Structures and mechanical properties of zone-drawn-zone-annealed blends of cocrystallizing poly(butylene terephthalate) and a poly(ether ester)

Abstract

SYNOPSISPoly(buty1ene terephthalate) (PBT) and a poly(ether ester) (PEE) based on PBT and poly(ethy1ene glycol) were melt-blended and extruded as films with quenching. They were then zone-drawn (ZD) and zone-annealed (ZA) at various stresses (between 10 and 50 MPa) at temperatures of 160 and 190°C. The goal was to improve their mechanical properties relative to those of the same blend, but cold-drawn (A = 5) and isothermally annealed with fixed ends at the same temperatures for 6 h. All samples were characterized by DSC, WAXS, SAXS, and static mechanical property measurements. In contrast to the isothermally annealed samples, the zone-drawn and zone-annealed ones exhibit one population of crystallites arising from the homo-PBT, as demonstrated by the DSC and SAXS measurements. In addition, however, the WAXS photographic patterns indicate that zone annealing a t 190OC results in isotropization of crystallites originating from the PEE, resulting in the formation of a microfibrillar-reinforced composite. It is assumed that some of the isotropic crystallization occurs on preexisting homo-PBT crystallites, i.e., a partial cocrystallization occurs, improving the adhesion between the components of the blend. The structural features created in the zone-drawn-zone-annealed materials result in higher values of the Young's modulus and tensile strength in comparison to the materials receiving the simple isothermal treatment (1,200 vs. 480 MPa and 213 vs. 113 MPa, respectively

Transforming polymer blends into composites: a pathway towards nanostructured materials

“…In the first studies on MFCs, the composites were prepared on a laboratory scale performing every one of the aforementioned three processing stages separately, one after another. Blending was realized in a laboratory mixer or a single‐screw extruder to obtain non‐oriented strands that were afterward cold‐drawn in a machine for tensile testing, followed by annealing of the oriented strands with fixed ends 26–28, 33–36. Obviously, this discontinuous scheme is difficult to apply in large‐scale production.…”

X‐Ray Scattering Studies on Multiphasic Polymer Systems

“…Blending was realized in a laboratory mixer or a single-screw extruder to obtain non-oriented strands that were afterward cold-drawn in a machine for tensile testing, followed by annealing of the oriented strands with fixed ends [13][14][15][19][20][21][22]. Obviously, this discontinuous scheme is difficult to apply in large-scale production.…”

“…In the first studies on MFCs, the composites were prepared on a laboratory scale performing every one of the aforementioned three processing stages separately, one after another. Blending was realized in a laboratory mixer or a single-screw extruder to obtain nonoriented strands that were afterward cold-drawn in a machine for tensile testing, followed by annealing of the oriented strands with fixed ends [13][14][15][19][20][21][22]. Obviously, this discontinuous scheme is difficult to apply in large-scale production.…”

“…19 shows the effect of incorporation of MMT for fixed processing conditions (but expectantly for different thermomechanical environments due to the increase onmelt viscosity by the incorporation of MMT). The addition of MMT affects the microstructure of the mouldings (e.g.…”

CRYSTALLIZATION IN PARTIALLY MOLTEN ORIENTED BLENDS OF POLYCONDENSATES AS REVEALED BY X-RAY STUDIES*

“…We have investigated a similar blend, containing a poly(ether ester) with soft segments based on poly(ethylene glycol) [24,31] and a much lower PBT content (49 or 75 wt%). The blend was drawn and subsequently annealed at a temperature between the melting temperatures of PEE (191°C) and homo-PBT (226°C).…”