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  • Polymer and Materials Science  (1,318)
  • Fluid Mechanics and Heat Transfer
  • Industrial Chemistry
  • 1995-1999  (1,188)
  • 1955-1959  (276)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 41 (1996), S. 419-425 
    ISSN: 0959-8103
    Keywords: polyurethane ; cell growth ; phase separation ; hydrogen bonding index ; cytotoxicity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyurethanes (PU) with suitable soft segments have been found to be good blood-compatible polymers and have attracted much attention recently. In this study, various molar amounts of 4,4′-methylene bisphenyl isocyanate reacted with poly(tetramethylene oxide) were synthesized to explore the optimal ratio of hard/soft segments for cell attachment and proliferation in in vitro systems. Differential scanning calorimetry and dynamic mechanical analysis were used to determine the physical properties, hydrogen bonding index (HBI) and transmission electron microscopy to observe the phase-separation phenomena in the materials, and 3T3 fibroblast to evaluate the dependence of the cell proliferation at 37°C on the material properties. Our results show that cell attachment and proliferation are closely related to the cell growth surface, which in turn is controlled by (1) the ratio of hard to total segment concentration and (2) the recrystallization temperature (Tc) of PU. To obtain a good cell growth surface, the ratio of hard to total segment concentration is found to be between 0.4 and 0.6, and HBI is between 1.5 and 2.1. Furthermore, when the Tc of PU is near the physiology temperature, a stable surface for cell growth can be provided. The shorter molecules in the soft segment region can rearrange the molecular chain at 37°C.
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 69-76 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Low to moderate molecular weight terpene-anhydride resins were synthesized and evaluated in coatings applications. The terpenes used were terepinolene, β-pinene, and alloocimene. The comononmers used were maleic or itaconic anhydride. The terpene-anhydride resins were used to formulate solvent-borne coatings with an epoxy or diol as a coreactant. The coatings were evaluated as films over aluminum or steel panels. When a diol was used as a coreactant, the film properties were relatively poor. When epoxy was used as a coreactant, the properties of the films were much improved in terms of resistance to solvent and hardness. © 1995 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 645-653 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Collagen has been widely coated or grafted onto polymer surfaces to improve the biocompatibility of materials. To better support the growth of endothelial cells on polyurethane (PU), collagen was grafted to the carboxyl group enriched PU through 1,2-bis(2,3-epoxypropoxy)ethane linking. Our results demonstrated that collagen in various conditions may result in different forms being grafted to the PU substrate, which subsequently affected the growth of endothelial cells. Collagen predialyzed against physiological phosphate buffered saline (PBS) could be reconstituted into native type fibrils with a bigger diameter at 37°C than could collagen neutralized by titration with NaOH. At low temperature, titrated collagen formed flosslike fibrils packed in a ball with cobblestonelike morphology. The amount of collagen grafted was related to the condition of the collagen used, which in consequence affected the diameter of the collagen fibril formed and the growth of endothelial cells. In conclusion, reconstituted collagen fibrils formed from collagen in PBS at 37°C grafted in the highest amounts to an epoxy-PU substrate and that optimally supported the growth of endothelial cells. Such prepared materials may be potentially good vascular bioprosthetic materials and may provide a wide range of biological applications. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 176-183 
    ISSN: 0021-9304
    Keywords: hydroxyapatite ; crystallinity ; materials characterization ; alkaline phosphatase activity ; osteocalcin concentration ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The clinical success of dental implants is governed by implant surfaces and bone cell responses that promote rapid osseointegration and long-term stability. The specific objective of this study was to investigate osteoblast precursor cell responses to hydroxyapatite (HA) surfaces of different treatments. Since the nature of bone cell responses in vitro is influenced by the properties of HA ceramics, this study was divided into two components: a chemical and crystallographic characterization of the HA ceramics and an in vitro cell culture study. The sintered HA samples were observed to have the highest crystallite size as compared to the as-received HA and calcined HA samples. No differences in the surface roughness and chemical composition were observed among the sintered, calcined, and as-received HA surfaces. In concurrence with the X-ray diffraction, high resolution XPS resolution of Ca 2p also indicated a higher crystallinity on sintered HA samples as compared to the calcined and as-received HA samples. As indicated by increased alkaline phosphatase-specific activity, increased cell-surface and matrix-associated protein, and 1,25 (OH2) vitamin D3-stimulated osteocalcin production, a more differentiated osteoblast-like phenotype was observed on the sintered HA surfaces compared to the as-received HA and calcined HA surfaces. An increased osteoblast-like cell activity on the sintered HA surfaces suggested that the crystallite size of HA surfaces may play an important role in governing cellular response. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 176-183, 1998.
    Additional Material: 12 Ill.
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  • 5
    ISSN: 0021-9304
    Keywords: biodegradable barrier films ; canine periodontal defects ; rabbit subcutaneous implants ; mass loss ; polymer degradation rate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biodegradable barrier films were made by coagulating a solution of poly(DL-lactide) in N-methyl-2-pyrrolidone on porous polyethylene pads wetted with saline solution. The semisolid films were cut into 10 × 10 mm barriers and implanted subcutaneously in rabbits. At monthly intervals, the polymer implant sites were compared histologically to those implanted with USP negative control plastic. The polymer films were retrieved from the surrounding tissue, dried, weighed, and the changes in molecular weight determined using gel permeation chromatography. The molecular weight of the polymer decreased at a relatively constant rate over 5 months; however, no significant mass loss occurred until 5 months postimplantation. Also, no distinct histological differences were noted between the polymer barrier and the control plastic sites until 6 months when histiocytes and multinucleated giant cells showed a modest increase around fragmented polymer films. Similar barrier films also were fitted over naturally occurring buccal dehiscence defects in beagle dogs and the tissue sites compared histologically at 6 months to sham-operated control sites. New bone and dense connective tissues closely approximated segments of the remaining polymer and demonstrated the biocompatibility of the biodegradable films. Histomorphometric analyses of treated sites compared to sham controls showed that the polymer barrier is effective in promoting bone and cementum regeneration in periodontal defects in dogs. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 42, 303-311, 1998.
    Additional Material: 7 Ill.
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  • 6
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 3081-3093 
    ISSN: 0887-6266
    Keywords: block copolymers ; thin films ; cross-sectional TEM ; terraces ; defects ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The morphologies of thin, substrate-free block copolymer films have been examined by cross-sectional TEM. Two poly(styrene-b-butadiene) diblock copolymers were studied: one that forms PS cylinders and the other that forms PB cylinders in the bulk. Films were annealed while supported by metal TEM grids, embedded, and ultramicrotomed in crosssection. We find that at the metal support the film forms a meniscus-like region, or Plateau border, which exhibits the bulk morphology. Away from the border, the film thickness decreases and regions of terraced in-plane cylinder domains occur until a minimum thickness is reached. The minimum thickness region of the PB majority copolymer in cross-section shows a PS interlayer penetrated by a hexagonal array of circular PB channels that connect upper and lower PB surface layers, and a total thickness of 25-27 nm. The minimum thickness region of the PS majority copolymer in plan view shows no image contrast, but in cross-section reveals a continuous PS interlayer covered by layers of PB, and a total thickness of 20 nm. Comparisons with the chain dimensions suggest a bilayer arrangement for both morphologies with strongly perturbed chain conformations in the surface layers. © 1996 John Wiley & Sons, Inc.
    Additional Material: 19 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 38 (1996), S. 437-438 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Propellants, Explosives, Pyrotechnics 22 (1997), S. 249-255 
    ISSN: 0721-3115
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The explosive performance of ∊-CL-20 was found to be approximately 14% greater than HMX as determined by cylinder expansion and tantalum plate acceleration experiments. This makes it the most powerful explosive ever tested at small volume expansions of the detonation products. In general CL-20 is more sensitive than HMX. However, the sensitivity of CL-20 to one-dimensional shock loading was found to be similar to HMX.
    Additional Material: 10 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 801-809 
    ISSN: 0887-624X
    Keywords: zwitterion ; hydroxide inner salt ; polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The zwitterion, 1-[4-[(4-hydroxy-1-naphthyl)thio]butyl]quinuclidinium hydroxide inner salt, was synthesized from tetrahydro-1-(4-hydroxy-1-naphthyl)thiophenium hydrochloride and quinuclidine and characterized by NMR and IR spectroscopy. Polymerization of the zwitterion was studied over the temperature range 175-225°C. The polymer was identified as poly(1,4-piperidinediylethyleneoxy-1,4-naphthylenethiotetramethylene) based on NMR and IR spectroscopy. The polymer was found to contain 3-butenylthio and 4-hydroxy-1-naphthyl end groups. Based on the signal area of the olefinic end group, the polymer M⊼n varied between 8500 and 13,000. The highest molecular weight was achieved at the lowest temperature, indicating that termination became more favored at higher temperature. A mechanism is proposed to describe the polymerization. © 1996 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
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