline regions of poly(ethylene terephthalate) (PET) are associated with the trans glycol conformation of the polymer repeat unit. Amorphous regions are largely associated with the gauche conformation. We describe experiments which follow the development of trans conformers at the surface and in the bulk of amorp…
A thorough study of the series has been carried out. All of the samples have the same orthorhombic crystallographic structure. However, the magnetic, magnetoelastic and electrical properties show drastic changes with the Tb content. The decrease in the intensity of the ferromagnetic double-exchange interaction has bee…
The relaxation of the magnetization in big molecular groups embedded in crystals is studied and compared with experimental data on Mn 12 O 12 . At sufficiently high temperatures (T > 2 K in Mn 12 O 12 ) the relaxation is thermally activated, and the exchange of energy with phonons produces relaxation through a casc…
Various amounts of hydroxy terminated PDMS were linked into PLLA chains via in-situ ring opening polymerization at a very low content of SnOt2. The 1H and FTIR spectra provided evidence for the incorporation of the PDMS in the PLLA chains. The molecular weights, Tg, Tm, crystallinity and the heats of fusion decreased…
Poly(N-acylethylenimines) with epoxy or imidazole groups randomly attached to the end of the side chains were synthesized from decenyl/heptyl oxazoline random copolymers. They are named as DH(m/n)–epoxy and DH(m/n)–imidazole, respectively, and the starting polymers are named as DH(m/n), where m and n represent the cal…
The empirical form for the dependence, Tg(n) ≅ Tg(∞)·(1 + α/n), of the glass transition temperature Tg on the average number n of repeat units between crosslinks, is generalized for randomly crosslinked high polymers. The new form, Tg(n) ≅ Tg(∞) · [1 + c/(n·Nrot)], is based on a correlation study of data for 77 sample…
Specialist Periodical Reports provide systematic and detailed review coverage of progress in the major areas of chemical research. Written by experts in their specialist fields the series creates a unique service for the active research chemist, supplying regular critical in-depth accounts of progress in particular ar…
The equilibrium oxygen chemical potential of mixed oxygen ion and electron conducting perovskites ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CoO}}_{3\ensuremath{-}\ensuremath{\delta}}$ was measured as a function of $\ensuremath{\delta}$ and x by high temperature oxygen coulometric titration. An almost…
We demonstrate that the electrical excitation of Er ions incorporated within the depletion layer of a p+−n+ Si diode allows one to simultaneously obtain efficient pumping of rare earth ions and a fast turnoff time of the electroluminescence signal. In fact it is found that during pumping, under reverse bias at the bre…
Two sources of room temperature visible luminescence are identified from SiO2 films containing ion beam synthesized Si nanocrystals. From a comparison of luminescence spectra and photoluminescence decay lifetime measurements between Xe+-implanted SiO2 films and SiO2 films containing Si nanocrystals, a luminescence fea…
The thermodynamic origin of disordered intergranular films commonly found in covalent ceramic materials is studied by molecular-dynamics simulation. Our studies show that all high-energy grain boundaries in a model covalent material, silicon, exhibit a universal amorphous structure, whereas low-energy boundaries are c…
Ab initio cluster methods are used to investigate vacancy-impurity complexes in diamond. We assign the 1.682 eV, twelve-line optical band to a vacancy-Si complex which has a very unusual, possibly unique structure with a Si atom at the center of a split vacancy. The method also successfully accounts for the 1.945, 2.1…
Here we report on the finding of pure boron nitride (BN) nanotubes that do not contain any additional inclusions and on a new method for their growth: laser heating of boron nitrides at high nitrogen pressure (5–15 GPa). The multiwalled nanotubes were observed using high resolution electron microscopy and were chemica…
This 1996 book summarises the state of knowledge on the microscopic behaviour of oxide surfaces. The first chapter of the book summarises classical approaches, introduces the concept of ionicity, and describes the mixed iono-covalent character of the oxygen cation bond in bulk materials. The next three chapters focus…
A new approach, plasma-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA), was used to introduce PEG graft chains with hydroxyl end groups onto a polyurethane (Tecoflex) surface. After argon plasma treatment and subsequent exposure to air, graft polymerization onto Tecoflex films was allowed to…
Microporous polypropylene fibers were prepared by stretching polypropylene fibers containing poly(methylsilsesquioxane) filler. The properties of the resultant fibers are controllable by adjusting the filler content and stretching degree. The resultant fibers have a fine texture of polypropylene fibrils, in which the…
Two liquid crystal forming polysaccharides, hydroxypropyl cellulose and chitosan, were blended in aqueous acetic acid solutions and were crosslinked with dialdehydes (glyoxal and glutaraldehyde) as crosslinker and hydrochloric acid as catalyzer. The crosslinkability, morphology, solubility, and tensile properties of t…
Three linear low density polyethylene (LLDPE) resins of similar melt index and density were synthesized with different comonomers in the Unipol pilot-plant scale reactor. The molecular structure, blown film morphology, and film strength properties of the resins have been comprehensively characterized. The film dart dr…
Nylon-nitrile rubber blends having different plastic-rubber component ratios (100/0, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, and 0/100) were prepared by melt mixing technique in a Rheocord-90 at a temperature set at 180°C. The mixing characteristics of the blends have been analyzed from the rheographs. The mo…