Thermal Characterization of a Microlayered Polycarbonate/Polymethyl Methacrylate Composite

1996 ◽  
Vol 461 ◽  
Author(s):  
Alex J. Hsieh ◽  
Alex W. Gutierrez
Keyword(s):  
Glass Transition ◽  
Polymethyl Methacrylate ◽  
High Speed ◽  
Thermal Characterization ◽  
Mechanical Analysis ◽  
Transition Temperatures ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
High Speed Impact ◽  
The Individual

ABSTRACTThermal behavior of a coextruded microlayer composite with 388 alternating layers of polycarbonate and polymethyl methacrylate (PMMA) was investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Two distinct glass transition temperatures were observed with DSC for the coextruded composite, however both were shifted very slightly towards each other, compared to the glass transition temperatures of the pure components, indicating limited miscibility. Adhesion between the alternating microlayers appeared to be very good; delamination did not occur after the microlayer composite was subjected to a high speed impact test. Adhesion is attributed to limited miscibility since little mixing resulted from the laminar flow which was required in the coextrusion process. DMA results revealed an additional damping peak, which was not observed with DSC, at a temperature between the glass transitions of the two components. This intermediate transition peak is more sensitive to change in frequency compared to the response for the individual pure components.

Synthesis and Properties of Poly (N-arylenebenzimidazole ketone)s

2014 ◽  
Vol 881-883 ◽  
pp. 165-168
Author(s):  
Xiang Wang Cui ◽  
Lin Zhang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Coupling Reaction ◽  
Transition Temperatures ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures

Two bis (benzimidazoyl) monomers were synthesized, and Poly (N-arylenebenzimidazole ketone) s were prepared by N-C coupling reaction that replaced the NH sites from the bis (benzimidazolyl) derivatives with activated difluorides monomers in sulfolane at 210 °C. All the resulting polymers showed easy solubility compared with traditional polybenzimidazoles. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>240 °C), good thermostability and high decomposition temperatures (>460 °C).

Novel allyl and propenyl monomers for modification of the bismaleimide resins, with excellent dielectric properties and high glass transition temperatures

2019 ◽  
Vol 32 (1) ◽  
pp. 116-126
Author(s):  
Chunyan Qu ◽  
Jiaying Chang ◽  
Changwei Liu ◽  
Dezhi Wang ◽  
Wanbao Xiao ◽  
...  
Keyword(s):  
Glass Transition ◽  
Bisphenol A ◽  
Dielectric Constants ◽  
Resonance Spectroscopy ◽  
Transition Temperatures ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Bismaleimide Resin ◽  
Glass Transition Temperatures ◽  
Bismaleimide Resins

Two new monomers were prepared by the reaction of 2-allylphenol and 4,4′-biphenyldicarbonyl chloride under different reaction conditions. The monomers were characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The curing processes of N, N-4,4′-bismaleimidodiphenylmethyene with 4,4′-bis(2-allylphenyl) biphenyldicarbonylate (BABC) and 4,4′-bis(2-propenylphenyl benzoate) ether (BPBE) were studied by rheological analysis and differential scanning calorimetry. Melting points of two monomers, BABC and BPBE, are 64°C and 121°C, respectively. The ABMI [4,4′-bis(2-allylphenyl)biphenyl bismaleimide] and PBMI [4,4′-bis(2-propenylphenyl)biphenyl bismaleimide] resins showed exothermic peaks at 233°C and 204°C, respectively. The measured melting points are significantly lower than that of the traditional bismaleimide resin which is modified by allyl bisphenol A. Dynamic mechanical analysis of the materials showed glass transition temperatures of ABMI and PBMI to be in the range of 213–258°C and 302–339°C, respectively. Thermogravimetric analysis of the cured resins showed 5% weight loss for ABMI and PMBI at 437°C and 428°C, along with char residues of 35.6–39.5%, respectively, at 800°C under nitrogen atmosphere. Furthermore, dielectric constants of propenyl-modified resins were lower (2.46–3.10) with dissipation factors of 0.0034–0.0036, compared with those of allyl bisphenol A resins.

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