The relationship between copolymer composition and transition temperatures was studied by means of differential scanning calorimetric
analysis and dynamic mechanical spectroscopy. Six samples of ethylene vinyl acetate (EVA) copolymers containing from 5 to
40 mass per cent of vinyl acetate (VA) were studied. The differential scanning calorimetric analysis revealed that each EVA
copolymer displays two endothermic peaks (Tm1 and Tm2 ) in the melting zone. Dynamic mechanical spectroscopy was used to determine the primary relaxation temperature (Tα ) for EVA copolymers. This latter characteristic is relatively insensitive to the level of vinyl acetate contained in the
copolymer and is influenced by the pulsation frequency ω, also named the angular frequency.
Poly(vinyl chloride) was blended with ethylene-vinyl acetate copolymer containing 70 wt% of vinyl acetate. The system shows
a single glass transition temperature for all compositions, indicating their miscibility. TheTgvs. composition curves display an inflection, which changes with the chemical environment of the initial solution. The best fit
to the shape of the curve was well reproduced by the Kovacs-Braun equation. The δTg values reveal local heterogeneity, which means no total miscibility at a molecular level. Negative values of the Flory-Huggins
interaction parameter were obtained from the calorimetric data.
Authors:L. Häuβler, G. Pompe, V. Albrecht, and D. Voigt
Ethylene vinyl acetate copolymers were investigated by means of simultaneous thermal analysis (STA) and pyrolysis gas chromatography (Py-GC). Both devices are coupled to a mass spectrometer (MS). STA-MS revealed that the calibration with poly(vinyl acetate) leads to sufficient accuracy in relation to the vinyl acetate (VA) content, because of the linear calibration plot.Quantitative determination of VA by means of Py-GC-MS was carried out at both 500 and 700°C. The calibration plot in this method was linear provided that the mass of VA did not exceed a critical value.
When ethylene-vinyl acetate copolymer, EVA, is heated, a two-stage thermal degradation occurs following its melting. The vinyl
acetate content of the copolymer was determined to be 43.8% by using TA 2950 and TA 2050 thermogravimetric instruments. TG/FTIR
was used to detect the evolved gas. Acetic acid and trans-1-R-4-R'-cyclohexane were the main products evolved from EVA in
the first and second stage, respectively. The apparent activation energies were determined for both stages by differential
The synergistic effects of zinc oxide (ZnO) with layered double hydroxides (LDH) in ethylene vinyl acetate copolymer/LDH (EVA/LDH)
composites have been studied using thermal analysis (TG), limiting oxygen index (LOI), UL-94 tests, and cone calorimeter test
(CCT). The results from the UL-94 tests show that the ZnO can also act as flame retardant synergistic agents in the EVA/LDH
composites. The CCT data indicated that the addition of ZnO in EVA/LDH system can greatly reduce the heat release rate. The
TG data show that the ZnO can increase the thermal degradation temperature and the charred residues after burning.
Authors:J. Rychly, A. Dalinkevich, I. Janigová, and L. Rychlá
The decomposition of polyethylene and ethylene-vinyl acetate copolymers in composites with Al(OH)3 and Mg(OH)2 (60% by wt.) has been estimated from the aspect of the extent of synchronization of the two fundamental processes, the release
of water and flammable volatiles from a polymer and the effect of this on the resulting polymer flammability. An attempt has
been made to implement the peculiarities of decomposition observed for each system to the fire behaviour of these materials.
Authors:M. Dolores Fernández and M. Jesús Fernández
The thermal degradation of ethylene-vinyl acetate (EVA), ethylene-vinyl-3,5-dinitrobenzoate (EVDNB) and ethylene-vinyl alcohol
(EVAL) copolymers have been studied using differential thermal analysis (DTA) and thermogravimetry (TG) under isothermal and
dynamic conditions in nitrogen. Thermal analysis indicates that EVA copolymers are thermally more stable than EVDNB samples.
The degradation of the copolymers considered occurs as an additive degradation of each component polyethylene (PE) and poly(vinyl
acetate) (PVA), poly(vinyl-3,5-dinitrobenzoate) (PVDNB) or poly(vinyl alcohol) (PVAL). The apparent activation energy of the
decomposition was determined by the Kissinger and Flynn-Wall methods which agree well.
Authors:Mariano Pracella, Cristiano Pancrazi, Md. Minhaz-Ul Haque, and Aldo D'Alessio
articles we examined the compatibilization processes and the properties of thermoplastic composites based on isotactic polypropylene [ 8 ], poly( l -lactide) [ 9 ] and ethylene–vinylacetatecopolymers [ 10 ] with hemp, cellulose and other natural fillers