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  • Polymer and Materials Science  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    Methacrylate-based block ionomers I: Synthesis of block ionomers derived from t-butyl methacrylate and alkyl methacrylatesDedicated to Professor Maurice Morton to commemorate the establishment of the Maurice Morton Institute of Polymer Science at the University of Akron. (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 33 (1994), S. 205-216 
    Details
    ISSN: 0959-8103
    Keywords: block ionomer ; anionic polymerization ; methacrylates ; 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: Diblock and triblock copolymers of t-butyl methacrylate (tBMA) with 2-ethylhexyl methacrylate (EHMA) and n-hexyl methacrylate were prepared via alkyl lithium initiation and sequential addition techniques in THF at -78°C. The tBMA blocks were quantiatively and selectively hydrolyzed to afford poly(methacrylic acid) (PMAA) blocks which were then neutralized with alkali metal bases to form block ionomers. The unhydrolyzed copolymers had a phase mixed morphology as evidenced by thermal analysis while the hydrolyzed and neutralized polymers were multiphase materials. The carboxylic acid and ioncontaning triblock copolymers formed gels in nonpolar solvents which could be disrupted by the addition of polar additives. Certain carboxylic acid and ioncontaining EHMA/tBMA diblock copolymers also showed this behavior. The triblock ionomers did not show thermoplastic flow prior to degradation, except at the lowest ionic content studied (2%).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210330212
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  • 2
    Electronic Resource
    Electronic Resource
    Polyurethane elastomers based on molecular weight advanced poly(ethylene ether carbonate) polyols. III. Effects of diisocyanate modified diols (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 3241-3253 
    Details
    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: A series of diisocyanate-modified, molecular weight advanced poly(ethylene ether carbonate) diols has been prepared, characterized, and formulated into polyurethane elastomers using a prepolymer process. Properties were compared to a polyurethane elastomer control in which the only variable was the diisocyanate modification. The diisocyanate modification produces polymers with increased modulus (445-730% at 25°C), improved tensile strength and hardness properties and reduced (improved) coefficients of linear thermal expansion, while still passing the notched Izod impact test. The tensile strength at break increases with increasing number of urethane moieties in the soft segment and the elongation at break also increases. The plaques studied appear to have a three-phase morphology - a soft segment continuous phase containing amorphous hard segment, an amorphous hard segment phase plasticized by about 11% of the soft segment material, and a crystalline hard segment. The polymers based on the diisocyanate modified polyols are significantly more phase mixed than the control due to the increased amount of hard segment-soft segment interactions taking place. The improved properties of the polymers made with the modified polyols are due to their higher hydrogen bonding protential which gives more physically crosslinked polymers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070421217
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  • 3
    Electronic Resource
    Electronic Resource
    Polyurethane elastomers based on molecular weight advanced poly(ethylene ether carbonate) diols. I. Comparison to commercial diols (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 487-507 
    Details
    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: Poly(ethylene ether carbonate)diols (2025 mol wt) have been made by the molecular weight advancement of lower molecular weight oligomers and have been fabricated into polyurethane elastomers by reaction with 4,4′-MDI and 1,4-butanediol using the prepolymer method. Polymer structure has been delineated by carbon-13 NMR. Comparisons have been made to a series of elastomers based on other polyester and polyether polyols (2000 mol wt) under conditions where the only variable was the soft segment structure. The poly(ethylene ether carbonate) diol gives a polymer with a partially phase mixed morphology, a higher ambient temperature modulus, and a lower ΔHm than the other polyester polyols. This lower ΔHm leads to a significantly lower rubbery plateau modulus than the other polyester polyols. Phase mixing is increased by post-curing at 150°C. Organic solvent resistance is the most outstanding property. The poly(ethylene ether carbonate) diol produces a polymer with predominantly polyester polyol features.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410304
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  • 4
    Electronic Resource
    Electronic Resource
    Polyurethane elastomers based on molecular weight advanced poly(ethylene ether carbonate) diols. II. Effects of variations in hard segment concentration (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 509-525 
    Details
    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: A series of polyurethane elastomers were studied in which the soft segment composition was a molecular weight advanced poly(ethylene ether carbonate)diol (2025 mol wt) and the hard segment composition was based on MDI/1,4-butanediol. These polyurethane elastomers had a constant soft segment composition and block length, a constant hard segment composition, but a variable hard segment block length and concentration (31.9-65.2 wt % hard segment). Properties such as rubbery plateau modulus, solvent resistance, melting point, hardness, tensile strength, and hard segment run length all improve with increasing hard segment concentration. DMA and DSC data indicate a partially phase mixed morphology. However, phase mixing must occur at domain boundaries since the soft segment Tg is nearly invariant with hard segment concentration. Annealing studies indicate that the optimum post-cure temperature, for 1 h, is about 175°C.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410305
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  • 5
    Electronic Resource
    Electronic Resource
    BoneSource™ hydroxyapatite cement: A novel biomaterial for craniofacial skeletal tissue engineering and reconstruction (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 43 (1998), S. 428-432 
    Details
    ISSN: 0021-9304
    Keywords: BoneSource™ ; hydroxyapatite cement ; biomaterial ; craniofacial skeletal reconstruction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: BoneSource™-hydroxyapatite cement is a new self-setting calcium phosphate cement biomaterial. Its unique and innovative physical chemistry coupled with enhanced biocompatibility make it useful for craniofacial skeletal reconstruction. The general properties and clinical use guidelines are reviewed. The biomaterial and surgical applications offer insight into improved outcomes and potential new uses for hydroxyapatite cement systems. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 428-432, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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