Styrene-isoprene copolymers

G-5—G-9 Aromatic Modified Aliphatic Petroleum Resins. Compatibihty with base polymers is an essential aspect of hydrocarbon resins in whatever appHcation they are used. As an example, piperylene—2-methyl-2-butene based resins are substantially inadequate in enhancing the tack of 1,3-butadiene—styrene based random and block copolymers in pressure sensitive adhesive appHcations. The copolymerization of a-methylstyrene with piperylenes effectively enhances the tack properties of styrene—butadiene copolymers and styrene—isoprene copolymers in adhesive appHcations (40,41). Introduction of aromaticity into hydrocarbon resins serves to increase the solubiHty parameter of resins, resulting in improved compatibiHty with base polymers. However, the nature of the aromatic monomer also serves as a handle for molecular weight and softening point control. 

Now again, a state of inhomogeneity in polymers, so especially interesting in films and interfaces, occur when discontinuities are built into the main valence chains and networks. Block polymers are the classic embodiments of this. Many periodic distances separating domains in such alternating or rhymthic copolymers have been reported. These indicate existence of phases in laminar domains and, in other cases, of spherical domains.(51) Cases are shown experimentally for styrene/isoprene copolymers and also for styrene/butadiene.(52,53,54)... 

Akbulut and Toppare also found very similiar effects upon copolymer composition, total conversion and R.M.M. control in the styrene-isoprene copolymer system [83] with the analogous traces to Figs. 6.19 and 6.20 shifted to slightly more anodic values and with a better total conversion at high potential in the presence of 25 kHz ultrasound. 

The addition of an elastomer (typically a high butadiene content SBS) to SBC will serve to enhance further the elastomeric properties of the SBC. One key feature mentioned previously was improvement in hinge life properties. SBS copolymers can also be added to thermoformed sheet in blends of SBC and crystal polystyrene. The SBS does cause some loss of clarity, but gives more impact resistance to the sheet. Selection of the proper SBS can result in minimal loss of clarity, typically at 3-10% loadings. Styrene-isoprene copolymers (SIS) have also been tested with SBC and can give similar results in impact property improvement. 

Methods have been developed for the analysis of hydrocarbon polymers (e.g. styrene, butadiene and isoprene) by MALDI-TOF-MS, through the attachment of Ag(acac) to matrices of tran5-3-indoleacrylic acid or l,4-bis(2-(5-phenyloxazolyl))benzene . SUver-cationized molecular ions were produced for polymers of styrene, butadiene and isoprene up to mass 125,000 Da. For lower-mass styrene polymers, the resolved oligomer molecular ions provide information concerning the end group. This technique permits the analysis of many commercially important materials such as acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile, styrene-methyl methacrylate and styrene-isoprene copolymers. The use of the salts of transition metals other than Ag, Cu or Pd as the cationizing agents fails to cationize polystyrenes in MALDI. The ability of MALDI to reduce metals to the oxidation state 4-1 is critically important to polystyrene cationization, as without this reduction MALDI tends to fail to form polystyrene-metal cations. Cu(acac)2 was used for the verification of the above . 

For the case of homopolyisoprene/styrene-isoprene copolymer mixtures [364], it was shown that the miscibility increases in the order four-arm star-block < triblock < diblock. Increased incompatibility was observed in the pair poly(isoprene-g-styrene)/polyisoprene [365] even when the molecular weight of the homopolymer was much lower than the PI segment length between junction points of the graft copolymers. 

The film preparation technique has been described elsewhere (3). It should be noted that films are observed directly and by phase contrast microscopy. Thus, we can compare the emulsifying effect of different styrene-isoprene copolymers (random, block, and graft copolymers) of the same overall composition (40 wt % PS, 60 wt % PI) and practically the same molecular weight (Mn — 50,000) in a given PS-PI blend, where Mn of PS is 45,000 and Mn of PI is 25,000. The appearance of the films obtained with different blend compositions is depicted in Figure 1. Hazy or opaque areas are striped. From Figure 1, it appears that random copolymers always cause hazy films which means... 

The ability of living polymers to resume growth with the addition of fresh monomer provides an excellent opportunity for the preparation of block copolymers. For example, if a living polymer with one active end from monomer A can initiate the polymerization of monomer B, then an A-AB-B type copolymer can be obtained (e.g., styrene-isoprene copolymer). If, however, both ends of polymer A are active, a copolymer of the type B-BA-AB-B results. Examples are the thermoplastic rubbers polysty-rene-polyisoprene-polystyrene and poly(ethylene oxide)-polystyrene-poly(ethylene oxide). In principle, for fixed amounts of two monomers that are capable of mutual formation of living polymers, a series of polymers with constant composition and molecular weight but of desired structural pattern can be produced by varying the fraction and order of addition of each monomer. 

Ha MLP, Grady BP, Lolli G, et al. (2007) Composites of single-walled carbon nanotubes and styrene-isoprene copolymer larices. Macromol Chem Phys 208 446-456... 

Unsaturated elastomers can be readily metallated with activated organolithium compounds in the presence of chelating diamines or alkoxides of potassium or sodium. For example, polyisoprene, polybutadiene, styrene-butadiene copolymers, and styrene-isoprene copolymers can be metallated with n-butyllithium TMEDA complexes (1/1 or 1/2 ratio) to form allylic or benzylic anions. The resulting allylic anion can be employed as an initiator site to grow certain branched or comb polymer species. These polymers can include polystyrene, which would form hard domains, or polybutadiene, which forms soft domains. 

The NIR in situ process also allowed for the determination of intermediate sequence distribution in styrene/isoprene copolymers, poly(diene) stereochemistry quantification, and identification of complete monomer conversion. The classic one-step, anionic, tapered block copolymerization of isoprene and styrene in hydrocarbon solvents is shown in Figure 4. The ultimate sequence distribution is defined using four rate constants involving the two monomers. NIR was successfully utilized to monitor monomer conversion during conventional, anionic solution polymerization. The conversion of the vinyl protons in the monomer to methylene protons in the polymer was easily monitored under conventional (10-20% solids) solution polymerization conditions. Despite the presence of the NIR probe, the living nature of the polymerizations was maintained in... 

Figure 7.15. The fracture energy against the crack velocity for a polyisoprene elastomer in contact with a polystyrene substrate, in the presence and absence of a layer of styrene-isoprene copolymer. The relative molecular masses of the styrene and isoprene blocks were 60 000 and 66 000, respectively. 0,11 = 0.053 , 2 = 0.01 and , 2 = 0. After Creton et al. (1994).

Butyl rubber was and is enormously successful both technolc cally and in the business sense. But other Sparks inventions and coinventions also were commercially successful. Examples are styrene-isobutylene copolymers as coating for paper and paper milk bottles, styrene-isoprene copolymers as artificial leather, colored asphalt paving materials, oxo alcohols, and oxo ester plasticizers. During his brief period of employment as a research supervisor at USDA s Northern Regional Research Center, Peoria, Illinois, Dr. Sparks initiated work on dimer acids... 

Apart from these studies of single block dimensions in domains, there have only been two other published attempts. Han et al. makes a brief reference to results obtained for lamellar styrene-isoprene copolymers. Since no data were given, no... 

Some specific recent applications of the chromatography-mass spectrometry technique to various types of polymers include the following PE [130, 131], poly(l-octene), poly(l-decene), poly(l-dodecene) and 1-octene-l-decene-l-dodecene terpolymer [132], chlorinated polyethylene [133], polyolefins [134,135], acrylic acid, methacrylic acid copolymers [136, 137], polyacrylate [138], styrene-butadiene and other rubbers [139-141], nitrile rubber [142], natural rubbers [143,144], chlorinated natural rubber [145,146], polychloroprene [147], PVC [148-150], silicones [151,152], polycarbonates (PC) [153], styrene-isoprene copolymers [154], substituted PS [155], polypropylene carbonate [156], ethylene-vinyl acetate copolymer [157], Nylon 6,6 [158], polyisopropenyl cyclohexane-a-methylstyrene copolymers [195], cresol-novolac epoxy resins [160], polymeric flame retardants [161], poly(4-N-alkylstyrenes) [162], pol)winyl pyrrolidone [31,163], vinyl pyrrolidone-methacryloxysilicone copolymers [164], polybutylcyanoacrylate [165], polysulfide copolymers [1669], poly(diethyl-2-methacryloxy) ethyl phosphate [167, 168], ethane-carbon monoxide copolymers [169], polyetherimide [170], and bisphenol-A [171]. 

Jackson and Walker [7] studied the applicability of pyrolysis combined with capillary column GC to the examination of phenyl polymers (e.g., styrene-isoprene copolymer) and phenyl ethers e.g., bis[w-(w-phenoxy phenoxy)phenyl]ether. In the procedure the polymer sample is dissolved in benzene. The pyrolysis Curie point temperature wire is dipped 6 mm into the polymer solution. The polymer-coated wires are then placed in a vacuum oven at 75-80 °C for 30 minutes to remove the solvent. Figure 6.2 shows a characteristic pyrogram of the copolymer (isoprene-styrene) resulting from a 10-second pyrolysis at 601 °C. When the polyisoprene is pyrolysed, C2, C3, C4, isoprene, and CjoHig dimers are produced. When PS is pyrolysed, styrene and aromatic hydrocarbons are the products. Figure 6.2 shows that the copolymer product distribution and relative area basis resemble the two individual polymer product distributions. 

One way to approach the problem with the hysteretic loss associated with the onset of the polystyrene glass transition in vulcanized S-I-S polymers is with block copolymers having small random styrene-isoprene copolymer end-blocks, and a pure polyisoprene center block, IS-I-IS. The copolymer composition is chosen to produce a Tg of 40-45 C, at about 60% styrene content. At temperatures experienced in "green processing or tire building the block copolymer would be below Tg and strong, while at the elevated temperatures typically experienced by the vulcanized product in actual use, the end-blocks would be above their glass transition temperature... 

Hashimoto, in comparing a tapered styrene-isoprene copolymer (47% styrene, 50K Mol weight) to the same composition and molecular weight of pure styrene-b-isoprene polymer with equal block sizes, found a value of Tc of 150 C for the tapered polymer and 250 C for the pure polymer.One could expect the Tc to be even lower in the case where the end-blocks were uniform random copolymer and the center block was isoprene of much higher molecular weight. The equation for the temperature dependence of the interaction parameter is ... 

Figure 2. Segmental density distribution of block copolymers with styrene-isoprene copolymer random and tapered terminal blocks segments. The upper figure is for a random styrene-isoprene copolymer end-block with uniform composition. The lower figure is that of a severely tapered copolymer end block. The A domain is viewed as equivalent to a block copolymer which is itself microphase-separated with its own interphase region. 

One or Both Monomers Dienes. As in homo-polydienes, very irregular structures can result from cisjtrans or 1,2-addition, as exemplified particularly by a C study of styrene-isoprene copolymer in which the distribution of styrene and m-buta-1,4-, rrans-buta-1,4- and buta-1,2-diene was examined. Similar studies of styrene-butadiene, , ethylene-butadiene, and butadiene-isoprene systems have been reported. 

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