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Point Decreased (point + decreased)
Selected AbstractsPreparation of highly branched polyethylene using (,-diimine) nickel complex covalently supported on modified SiO2JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Hongliu Jiang Abstract Bis(4-(4-amine-3,5-diisopropylbenzyl)-2,6-diisopropylphenylimino) acenaphthene NiBr2 (Catalyst I) was synthesized. The complex covalently supported on Et3Al-treated silica (SC) and used for ethylene polymerization was produced with cocatalyst of common inexpensive alkylaluminum compounds. Polyethylenes (PEs) with branching numbers of 12.94 (1000C) to 116.02 (1000C) were prepared in heptane. The polymerization conditions, such as the cocatalyst, Al/Ni ratio, and temperature, had significant effects on catalytic activity and properties of polyethylenes. Confirmed by high-temperature 13C NMR, the polyethylenes synthesized contain significant amounts of not only methyl but also ethyl, propyl, butyl, pentyl, and other long branches (longer than six carbons). The branching degree of polyethylenes increased with temperature, while their molecular weight and melting point decreased correspondingly, resulting in linear semicrystalline to totally amorphous polymers. The formation of the branches could be illustrated by the chain walking mechanism, which controlled their specific spacing and conformational arrangements with one another. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 103: 1483,1489, 2007 [source] Synthesis and characterization of urethane vinyl ether crystalline monomersPOLYMER INTERNATIONAL, Issue 3 2006Zhaohua Zeng Abstract UV powder coatings combine the advantages of both conventional thermoset powder coatings and liquid UV-curing coatings. In this paper, a series of crystalline monomers based on urethane vinyl ether have been synthesized by reaction of hexamethylene diisocyanate (HDI) with hydroxybutyl vinyl ether (HBVE) or together with a saturated alcohol such as 1-octanol, 2-butoxy ethanol and 2-ethoxy ethanol. The crystallinity of the monomers was characterized by DSC, WAXD and polarizing microscopy. It was found that the melting point of the monomer can be expediently adjusted to an adequately low level by changing the type and/or the amount of the saturated alcohol added during the synthesis procedure. Thus, when 20,40 mol% of HBVE was replaced by a saturated alcohol, the melting point decreased to around 75,90 °C, which is suitable for UV-curing powder coating formulations. Copyright © 2006 Society of Chemical Industry [source] Textural properties of raw Atlantic salmon (Salmo salar) fillets measured by different methods in comparison to expressible moistureAQUACULTURE NUTRITION, Issue 2 2001Jonsson Textural properties of fresh Atlantic salmon (Salmo salar) fillets were measured on seven locations along the fillet by four different instrumental methods, and were correlated to expressible moisture. Two methods were based on puncturing, either by using a flat ended cylinder, measuring hardness at different distances into the fillet and the first fracture (yield point) of the muscle fibres, or by a non-destructive method using a spherical probe to measure the hardness of the fillet. The other two methods were based on Kramer shear-compression cell or Warner-Bratzler shear cell, by shearing the fillet with blades, measuring the shear force (toughness). The ability to separate textural properties in different muscle segments by using these four methods were compared. The expressible moisture, was determined by using the filter paper method by compression. Hardness and shear force of the fillets generally increased from the anterior to the posterior part of the fillet while the necessary force applied to map the yield point decreased towards the tail section. The results from the present study indicated that the puncture method with the spherical probe and the shearing device by Warner-Bratzler were better suited for measuring differences in the textural properties between different parts of raw salmon fillet, than the flat ended cylinder and Kramer shear compression cell. The expressible moisture, varying between 1.8 and 2.7%, showed a significant (P < 0.05) linear correlation with the spherical probe texture measurements (r=0.83) and the Kramer shear compression cell (r=0.77). [source] In vivo mandibular elastic deformation during clenching on pivotsJOURNAL OF ORAL REHABILITATION, Issue 2 2002Ting Jiang Lower rigidly connected long span bridges supported by natural abutments or implants sometimes become loose, come off, or fracture after a period of usage. Many reasons have been discussed for these failures. However, few researchers have shown the influence of mandibular elastic deformation on the abutments, although this influence is likely to produce a distortion force between the abutment and prosthesis. Therefore, this study measured the elastic deformation of the human mandibular arch during clenching on pivots by using charge-coupled device (CCD) cameras and an image analysing system. When the subjects clenched on the canines (unilaterally or bilaterally) or bilateral second molars, no mandibular deformation was found; whereas when the subjects clenched on the unilateral second molars, the mandibular arch on the non-pivot side moved upward and inward and the straight line distances between the right and left measurement points decreased by 0·2 mm. The magnitude of deformation is smaller than the depressible limit of periodontal membrane. This suggests that the influence of mandibular deformation on the connected prosthesis is negligible in the case of the natural root supported long span bridge but should probably be considered in the case of the implant supported bridge. [source] | ||||||||||