Styrene 1126 INDEX

Monomers such as methyl methacrylate [80-62-6] are often used in combination with styrene to modify refractive index and improve uv resistance. Vinyltoluene [25013-15-4] and diaHyl phthalate [131-17-9] are employed as monomers in selective mol ding compositions for thermal improvements. 

For acrylate polymers with higher levels of carboxylic acids, THF can be modified by the addition of acids such as acetic, phosphoric, or trifluoroacetic. Levels as high as 10% acetic acid are considered acceptable by most manufacturers for their styrene/DVB columns. If such a modified mobile phase is used, it may need to be premixed rather than generated using a dynamic mixing HPLC pump because on-line mixing often leads to much noisier baselines, particularly when using a refractive index detector. 

In general, the multiphasic heterogenous nature of the impact grade styrene-based polymers is the root cause of their opaque-turbid nature. In determining the transparency of the blends, size and the size-distribution pattern of the dispersed phase along with the refractive index difference between the continuous and the dispersed phases are two very important criterion [133]. 

Figure 6. Cumulative dispersion index vs. conversion with batch-mass styrene...

The determination of the molecular weight of nanoparticles is performed by gel permeation chromatography (GPC). The experimental setup consists of a high performance liquid chromatography system with a size exclusion column and a refractive index detector. The nanoparticles are usually freeze-dried and dissolved in tetrahydrofuran for analysis on the system. Poly(styrene) or poly(methylmethacrylate) standards are used to calibrate the column, to enable the determination of number average molecular weight (Mn), as in... 

Fig. 56. Dependence of specific refractive index increment on conversion of monomers to polymer for a styrene/acrylonitrile/methyl methacrylate terpolymer in methyl ethyl ketone at 20 °C and 436 nm. (a) - partial azeotrope, (b) terpolymer with composition distribution163 ...

Dow Chemical has launched a range of foams which are said to exceed industry standards for softness and toughness. This article supplies brief details of the foams which are based on Dow s Insite catalyst technology. Synergy Soft Touch Foams are produced using Dow s Index Interpolymers, a new thermoplastic polymer family based on the copolymerisation of ethylene and styrene. The foams are offered in three grades of softness, and other properties include shock absorption, vibration damping and insulation. 

Several other produces have been developed based on the relatively new soluble stereoregulating catalysis systems. Index, an ethylene-styrene interpolymer, was introduced in 1998... 

Fig. 3-22 Dependence of number-average molecular weight ( ) and polydispersity index (A) on monomer conversion for ATRP polymerization of bulk styrene at 110°C with CuBr, 1-phenylethyl bromide (I), and 4,4-di-5-nonyl-2,2 -bipyridine (L). [M] = 0.087M [CuBr]0 = [L]0/2 = [I] = 0.087 M. After Matyjaszewski et al. [1997] (by permission of American Chemical Society, Washington, DC) an original plot, from which this figure was drawn, was kindly supplied by Dr. K. Matyjaszewski.

The DnPont photopolymeric system consists of polymeric binder resins, e.g. PVA, PMMA, cellnlose acetates and styrene-acrylates, reactive acrylic monomers, e.g. aryloxy or alkoxy acrylates, a dye sensitiser and a radical or charge transfer photoinitiator, e.g. DEAW and HABI respectively (see Chapter 4, section 4.5.2), and plasticisers. The process for producing the refractive index structures is as follows ... 

According to their recent reports [11], 5 provides livingness of polymerization for styrene (ST) and methyl methacrylic acid (MA). Irrespective of the type of monomer, the initiator efficiency / was over 0.9, and the polydis-persity index, Mw/Mn (Mw weight-average molecular weight, Mn number-average molecular weight), was close to unity (approximately 1.2). The polymerization rate was very low (on the order of an hour), i.e., a very slow... 

The use of multidetector GPC greatly increases the power of SEC, particularly in the case of copolymers. For copolymers of styrene-maleic anhydride (SMA), not only can the molecular weight distribution be determined, using a differential refractive index (DRI) detector, but also the compositional information of SMA (styrene content or acid number) by combining chromatograms from DRI and UV detectors [9]. 

Fig. 8. R/Platelet in individual platelets adhering to polymer surfaces. HSB data were statistically confirmed to be different from PSt (P < 0.5), HSR (P < 0.5) and PHEMA (P < 0.5) after 40 s R/Platelet (an index of cytoplasmic free calcium concentration) is the ratio of fluorescence emission intensitie of a Ca2 + indicator dye (Fura 2) loaded in platelets when they are excited at 340 nm and 380 nm. (Reproduced from J Biomed Mater Res [Ref 84 Prevention of changes in platelet cytoplasmic free calcium levels by interaction with 2-hydroxyethyl methacrylate/styrene block copolymer surfaces] through the courtesy of John Wiley Sons, Inc.)...

The last property is related to the processing of the rubber in the tire making equipment. By using organo-lithium compound in this case, it was possible to maintain a vinyl content not greater than 18, but to produce a polybutadiene styrene copolymer that has random block styrene and without the use of polar modifiers, which normally will increase the 1,2 content. This copolymer, when compounded in the tread recipe, as shown in the Table XVI, gave properties that are actually equivalent to that of emulsion SBR and in some cases even better. This is particularly true in the properties of the Young modulus index, which showed between -38 to -54 C the Stanley London Skid Resistant, in which the control is 100, shows that 110-115 was obtained. 

A pressure glass vessel was charged with a cyclohexane solution of butadiene (60 g) and styrene (15 g) and treated with 11.7 ml of the step 1 product and the mixture polymerized at 50°C for 2.5 hours. The conversion was approximately 100%. Thereafter, 0.5 ml of 5% 2,6-di-f-butyl-p-cresol dissolved in isopropanol was added and the mixture precipitated in an isopropanol solution containing slight amounts of hydrochloric acid and BHT. The mixture was dried and the product isolated having an Mn of 1.74 x 105Da with a polydispersity index (PDI) of 1.02 and MLi+4 (100°C) of 22. 

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