Polybutadiene - continued distribution

The observation that broad, bimodal styrene, block length distributions tend to favor continuity of the polybutadiene phase is not confined to 75% styrene content. Thus, a limited study at 50% styrene showed that polybutadiene-continuous compositions could be prepared by broad blending in place of the normal alternating lamellar structures characteristic of this composition. 

A structural model, based on a complex process of stretch induced ordering in the polyacetylene domains, was proposed to account for these observations. Support for this model was obtained using electron microscopic techniques. Low polyacetylene content blends (<20% PA) were found to consist of discrete polyacetylene domains dispersed in a continuous polybutadiene matrix. In the high polyacetylene content blends (>70% PA), both phases were simultaneously continuous, forming an interpenetrating network structure. Blends with intermediate compositions consist of both continuous and isolated domains of polyacetylene distributed throughout the polybutadiene matrix. 

To improve the processibility of linear polybutadiene with its narrow molecular weight distribution, one can continuously add initiator in the course of the polymerization, vary the reaction temperature, or force long-chain branching by addition of divinyl compounds [68-74]. Addition of small amounts of ethers or tertiary amines alters the vinyl content from some 12% to more than 70% (Table 2). Bis(2-methoxy)ethyl ether and l,2-bis(dimethylamino)ethane as well as crown ethers [75,76] are particularly effective. The microstructures of the products are determinated by IR [77-87], NMR [88-99], x-ray diffraction, and other methods [100,101]. 

BASF offers a full range of natural and black ABS resins imder the Terluran trade name. Terluran Standard grades were developed specifically to meet the requirements of major customers. Terluran Standard ABS is a two-phase polymer blend. A continuous phase of styrene-acrylonitrile copolymer (SAN) gives the materials rigidity, hardness and heat resistance. The toughness of Terluran Standard is the result of microscopically fine polybutadiene rabber particles imiformly distributed in the SAN matrix. Terluran Standard has a light and very consistent natural colour. 

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