Thermoplastic block copolymers

Thermoplastic block copolymers were used for pressure-sensitive and hot-melt rubber adhesives as from the middle sixties. These adhesives found application in packaging, disposable diapers, labels and tapes, among other industrial markets. The formulation of these adhesives generally includes an elastomer (generally containing styrene endblocks and either isoprene, butadiene or ethylene-butylene midblocks) and a tackifier (mainly a rosin derivative or hydrocarbon resin). 

Gergen, W. P. and Davison, S., Thermoplastic block copolymer blends, US Patent 4101605, 1978. 

Bifunctional Initiators. One notable omission from lithium alkyl initiators has been a bifunctional species soluble in hydrocarbon solvents. This would allow the production of living polydianions from isoprene and butadiene with predominantly a cw-1,4 microstructure in the backbone, the latter in turn being a convenient source for the production of ABA thermoplastic block copolymer... 

MAJOR APPLICATIONS Molding plastic, molecular component of polyether ester thermoplastic block copolymer elastomer, fiber and plastic forming, used in tooth and paint brush and in bristles and filler fabrics. 

Aromatic Polyester Estercarbonate A thermoplastic block copolymer of an aromatic polyester with polycarbonate. Has higher heat distortion temperature than regular polycarbonate. 

Polyallomer Crystalline thermoplastic block copolymers of ethylene, propylene, and other olefins. Has good impact strength, flex life, and low density. 

A crosslinking technique, based on the use of thermoplastic/block copolymers discussed in Section 1.5, has recently been developed for limiting flow at high extensions. 

Conventional shape memory polymers are segmented polyfur-ethane) s and have hard segments that include aromatic moieties (70,71). But a series of other thermoplastic block copolymers with thermally induced shape memory effects have been summarized (69). 

Most of these tie layers are based on modified polyolefins or their copolymers. lonomers such as Surlyn may also be used as a tie layer. The functionality of the adhesive layer derives from comonomers snch as acrylic acid, methacryUc acid, maleic anhydride or vinyl acetate. Styrene-isoprene-styrene thermoplastic block copolymers blended with polyolefins can be used as tie layers. The level of addition of these grafted units is... 

N. Busko, F. Tanasa, A. Barantseva, M. Zanoaga, V. Grishchenko, Study of properties of some new thermoplastic block copolymers and their corresponding blends with secondary polyethylene, Polymer Testing 27 (7) (2008) 807-817. 

Polymer modified asphalt originated in Europe in the early 1960s. Atactic PP is still used today in asphalt compositions mainly in Europe, Mexico and Asia. A PP copolymer containing 2-10% ethylene is more popular in USA. Thermoplastic block copolymers with styrene end blocks or with a diene midblock like S-B-S and styrene-isoprene-styrene (SIS) and their hydrogenated versions are common modifiers for asphalt [40]. 

Table 1. Possible Combinations of Hard-Segment- and Switching-Segment-Determining Blocks in Linear, Thermoplastic Block Copolymers with Thermally Induced Shape-Memory Effect ...

In the literature, many routes to synthesis of block copolymers are given, but on commercial scale, only the anionic solution process is used. In the case of solution SBR great care is taken to assure random distribution of monomeric imits. In block copolymers great care is taken to assure that the butadiene and styrene units exist as blocks. The thermoplastic block copolymers, especially those with... 

The feed preparation and reactor sections of thermoplastic block copolymer production process are similar to the solution SBR process (36,39,40,42-45). Styrene, butadiene, and solvent are purified by distillation, followed by passing the reactants and solvent over alumina columns and molecular sieves (Fig. 8). 

Thsrrnoplastic Block Copolymers. Most well-known thermoplastic block copolymers are the K-Resin family (36,46) (Phillips Petroleum Co.). These contain about 27% butadiene in a star-block form (Fig. 9). 

Gahvarl, F., Effects of Thermoplastic Block Copolymers on Rheology of Asphalt, J. Mater. Civil Eng., 9(3) 111-115 (1997)... 

The commercial introduction of the thermoplastic block copolymers in 1965 gave impetus to the development of high performance pressure sensitive and hot melt adhesives. These unique materials, based on styrene endblocks and either isoprene, butadiene, or ethylene-butylene midblocks, have become established as the elastomer of choice in some of the fastest growing segments of the adhesive and sealant industry. 

Figure 4.10 Proposed mechanism for hydrogen bonding across the interface of a SBS thermoplastic block copolymer substrate after being subjected to an halogenation pretreatment and using a polyurethane adhesive [78].

It should be also mentioned that thermoplastic block copolymers composed of chemically different blocks can be considered as potential compatibilizers for the production of some polymer blends, including those of reactive polymers. 

Albertsson A-C, Ljungquist O (1988a), Degradable polymers. IV. Degradation of aliphatic thermoplastic block copolymers , J Macromol Sci Chem, A25, 467 98. 

Thermoplastic block copolymer from Styrene and butadiene containing carboxylic groups (ANSI/ASTM)... 

The DMA trace (containing both modulus and tan 8 plots) for a car mat is shown below in Figure 6.12. This product was a blend of a thermoplastic block copolymer rubber (SBS) and polypropylene. The Tg for the butadiene phase within the SBS is apparent at —68°C. The transitions above this temperature are complex, being due to a combination of the contributions from the Tg of the styrene phase within the SBS and the Tg of the polypropylene. It was not possible to collect data above 150°C due to the sample melting as the melting point of the polypropylene component in the sample was reached. 

Segmented SMPUs are thermoplastic block copolymers having the unique mechanical properties, which is due to the pseudo-elasticity and thermal-responsive shape memory effect. Due to the presence of soft and hard segments, in which the former comprises the reversible phase while the latter forms the frozen phase, the material can restore its original shape upon... 

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