Poly blend solution preparation

Preparation of Polymer Blends. A series of polymer blends was prepared by co-solutioning predetermined amounts of the poly(m-phenylene)isophthalate/terephthalate (80/20) with poly (m-phenylene)phenyl phosphonate, in methylene chloride. The polymer blends were recovered by evaporating the solution to dryness and ground to 40 mesh with a Wiley Mill. The composition of these blends and their analyses are summarized in Table I. 

Before discussing theoretical approaches let us review some experimental results on the influence of flow on the phase behavior of polymer solutions and blends. Pioneering work on shear-induced phase changes in polymer solutions was carried out by Silberberg and Kuhn [108] on a polymer mixture of polystyrene (PS) and ethyl cellulose dissolved in benzene a system which displays UCST behavior. They observed shear-dependent depressions of the critical point of as much as 13 K under steady-state shear at rates up to 270 s Similar results on shear-induced homogenization were reported on a 50/50 blend solution of PS and poly(butadiene) (PB) with dioctyl phthalate (DOP) as a solvent under steady-state Couette flow [109, 110], A semi-dilute solution of the mixture containing 3 wt% of total polymer was prepared. The quiescent... 

The composite systems studied by Takayanagi et al. (1980) used the polyaramides poly(p-phenylene terephthamide), PPDT, or pol.y-p-benzamide (PBA) as the reinforcing component with nylon 6 or nylon 66 as the ductile matrix polymer. Block copolymers of one of the aromatic polyamides with one of the nylon polymers were also evaluated. The blends were prepared by extruding the sulfuric acid solutions of polymers into a... 

Two-dimensional deuteron NMR was used to analyze miscibility in blends of poly-1,4-polyisoprene with polyvinylethylene (PIP/PVE) [Arendt et al., 1994 Chung et al, 1994]. The blends were prepared by casting 3 wt% toluene solution. The rate of reorientation as a function of temperature near T was determined for both components. It was found that the system is miscible, but the glass transition is broad owing to the wide distribution of segmental motions arising from the differences in the rates of the two polymers. As a result, the PIP/PVE blends were found to be rheologically complex. In spite of miscibility the time-temperature superposition was found to be invalid. 

Recently, combinations of polymers meeting the basic concept of molecular composites have been reported. Poly-(p-phenylene terephthalamide) miscibility with PA-6 and PA-66 was reported [Kyu et al., 1989]. The blends were prepared by rapid coagulation of methane sulfonic acid solutions in water. Above 70% of the rigid rod polymer, polyamide crystallization disappears implying a level of intermixing of the blend constituents. However, thermal treatment results in phase separation thus indicating metastability for this combination. 

Chitosan, sodium chondroitin sulfate, and pectin-nanofibrous mats were prepared from the respective polysaccharide/poly(ethylene oxide) blend solutions by electrospray. Unblended polysaccharide solutions showed low processability, i.e., the solutions could not be electrosprayed. The addition of 500 kDa poly(ethylene oxide) to chitosan solutions enhanced the formation of a fibrous stmcture. Sodium chondroitin sulfate/poly(ethylene oxide) and pectin/poly(ethylene oxide) blend solutions were generally too viscous to be sprayed at 25 °C, but at 70 °C the fibrous stmcture was formed [61]. 

Polyester 9a, which has amino sulfonic acid moieties, was obtained by a liquid/solid biphase polycondensation of terephthalyl chloride and fV,A-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid in trimethylphosphate using triethylamine as an acid acceptor [29]. A thin film of blends was prepared by casting a solution containing 9a, poly(vinyl alcohol) and Ni or salts. 9a and the metal salts formed an interpenetrating network as shown in 9b. The blends exhibit an electrical conductivity up to 10 S cm (for an experiment see Section 5.4, Experiment 5-3). 

The incompatibility of natural rubber/poly(methyl methacrylate) blends was also confirmed in solid form using scanning electron microscopy (Figure 13.4). For the solid natural rubber/poly(methyl methacrylate) blended films prepared by solution mixing and casting methods, the low level of the poly(methyl methacrylate) phase was found to be dispersed as domains in the continuous natural rubber matrix. The increasing amount of poly(methyl methacrylate)... 

Polymers can also be swollen with the solution of an oxidant, blotted with tissue or filter paper and dried, retaining the oxidant as a filler in its bulk. The blend is obtained by exposing the polymer containing the oxidant to vapors of the heterocyclic monomer in a closed chamber. Blends were prepared using this method and combining polypyrrole with cellulose [28], with poly (ethylene terephthalate) [29] or with Nylon [30]. 

The first successful preparation Spasova et al. (2004) of chitosan-containing nanofibers achieved by electrospinning chitosan/ poly(ethylene oxide) (PEO) blend solutions. 

Spasova, M., N. Manolova, D. Paneva, and I. Rashkov (2004). Preparation of chit-osan-containing nanofibres by electrospinning of chitosan/poly(ethylene oxide) blend solutions. e-polymers, no. 056, www.e-polymers.org. 

An excellent example of the capabilities of this technique was provided by Mokarian-Tabari et al. [167], who investigated the phase separation of immisdble polymers during spin coating from a common solvent. The FRES technique, combined with NRA, was used for a quantitative analysis of the polymer blend films prepared from a solution of polystyrene (d-PS) and poly(methylmethacrylate) (h-PMMA). The data obtained showed an evident stratification in the film, with a segregation of d-PS to the surface and an increase in PMMA content with distance from the surface (see Figure 23.37). 

PANI-CSA solutions are prepared by dissolving the em-eraldine base form of PANI and CSA at 0.5 molar ratio of CSA to phenyl-N repeat unit in m-cresol [27-30]. This solution is then mixed in the appropriate ratio with a solution of PMMA in m-cresol. Films of thickness 20-60 (xm were obtained by casting the blend solution onto a glass plate. After drying at 50°C in air for 24 h, the poly-... 

Poly(vinyl acetate)/lignin and poly(e-caprolactone)/lignin blends were prepared by casting chloroform solutions of PVAc (Mw 140 kDa) and PCL (Mw 80 kDa) mixtures containing 9-30% by weight of lignin (Table 2). 

Poly(vinyl alcohol)/lignin (PVAL) blends were prepared by casting aqueous solution of 88% hydrolyzed PVA (PVA88) and basic OL, in order to attain a lignin content in the resulting blends ranging between 8 and 30% by weight (Table 2). 

The polymer blends were prepared by solution blending and freeze drying. The solvent-free freeze dried powders were subsequently compression molded and cut into DMA-sized pieces for analysis. Keinath has successfully used the polymer blending technique coupled with the negative second derivative data treatment to characterize the Tp, Tg, and Tn transitions in a scries of eight different poly( -alkyl methaciylate)s encapsulated in a continuous matrix of poly(dimethyl jrfiraiylene oxide). ... 

A blend of poly(a-methyl styrene) with 100.3 kg/mol molecular weight and its hexamer was prepared through the following method. First, 40 mg mixture containing 68 wt% polymer and 32 wt% hexamer were dissolved in 8 ml dichloromethane (HPLC grade, Aldrich), and the solution was allowed to equilibrate at room temperature for 24 hr. Then, the solution was exposed to air in the hood for 24 hr at 30 C to evaporate most of the solvent before exposing to vacuum for another 24 hr at room temperature. The and PDI were calculated and are also shown in Table 1. Similar blends were prepared in previous work [17] the DSC data are examined in this work. 

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