Heat-aging resistance

Antioxidants (qv) usually provide only a marginal improvement ia heat aging resistance because of the inherent oxidation resistance of the saturated backbone of ACM. The antioxidants most frequently used are nonvolatile amine compounds. 

Polymers with very good heat resistance (both in terms of deformation and of heat aging resistance) but which may be processed by conventional techniques, e.g. polysulphones and poly(phenylene oxides). 

Heat aging resistance does not appear to be as good as with the bis-phenol A epoxide but outdoor weathering is said to be superior. 

There is a frequent dememd for materials suitable for housings for computer, domestic, electrical and automotive equipment. In these applications toughness, excellent surface finish, surface durability, reasonable rigidity, dimensional stability, good weathering behaviour and low water absorption are common requirements. In these applications ABS is frequently considered first but its limited deflection temperature and heat aging resistance may lead to other... 

Transparent polyethylene is characterized by an enhanced freeze- and heat-aging resistance, and also by a... 

Excellent compression set and good heat aging resistance... 

Properties of GPO. GPO has excellent low-temperature properties, excellent dynamic properties ressembling that of natural rubber, a good ozone resistance and good heat aging resistance [116]. 

Ethylene-propylene elastomers are one of the main choices of automotive chemists and material engineers for sealing applications, as well as isolation systems, weather stripping, electrical components, etc. Heat aging resistance up to 130°C can be expected with certain sulfur cures and up to 160°C with peroxide-cured compounds [3], They also respond well to high tiller and plasticizer loads. Typical properties are shown in Table 8.7 [4],... 

In addition to the excellent oil resistance and heat aging resistance, the ECH homopolymer has particularly good air retention properties, by a factor of two better than butyl rubber. 

This class of blends was introduced in 1989, as a lower cost alternative to EPDM/PP blend. Its heat-aging resistance and use temperature limits are, however, inferior to the EPDM/PP blends. 

Rat Rattanasom, N., Prasertsri, S. Relationship among mechanical properties, heat ageing resistance, cut growth behaviour and morphology in natural mbben Partial replacement of clay with various types of carbon black at similar hardness level. Polymer Testing 28 (2009) 270-276. 

In addition to the conventional diallyl ortho-phthalate, diallyl J5t>-phthalate (DIAP) is also available commercially. It is more expensive but offers higher heat deflection temperature and heat aging resistance (Table 3.28). 

Polyphenylquinoxalines were cross-linked by acetylenic end-groups (Fig. 3.52), giving Tg = 321°C and good resistance to hot humid aging, but the addition of aliphatic hydrocarbon structure apparently sacrificed heat-aging resistance. Propargyl ether of bisphenol A (Fig. 3.53) was cured to a thermoset plastic with = 360°C. 

Heat aging resistance Excellent (upto 150 °C) Moderate (<100 °C) Good (to 120 °C)... 

Another extrusion-grade polyamide blend is a reactively compatibihzed PA6/polyolefin (PP or LDPE) alloy with some additional olefinic elastomer present for lowering the modulus (Jacquemet et al. 2000). Such low-modulus PA blends (Orgalloy LT series, Arkema) have been qualified for use in automotive under-the-hood air-intake systems such as clean air tubes and ducts. Low density, high chemical resistance to oil and greases, heat-age resistance, fatigue, and vibration resistance have been the main criteria for the selection of this blend in automotive air-intake duct applications. 

TPOs combine the advantages of elastomers and the extrudability of thermoplastics. TPOs are used in special cases where requirements, such as heat aging resistance, ozone resistance, low-temperature flexibility, flame retardancy and generally good chemical resistance, are to be fulfilled. TPOs allow the combination of relatively good mechanical properties with high flame retardancy and low smoke emission therefore, TPOs are preferred in critical environments, such as oil platforms, tunnels and underground. Their use is limited to LV cables. 

The thermoplastic IPNs have outstanding resistance to shrinkage and distortion on heat aging, resistance to ozone, and an improved balance of mechanical properties. 

The results indicate that the influence of UV stabilisers on heat ageing stability, when used in conjunction with pigments and antioxidants, is extremely difficult to predict in general terms. The results presented for four commercially employed UV stabilisers in Table 9.21 and Figure 9.19 indicate that in some instances UV stabiliser actually appears to enhance the heat ageing resistance, whereas in other instances antagonistic effects are shown, notably when such pigments as ferric oxide and cadmium sulfoselenide are employed. 

Successful applications of NDs in polymer nanocomposites for electronics materials [233] materials having proton conductivity [234] or enhanced thermal conductivity [235] for selective membranes, sensors, catalytic systems, nonlinear optical materials [230, 236], and elastomers of enhanced strength, wear and heat-ageing resistance [230,237,238] can all serve as examples. 

Hairdryers, irons and kitchen appliances Rigidity, brilliant surface gloss, good heat ageing resistance, antistatic properties, high HDT, mar resistance... 

Whilst the cross-linking is slow when the resin is the sole vulcanizing agent the reaction is increased tenfold by the use of stannous chloride dihydrate (up to 4 parts phr). These networks have good heat ageing resistance. 

Like the ethylene-propylene copolymer rubbers these rubbers are saturated and exhibit good oxygen, ozone and heat ageing resistance whilst those based on methyl acrylate also have some claim to oil resistance. 

Stabilized for both processing and Icmg-tera heat aging resistance. 

Copolymers of ethylene and methyl acrylate, and ethylene acrylics, have a fully saturated backbone, providing heat-aging resistance and inherent ozone resistance. They are compounded in a Banbury mixer and fabricated by injection molding, compression molding, resin transfer molding, extrusion, and calendering. 

BIMSM may be used instead of halobutyl rubber because it possesses a saturated backbone that imparts a heat aging resistance superior to XIIR. Also, tires can be constructed with a BIMSM-based innerliner that will hold air longer than conventional innerliners based on XIIR. 

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