Nylon tensile strength

In spite of thein many desirable properties, acryhcs have not penetrated the industrial fibers market to any significant degree. As a filter medium, for example, acryhcs lack sufficient abrasion resistance and dimensional stabihty at elevated temperatures to find universal acceptance. As a fiber for ropes and fish nets, acryhcs excel in resistance to weathering but lack sufficient tensile strength. High tenacity continuous filament nylon, polyester, and uv-stabihzed polyolefin are generally chosen even though the stabihty of these fibers toward sunlight and chemical exposure is inferior to acryhc fibers. Geotextiles (qv) is another large volume market. Here again acryhcs have exceUent properties but are too costly.  [c.283]

Nylon-6. Nylon-6—clay nanometer composites using montmorillonite clay intercalated with 12-aminolauric acid have been produced (37,38). When mixed with S-caprolactam and polymerized at 100°C for 30 min, a nylon clay—hybrid (NCH) was produced. Transmission electron microscopy (tern) and x-ray diffraction of the NCH confirm both the intercalation and molecular level of mixing between the two phases. The benefits of such materials over ordinary nylon-6 or nonmolecularly mixed, clay-reinforced nylon-6 include increased heat distortion temperature, elastic modulus, tensile strength, and dynamic elastic modulus throughout the —150 to 250°C temperature range.  [c.329]

Crystallinity. Linear polyamide homopolymers consist of crystalline and amorphous phases and are termed semicrystalline. Crystallinity enhances yield strength, hardness (qv), abrasion resistance, tensile strength, elastic and shear modulus, and probably resistance to thermooxidation (16), but it decreases moisture absorption and impact strength. Most commercial samples of nylon-6,6 and nylon-6 ate 40—50% crystalline by weight, as determined by density measurements. A low degree of crystallinity can be achieved in these polymers by rapidly quenching them below room temperature from the melt, but this state is unstable and the sample quickly crystallines if it is warmed, subjected to mechanical stress such as drawing, or exposed to moisture or to other plasticizers (qv). A permanent reduction in the degree of crystallinity can be achieved by chemical modification, eg, through the use of unsymmetrical monomers, copolymers, or substitution at the amide nitrogen, but then most of the desirable physical properties are lost. A few properties are improved, however, such as film clarity.  [c.220]

Nylon-4,6 has a high melting temperature (T, = 295° C), high crystallinity, and a much faster crystallization rate, ie, four to eight times faster than that for nylon-6,6. As an unfilled plastic, nylon-4,6 has a high tensile strength, 80 MPa (12,000 psi), compared to 55—65 MPa (8250—9750 psi) for other polyamides when filled with 30% glass, it has a heat deflection temperature of 285°C, vs 190—240°C for most other polyamides (160). Its dielectric properties have been well documented (161). AH these properties make nylon-4,6 a good candidate for high temperature appHcations and end uses that require good resistance to impact and abrasion. Nylon-4,6 has been studied for fiber appHcations (162) and as tire cord it is claimed to be 30% better than nylon-6,6 in flat-spot index measurements, which is even better than polyester in this test (155). Besides its limited stabHity in the melt phase, its other  [c.235]

Moisture Absorption. A characteristic property of nylon is the abiUty to absorb significant amounts of water (13) (Fig. 1). This again is related to the polar amide groups around which water molecules can become coordinated. Water absorption is generally concentrated in the amorphous regions of the polymer where it has the effect of plasticizing the material by intermpting the polymer hydrogen bonding, making it more flexible (with lower tensile strength) and increasing the impact strength. The T is also reduced. Moisture absorption, determined by both the degree of crystallinity and the density of amide groups, is, as with the melting point, reduced with increasing length of aUphatic groups in the chain. Aromatic monomers also reduce the moisture absorption. Nylon-6 has a higher moisture absorption than nylon-6,6 because of its lower crystallinity. The effect of moisture absorption on the mechanical properties of nylon-6,6 is included in Table 3.  [c.267]

The semicrystalline stmcture of most commercial nylons imparts a high strength (tensile, flexural, compressive, and shear) as a result of the crystallinity and good toughness (impact strength) due mainly to the amorphous region. The properties of nylon ate affected by the type of nylon (including copolymerization), molecular weight, moisture content, temperature, and the presence of additives. Strength and modulus (stiffness) are increased by increasing density of amide groups and crystallinity in aUphatic nylons impact strength and elongation, however, are decreased. Nylon-6 having a lower crystallinity than nylon-6,6 has a higher impact strength and slightly lower tensile strength. Nylons containing aromatic monomers tend to have increased stiffness and strength by virtue of the greater rigidity of the chains. Increasing molecular weight gives increased impact strength without having a significant effect on tensile strength. Moisture content affects the properties of nylon-6 and nylon-6,6 the effect is similar to that of temperature. Increasing moisture content reduces theT above which the modulus and tensile strength drop significantly however, some polyamides with a high T, such as those containing aromatic monomers, have Httle change in properties with changing moisture as the T remains above room temperature. Increasing moisture for nylon-6 and nylon-6,6 also gives a steady increase in impact strength as a result of increa sing plasticization, although at very low temperatures moisture can embrittle nylon. For nylons that absorb lower amounts of water, the effects on properties ate less.  [c.269]

Chemical Resistance. The chemical resistance of PPS compounds is outstanding, even at elevated temperatures, but as an organic polymer, PPS can be affected by some chemicals under certain conditions. Time and temperature are critical factors which must be considered when determining the level of chemical resistance requited for a specific appHcation. The effective chemical resistance should be evaluated on the basis of how well the material performs over time to chemical exposure relative to the requited performance level. In a comparison of chemical resistance of various plastics (125), five materials were exposed to 127 different reagents for 24 h at 93°G. A passing grade was assigned if the material retained at least 75% of its initial tensile strength. PPS was the best performer, passing on 120 reagents. PhenoHc resins were closest at - 109, followed by nylon at 70, PPO at 65, and PG at 50. More detailed discussions of specific chemical exposure have been pubHshed (1,3). To characterize the chemical resistance of PPS compounds, tensile specimens of 40% glass-filled PPS were immersed in various chemicals at 93°G and tested periodically for thek retention of tensile strength. Based on these data, a rating was estabUshed as a general guide to illustrate the degrees of chemical resistance one might expect PPS compounds to exhibit within a chemical class (125).  [c.448]

The major effects of air pollution on fabrics are soiling and loss of tensile strength. Sulfur oxides are considered to cause the greatest loss of tensile strength. The most widely publicized example of this type of problem has been damage to women s nylon hose by air pollution, described in newspaper accounts. The mechanism is not understood, but it is postulated that fine droplets of sulfuric acid aerosol deposit on the very thin nylon  [c.130]

The distance between the repeating —CONH— group. It is the presence of the —CONH— groups which causes the aliphatic polyamides to differ from polyethylene, and the higher their concentration the greater the difference. As a rule, the higher the amide group concentration, i.e. the shorter the distance between —CONH— groups, the higher the (a) density (b) forces required to mechanically separate the polymer molecules and hence the higher the tensile strength, rigidity, hardness and resistance to creep (c) the and heat deflection temperature (d) resistance to hydrocarbons (e) water absorption. Nylon 11 has twice the distance between amide groups of that in nylon 6, and consequently is intermediate in properties between nylon 6 and polyethylene.  [c.488]

Mechanical properties of freshly injected compositions are similar for the two nylons but, after conditioning, differences arise largely due to the plasticising effect of the moisture present. Thus for tensile and flexural yield stress, tensile strength and modulus of elasticity, nylon 66 gives slightly higher figures. Yield elongation and elongation at break are greater with nylon 6. Izod impact strengths are similar, with nylon 6 giving marginally higher values.  [c.500]

Cloths from synthetic fibers are superior to many of the natural cloths thus far considered. They do not swell as do natural fibers, are inert in many acid, alkaline and solvent solutions and are resistant to various fungus and bacterial growths (the degree depending on the particular fiber and use). Several synthetic fibers resist relatively high temperatures, and have a smooth surface for easy cleaning and good solids discharge. Some of the most widely used synthetic filter media are nylon, Saran, Dacron, Dynel, Vinyon, Orion, and Acrilan. Table 2 compares the physical properties of several synthetic fiber filter media. Tightly woven, monofilament (single-strand) yarns consist of small-diameter filaments. They tend to lose their tensile strength, because their small diameters reduce their permeability thus multifilament yarns are normally used. Monofilament yarns in loose weaves provide high flowrates, good solids discharge, easy washing and high resistance to blinding, but the turbidity of the filtrate is high and recirculation is usually necessary, initially at least.  [c.129]

Figure 15 (A) Tensile strength versus draw ratio of nylon 46-Vectra B (75 25 wt ratio) and (B) tensile modulus of the blends when 2.7 wt% of SA-g-EPDM was added. Lines are guides for eyes. Closed symbols are mechanical properties of the binary nylon 46-Vectra B blend (75 25 wt ratio) Source Ref. 57. Figure 15 (A) Tensile strength versus draw ratio of nylon 46-Vectra B (75 25 wt ratio) and (B) tensile modulus of the blends when 2.7 wt% of SA-g-EPDM was added. Lines are guides for eyes. Closed symbols are mechanical properties of the binary nylon 46-Vectra B blend (75 25 wt ratio) Source Ref. 57.
Tensile properties of synthetic and natural fibers (or yam) are measured from stress—strain curves as shown in Figure 2. These measurements are not only important in determining the suitabiUty of a nylon fiber for a specific end use, but also in comparing it to other fiber types. The toughness of nylon is similar to polyester, but higher than sHk, Nomex, wool, Kevlar, and cotton. Nylon has a lower modulus than polyester, cotton, sHk, Nomex, and Kevlar, the last two produced by Du Pont. SHk has higher strength and lower elongation than standard nylon and polyester textile fiber.  [c.247]

Plastics increase in strength as the temperature is decreased, but this is also accompanied by a rapid decrease in elongation in a tensile test and a decrease in impact resistance. Teflon and glass-reinforced plastics retain appreciable impact resistance as the temperature is lowered. The glass-reinforced plastics also have high strength-to-weight and strength-to-thermal conductivity ratios. All elastomers, on the other hand, become brittle at low temperatures. Nevertheless, many of these materials including rubber. Mylar, and nylon can be used for static seal gaskets provided they are highly compressed at room temperature prior to cooling.  [c.1127]

In a partially crystalline homopolymer, nylon 6, property enhancement has been achieved by blending with a poly(ethylene-co-acrylic acid) or its salt form ionomer [24]. Both additives proved to be effective impact modifiers for nylon 6. For the blends of the acid copolymer with nylon 6, maximum impact performance was obtained by addition of about 10 wt% of the modifier and the impact strength was further enhanced by increasing the acrylic acid content from 3.5 to 6%. However, blends prepared using the salt form ionomer (Sur-lyn 9950-Zn salt) instead of the acid, led to the highest impact strength, with the least reduction in tensile  [c.151]

Most of the polymer s characteristics stem from its molecular stmcture, which like POE, promotes solubiUty in a variety of solvents in addition to water. It exhibits Newtonian rheology and is mechanically stable relative to other thermoplastics. It also forms miscible blends with a variety of other polymers. The water solubiUty and hot meltable characteristics promote adhesion in a number of appHcations. PEOX has been observed to promote adhesion comparable with PVP and PVA on aluminum foil, cellophane, nylon, poly(methyl methacrylate), and poly(ethylene terephthalate), and in composite systems improved tensile strength and Izod impact properties have been noted.  [c.320]

When nylon-6,6 was first iatroduced, its maia attractioa was as a fiber-forming material the streagth, elasticity, and high dye uptake of which were considered the most important properties, along with the abiUty to withstand ironing temperatures. It soon became apparent, however, that the properties of the material held many advantages for use as a plastic. In particular, the relatively high tensile strength and stiffness, together with good toughness, high melting poiat (and therefore temperature stabiUty), and good chemical resistance, all combiaed to allow a wide range of appHcations. The material soon came to be seen as an engineering plastic that could be used for metal replacement ia stmctural or semistmctural ead uses. These properties are preseat to a greater or lesser exteat ia the eatire semicrystalline polyamide family, together with the "Achilles heel" of ayloa, ie, the hygroscopic aature that leads to moisture uptake, change of properties, and the potential for hydrolysis.  [c.266]

Reinforcement. Nylon is particularly suitable for reinforcement and the melt incorporation of short glass fibers has long been practiced, being developed around 1960 by ICI in England (35) and Fiberfil Inc. in the United States (36). The tensile strength of nylon-6,6 is increased by more than 2.5 times and stiffness by almost 4 times by adding 30% glass fiber. Glass fiber also improves dimensional stabiUty, notched impact strength, and long-term creep, and is normally used in the 15—60% (wt/wt) range. The glass fibers used need to be treated with a specific siting to enable bonding with the nylon and dispersion in the melt the size formulations are proprietary but often contain an aminosilane coupling agent and a polyurethane or acryUc binder.  [c.275]

Nylons are tough under many impact conditions but may be notch-sensitive and brittle, particularly at low temperatures. In mbber modification, an elastomeric second phase is incorporated, usually by mechanical blending with a variety of chemically modified elastomers (eg, maleic anhydride) to effect interaction between the nylon matrix and the elastomer phase. Importantly, the morphology of the elastomer phase is influenced by the degree of chemical reaction between the two phases. The control of mbber-phase morphology is critical in determining the mechanical properties of the modified nylons (234,287). Significant improvements in ductihty are accompanied by a corresponding drop in flexural modulus and tensile strength. Nylons may be toughened by the solution polymeri2ation of caprolactam in the presence of ethylene—propylene elastomers (288). Impact properties of these heterophase polymers are often comparable to those prepared by melt-blending.  [c.421]

Cord materials such as nylon, polyester, and steel wire conventionally used in tires are twisted and therefore exhibit a nonlinear stress—strain relationship. The cord is twisted to provide reduced bending stiffness and achieve high fatigue performance for cord—mbber composite stmcture. The detrimental effect of cord twist is reduced tensile strength. Analytical studies on the deformation of twisted cords and steel wire cables are available (22,56—59). The tensile modulus E of the twisted cord having diameter D and pitchp is expressed as follows (60)  [c.86]

Polyamides. The production of ahphatic polyamides, or nylons, consumes a large portion of the total production of the diacids. These polyamides find apphcation in apparel and carpet fibers, engineering plastics, nylon copolymers for monofilament, wine-coating, and molding resin apphcations. An interesting potential apphcation for nylon-5,7, prepared from pimelic acid and 1,5-pentanediamine, is as a conducting polymer (107). The polyamide produced from suberic acid and 1,4-cyclohexanebis(methylamine) has an exceptionally high melting point (295°C) that enables high melt processing temperatures to be employed without concurrent thermal decomposition it has properties weU-suited for fiber, film, and molding plastic apphcations (108). The 6,9, 6,10, and 6,12 nylons, derived from azelaic, sebacic, and dodecanedioic acids respectively, find apphcation in engineering plastics, bristles, and fibers. These nylons are more moisture-resistant than is the adipic based nylon-6,6. The ahcychc nylon, Du Font s Quiana, derived from dodecanedioic acid and bis(4-aminocyclohexyl)methane, was introduced as a replacement for silk in 1968 (109). A recent patent describes the incorporation of dodecanedioic acid into nylon-6,6 to improve the fibers dyeabihty (110). Brassyhc acid based nylons 13, 6,13, and 13,13 are very moisture resistant. Azelaic and sebacic acids find apphcation in dimer acid based polyamides and contribute to higher tensile strength and higher melting point resins.  [c.64]

Compared with nylon 66 fibres, the polyurethane fibres (known as Perlon U) have a tensile strength at the higher end of the range quoted for nylon 66, they are less prone to discolouration in air, are more resistant to acid conditions and they have a lower moisture absorption. On the debit side they are less easy to dye, are hard, wiry and harsh to handle and have too low a softening point for many applications. They are currently of little importance but have found some use in bristles, filler cloths, sieves and a few other miscellaneous applications.  [c.783]

Cotton bags are used in standard installations and are the most economical. A maximum operating temperature of 180 °F is recommended for continuous use with 225 °F allowed for surge conditions. Wool bags are used for applications with dust particles of a combustible nature, or with operating temperatures of 200 °F and an allowable surge temperature of 250 °F. Nylon has a greater tensile strength than cotton or wool and provides excellent abrasion resistance. Fiberglass is most resistant to high temperatures, with a maximum operating temperature of 500 F. To increase the allowable temperature, fiberglass filters are silicone treated to permit their use in applications such as in carbon black production plants. Replacement of bag filters generates the highest maintenance and cost of the system. Typical causes of bag failure include too high of a gas to cloth ratio, metal-to-cloth abrasion problems, chemical attack by the gas stream or particulates, inlet velocity abrasion, and excessive gas temperatures. The quality of the fabric and method of cleaning are additional factors to consider in evaluating service and maintenance costs. If a filter bag tears. It is important to repair the bag as quickly as possible to prevent abrasion to adjacent bags by jet streams of dust discharging out of the damaged bag. This type of bag failure is limited to inside bag collection types of dust collectors. The speed of repair is determined by the opacity of the outlet bag. In a compartmentalized system, broken bags can be found by monitoring the emissions while isolating one compartment at a time. To prevent a higher filter velocity, damaged filter bags within a compartment should not be replaced with clean bags. The higher velocity could create greater pressure drop or failure due to dust abrasion. An alternative is to plug or tie off the flow. To recap, the first step in selecting a fabric filter is to define the magnitude of the particulate loading. Knowledge of the particulate matter collected, properties of the gas stream, and the cleaning method are essential to proper design. Improper design leads to low efficiency and unscheduled maintenance. Prior to selection, results from a related application should be investigated. An alternative is to operate a pilot unit to ensure the most optimum gas-to-cloth ratio for a specified pressure drop. With proper design, operation, and maintenance, better than 99.9% efficiency can be achieved, depending on the application. A major advantage of fabric filters, is their ability to operate at a high efficiency at all loads from maximum down to very low gas flow. Some disadvantages of the system are the space requirements and high maintenance costs. Other problems associated with fabric filters are plugging of the fabric due to operation below the dew point or break down of the filter bags, resulting from high temperatures.  [c.341]

See pages that mention the term Nylon tensile strength : [c.274]    [c.597]    [c.598]   
Plastics materials (1999) -- [ c.783 ]