Kraton rubber

Kraton" rubber business before he retired some years ago. I picked up the task of presenting Kraton 101 the Basics , once he had left, and this material has been shared with hundreds of people along the way, with people new to the business, and with customers. That important legacy continues today, and in a parallel universe I know Geoff is still in the front lines ably explaining, in simple, but not simpler terms, what makes these polymers as fresh and new as they were when they we first understood over 30 years ago. 

AB and ABA block copolymers may also be prepared by coupling the "living" anion with a suitable anion reactive coupling agent. The coupling agents include methylene halides, epoxides, phosgene, as well as some anhydrides. The Shell Kraton rubbers are prepared in this manner. Methylene chloride, as shown below, is employed to couple the AB block macroanions. 

The Box-Behnken Statistical Design is shown in Table 5.2. Material-related input variables (HDPE fraction, Kraton rubber concentration) and processmixing-related input factors (screw speed, in revolutions per minute) and their design ranges are shown in Table 5.3 and 5.4, respectively. Responses of interest are compounded blend mechanical properties and overall conversion costs. 

Response surfaces showing the effects of composition on mechanical properties are compared with the compatibilized blend and the glass-fiber-reinforced composite in Fig. 5.7 and 5.8. Regression models for the compatibilized blends are shown below the response surface graphs (Fig. 5.7, a-e) versus reinforced (Fig. 5.8, a-e) blends shows a marked difference in the nature of the responses. Most notably, the curvature in the response observed in the compatibilized blends has vanished, and the response is a function of Kraton rubber only for the flexural modulus, notched Izod impact, and tensile strength. Similarly, the heat distortion temperature is now only a linear function of Kraton and HDPE levels. Finally, elongation at break has been reduced to a single value (3.43 0.45%), as more than 90% of the variability in the data was explained by the mean value. Thus,... 

The shift in allowable compositions is the direct result of the elongation at break response shifting with changing rpm. As described above, as rpm increased, elongation at break increased for a given composition. Mechanical properties for a given blend composition (% HDPE, % Kraton rubber) and operating rpm se-... 

Block copolymers containing 20-40% styrene are also useful as impact modifiers for ignition-resistant HIPS as well as other polystyrene resins. Kraton rubbers are available from Shell Chemical Co. and Vector rubbers are available from Dexco Polymers (a joint venture between The Dow Chemical Co. and The Exxon Chemical Co.). Both grades are used extensively for this purpose as are other similar products from other suppliers. Kraton rubbers are usually triblock copolymers of SBS type. The center block is polybutadiene with terminal blocks of polystyrene (49-51). By far the largest use of block copoljuners is in the form of TIPS resins. There are a number of suppliers, with Phillips Petroleum and BASF... 

The living nature of polystyryl anion has been applied for the system of diblock, triblock, and multiblock copolymers [67 70]. Examples for commercial products are Kraton rubber (Shell Oil Co.), a styrene butadiene styrene triblockcopolymer, and Styrolux (BASF AG), a styrene-butadiene-styrene starblockcopolymer. First, a block polystyrene can be prepared that remains active then a new monomer can be added. Termination with dimethylsilicium dichloride yields a triblock copolymer ... 

Resin Group II (end-block compatible resins). These resins increase or decrease the end-block Tg value of Kraton samples without changing the value of the mid-block domain. These resins also increase simultaneously the modulus values of the Kraton rubber. Aromatic resins, A-F in Table 6, belong to this group. The changes of end-block depend on the of... 

Hydrogenated SBS triblock polymers have become increasingly important (Kraton G by Shell). With the original polybutadiene block comprised of 65% 1,4-and 35% 1,2-structures the elastomeric central block is equivalent to that of a high-ethylene ethylene-butene rubber. 

Kraton Polymers has developed a multiarm SIS (Kraton 1320X [37,46,47,50]) and SBS (Kraton KX-222C, [48,49]) for rapid UV/e-beam cure. Besides heat resistance improvements, plasticizer resistance is also improved in cured rubber-based systems. The dioctyl phthlate plasticizer common in PVC backing films is soluble in the styrenic domains of SBCs. Crosslinking of the mid-block provides cohesion even after plasticizer attack [51]. 

Kraton, the yellow rubber-like material often found on the bottom of running shoes, is a copolymer whose structural information is known. It is formed from a group of styrene units, i.e., a block of polystyrene, attached to a group of butadiene units, or a block of... 

The hydrogenation of the centre block of SBS copolymer produced oxidation stable thermoplastic elastomer. This product was commercialized by the Shell Development Company under the trade name of Kraton G. The field of thermoplastic elastomers based on styrene, 1-3-butadiene or isoprene has expanded so much in the last 10 years that the synthetic rubber chemist produced more of these polymers than the market could handle. However, the anionically prepared thermoplastic system is still the leader in this field, since it produced the best TPR s with the best physical properties. These TPR s can accommodate more filler, which reduces the cost. For example, the SBS Kraton type copolymer varies the monomer of the middle block to produce polyisoprene at various combinations, then, followed... 

HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HNS NTO NTO/HMX NTO/HMX NTO/HMX PETN PETN PETN PETN PETN PETN PETN PETN PETN PETN RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX TATB/HMX Cariflex (thermoplastic elastomer) Hydroxy-terminated polybutadiene (polyurethane) Hydroxy-terminated polyester Kraton (block copolymer of styrene and ethylene-butylene) Nylon (polyamide) Polyester resin-styrene Polyethylene Polyurethane Poly(vinyl) alcohol Poly(vinyl) butyral resin Teflon (polytetrafluoroethylene) Viton (fluoroelastomer) Teflon (polytetrafluoroethylene) Cariflex (block copolymer of butadiene-styrene) Cariflex (block copolymer of butadiene-styrene) Estane (polyester polyurethane copolymer) Hytemp (thermoplastic elastomer) Butyl rubber with acetyl tributylcitrate Epoxy resin-diethylenetriamine Kraton (block copolymer of styrene and ethylene-butylene) Latex with bis-(2-ethylhexyl adipate) Nylon (polyamide) Polyester and styrene copolymer Poly(ethyl acrylate) with dibutyl phthalate Silicone rubber Viton (fluoroelastomer) Teflon (polytetrafluoroethylene) Epoxy ether Exon (polychlorotrifluoroethylene/vinylidine chloride) Hydroxy-terminated polybutadiene (polyurethane) Kel-F (polychlorotrifluoroethylene) Nylon (polyamide) Nylon and aluminium Nitro-fluoroalkyl epoxides Polyacrylate and paraffin Polyamide resin Polyisobutylene/Teflon (polytetrafluoroethylene) Polyester Polystyrene Teflon (polytetrafluoroethylene) Kraton (block copolymer of styrene and ethylene-butylene)... 

Thus, in alkyd, polyester, and epoxy coatings applied to CRS, phosphatized steel, and aluminum, the use of ZAs APG (aminofunctional) and CPG (carboxy-functional) has allowed for the virtual elimination of blister formation and corrosion after 300 h of salt fog exposure. The use of multifunctional ZAs in a Kraton base adhesive has allowed for a 52% increase in T-peel strength on EPDM rubber when compared with the same adhesive containing aminofunctional silane. Incorporation of mercaptofunctional ZA into crosslinkable elastomers has... 

The sample sheets were prepared by pouring a 10% solution of Kraton 102 in the appropriate solvent into a carefully leveled glass tray with a piece of plate glass cemented to the bottom. The entire tray was placed on a composite cork-rubber cushion to help damp out vibrations. The tray was covered with a piece of cardboard with numerous pinholes to allow the solvent to evaporate. After several days the sheet was removed and kept at room temperature for two weeks before strips were cut. To check for residual solvent, several strips were preweighed and then exposed to vacuum at room temperature for 48 hours. No change in weight was observed. 

Figure 19.11 Loading/unloading/reloading curves of rubber (35% Kraton)-modified sPS with entropic effects in reloading mode (a) specimen injection moulded into a mould at 120°C (b) annealed for 30 min at 180°C...

Figure 19.13 shows the dynamic mechanical properties of such a blend of sPS with a mixture of Kraton G 1651 (15 %) and microsuspension rubber particles (20%) consisting of 60% butyl acrylate (BA) core grafted with 40% styrene shell (S//BA). The glass transition temperatures of the Kraton (-60 °C) and the butyl acrylate (-45 °C) phases can be easily distinguished from one another. The TEM image of such a product after deformation is shown in Figure 19.14. The annealed specimen is shown since the two rubber types are better discernible than in the nonannealed sample. As expected, crazing and voiding in the rubber particles dominate. The product had the following notched impact strengths (ISO 179/eA) injection moulded (80 °C mould temperature) 6.3, injection moulded (140 °C) 4.0 and annealed 3.7kJ/m2.

Figure 19.13 Dynamic shear modulus (cycles/s) of sPS, rubber modified with a mixture of 15 % Kraton G 1651 and 20 % S//BA particles produced in microsuspension...

Figure 21.9 Rubber midblock effect on dynamic properties of comparable block copolymers by I. Kadri, Shell Chemical Company, Kraton Polymers (internal communication), SRTCL Laboratory, Louvain, Belgium (1999)...

KRATON Shell Kraton Dl 102 rubber SMMA = Nova NAS 21 styrene methy methacrylate copolymer. 

---