Effects of annealing on structure and properties of TLCP/PEN/PET ternary blend fibers

Abstract

Thermotropic liquid crystalline polymer (TLCP)/poly(ethylene 2,6-naphthalate) (PEN)/poly(ethylene terephthalate) (PET) ternary blends were prepared by melt blending, and were melt-spun to fibers at various spinning speeds in an effort to improve fiber performance and processability. Structure and property relationship of TLCP/ PEN/PET ternary blend fibers and effects of annealing on those were investigated. The mechanical properties of ternary blend fibers could be significantly improved by annealing, which were attributed to the development of more ordered crystallites and the formation of more perfect crystalline structures. TLCP/PEN/PET ternary blend fibers that annealed at 180 o C for 2 h, exhibited the highest values of tensile strength and modulus. The double melting behaviors observed in the annealed ternary blend fibers depended on annealing temperature and time, which might be caused by different lamellae thickness distribution as a result of the melting-reorganization process during the DSC scans.

correlations of mechanical properties and microstructural parameters in annealed drawn film of liquid crystalline polymer in situ reinforced PP

“…The moduli of films annealed for 30, 60, 90, 120 and 180 min are about 8, 21, 38, 33 and 50% for MD and 53, 61, 78, 97, and 117% for TD, respectively, higher than those of the UA film. This indicates that the YM of the TLCP/PP films can be effectively enhanced through a simple thermal annealing process which agrees well the work of Kim et al [33] reported that mechanical properties of TLCP/PEN/PET fibers increased significantly with annealing process. Moreover, the MD-moduli are intensely higher than TD-moduli, for each annealing time.…”

“…This suggests that the relative level of molecular orientation of PP well corresponds to the significant enhancement of mechanical properties of annealed TLCP/PP composite film, rather than X c , X c,a and L, in both MD and TD directions. The possible reason for this behavior could be that, generally, the molecular orientation in both the dispersed TLCP fibrils and the TP matrix phase plays an important role in the improvement of mechanical properties of TLCP in situ reinforced TPs composites [7,33,36]. However, these results differ from the results reported by Ferrer-Balas et.…”

“…Seo et al [32], studied the interfacial reinforcement of a functionalized PP and TCLP blends and reported that the fracture toughness increased with annealing time. Kim et al [33] also found that the mechanical properties of ternary TLCP/PEN/PET fibers significantly improved by annealing conditions, attributing to the increase of ordered crystallites and perfect crystalline Relative intensity…”

“…Furthermore, it is also well known that annealing of the final polymeric materials causes the various modifications at microscopic level such as reorganization of amorphous segments, rearrangement of crystal segments and reduction of defects and residual stress/strain [29]. Therefore, the influences of annealing on the mechanical and impact/fracture properties, crystal structure, thermal behavior and morphology of neat PP and its blends are widely explored in the last decade [22][23][24][25][26][27][30][31][32][33]. For example, Poussin et al [25], reported that crystallinity, density and apparent crystal size of the α-phase of PP sheet were rapidly increased in the first 5 min of treatment at 125 °C due to the favorite of molecular mobility in the amorphous phases.…”

Thermal decomposition behavior and durability evaluation of thermotropic liquid crystalline polymers

“…5 Recently, aromatic polyester TLCPs have been used as high performance engineering plastics. 6,7 They have high heat-resistance and excellent mechanical properties due to their rigid, rod-like aromatic chain structure, resulting in their utilization in various industrial fields where the higher thermal stability is required.…”