Ultrahigh strength and modulus copolyamide films with uniaxially cold-drawing induced molecular orientation

Abstract

The tensile strength of polymer films is generally lower than 200 MPa. Copolyamide (CPA) films with ultrahigh strength (approximately 317-865 MPa) and high modulus (approximately 3.96-11.76 GPa) were obtained by uniaxial cold-drawing and heat treatment. The relationship between structures and properties in the orientation state was also investigated. The results of Fourier transform infrared (FTIR) spectroscopy indicate that hydrogen bonding interactions change a little with drawing. Wide-angle X-ray diffraction patterns show orientational stretch induces -ordered packing after drawing 100%. The tensile strength and modulus of the drawn CPA films are improved approximately 41%-173% and 9%-197% compared to undrawn films. Dichroic ratios obtained under polarized FTIR spectroscopy represent overall orientation factors. The decrease of dichroic ratios at about 3300 cm À1 and 1650 cm À1 and the increase of dichroic ratios at 1515 cm À1 prove that the orientation of macromolecular chains is improved along stretch direction. What's more, the degree of orientation is further increased after heat treatment, which is the phenomenon of spontaneous orientation. The degree of spontaneous orientation increases with the increase of cold-drawing ratio. Thus, the initial orientation in colddrawing and spontaneous orientation during heat treatment leads to ultrahigh modulus and high strength.

Dynamic viscoelasticity and molecular orientation in uniaxially drawn PC/PET blends

“…Because the orientation degree can be enlarged through hot drawing and be associated well with the dynamic viscoelasticity for neat PC, the dumbbell-shaped sample of blends was also uniaxially drawn on a Shimadzu tensile machine (Shimadzu, AG-X plus, Japan), equipped with a temperature-controlled oven. The drawing was operated at 130 C with four different drawing speeds (5,10,20, and 40 mm min −1 ). The stretching stroke was 50 mm.…”

“…The oriented structure plays an important role in viscoelasticity of polymers. [3][4][5][6][7][8][9][10] Miranda et al 7 explored the influence of orientation induced by uniaxial drawing on the crystalline structure and relaxation of poly(ethylene tetrafluoroethylene). van Berkel et al 8 investigated the interplay between the level of orientation and the relaxation processes occurring in poly(ethylene 2,5-furandicarboxylate) and poly(ethylene terephthalate) (PET).…”

“…Ghazaryan et al 9 found that the uniaxial plastic deformation could decelerates or prohibits the physical aging in poly(L-lactic acid), but the orientation improved mechanical properties were not affected by physical aging. Luo et al 10 discussed the orientation dependence of viscoelasticity, and the effect of uniaxial colddrawing and heat treatment on molecular orientation of copolyamide. All the literature suggested that the change of dynamic viscoelasticity can be explained by an increase in molecular orientation.…”

“…To achieve cracking resistance performance improvement, a critical issue is managing the viscoelasticity of PC. The oriented structure plays an important role in viscoelasticity of polymers . Miranda et al .…”

The introduction of benzimidazole and ether moieties into poly(p-phenylene terephthalamide): effects on its microstructure, interactions and properties

“…Research on the co-poly(p-phenylene terephthalamide) (co-PPTA) ber was rst started by the Russian Research Institute of Chemical Industry. 11 In 1972, Russian scientists rst used benzimidazole diamine (BIA) and terephthaloyl chloride (TPC) monomer to carry out the industrial synthesis and spinning of a high-strength and high-modulus aramid ber, SVM. Subsequently, Russian scientists introduced p-phenylene diamine (p-PDA) into the SVM molecular chain to produce Armos ber, and they registered a patent in 1978.…”