"DMA is a widely used technique to detect weak glass transitions easily and precisely due to its higher sensitivity as compared to DSC. Hence, it is widely used to investigate relaxation of polymer segments , polymer miscibility  and thermal degradation behaviour  in polymer blends and polymer composites. "
[Show abstract][Hide abstract] ABSTRACT: High performance polymer matrix composites based on poly(ether–ether–ketone) (PEEK) as matrix and aluminum nitride particle (AlNp) as filler were prepared. The effect of AlNp on the storage modulus, loss modulus, mechanical loss factor, and glass transition were investigated. The AlNp reinforcement is more pronounced above glass transition temperature (Tg). Composite containing 70 wt.% AlNp exhibit about 100% increase in storage modulus at 50 °C and about 500% increase at 250 °C, and 19 °C increase in glass transition temperature as compared to pure PEEK. Peak height of tan δ for composites was decreased to one sixth of the pure PEEK. It is probably due to improved crystallinity of PEEK and strong interaction between the AlNp and PEEK matrix. SEM reveals excellent distribution of AlNp in PEEK matrix and good interaction between AlNp and PEEK matrix.
Composites Part A Applied Science and Manufacturing 02/2007; 38(2-38):516-524. DOI:10.1016/j.compositesa.2006.02.017 · 3.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Samples of cast bisphenol-A and cycloaliphatic epoxy insulation
were quenched from a temperature above T<sub>g</sub> (170°C) to room
temperature. Variations in dielectric, thermal and mechanical properties
were examined during subsequent sub-T<sub>g</sub> annealing (physical
aging). It was found that the impact strength of the epoxy insulation
decreased considerably with physical aging. Moisture intake and
subsequent dielectric loss at room temperature were also found to
decrease with physical aging. Glass transition temperature and excess
enthalpy measured by DSC demonstrated significant increase with
increased sub-T<sub>g</sub> annealing. On the other hand, dielectric
properties showed different changing patterns during sub-T<sub>g</sub>
annealing in different epoxy systems. It is concluded that epoxy
insulating materials should be properly annealed before assessing their
dielectric and other physical properties because of the possibility of
unknown rapid cooling histories
IEEE Transactions on Dielectrics and Electrical Insulation 03/1994; 1(1-1):9 - 17. DOI:10.1109/94.300227 · 1.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mechanical behaviour play an important role in the election of an epoxidic formulation of well determined properties as it
has a marked influence on both structural and external factors.
Temperature and time strongly act on polymers properties owing to their viscoelastic nature.
Knowledge of the dynamic moduli and properties of polymeric materials is indispensable for the design of this materials. At
the same time, the influence of the temperature on polymers behaviour may be studied once the activation energy is known.
In this paper the different dynamic moduli and activation energy are measured using a Perkin Elmer DMA 7.
The relationships between the dynamic mechanical properties and the molecular weight of the polymers make possible the calculation
of the molecular weight.
Results reasonably agree with literature values.
Journal of Thermal Analysis and Calorimetry 06/1994; 41(6):1543-1550. DOI:10.1007/BF02549952 · 2.04 Impact Factor
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