TYRE SIDEWALL

A tyre retreading process in which new rubber is apphed as tread, on the tyre shoulders and on the tyre sidewalls. 

Wire and cable insulations, weather stripping, tyre sidewalls, hoses, seals... 

Zhang, H., 2009. EPDM rubber in blends with NR/BR- elastomers for ozone resistant tyre sidewall applications. PhD Thesis, University of Twente, Enschede, Netherlands. 

Adhesion of EPDM elastomers to polar substrates, for radiator hoses and V-belts, and of general purpose rubbers to carcass in tyre sidewall compounds is also improved, as is co-vulcanization of EPDM with polar rubbers. 

Particularly synergistic properties can be obtained using ternary polymer blends that cannot be achieved with binary blends. Ternary blends based on NR, BR and EPDM have been used for tyre sidewalls and show excellent ultimate properties, better ozone resistance and fatigue resistance under dynamic load. Spedlic morphology development, crosslinking behaviour and their correlation to mechanical properties of different ternary rubber blends like butyl rubber (IIR)/NR/SBR and NR/BR/SBR blends have been well... 

Substitutes for wax to provide protection of tyre sidewalls against static ozone cracking are examined. The use of low levels of wax or its complete elimination in the tyre sidewall by combinations with dialkyl paraphenylene diamine (77PD) or 2,4,6-tris - (N-1,4 dimethyl pentyl-p-phenylene diamino) 1, 3, 5 triazine (TAPDT) is discussed for the long term resistance to dynamic ozone crack resistance. In addition, a mechanism is proposed to explain how ozone reacts with antiozonants, which involves a scavenging function. 5 refs. 

A US manufacturer of precise non-contact product and process measurement systems, Bytewise Measurement Systems, has introduced a dedicated tyre sidewall bulge/ dent inspection system. Full details are given under the headings why measure tyre sidewalls , principle of operation, benefits of laser measurement technology, letter elimination software, and summary. 

A review is made of the literature describing the surface discolouration of black tyre sidewalls caused by exposure to ozone and formulation studies undertaken to overcome this problem. Methods examined include the use of nonstaining antiozonants and blending inherently ozone resistant rubbers such as EPDM, halobutyl rubbers and brominated isobutylene-paramethylstyrene copolymers with NR and/or polybutadiene. 67 refs. 

The addition of EPDM to compounds for tyre sidewalls to improve their ozone resistance was at first limited to the types containing dicyclopen-tadiene. Recently, and with equal success, a few ENB types have been used, such grades also having a low propylene content and medium-high unsaturation. In addition to being used in white compounds, EPDM is now also used in black compounds. 

As mentioned in Section 8.1.1, ethylene-propylene elastomers are currently used in compounds for tyre sidewalls. In this application also ternary blends have been used, including halogenated butyl rubber.With regard to EPDM and butyl rubber blends, there are no covulcanisation problems because both have a similar level of unsaturation. 

BLACK TYRE SIDEWALL COMPOUNDS BASED ON BROMINATED POLYISOBUTYLENE-CO-P-METHYLSTYRENE ELASTOMER AND ACCELERATED WITH 1,6-HEXAMETHYLENE BISSODIUM THIOSULPHATE Ignatz-Hoover F Newman N F Flexsys America LP Exxon Chemical Co. 

The disodium salt of hexamethylene bisthiosulphate (HTS) was evaluated as an accelerator in the zinc oxide mediated vulcanisation of tyre sidewall compounds containing a brominated isobutylene-p-methylstyrene copolymer. Rheometer profiles of blends with polybutadiene cured with sulphenamide, sulphur, zinc oxide and HTS showed a characteristic delayed action fast cure kinetic profile, while the same blends cured without HTS exhibited undesirable cure characteristics, with long early cure and fast late cure. Many vulcanisation characteristics and vulcanisate properties were largely dominated by a single cure component. State of cure was dominated by sulphur level, scorch delay and early cure time by HTS loading, and the time to reach t90 by the sulphenamide level. Time of flight secondary ion mass spectroscopy imaging showed that HTS favourably affected the distribution of curatives in blends with SBR. 11 refs. 

Formerly termed braced tread, rigid breaker or belted tyre. A pneumatic tyre in which the cords of the casing plies run directly across the tyre section from bead to bead, and not at an angle as in a cross-ply tyre the breaker in a radial-ply tyre is an inextensible band which runs circumferentially round the tyre between tread and casing. It is made up of layers of bias cut fabric set at discrete angles to confer the required stability in the tread but maintain the flexibility in the sidewall. 

A thin rubber sheet applied in the replacement of the sidewall pattern details in the retreading of pneumatic tyres. A similar film of rubber specially compounded to resist oxygen or ozone or to prevent the migration of carbon black into a lighter rubber, e.g., a tyre white sidewall. 

In all tyres there are three types of components, the reinforcement layer(s), the rubber parts and the steel bead wires which locate a tyre to the wheel, or rim of a vehicle. Rubber is used in packing strips, inner lining, sidewalls and the abrasion-resistant tyre tread. 

A typical automobile tyre consists of several parts (Fig. 5). The tread and sidewall make up the outside of the tyre. The tread is the portion of the tyre that comes into contact with the road, whereas the sidewall, or wall, is the side of the tyre that connects the tread and the bead. The tread is reinforced from underneath by the belt, which comprises a set of fabrics and/or wires. The plies, found in association with the belt, are layers of rubber-coated cords, which are typically made of fabric, polymer, fibreglass, or steel. The set of belts and plies is often collectively referred to as the cord, or cord body, of the tyre. The cords of the tyre wrap around the bead, the part of the tyre that rests on the tyre rim. The bead consists of both mbber bead filler and a series of steel bead wires. The last major part of the tyre, the innerliner, is a low-permeability... 

High cis- 1,4-poly butadiene is manufactured on a large industrial scale and occupies a well-defined position in the elastomers market. It is employed mainly in the tyre industry, where it is blended with natural rubber and/or with styrene-butadiene rubber and applied in either sidewalls, threads or rims of tyres. It should be noted in this connection that natural rubber, in contrast to its synthetic counterpart, displays some physical properties that appear to be useful in the manufacture of tyres for heavy-duty machines. The fact is that some non-hydrocarbon substances appearing in natural rubber in small amounts (such as polypeptides) protect the high-dimensional tyre formed against collapsing prior to the vulcanisation process and thus enable a high-quality product to be obtained. 

The textile elements of tyres comprise reinforcing elements within the sidewalls and across the tread using continually developing structures which have come a long way from the CTOSS-ply or bias ply stractures of the post-war period in which fibre/fabric content could be as high as 21% (Fig. 11.1 (a)). Modem radial ply stmctures, on the... 

Recent developments by DuPont in high performance car tyres have shown that inclusion of para-aramid as Kevlar EE, which is a pre-dispersed form of Kevlar pulp, in the rubber sidewall apex increases stiffness and improves cornering efficiency. The apex is part of the located radially outward of the tyre s bead (see Fig. 11.1 (a) and (b)). The EE stands for Engineered Elastomer and DuPont has introduced Kevlar EE into beltings, seals and gaskets, and bicycle tyres to improve resistance to abrasion, tear and puncture, modulus, and cut and chip resistance. ... 

Fast extruding furnace carbon black FF N550 Oil furnace 53 43 Medium high reinforcement, high modulus and hardness, low die swell and smooth extrusion, used in tyre inner lines, carcass and sidewall compounds and hose and other extruded goods... 

General-purpose furnace carbon black GPF N660 Oil furnace 63 36 Medium reinforcement and modulus, good flex and fatigue resistance, low heat build-up, used in tyre carcass, inner lines and sidewalls, sealing rings, cable jackets, hose and extruded goods. 

Laser desorption MS has been used for direct analysis of rubber additives, in situ at the surface of elastomeric vulcanisates [201,202]. For example, the technique was used to analyse a sample of truck tyre that displayed premature sidewall cracking. By using a single laser pulse, the molecular ions of several intact molecular species (AOs, antiozonants and a production impurity of an additive) were observed on the rubber surface. Also McClennen et al. [203] have used controlled laser energy to desorb organic additives from a rubber vulcanisate. 

When the tyre is loaded by the weight of the vehicle, the sidewalls are deformed in the region immediately above the road contact area. As the wheel rotates, the contact area moves round the tyre, and so too does the area of deformation of the sidewall (Figure 7.9). 

For this reason, the sidewalls of a tyre are constructed of rubber with the least energy loss. When cost is not a factor, this means the use of a special low loss rubber such as polybutadiene. However, it is important to recognise that cost is often a factor, and many less expensive tyres have sidewalls constructed of cheaper natural rubber, with consequent higher heat generation and more severe restrictions on vehicle speed. 

So, a top quality tyre, as required for high speed litxury vehicles, is constructed of three different kinds of rubber in the sidewall (often polybutadiene blends), carcase (natural rubber) and tread (often butyl rubber blends). For a less expensive tyre, constructed totally of natural rubber, a similar (though lesser) effect can be achieved by using more flexible, lightly vulcanised, rubber in the sidewall and higher modulus, more extensively vulcanised, and so more tightly cross-linked, rubber in the tread. 

Truck tyre durability is discussed with reference to the importance of identifying the mode, initiation point, propagation and cause of failure. The process is illustrated for two possible types of failure mode, i.e. tread separation and breaker/ply ending separation. In the development of new compounds, it is important to consider the operating conditions (strain/stress/temp. levels) of the component in the running tyre. The use of compound fracture mechanical behaviour measurements in the development of sidewall compound with improved cut initiation/propagation resistance is described. The retreadability of the truck tyres is also considered with... 

The influence of polymers and additives on the service life of non-tread tyre components is discussed on the basis of results obtained from studies of inner liner, belt and sidewall compounds. The effects of the bromine content of bromobutyl rubbers on the performance of inner hners, and of sulphenamide accelerators on the adhesion of NR belt compounds to brass coated steel cords were investigated. The mechanical properties and ageing and ozone resistance of black sidewall compounds consisting of NR blends with neodymium catalysed polybutadiene protected with different antioxidants and antiozonants were also evaluated. 5 refs. 

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