Polymer-mold interaction

By the addition of glass fibers, textile fibers, or chopped fabrics to crossfinkable polymers molding materials are produced with increased tensile strength, stif tess, and thermal stability compared to the filler-free polymers. The so-called reinforcing fillers, like carbon black, have good adhesion to the matrix due to specific surface interactions and their characteristic geometry. 

For some decades plasticizers have gained industrial importance because their primary role is to improve flexibility and processability of polymeric materials. In general, plasticizers are low-molar-mass compounds (LMMC) that can disrupt polymer chain interactions by forming secondary bonds with polymer chains. Lubricants increase the overall rate of processing or improve the release properties during processing and molding operations. ... 

Recent chromatographic data indicate that the interactions between the hydrophobic surface of a molded poly(styrene-co-divinylbenzene) monolith and solutes such as alkylbenzenes do not differ from those observed with beads under similar chromatographic conditions [67]. The average retention increase, which reflects the contribution of one methylene group to the overall retention of a particular solute, has a value of 1.42. This value is close to that published in the literature for typical polystyrene-based beads [115]. However, the efficiency of the monolithic polymer column is only about 13,000 plates/m for the isocratic separation of three alkylbenzenes. This value is much lower than the efficiencies of typical columns packed with small beads. 

Polystyrene blended with 2% of polymer 3 was injection molded into 1/8-inch wide flex and tensile bars for mechanical measurement. It had no effect on the flexural modulus of polystyrene, but a significant improvement in the initial modulus with a concomitant sacrifice in the maximum strength was obtained. Weak cross-linking of polystyrene by polymer 3 through aryl-aryl interaction might be responsible for the high initial modulus. 

The multiple-quantum (MQ)/MAS NMR is one of the 2D NMR methods, which is capable of averaging out the second-order quadrupolar interaction in nuclei with spin > 1/2 such as H, "B, O, etc. The "B MQ/ MAS NMR measurements on boron as contained in silyl-carborane hybrid Si-based polymer networks considered here. The molded samples are cut into small pieces to insert them into a 4-mm NMR rotor and spun at 12 kHz in a MAS probe. The observation frequency of the "B nucleus (spin number I = 3/2 and isotope natural abundance = 80.42%) is 96.3 MHz. Excitation of both the echo (—3Q) and anti echo (+3Q) coherences is achieved by using a three-pulse sequence with a zero quantum filter (z-filter). The widths of the first, second, and third pulses are 3.0 4.1 ps, 1.1-1.6 ps, and 19-28 ps, respectively. The z-filter is 20 ps. The recycle delay time is 6-15 s and the data point of FI (vertical) axis is 64 and for each the number of scans is 144. Then, the total measurement time is 15-38 h. The phase cycling used in this experiment consists of 12 phases. Boron phosphate (BPO4 3 = 0 ppm) is used as an external standard for "B. The chemical shift value of BPO4 is —3.60 ppm from BF3 O(C2H5)2 which is used as a standard reference in " B NMR in the liquid state. The transmitter frequency of " B is set on peak of BPO4 for a trustworthy chemical shift after Fourier transform." " ... 

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