TR
Rubbers > Group R
SBS - Copolymer styrene-butadiene-styrene | ||||||||
| Products range | ||||||||
In Mexpolimeros we offer a wide range of SBS elastomers and their compounds developed according to their needs, ensuring quality products and service. Te have grades and compounds, opaque, translucent, crystals, compounds of low densities products for industrial applications with excellent characteristics of environmental resistance, such as oil and grease, acids and solvents, high temperatures. XPRENE B is divided into a wide range of products such as soft touch, expandable, high temperature resistant, low compression set, halogen flame retardant and many other specialty categories. The wide range of additives and olefins incorporated into our compounds have allowed us to create a vast array of products that can replace either the PVC elastomer used in footwear or natural rubber gaskets and seals manufactured. |  | |||||||
| Block copolymer styrene butadiene | ||||||||
SBS block copolymers , also known as Styrene-butadiene-styrene (SBS) thermoplastic elastomers , flows easily into the processing at different temperatures and act as elastic rubbers reinforced under normal application conditions. It is a type of copolymer called a block copolymer. Its backbone is composed of three segments; a sequence of repeating units of styrene, a labeling sequence butadiene repeat units and topped with another block of styrene units to give a block copolymer of styrene-butadiene-styrene (SBS). Block copolymers of styrene-butadiene are polymerized in solution and have different, linear, radical and multiarmed structures. They are free flowing materials showing different viscosities to adapt their properties to multiple applications that can be used. The linear degrees of low molecular weight offer very good flowability, are prized for their transparency and processability. The radial degrees showed resistance molding, and offer superior mechanical properties with high performance modification. The multilink degreesshow a combination of low viscosity with temperature resistance. This performance makes them suitable for a wide range of technical applications such as compositions, adhesives and sealants, asphalt modification for roads and pavements waterproofing membranes. They are also used in applications Shoeleather and polymer modification. SBS Elastomer meet different food contact applications. The typical presentation of these products can range from soft lumps versions powder. Block copolymers of styrene-butadiene have different, linear, radical and multiarmed structures. SBS linear low molecular weight provide good transparency and processabilityBuende flow thanks to the radial degrees provide superior mechanical properties at high yield modification and increased resistance of cast iron, the degree multi-arm provide a combination of low viscosity and better temperature resistance. |  | |||||||
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| Properties | ||||||||
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| Physical and mechanical properties | ||||||||
Polystyrene is a tough hard plastic, and this gives SBS thermoplastic durability. Polybutadiene is rubbery, and this gives SBS elastomer its rubber-like properties. In addition, the polystyrene chains tend to cluster. When a group of styrene SBS molecule binds to a group, and the other strand of the same polystyrene SBS molecule binds to another group, the different groups are attached with rubbery polybutadiene chains. This gives the material the ability to retain its shape after being stretched.At room temperature (below the glass transition temperature of polystyrene) adding styrene block cluster (domains) to act as physical crosslinks rigid, maximizing the high elastic properties of the butadiene block. At elevated temperatures the styrene domains are unraveled and the polymer becomes a, suitable for extrusion and injection molding thermoplastic melt. The elastic properties of stretch and recovery SBS elastomer match conventional vulcanizate, but the advantage is that there is a stage of "healing", and the processing time and power consumption are greatly reduced. Also the SBS can be processed from solution. However the thermoplastic SBS has degradation problems at high temperatures and butadiene content makes it prone to oxidation and wear, without suitable antioxidants. The SBS offers excellent surface friction coefficient, low permanent deformation, a tensile strength. The material can be temporarily deformed by compression or elongation, but when these forces cease, the material returns to its original shape . XPRENE B thermoplastic elastomers and have elastomeric properties but are processed as plastics. |  | |||||||
| Thermal properties | ||||||||
The glass transition temperature (Tg) of the polybutadiene blocks is typically -90 ° C, while the Tg of the polystyrene blocks is + 100 ° C. Therefore, at any temperature between -90 ° C and + 100 ° C, SBS act as an elastomer physically crosslinked. The operating temperature is guaranteed from -55 ° C to + 70 ° C.These unsaturated TPE low tend to have weatherability and quite poor UV and a moderate stability at elevated temperatures due to their double bonds. They must be tested for possible yellowing or brittleness. This group of products is sometimes also described as TR. At high melting temperatures and during recycling, it is important to be careful with undesired bonds. For this family of products is very important in the footwear industry. |  | |||||||
| Electrical properties | ||||||||
SBS elastomer is usually good insulator with high electrical resistivity relative, being nonpolar. However, the electrical properties of the compounds of XPRENE B are dependent on the ingredients used in the mixture of the elastomer base. Antistatic compounds do SBS and even conductive by the incorporation of sufficient amounts of graphite, special types of carbon black, certain metal powders or polar products in the rubber mixture. However, the conductivity obtained by these means does not resemble that of metals.It is not possible to make a clear distinction between insulating elastomer, antistatic and drivers. SBS polymers generally having a resistivity below 10² Ohms are considered conductors; between 10¹³ and 10² Ohms, antistatics; and above 10¹³ Ohms, insulators. |  | |||||||
| Optical properties | ||||||||
| One of the features of a two - phase system is that light is scattered when passing from one phase to another, resulting in different levels of transmission of light, in the case of SBS polymer also have high transparency degrees. |  | |||||||
| Chemical properties | ||||||||
SBS polymers well resist stress crack (stress cracking) acid, hydroxides, methanol and ethanol, absorb oil, fats, aliphatic hydrocarbons. Instead not Reisten polar hydrocarbons, aromatic hydrocarbons, carboxylic acid, gasoline, oil ASTM No 1 Paraffiico, ASTM # 3 oil Aromatic, toluene and benzene. Good water resistance but poor resistance to water vapor. Low resistance to oils (animal and plant). The chemical nature unsaturated SBS rubber makes XPRENE B is sensitive to the action of heat from UV and ozone, but the use of special additives improves resistance to these environmental effect. |  | |||||||
| Polimerization | ||||||||
Block copolymers of styrene-butadiene is polymerized in solution, ys and is available a full portfolio of linear, branched and radial degrees. In the polymerization, the diblock copolymer styrene-butadiene living becomes a linear SBS triblock copolymer by subsequent addition of a difunctional coupling agent, whose amount can vary for different yields polymers coupled SBS and uncoupled SB. Alternatively, the addition of a coupling agent with a functionality of three or more leads to the formation of copolymer SBS radial blockWhose number of arms SB depends on the structure of the polyfunctional coupling agent. When styrene is added instead of the coupling agent, we refer to the polymerization SBS three stage copolymer leads to linear SBS. Finally, we must add a terminating agent to terminate the active chain ends. Chemical residues of termination reactions or coupling must be inactive to the antioxidant to prevent the yellowing of SBS copolymer. Based on the above, it follows that the linear SBS can be obtained from the three stages, a polymerization process and the two stages, while the radial SBS can only be obtained from the polymerization process of the two stages. When the polymerization reaction of butadiene and styrene is carried out simultaneously in a batch reactor, a copolymer of SB type is obtained. In this case, the polybutadiene blocks and polystyrene are joined through a polymer chain portion (taper) in which a progressive variation of the composition is observed.The resulting lack of the second polystyrene block does not allow the mechanical properties of pure triblock copolymers, but improves other useful properties for adhesives and modifications bitumen. Dry and oil extended grades are available in different forms: pellets, granules and powder. |  | |||||||
| Processability | ||||||||
The SBS belong to the class of thermoplastic elastomers having the mechanical properties of rubber at room temperature and thermoplastic processing capabilities. The SBS polymers are rubbery without being crosslinked, so it is easy to process to achieve useful forms, usually processed more or less at 140 to 200 ° C. SBS resin can be easily molded by injection, extrusion or molding, of injection, blow molding, co-stapaggio, overmolding, 2K. |  | |||||||
| Overmolding - 2K | ||||||||
Adhesion to a wide range of polar and nonpolar substrates such as PP, PA, ABS, PC, PS, SAN, ASA, PC / ASA, PBT, PET, ABS / PC etc. also it has a very good adhesion to PE compared with SEBS and SEPS. For the selection process overmolding or 2K in certain TPEs vary the bond strength in the application, for example if the molding process is chosen for multi shot (multi-shot) compared to the insert molding, the first certain promotes increased binding strength or binding because the two materials melt joining state, while the latter gives a poor bond since one of the two materials (plastic) is superimposed on the other that is not cast (metal). So the selection process to be applied is a key to produce a high quality factor. Within the selection of material, It depends on the company and product handling, where one has to consider the characteristics of each material for the application of overmolded, as there are a variety of materials having different properties that provide softness, texture, adhesion, and wall thickness of the material. For the effect of the thickness is necessary to know the hardness of the material, for example when it has a TPE material with a low thickness (typically> 1mm) would be perceived harder and vice versa when there is more than 1mm thickness will feel smooth. To ensure a good link overmolding their searches a thickness in the range 1.5mm for most applications overmolding. since there are a variety of materials having different properties that provide softness, texture, adhesion, and wall thickness of the material. For the effect of the thickness is necessary to know the hardness of the material, for example when it has a TPE material with a low thickness (typically> 1mm) would be perceived harder and vice versa when there is more than 1mm thickness will feel smooth. To ensure a good link overmolding their searches a thickness in the range 1.5mm for most applications overmolding. since there are a variety of materials having different properties that provide softness, texture, adhesion, and wall thickness of the material. For the effect of the thickness is necessary to know the hardness of the material, for example when it has a TPE material with a low thickness (typically> 1mm) would be perceived harder and vice versa when there is more than 1mm thickness will feel smooth. To ensure a good link overmolding their searches a thickness in the range 1.5mm for most applications overmolding. 1mm) would be perceived harder and vice versa when it is thicker than 1mm will feel smooth. To ensure a good link overmolding their searches a thickness in the range 1.5mm for most applications overmolding. 1mm) would be perceived harder and vice versa when it is thicker than 1mm will feel smooth. To ensure a good link overmolding their searches a thickness in the range 1.5mm for most applications overmolding. |  | |||||||
| Compounds | ||||||||
The products of class XPRENE B is obtained by mixing in compoundSBS resin, oil, polystyrene, additives, and some grades have reinforcements of a continuous phase morphology. The SBS elastomeric phase gives the material the elastic properties and the softness, the PS plastic phase provides the material with the mechanical properties and hardness and is characteristics that it maintains at low temperatures, up to -45 ° C. The inclusion of a charge to a polymeric matrix can describe a compatibilization effect between immiscible or immiscible mixtures and thus also exhibit excellent electrical conductivity, hardness, rigidity, mechanical and thermal resistance, and even to provide bactericidal properties to the new material. Polymer melt mixing has been the fast track for the design of new resins that seek to combine the properties of SBS and PS, to reach the superiority of certain characteristics due to the synergy that they can present. |  | |||||||
| Applications | ||||||||
The granules SBS is very soft-looking rubber is mostly used in applications where mechanical performance and chemical characteristics are less important and in which the soft touch and the handle is valued. L as typical applications are, profiles, housewares, handles, knives, handles, fittings, feet, storage, to slip lfombras, slip inserts, knobs, buttons, seals, profiles, covers pedal, tools electrical, seals for cables, plugs and sockets, handles "soft touch" for various utensils, fist bicycle, motorcycle fist, biter,Grip pen, toothbrush, fishing baits, ball rehabilitation, medical mattress, overprinted soft edges on decks, boxes garden tools, knobs, dampers, fins, masks, caps, terminal, non - slip, housewares, caps , toys, appliances, sealing rings, cable glands, save-remote, furniture, glass cleaners, drain cleaners for sinks, legs, construction, seats, clothing doors, handles, seats, sorpresitas. The SBS pellets in the industry of shoes, insoles, soles, fences, boots in many transparent, matte shapes and bright , aged and any color. They are alsosuitable for a wide range of technical applications such as compositions, adhesives and sealants, asphalt modification for roads and pavements waterproofing membranes. They are also used in applications modifying the polymer, automotive, seals, carpets, seals FDA, coatings lids of bottles, conveyor belts, gum, hoses, rolls, insulators, polystyrenes, friction, technical articles, adhesives, castings , O - rings, paper and textile coatings, to mortiguadores for wood sheets, profiles backlashes, g uarniciones for sprinklers, flexible rubber components for bedsteads , bases stairs Scaffold or end pieces, rubber bumpers, door handles , flexible coverings, etc. |  | |||||||