Effects of crystalline forms on the deformation behaviour of nylon-6
1998; Elsevier BV; Volume: 39; Issue: 19 Linguagem: Inglês
10.1016/s0032-3861(97)10132-x
ISSN1873-2291
AutoresMasayoshi Ito, Kazuko Mizuochi, Tetsuo Kanamoto,
Tópico(s)Liquid Crystal Research Advancements
ResumoSolid-state coextrusion draw was carried out for films of aggregates of solution- and melt-grown crystals of nylon-6 with α- and γ-forms. Under ordinal crystallization conditions, the crystal form was primarily a monoclinic α-form. Thus, α-crystals were converted to the γ-form by iodine treatment, followed by treatment with aqueous solution of sodium thiosulfate. The maximum extrusion draw ratio achieved (EDRmax) at temperatures in the range of 100–180°C was greatly affected by both the crystal forms and the initial morphologies. At a given crystal morphology, the EDRmax for the γ-crystals was higher than the α-crystals. Further, the efficiency of draw evaluated from the crystalline chain orientation was higher for γ-crystals than α-crystals. For films with α-crystals, the intercrystalline network has an important role in transmitting the stress on draw. On the other hand, for films with γ-crystals, the effect of intercrystalline network on the efficiency of draw was less prominent. These results were almost independent of the extrusion temperature studied. The effect of crystal form on the ductility is explained based on the difference in the interchain interactions due to hydrogen bonding in the crystalline regions.
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