Microfibrillar reinforced composites from binary and ternary blends of polyesters and nylon 6

Abstract

Binary (1:1 by weight) and ternary (1:1:1 by weight) blends of polyethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), and Nylon 6 (PA 6) as well as the homopolymers are extruded as strips and ultraquenched from the melt. After zone drawing and additional annealing at Ta = 220 or 240 °C for 5 or 25 h with fixed ends in vacuum, the samples are studied by DSC, WAXS, solubility, and mechanical testing. It is found that all components in the blends are oriented and perfection of the structure is observed at T, = 220 °C. At T, = 240 °C isotropization of PBT and PA 6 takes place in their blends with PET, the orientation of the latter being preserved; i.e., microfibrillar reinforced composites are obtained. Their mechanical properties are comparable to those of glass fiber reinforced PBT and PA 6. During prolonged thermal treatment, in addition to isotropization, chemical interactions (additional condensation and exchange reactions) take place at the interfaces, resulting in the formation of copolycondensates playing the role of compatibilizers. The initially multiblock copolymers randomize with the progress of annealing, losing their crystallization ability, as proved by DSC, WAXS, and solubility measurements. Finally, the entire amounts of PBT and PA 6 become involved in the copolymers, converting in this way the starting homopolymer matrix of the microfibrillar reinforced composite into a copolymer one. This change in the chemical composition affects the overall behavior of the composites.

Morphology and properties of PET/PA-6/E-44 blends

“…mechanical properties of the blends. It was reFive samples were tested in each case, and the ported 5,6 that the microfibrillar-reinforced comaverage value was reported. All the tests were posites of PET and PA-6 had good mechanical performed at ambient temperature.…”

Miscibility in Two Blend Systems of Homologous Semicrystalline Aryl Polyesters Involving Poly(trimethylene terephthalate)

“…Of these, PET and PBT are more widely known as commercially important polyesters, each with unique properties as engineering resins or textile fibers, while PTT is a relatively new comer that possesses interesting balance of desired properties. Blends of PET and PBT have been more widely studied in early time, [11][12][13][14][15][16] however, blends of all semicrystalline constituents involving PTT have yet to be explored. Thus, miscibility (in amorphous regions) in blends of these aryl polyesters may further help in exploiting the useful properties by combining two or three of these different aryl polyesters.…”

Conductivity of microfibrillar polymer-polymer composites with CNT-loaded microfibrils or compatibilizer: A comparative study

“…However, in most of these cases the two polymers have weak interfacial adhesion, resulting in poor mechanical properties of the blend. This can be improved to a certain extent by applying the concept of microfibrillar composites (MFCs) [36][37][38][39]. Microfibrillar composites are prepared from immiscible polymer blends, where the reinforcement is provided by fibrils of the minor component [37,38].…”

“…This can be improved to a certain extent by applying the concept of microfibrillar composites (MFCs) [36][37][38][39]. Microfibrillar composites are prepared from immiscible polymer blends, where the reinforcement is provided by fibrils of the minor component [37,38]. Requirements to be met in the choice of blend components [39] include: i) both polymers should be amenable to a sufficient amount of drawing to produce microfibrils with high molecular orientation, ii) melting temperature of the minor component should be at least 40 K above that of the matrix polymer, in order to prevent melting of fibrils during consolidation, iii) both polymers should be processable at a single temperature without degrading, iv) blend composition should be selected in that way that the minor component forms a dispersed phase in the matrix.…”