Monofilament tensile properties

The effect of the annealing temperature on the initial modulus is also presented in Figure 20.8. The moduli of monofilaments annealed at 160 °C for 30 min are higher than those of normal monofilaments, because the matrix polymers are recrystallized with a low PHB content, and the LCP molecules in the domain are reoriented with a high PHB content. The thermal treatment of the PHB/PEN/PET fibers can be an effective way to improve the tensile properties, especially the tensile modulus, and high-speed winding may be a promising way to obtain fibers... 

EFFECT OF DRAWING SCHEMES ON TENSILE PROPERTIES OF MONOFILAMENT FIBERS... 

Copolymers I-III were extruded into monofilaments and the tensile properties after drawing and annealing are shorn in Tables II and III. The reported data indicate that copolymeric monofilaments can be made to have equivalent or higher tensile strength as con ared with those made from PDS. 

To simulate the in vivo performance of the drawn monofilaments, a study of their BSR at 37°C was conducted in a phosphate buffered solution at pH 7.4. Typical BSR data are noted in Table 2.2. The tensile properties of the... 

The composition and thermal data of typical polymers and tensile properties of their respective nonsterile monofilaments are summarized in Tables 3.3 and 3.4, respectively. The monofilaments were then radiochemically sterilized using 5 and 7.5 kGy gamma radiation and a polyformaldehyde package insert as described earlier by Correa et al. ° The tensile properties of typical sterile monofilament sutures and their BSR profiles were determined after incubation in a phosphate buffer at 37°C and pH 7.4 to simulate their in vivo profile. The tensile properties and BSR data of a typical radiochemically sterilized monofilament suture are summarized in Table 3.5. 

Two of the early polymers described in Table 8.1 were melt spun into monofilament sutures, which exhibit the tensile properties shown in Table 8.3. 

ASTM D 2256- 95 provides a method for the determination of the tensile properties of monofilament, multifilament, and spun yarns, wither single, plied, or cabled, providing that the yarns do not extend more than 5% when the tensile force is increa.scd from 5 mN tex to 10 mN tex. The method covers the measurement of breaking force and elongation at break, tenacity (at break), initial modulus, and breaking toughness. Options arc included for knotted and looped forms (for which sec also ISO 2062). 

Additionally, it imparts higher warp tensile properties to the fabric for greater resistance to stretch from the mass of heavy cakes. In the case of the multifilament and staple-fibre yam combination, the inclusion of a staple-fibre weft yam provides the scope for improved resistance to mechanical damage whilst maintaining high particle collection efficiency and acceptable throughput rate. Similarly, the inclusion of a multifilament weft yam in a monofilament and multifilament fabric will lead to an improvement in filtration efficiency, especially if it is suitably texturised. 

The video-extensometer eliminates the use of an external extensometer, which can cause micro-cracking during handling. Furthermore, small-sized specimens in the micron range may be tested using this method. Here, the video-extensometer was used to evaluate the tensile properties of silicon carbide monofilaments 100 pm in diameter and to determine the change in distance, A1 between the marked targets, caused by the mechanical strain to the specimen. The strain is then calculated in the conventional manner, as indicated in Eq. (1.6), rewritten here as ... 

Table 8 Tensile properties of drawn, annealed monofilaments copolymers of PDO-PGA segmented ...

The copolymers were extruded into monofilaments using an INSTRON capillary rheometer. The extrudates were drawn in two stages at about 54 C and then about 74 C using draw ratios of about 4.5 and 1.3X, respectively. After annealing, tensile properties were measured (Table 11). 

Using methods previously described, poly(p-dioxanone-co-ethylene propylene oxide) copolymers were melt extruded into monofilaments. Tensile strengths were found to be equivalent to PDS homopol)Tner, but handling properties were improved (Bezwada and Shalaby, 1991). 

Table V. Tensile Properties of Two-stage Drawn PP/LC3000 Monofilament Fibres (PP/LC3000 ratio w/w 100/10)...

The polymerization of p ra-dioxanone as well as that of methyl and dimethyl homologues were described by Doddi et al. [183]. Poly(ptira-dioxanone) is primarily used as the absorbable suture material PDS (manufactured by Ethicon Inc.) because of its good tensile properties with respect to PGA and its ability to form monofilaments [28]. PDS material has been investigated for arterial regeneration in rabbit [184] and for internal suspension and fixation of facial fractures clinically [185], for cerclage of the eyeball [186], for closure of abdominal wounds [187] and for orbital floor reconstruction [188] as well as for use in pediatric cardiovascular operations [189] and in orthopeadic surgery [190]. 

Copolymers of S-caprolactone and L-lactide are elastomeric when prepared from 25% S-caprolactone and 75% L-lactide, and rigid when prepared from 10% S-caprolactone and 90% L-lactide (47). Blends of poly-DL-lactide and polycaprolactone polymers are another way to achieve unique elastomeric properties. Copolymers of S-caprolactone and glycoHde have been evaluated in fiber form as potential absorbable sutures. Strong, flexible monofilaments have been produced which maintain 11—37% of initial tensile strength after two weeks in vivo (48). 

However, there remain numerous end-use applications which require significant improvements in the properties PET has to offer. These include higher tensile strength and modulus for tyre reinforcement yams and monofilament applications, higher temperature resistance for hot-fill containers and films, and greater gaseous barrier for longer shelf-life requirements (e.g. fruit juice and beer markets). 

In all cases the anisotropic polymerization mixtures (10% by weight) could be used directly in the formation of dry-jet wet-spun fibers. Monofilament fibers were obtained by coagulation in water, tension dried at 150 °C and heat treated at 500-600 °C with a 30s residence time. The best fibers were obtained from the high molecular weight PBZT polymer (VII) which exhibited modulus values that ranged between 172 GPa and 207 GPa and tenacity values up to 2.4 GPa. Unfortunately, the compressive property as measured by the tensile recoil test was only 380 MPa, showing only a slight improvement over PBZT. 

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