Mechanical properties and permeability of polypropylene and poly(ethylene terephthalate) mixtures

Abstract

The synthetic membranes currently used for soil stabilization and road construction are mainly made of polypropylene and of polyesters. They are used separately for each application. The polymer used has an effect on the wettability and, the permeability of the membrane. The polypropylene membranes, for instance, have a zero wettability, whereas it is high for polyester membranes. This paper reports on the mechanical properties and the permeability of mixtures of polypropylene (PP) and poly(ethylene terephthalate) (PET). The elastic modulus of the mixture was at a minimum for a 50/50 mixture. For the other compositions, the moduli gave a positive deviation as compared with the additivity equation results. This is probably due to the fact that pure PET has a fragile behavior at the temperature at which the mechanical tests were run. This 50/50 composition corresponds to the domain where a phase inversion occurs. The permeability to water vapor gave an S‐shape curve that is typical of a “mixture” of immiscible polymers. The diffusion of the water molecules is controlled by the continuous phase. To compatibilize the two homopolymers, a 94/6 copolymer of PP and of polyacrylic acid was added, at various levels, to a 60/40 mixture of PET and PP: This did not affect markedly the elastic modulus. The yield stress increased, however, indicating that we had a better adhesion and that the copolymer seems to have a certain emulsifier effect, increasing the quality of the dispersion.

Blends of the alternating ethylene–tetrafluoroethylene copolymer with poly(vinylidene fluoride)

“…Marked negative deviations from simple additivity are observed from the figures for both the ultimate strength and the elongation at break over the entire composition range, which is typical for an essentially incompatible system. [20][21][22][23][24][25] It may be reasonable to conclude that interfaces between ETFE and PVF 2 are weakly bonded with rather poor interaction. .…”

The influence of partial emulsification on coalescence suppression and interfacial tension reduction in PP/PET blends

“…1 Blends of PET with polyolefins are known to improve certain properties of the PET when an interfacial modifier is added to the blend. [2][3][4][5][6][7][8][9][10][11] Barlow et al 2 and Chen et al 3,4 showed that styrene-ethylene-butylenestyrene (SEBS) results in an increase of the ductility of such a blend. Nevertheless, more pro-nounced effects are observed when a functionalized copolymer is used and, more precisely, a grafted maleic anhydride SEBS copolymer.…”

“…This forms an in situ generated SEBS-g-PET during melt blending. It is well know in the literature that primary alcohols with a hydrocarbon chain longer than C 5 have a tendency to react with cyclic anhydride functions. 13 The esterification is an exothermic reaction that follows second order kinetics.…”

Study on Properties of Polymer Blends from Polypropylene with Polycaprolactone and Their Biodegradability

“…Without any specific interactions, PP is unlikely to form miscible blends or even to adhere to other polymers (3). There are several examples of PP blended with polyesters (4,5). Typically when PP is blended with the liquid crystalline polyester (LCP), the mechanical strength is improved due to fiberlike LCP phases in the flow direction.…”

“…By addition of some maleic anhydride modified PP in the melt blending of PP and LCP, impact and tensile strength of blends significantly improved (4). Blends of PP and poly-(ethylene terephthalate) (PET) have likewise been improved by the addition of acrylic acid modified PP (5). Therefore, the presence of chemical functionalities such as carbonyl and hydroxyl groups would be usefull to increase interaction such components in a polyblend.…”