Materials Literature
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While the time dependence of the friction on a tagged particle in a dense liquid has been investigated in great detail, a similar analysis for the viscosity of the medium and the interrelationship between the two has not been carried out. This is despite the close relation always assumed, both in theoretical and exper…
This paper presents dipole moments, static polarizabilities, first hyperpolarizabilities and second hyperpolarizabilities calculated in the framework of density functional theory. All calculations have been performed using a finite field approach implemented in our new density functional theory program ALLCHEM. The ca…
It has long been appreciated that both temperature and density play roles in determining the extremely super-Arrhenius, low-temperature behavior of the viscosity and long α-relaxation times that characterize fragile supercooled liquids. But what has not been generally appreciated, and what we believe we have establish…
We have studied the nucleation and the physical properties of a -1/2 wedge disclination line near the free surface of a confined nematic liquid crystal. The position of the disclination line has been related to the material parameters (elastic constants, anchoring energy and favored anchoring angle of the molecules at…
Liquefaction of commodity polymers to oils and gases can be used to recover the energy value of these materials. This article reports liquefaction data for high-density polyethylene (HDPE), one of the major plastics in recycled material. Thermal degradation of HDPE to oil–gas mixtures required higher temperatures (450…
A series of polyacrylate–polyurethane networks (PUA) were synthesized and their pH-sensitive behaviors were studied. An unexpected swelling–deswelling behavior was observed as the composition changed. Dynamic mechanical thermal analysis and differential scanning calorimetry were used to initially explain this phenomen…
By means of homogeneous stepwise condensation method, both the Ni–polyyne copolymers with PPh3 and PBu3 ligands, and modified π-conjugated nickel-containing copolymers have been synthesized and confirmed by infrared (IR) analysis. The Ni–polyyne copolymers obtained are yellow powder having a Mw of about 1 ∼ 2 × 104 an…
Liquefaction of commodity polymers to oils and gases can be used to recover the energy value of these materials. This article reports liquefaction data for high-density polyethylene (HDPE), one of the major plastics in recycled material. Thermal degradation of HDPE to oil–gas mixtures required higher temperatures (450…
This paper describes the mechanism of discharge on the surface of an insulating plate in gas exposed to a very fast transient overvoltage (VFTO). The voltage consists of a sequence of steep short pulses on its front. A streak camera and a charge-measuring system were employed for the investigation. The leader channel,…
Vinyl trimethoxysilane grafting reactions of low-density polyethylene (LDPE) were performed in an extruder, followed by crosslinking with boiled water. The thermal properties of both silane-grafted and silane-grafted water-crosslinked LDPE were investigated using differential scanning calorimetry (DSC) and thermogravi…
Anhydride-cured epoxies are used in electrical engineering to manufacture insulators. The purpose of this study is to determine the modifications undergone by these resins when exposed to solar-type radiation (radiation with a wavelength of more than 300 nm). Two epoxy–anhydride systems have been studied. Using transm…
The use of graft copolymers of starch and glycidyl methacrylate (starch-g-PGMA) to improve the mechanical properties of composites with poly(hydroxy butyrate-co-valerate) (PHBV) has been investigated. In general, the tensile and flexural strengths of the composites were greater with starch-g-PGMA compared to untreated…
The phase behavior and rheology of binary blends of polystyrene (PS) and poly(α-methylstyrene) (PαMS), exhibiting upper critical solution temperature (UCST), and binary blends of PS and poly(vinyl methyl ether) (PVME), exhibiting lower critical solution temperature (LCST), were investigated. For the study, (i) PS-40/P…
In polyisocyanates with chiral azo chromophores a change of the helical conformation can be triggered photochemically. In this investigation we studied the correlation between the isomerization of the main chain and the photoisomerizable side groups by CD measurements. A few minutes of irradiation are enough to reach…
In contrast to most diblock copolymers which exhibit the classical upper critical ordering transition (UCOT), polystyrene- b -poly n -butyl methacrylate PS- b -PBMA has been shown to undergo ordering upon heating through a lower critical ordering transition (LCOT). Here we report the phase behavior of a family of dibl…
Three types of hydroxyl terminated poly(butadiene) (HTPB) networks having different NCO/OH reactive group ratios were prepared using three different reactive systems (i.e., Desmodur N-100 pluriisocyanate, isophorone diisocyanate (IPDI)/trimethylol propane (TMP), and hexamethylene diisocyanate (HMDI)/TMP). Desmodur N-1…
A series of mono- and disubstituted cationic porphyrins (1-8) were synthesized and investigated for their ability to bind and cleave DNA in the presence of light. In these porphyrins, the cationic substituents were introduced at various peripheral positions, i.e., the non-meso positions of the porphyrin system. The mo…
Blends of atactic poly[( R, S )-3-hydroxybutyrate], a-PHB, with poly(ε-caprolactone), PCL, and with poly( l -lactic acid), PLLA, were obtained in the form of compression-molded films. The phase behavior of the blends was different: a-PHB and PCL were totally immiscible, whereas a-PHB/PLLA blends were miscible over the…
We report the first evidence of the potential of new amphiphilic ABA-triblock copolymers as gelling agents for lamellar liquid crystalline L α phases. Recently, we described a new type of lamellar hydrogels which are not based on a polymer network swollen in water but are obtained by the addition of small amounts of a…
Smectic state morphology of the main-chain liquid crystal PB-14 polyester was studied by small-angle X-ray scattering (SAXS), differential scanning calorimetry, and transmission electron microscope methods. The PB-14 polyester forms isotropic liquid (I), smectic H (S H ), and crystalline phases in order of decreasing…