1995 - 2000


Blends of Polyaniline with Nitrilic Rubber
Vallim MR, Felisberti MI, De Paoli MA

75 (5): 677-684 JAN 31 2000

Nitrilic rubbers containing 29 or 45% of acrylonitrile were blended with polyaniline doped with different acids (chloridric, dodecylbenzenesulfonic, tetrapropylbenzenesulfonic, and p-toluenesulfonic acids). The blends were prepared by mechanical mixing in a roll-mill and vulcanized in a hot press. The volumetric conductivities and mechanical properties were evaluated. The results show that the polyaniline concentration strongly affects the behavior of the blends. Increasing the polyaniline content from 50 to 100 phr induces an increase in the electric conductivity from 10(-10) to 10(-8) S cm(-1); however, the blends become harder and more brittle than the crude rubber. Addition of polyaniline lowered the crosslinking degree, but produced a reinforcing effect in the elastomer.



Unsaturated Polyester Resins: Influence of the Styrene Concentration on the Miscibility and Mechanical Properties
Sanchez EMS, Zavaglia CAC, Felisberti MI

41 (2): 765-769 JAN 2000

Styrene is frequently used as comonomer for unsaturated polyester (UP) resins. Variations in the styrene content in the polyester affect the resulting properties. Dynamic mechanical tests show the phase separation in the cured resin with an increase of styrene concentration. The dependence of the glass transition temperature of the UP resin on the styrene content is complex and reflects a balance of elastic forces of the network and the immiscibility of polystyrene and UP. The thermal stability and the mechanical properties are governed by the phase behaviour of the mixture and therefore can be controlled by the styrene content.



Thermal degradation and Photo-oxidation of the ABS used for automotive applications.

Sanchez EMS, Ferreira MMC, Felisberti MI 


 9(4): 116-122 Dez 1999


The ABS degradation was investigated after thermal- (80°C) and photo-oxidative ageing (ASTM G53 and G24). These conditions were selected to simulate a car interior and the ABS lifetime weatherability. ABS changes were characterised by mechanical properties, melt flow index, carbonyl index (FT-IR), yellowing index and macro-photography of impact fracture. The results showed that each technique gives a characteristically answer for the ageing method. The multivariate analysis provided the degradation view as a function of the ageing method.



Poly(Vinyl Alcohol) and Poly(Vinylpyrrolidone) Blends: 2. Study of Relaxations by Dynamic Mechanical Analysis
Cassu SN, Felisberti MI

40 (17): 4845-4851 AUG 1999

Blends of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) were studied by dynamic-mechanical analysis (DMA). PVA with different degrees of hydrolysis (88 and 99 wt%) and PVP with different molecular weights (10.000 and 360.000 g/mol) were used to prepare the blends. DMA results showed that blends were miscible over the whole composition range studied. However, the E" modulus curves exhibit relaxations at the same temperature range below Tg for all blends, suggesting the presence of microenvironments in the blends. These microenvironments are associated to the hydrogen bonding between PVA-PVA in the crystalline and amorphous phase and PVP-PVA in the amorphous phase and in the amorphous-crystalline interface. The stiffness and the flexibility of these blends at 200 degrees C depend strongly on the blends composition, the molecular weight of PVP and the hydrolysis degree of the PVA as determined by the E' modulus curves.



Blends of Polyamide 6 and Epichlorohydrin Elastomers. I. Graft Copolymerization in the Melt Blending
Da Costa SCG, Goncalves MD, Felisberti MI

72 (14): 1827-1833 JUN 28 1999

With the purpose of improving the mechanical properties of the polyamides, the possibility of combining polyamides with elastomers has been used. The low compatibility of the resulting blends leads to deficient mechanical properties, and therefore, it is necessary to add the compatibilizer to the mixture or to produce the compatibilizer during the melting mixture. Usually, at least one of the components must contain a reactive functional groups. In the present work, blends of polyamide 6 (PA 6) and epichlorohydrin elastomers, polyepichlorohydrin (PEPI), and the equimolar copolymer poly(epichlorohydrin-co-ethylene oxide), EGO, with different compositions were prepared by mechanical mixture using a Banbury-type mixer. The blends were characterized by rheological measurements, the Molau test, elemental analysis, Infrared Spectroscopy by Diffuse Reflectance, Transmission Electron Microscopy, and X-ray Diffractometry. The blends of PA 6 with PEPI and ECO are heterogeneous, showing a morphology of elastomer particles dispersed in the polyamide matrix. The results of rheological measurements and the Molau test indicate a graft copolymerization in the interface between the polyamide and the elastomer, PA 6-g-elastomer, whose concentration decreases with the elastomer content. It was found that the grafting of PEPI and PA 6 changed the diffraction pattern of PA 6.



Blends of Polyamide 6 and Epichlorohydrin Elastomers. II. Thermal, Dynamic Mechanical, and Mechanical Properties
Da Costa SCG, Felisberti MI

72 (14): 1835-1841 JUN 28 1999

The mechanical blending of polyamide 6 and epichlorohydrin elastomers, polyepichlorohydrin, PEPI, and poly(epichlorohydrin-co-ethylene oxide), EGO, is accompanied by grafting copolymerization. In this work the influence of the graft copolymer on the thermal and mechanical properties of the blends is investigated. The blends are immiscible and the crystallinity degree normalized to the polyamide 6 contents in the blends is higher than expected. The X-ray diffraction results show that the grafting copolymer is also crystalline; hence, the presence of crystalline phase of copolymer can be responsible for the apparent enhancement of crystallinity. The DMA analysis reveals the presence of a shoulder in the peak corresponding to the PA 6 glass transition, as observed by loss modulus curves, which was assigned to relaxations of the grafting copolymer. Tensile tests show that the blends are more fragile than the PA 6, despite the graft copolymer. These results were attributed to the mechanical fragile interface constituted by a network type structure of the graft copolymer.



Blends of Poly(Methyl Methacrylate) and Polyamides
Carone E, Felisberti MI, Nunes SP

33 (14): 3729-3735 JUL 15 1998

The morphology of PMMA blends with different polyamides (PA-6, 6/9 and 12) was investigated by transmission electron microscopy, recognizing PA-6/PMMA as the most miscible pair. Blends of these polymers were prepared from solutions in m-cresol and formic acid and the morphology was highly dependent on the solvent. The morphology and the segregation degree of extruded PA-6/PMMA blends was investigated by scanning electron microscopy and dynamic-mechanical analysis. The compatibilization succeeded by the introduction of a block copolymer of polyamide and poly(ethylene oxide).



Flory-Huggins Interaction Parameter of Poly(Ethyleneoxide)/Poly(Epichlorohydrin) and Poly(Ethyleneoxide)/Poly(Epichlorohydrin-co-Ethyleneoxide) Blends
Silva MA, De Paoli MA, Felisberti MI

39 (12): 2551-2556 JUN 1998

Blends of poly(ethylene) oxide with poly(epichlorohydrin) and poly(epichlorohydrin-co-ethylene oxide) have been prepared by the freeze-drying method from benzene solutions of the polymer mixture at different compositions. The miscibility of the mixtures was studied by DSC. A single glass transition temperature is observed for all the blends studied. Measurement of the melting temperature (T-m) depression for the blends allowed determination of the Flory-Huggins interaction parameter (chi(12)) of the two polymers in the melt using the Nishi-Wang equation. The Hoffman-Weeks extrapolation was applied to obtain equilibrium T-m data. The values of the chi(12) Obtained from T-m depression data were negative for all blends. This suggests the miscibility of the components of the blends.



Poly(Vinyl Alcohol) and Poly(Vinyl Pyrrolidone) Blends: Miscibility, Microheterogeneity and Free Volume Change
Cassu SN, Felisberti MI

38 (15): 3907-3911 JUL 1997

Blends of crystallizable poly(vinyl alcohol) (PVA) with poly(vinyl pyrrolidone) (PVP) were studied by differential scanning calorimetry (d.s.c.). PVA with different degrees of hydrolysis (88 and 99 wt%) and PVP with different molecular weights (10 000 and 360 000 g mol(-1)) were used. The blends exhibited a single glass transition, as determined by d.s.c., suggesting the miscibility of the system over the whole composition range studied. The enthalpy of fusion (Delta H-f), as well as the glass transition temperature (T-g), heat capacity (Delta C-p) and glass transition width (Delta w), were also determined by d.s.c. These parameters changed with the degree of hydrolysis of PVA, PVP molecular weight and blend composition. The behaviour of Delta C-p vs blend composition was complex for the different pairs of blends, suggesting strong interaction between PVA and PVP. From the analysis of Delta w dependence on blend composition we concluded that blends containing PVP of 10 000 g mol(-1) exhibit a larger number of relaxations than blends containing high molecular weight PVP, indicating that the density of interactions is larger in the former.



Influence of Fecl3 on the Mechanical, Thermal, and Dynamic Mechanical Behavior of PVC
Mano V, Felisberti MI, De Paoli MA

30 (10): 3026-3030 MAY 19 1997

PVC films impregnated with FeCl3 were prepared by casting. The effect of FeCl3 on the mechanical properties of PVC resembles the plasticization effect in pol3rmeric matrices. Increasing the concentration of FeCl3 results in an increase in the strain at break and a decrease in the Young modulus, in the stress at yield, and in the stress at break. A concentration of 20 wt Ck causes a Young modulus drop of 59% in relation to pure PVC. The plasticization effect was also confirmed by the shift of T-g to lower temperatures with an increase in FeCl3 concentration. The UV/vis absorption spectrum of PVC film impregnated with 1 wt % of FeCl3 shows the characteristic absorptions of the FeCl4- ion (315 and 360 nm), suggesting the reversible formation of ion pairs responsible for the plasticization.



Thermal, Mechanical and Electrochemical Behaviour of Poly(Vinyl Chloride)/Polypyrrole Blends (PVC/PPY)
Mano V, Felisberti MI, Matencio T, De Paoli MA

37 (23): 5165-5170 NOV 1996

The conductivity, thermal, mechanical and electrochemical properties of poly(vinyl chloride)/polypyrrole blends are described in this paper. These blends were prepared by oxidative chemical polymerization of pyrrole, in the vapour phase, in PVC films impregnated with FeCl3. They were characterized by attenuated total reflectance FTi.r. spectra, differential scanning calorimetry and dynamic-mechanical analysis. Infrared reflectance spectra suggested that the polymerization occurs preferentially on the matrix surface producing sandwich-type structures. The mechanical, thermal and conducting behaviour showed a dependence on (1) initial concentration of FeCl3 in the matrix and (2) exposition time to pyrrole vapour. By cyclic voltammetry we observe that blends synthesized by oxidative chemical polymerization show electrochemical properties similar to blends prepared by electrochemical methods. Their conductivity varies from 10(-4) to 10(-1)S cm(-1). Dynamic-mechanical analysis results suggest a certain degree of miscibility among the polymeric components of the blend.