Nylon thermal properties

Polyamides can claim to have been the first engineering plastics as a result of their excellent combination of mechanical and thermal properties. Despite being iatroduced as long ago as the 1930s, these materials have retained their vitaUty and new appHcations, and iadeed new types of nylon continue to be developed. 

The glass transition temperatures of the nylons appear to be below room temperature so that the materials have a measure of flexibility in spite of their high crystallinity under general conditions of service. The polymers have fairly sharply defined melting points and above this temperature the homopolymers have low melt viscosities. Some thermal properties of the nylons are given in Table 18.4. 

A further approach is used by Bayer with their polyesteramide BAK resins. A film grade, with mechanical and thermal properties similar to those of polyethylene is marketed as BAK 1095. Based on caprolactam, adipic acid and butane diol it may be considered as a nylon 6-co-polyester. An injection moulding grade, BAK 2195, with a higher melting point and faster crystallisation is referred to as a nylon 66-co-polyester and thus presumably based on hexamethylene diamine, adipic acid and butane diol. 

Jha A. and Bhowmick A.K., Thermoplastic elastomeric blends of nylon 6/acrylate rubber Influence of interaction of mechanical and dynamic mechanical thermal properties. Rubber Chem. TechnoL, 70, 798, 1997. 

Research concerning nylon-elastomer blends has mostly focused on the improvement of mechanical and thermal properties. Their dynamic mechanical properties are quite important both for processing and engineering applications. Wang and Zheng have smdied the influence of grafting on the dynamic mechanical properties of a blend based on nylon 1212 and a graft... 

TABLE 1 Mechanical and Thermal Properties of Nylon-6 and Nylon-6-Clay Nanocomposites... 

Polymer-clay nanocomposites (PCN) are a class of hybrid materials composed of organic polymer matrices and organophilic clay fillers, introduced in late 1980s by the researchers of Toyota (Kawasumi, 2004). They observed an increase in mechanical and thermal properties of nylons with the addition of a small amount of nano-sized clays. This new and emerging class of pol miers has found several applications in the food and non-food sectors, such as in constmction, automobiles, aerospace, military, electronics, food packaging and coatings, because of its superior mechanical strength, heat and flame resistance and improved barrier properties (Ray et al., 2006). 

PEBA exhibit a two-phase (crystalline and amorphous) structure and can be classified as a flexible nylon. Physical, chemical, and thermal properties can be modified by appropriate combination of different amounts of polyamide and polyether blocks [149], Hydrophilic PEBAs can be prepared which can have specific applications in medical devices. Similarly to other thermoplastic elastomers, the poiyamide-based ones find applications in automotive components, sporting goods conveyor belting, adhesives, and coatings [150]. In recent years the world consumption was approximately 6400 tons per year with about 80% in Western Europe and the rest equally split between the United States and Japan [143],... 

Polymers are broadly classified as synthetic and natural polymers. Synthetic polymers have become significant since the 1940s and continue to replace glass, wood, constructional materials and metals in many industrial, domestic and environmental applications [2-5]. Synthetic polymers are made from hydrocarbons derived from petroleum. Some of these polymers, such as nylon, polyethylene, polyurethane and so on, are an indispensable part of our daily lives. Due to their stability and durability they offer good mechanical and thermal properties [6], making them suitable for a variety of applications, e.g., in automobiles, cosmetics, medicines, biosensors,... 

The rigidity imparted by the ring in the main chain results in better gas barrier and thermal properties than nylon 6. MXD6 also is reported to have better moisture resistance than EVOH. At 100% RH its oxygen barrier is superior to EVOH. At... 

Physical and thermal properties for Nylon 6,6 poly (hexamethylene adipamide) Epoxies have excellent electrical and thermal resistance. They are thermosets. Addition of fillers improves hardness, impact resistance and thermal conductivity. 

Physical and thermal properties for Nylon 6,6 poly (hexamethylene adipamide) Nylons are tough and strong and can be used over a wide temperature range ( 80 to 120°C). Nylons have a low coefficient of friction. This leads to extremely good abrasion resistance, further improved by adding surface lubricants or annealing at 150-200°C. Nylons perform unreliably in wet environments because they absorb water readily. 

An example of a typical material composition is the combination of a polymer and a filler. Because compounding is a techiuque that can complement the drawbacks of conventional polymers, it has been studied over a long period and its practical apphcations are well known. Reinforcing materials such as short-fiber are often used for compounding with thermoplastic polymers in order to improve their mechaiucal or thermal properties. Polypropylene and polyamide (nylon) are used for the thermoplastic polymers, while glass fiber and carbon fiber are mainly used as reinforcing materials. A few ttm... 

The high melting point of Nylon 6-6 (260°C) and Tg = 45 C, attribute superh thermal properties and a working temperature of 150 C. On the other hand, if no special protection is applied, Nylon because of its stmcture suffers from sensitivity to humidity (about 8% water absorption for Nylon 6-6), and to UV radiation and oxidation by the environment. 

Table 11.7 Comparative thermal properties of polyester and nylons 6 and 6.6...

EFFECT OF IONIZING RADIATION ON THE THERMAL PROPERTIES OF LINEAR HIGH POLYMERS. 2. NYLONS. 

Blending of polymers provides a simple and inexpensive method of nylon modification. The mechanical and thermal properties of nylons may be improved by blending with other polymers. However, it is not easy to obtain synergism in the meehanical properties of the blend components. Usually, incompatibility causes the mechanical properties of a nylon blend to fall far below the values predicted by the additivity rule for mixtures. 

Random copolymerization of aliphatic monomers develops elastomeric or rubbery nylons by reducing interchain attractions and lowering the decree of crystallinity by destruction of chain r ularity. Random copolymerization of ahphatic monomers generally decreases both meehanieal and thermal properties of nylorts but, in some cases, it allows rubber-like behavior in the copolymer. 

Figure 4.29 The dependency of viscosity on temperature for several isotropic pitches, a mesophase pitch and a typical thermoplastic polymer Ashland 240 (isotropic petroleum pitch) Aerocarb 60 (isotropic pitch distilled from A240) Aerocarb 75 (isotropic pitch distilled from A240) Source. Sumner MB, Thermal properties of heavy isotropic petroleum pitches. Carbon 88, Proceedings of the International Conference on Carbon, University of Newcastle upon Tyne, 52-54, Sep 18-23,1988, Mesophase (produced by pyrolysis of A240) Nylon 6 (a typical melt spur synthetic polymer). Source Reprinted from Whitehouse S, Rand B, Rheology of mesophase pitch from A240. Carbon 88, Proceedings of the International Conference on Carbon, University of Newcastle upon Tyne, 175-176, Sep 18-23, 1988.

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