Indene physical properties

The synthesis of poly(St-h-IB-h-St) triblock copolymer has been accomplished by many research groups [195-201]. The synthesis invariably involved sequential monomer addition using a difunctional initiator in conjunction with TiCU in a moderately polar solvent mixture at low (—70 to —90°C) temperatures. As already mentioned at the synthesis of poly(IB-f)-St) it is important to add St at 100% IB conversion. The selection of the solvent is also critical, coupled product that forms in intermolecular alkylation during St polymerization cannot be avoided when the solvent is a poor solvent (e.g., hexanes/MeCl 60/40 (v/v)) for polystyrene [202]. The formation of coupled product is slower in wBuCl or in MeChx/MeCl 60/40 (v/v) solvent mixture however, to obtain block copolymers essentially free of coupled product it is necessary to stop the polymerization of St before completion. Detailed morphological and physical properties of poly(St-h-IB-h-St) triblock copolymer have been reported [199, 203-206]. The two step sequential monomer addition method has also been employed to obtain poly(p-chlorostyrene-f)-IB- )-p-chlorostyrene) [68, 207], poly(indene-f)-IB- )-indene) [208], poly(p-tert-butylstyrene-f)-IB-h-p-tert-butylstyrene) [209], poly((indene-co-p-methylstyrene)-h-IB-f)-(indene-co-p-methylstyrene)) [210], poly(p-MeSt-f)-IB- )-p-MeSt) [202], and poly(styryl-POSS-i -IB-h-styryl-POSS) (POSS=polyhedral oligomeric silsequioxane) [211] copolymers. 

A series of low-molecular-weight resins from natural products or industrial side products is known as cumarone-indene-like resins, since these resins have similar physical properties to the actual cumarone-indene resins. For example, cyclopentadiene from the petroleum process dimerizes easily to what is known as dicyclopentadiene (lUPAC 4,7-methylene-4,7,8,9-tetrahydroindene). Dicyclopentadiene cationically polymerizes to polymers with different monomeric units. The commercially available polymers soften at 100-120°C and become insoluble as surface films on further heating. 

The physical properties of CPD and DCPD are given in Table 1. DCPD, 3a,4,7,7a-tetrahydro-4,7-methano-li7-indene, can exist in two stereoisomers, the endo and exo forms. Because commercially available DCPD is mostly the endo isomer, the properties in Table 1 are pertinent to those of the endo isomer. Spectroscopical information on CPD and DCPD can be found in (20) (mass spectrum), and (21) (nmr spectrum). References 2 (ir, nv, and Raman spectra). 

The similarity in chemical structure to isoprene explains why these are quite compatible with natural rubber and synthetic isoprene-based polymers (or block copoljuners). The C-9 aromatic hydrocarbon resins include indene- and styrene-based oligomers. Because of the difference in chemical structure these will associate with the end-blocks in S-I-S copolymers, and thus have a reinforcing effect and improve high temperature performance. Finally, mixtures of aliphatic and aromatic hydrocarbon resins are commonly used as a way to tailor compatibility and physical properties of the resultant PSAs. 

The sum of the mol fractions of toluene and m-xylene is 0.434. The sum of the mol fractions of benzene, n-heptane, o-xylene, and indene is 0.457. In this case, the physical properties of the phases may not be representative of a binary separation of the light key and heavy key that provided the basis for determining the number of theoretical stages required. Thus, the design HETP value obtained from physical properties of the system should be applied only to the number of theoretical stages determined by a rigorous method for multicomponent mixtures. 

Tackifiers. Although SBRs can be produced with tack, the physical properties of such polymers usually do not fully satisfy the application requirements. For this reason tackifying resins are normally incorporated into adhesives based on SBRs. These resins improve the kinetics of wetting and increase the overall Tg of the adhesive composition. Typical tackifiers for SBR are rosin-based materials, aromatic-containing petroleum hydrocarbon resins, alpha-pinene, coumarone-indene, and some phenolic resins. 

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