Microfibrillar-Reinforced Nylon-6/PET Fibers with Interfacial Bonding
Titel:
Microfibrillar-Reinforced Nylon-6/PET Fibers with Interfacial Bonding
Auteur:
Aharoni, Shaul M.
Verschenen in:
International journal of polymeric materials
Paginering:
Jaargang 38 (1997) nr. 3-4 pagina's 173-203
Jaar:
1997-12-01
Inhoud:
Microfibrillar-reinforced fibers (MRF's) with a majority of poly (ε-caprolactam) (Nylon-6) and a minority of poly (ethylene terephthalate) (PET) were melt spun. When triphenylphosphite (TPP) was masterbatched into the PET (PET MB) prior to spinning, some block polyamide/polyester copolymers were formed during the spinning, serving to bond the nylon matrix to the PET microfibrils. The mechanical and processing properties of such fibers were consistently better than those of comparable fibers of the same composition but without interfacial bonding. Fibers containing PET microfibrils have higher modulus than the corresponding nylon-6 blanks; and fibers containing bonded PET microfibrils have a modulus much higher than those containing unbonded PET microfibrils. At 3:1 draw ratio, the highest modulus approached 60 g/den and the highest strength was about 4.0 g/den. At 5:1 draw ratio, a modulus of over 80 g/den was achieved. Together with improvements in modulus, the glass transition temperature, Tg. of the nylon-6 matrix gradually increased as function of the fibers' draw ratio. In order for polyamide/polyester bonds to occur, the polyamide must contain at least one primary amine group per chain. The PET must be masterbatched with ca. 1.5% TPP, increasing its intrinsic viscosity (I.V.) from 0.69 to not higher than 0.80 dL/g. Fibers containing up to 30% PET MB could be easily spun and drawn to 3:1 and 5:1 either immediately or after time-lagging. MRF's containing 15%. 20%, 25% and 30% PET MB were processed and performed reasonably well. MRF's with 25% PET MB performed about as well as those with 30% PET MB, but were easier to spin and draw. Fibers containing 45% PET MB had poorer mechanical properties than MRF's containing 30% PET MB and showed large property, performance and processing fluctuations due to massive phase inversions randomly taking place in them. During the melt spinning, time and temperature dependence are interdependent. The best conditions with our equipment were found to be: barrel temperatures of 271-288 C, residence time of about 150 seconds, and spinnerette temperature of 260-266 C. Under these conditions, high levels of interfacial bonding, constant intrinsic viscosity, and filament uniformity were achieved.
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