Polybutadiene rubber , properties

This lower has a number of ramifications on the properties of polybutadiene. For example, at room temperature polybutadiene compounds generally have a higher resilience than similar natural rubber compounds. In turn this means that the polybutadiene rubbers have a lower heat build-up and this is important in tyre applications. On the other hand, these rubbers have poor tear resistance, poor tack and poor tensile strength. For this reason, the polybutadiene rubbers are seldom used on their own but more commonly in conjunction with other materials. For example, they are blended with natural rubber in the manufacture of truck tyres and, widely, with SBR in the manufacture of passenger car tyres. The rubbers are also widely used in the manufacture of high-impact polystyrene. 

NR, styrene-butadiene mbber (SBR), polybutadiene rubber, nitrile mbber, acrylic copolymer, ethylene-vinyl acetate (EVA) copolymer, and A-B-A type block copolymer with conjugated dienes have been used to prepare pressure-sensitive adhesives by EB radiation [116-126]. It is not necessary to heat up the sample to join the elastomeric joints. This has only been possible due to cross-linking procedure by EB irradiation [127]. Polyfunctional acrylates, tackifier resin, and other additives have also been used to improve adhesive properties. Sasaki et al. [128] have studied the EB radiation-curable pressure-sensitive adhesives from dimer acid-based polyester urethane diacrylate with various methacrylate monomers. Acrylamide has been polymerized in the intercalation space of montmorillonite using an EB. The polymerization condition has been studied using a statistical method. The product shows a good water adsorption and retention capacity [129]. 

Copolymers of styrene, especially with acrylonitrile, also attained increasing importance both in the unmodified form (30) and modified with rubber as ABS copolymers. The first products of this kind were blends of nitrile rubber and SAN (31). However, these only had mediocre mechanical properties because the interfacial compatibility was insufficient. The breakthrough came when nitrile rubber was replaced by a polybutadiene rubber which was grafted in emulsion with styrene and acrylonitrile... 

The information on physical properties of radiation cross-linking of polybutadiene rubber and butadiene copolymers was obtained in a fashion similar to that for NR, namely, by stress-strain measurements. From Table 5.6, it is evident that the dose required for a full cure of these elastomers is lower than that for natural rubber. The addition of prorads allows further reduction of the cure dose with the actual value depending on the microstructure and macrostructure of the polymer and also on the type and concentration of the compounding ingredients, such as oils, processing aids, and antioxidants in the compound. For example, solution-polymerized polybutadiene rubber usually requires lower doses than emulsion-polymerized rubber because it contains smaller amount of impurities than the latter. Since the yield of scission G(S) is relatively small, particularly when oxygen is excluded, tensile... 

Impact Properties. Chemical Nature of the Rubber. If the rubber is too compatible with the matrix, it will dissolve in the rigid material and disperse on a molecular scale. Little or no reinforcement will occur since the rubber particles become smaller than the radius of the tip of a stress-induced propagating crack. However if it is highly incompatible, good adhesion between rubber and matrix cannot be obtained. For example polybutadiene rubber adheres poorly to a styrene/acrylonitrile copolymer, but a nitrile rubber adheres well to the SAN copolymer. If grafting techniques are used however, compatibility is less of a problem since the rubber is chemically bonded to the matrix. 

The above described method was applied for characteristics of HIPS both commercial and obtained in laboratories by means of different methods using different types of polybutadiene rubbers. Micro-structure elements of this material are compared to their physical 6uid mechanical properties in table I. 

Table 12.9 Effect of polybutadiene rubber viscosity on ESCR properties of an extrusion-grade HIPS...

Table 12.10 Effect of structural properties on 7.8 % high-c-w polybutadiene rubber ESCR in an extrusion-like HIPS with ...

Like HIPS, acrylonitrile-styrene-butadiene (ABS) polymers have polybutadiene rubber incorporated into styrene-acrylonitrile copolymer (SAN), giving a resin consisting of a two-phase system with inclusions of rubber in a continuous glassy matrix. Again, development of the best properties requires grafting between the glassy and rubbery phases. 

Sadhu, S. Bhowmick, A.K. Preparation and properties of nanocomposites based on acrylonitrile-butadiene rubber, styrene-butadiene rubber, and polybutadiene rubber. J. Polym. Sci. B Polym. Phys. 2004, 42 (9), 1573-1585. 

Acetylene was polymerized in the presence of polybutadiene rubber and the blends were investigated for their electrical conductivity [Rub-ner et al., 1983 and Sichel and Rubner, 1985]. The electrical properties of these blends were explained in terms of the morphological features [Tripathy and Rubner, 1984]. In these investigations, a conductivity of 10 S/cm was achieved at PACE loadings above 30%. Polymerization... 

While the standard ABS resins, containing 10 to 25% polybutadiene rubber, indeed have a wide range of useful engineering properties, it is possible to extend further and improve these... 

A commercial blend of SMA and polycarbonate (Arloy , ARCO) was offered for some time, but recently it was discontinued. The polarity of SMA copolymer may account for the good degree of compatibility between the two resins. The blend contained the polybutadiene rubber normally used in SMA resins for impact strength. It exhibited good low temperamre impact strength (Table 15.8) and in many properties was similar to ABS/PC blend. 

MAJOR APPLICATION H-H PVC is mostly studied in academic field to understand its structure/property relationship, thermal degradation behavior, and mechanism. Its properties are compared to those of commercial head-to-tail PVC. Pure H-H PVC has no significant industrial applications. H-H PVCs containing 40-65 wt% of Cl, also called chlorinated polybutadiene rubber-resins, are used for coating, paint-based applications and the preparation of threads, tires, tubings, and films, etc. 

Starting in the 1980 s, a number of governmental recycling policies created a demand for recycled thermoplastic olefin (TPO) for post-consumer applications. Since polystyrenes and TPOs are not miscible, polystyrene-TPO diblock copolymers are being developed to reduce the interfacial tension in PS/TPO blends. TPOs are tough materials with low stififiiess properties. If blended with polystyrene, they improve the toughness of polystyrenes. If compatibilized, the properties of PS/TPO should be similar to styrene-hydrogenated polybutadiene rubbers. 

Reasonably early however in the development of telechelic polybutadiene/acrylonitrile, Brenner and Drake (22) showed that mercaptan- and carboxyl-terminated liquid polybutadiene/acrylonitrile did respond to electron-beam (1-5 megarads) and cure (2-3 seconds/pass) from the liquid to the solid state. The mercaptan polymer (3.1% RSH, 23% bound acrylonitrile, Mn 1700) cured more readily. CTBN as expected required 50-100% higher irradiation dosage levels. With both MTBN and CTBN-type products of higher acid content (6% vs 3%), gum rubber properties of 13.8-34.5 mPa were obtained with 60-100% elongation. The E-beam cures were carried out in air at ambient temperature. Thus, unformulated telechelic polybutadienes were shown to be substantive to cure in the presence of ionizing radiation. 

MABS is similar to ABS except for the addition of an additional monomer, usually methyl methacrylate. MABS is an amorphous, clear, transparent material with thermal and mechanical properties like ABS. The transparency is achieved by matching the refractive indices of the matrix resin (the transparent acrylate—acrylonitrile—styrene polymer) with the polybutadiene rubber impact modifier. MABS has the highest impact resistance of all the styrenic plastics. Sometimes called transparent... 

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