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  • 1980-1984  (5)
  • 1
    Electronic Resource
    Electronic Resource
    The hydrolytic stability of glass fiber reinforced poly(butylene terephthalate), poly(ethylene terephthalate) and polycarbonate (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 537-542 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: The hydrolytic stability of glass fiber reinforced poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET) and polycarbonate (PC) was studied. The activation energies in kcal/mole for hydrolysis are 26 for PBT and 23 for PET. Both PBT and PET contain 30 percent glass fiber reinforcement. The hydrolysis rates for a series of experimental PC's containing 10, 30 and 40 percent glass were obtained from GPC data. These increase with glass concentration but are lower than that of the unreinforced PC. Melt flow rate changes are a good measure of the hydrolytic degradation of PET. However, in the time scale of these experiments, the tensile properties of glass reinforced PBT and PC do not correlate well with M̄w changes, unlike unreinforced PBT and PC polymers. Consequently, to compare these three glass fiber reinforced polymers, estimates of failure time must be based on changes in tensile strength rather than melt flow rate.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231002
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrolysis of poly(butylene terephthalate) (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 260-264 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: The hydrolytic stability of poly(butylene terephthalate) (PBT) resins and compounds was studied. Rates of reaction were determined by measuring changes in melt flow rate. Hydrolysis was slightly accelerated by contact of PBT with glass containers and reduced by incorporation of some flame retardant additives. Melt flow rates were related to tensile elongation ofunfilled PBT and tensile strength ofthe glass fiber reinforced polymer and used as failure criteria. Reaction rates were used to predict failure times at various conditions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220408
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The effects of light and heat on the rubber content and impact strength of acrylonitrile-butadiene-styrene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 995-1001 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: DSC analysis of acrylonitrile-butadiene-styrene (ABS) samples either weathered outdoors for up to 10 years or aged at 71°C has shown that these plastics deteriorate most readily through the polybutadiene (BD) component. Oxidation of the BD in ABS leads to an increasing and broadening Tgas well as a decrease in ΔCp at Tg. The latter quantity can be used to quantitatively assay the amount of unoxidized rubber in a photo- or thermal-oxidized sample. The loss of impact strength of these resins with chemical aging can be correlated with the oxidation of the polybutadiene phase. Studies of rubber content as a function of sample thickness have revealed that an embrittled layer containing oxidized BD develops at the surface of an aged, 100 mil. ABS plaque (natural) and grows to a thickness of about 10 mils after 3 years exposure to sunlight. ABS containing carbon black is effectively screened from this photo induced degradation and consequently has much better retention of its initial impact strength values. In addition, carbon black was observed to retard thermal oxidation in some ABS samples. Lastly, it appears possible to do accelerated aging studies at elevated temperatures to evaluate the relative stabilities of various ABS formulations.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760201503
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The hydrolytic stability of some commercially available polycarbonates (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 370-375 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 number of commercially available polycarbonates, including formulations made flame retardant by two different modifications, have been exposed to conditions producing moderately rapid hydrolysis. Hydrolysis rates were calculated from molecular weight data determined by gel permeation chromatography and, in some cases, from melt flow rate data. The rates calculated by the two methods are in good agreement. In general, the standard formulations containing minimal additive packages are the most hydrolytically stable. Although one relatively new flame retardant polycarbonate demonstrates generally good resistance to hydrolysis, most of the flame retardant formulations appear to be quite susceptible to hydrolytic degradation. For these materials, hydrolysis under conditions encountered in use could cause significant decreases in impact strength within a few years.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220608
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  • 5
    Electronic Resource
    Electronic Resource
    Hydrolysis of polycarbonate to yield BPA (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 1777-1786 
    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: Elevated temperatures and high humidity decrease the molecular weight and impact strength of polycarbonate. Hydrolysis of injection molded polycarbonate (PC) bars stored in glass containers at 85°C and 96% relative humidity (RH) produced brown surface crystals within 30 days. Aging of PC bars at 96% RH and temperatures of 70°C and lower for longer periods of time formed a brown liquid coating on the PC. X-ray, DSC, and GPC measurements indicated that about 70 wt% of the surface crystals were bisphenol A (BPA). The remaining portion of hydrolysis products appeared to be higher molecular weight oligomers of BPA. The brown liquid was composed of supercooled liquid BPA, BPA oligomers, and water. Initial growth of BPA on the surface of a PC bar took place at the interface between the PC and the glass wall of the container. Apparently a water soluble extract from the glass container accelerated the hydrolytic degradation of PC; nevertheless, hydrolysis of PC occurred in the absence of glass - although at a slower rate. Hydrolysis studies were carried out on several commercial PC formulations. The PC resin containing only a heat stabilizer was least affected. Of the fiame retardant grades, the brominated PC hydrolyzed less rapidly than these particular compositions containing alkali metal sulfonic acid salts. A glass fiber reinforced PC was less stable than its unfilled parent compound. A hydrolytic stabilizer was ineffective against the attack of water under these conditions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260603
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