2. For the following 4 pairs of polymers below, rationalize (as best as possible

Question

2. For the following 4 pairs of polymers below, rationalize (as best as possible) the difference in Tgs (you’ll need to look up the Tgs): a) poly(methyl acrylate) and poly(vinyl acetate) b) poly(1-butene) and poly(2-butene) c) poly(ethylene oxide) and poly(vinyl alcohol) d) poly(ethyl acrylate) and poly(methyl methacrylate) 2. For the following 4 pairs of polymers below, rationalize (as best as possible) the difference in Tgs (you’ll need to look up the Tgs): a) poly(methyl acrylate) and poly(vinyl acetate) b) poly(1-butene) and poly(2-butene) c) poly(ethylene oxide) and poly(vinyl alcohol) d) poly(ethyl acrylate) and poly(methyl methacrylate) 2. For the following 4 pairs of polymers below, rationalize (as best as possible) the difference in Tgs (you’ll need to look up the Tgs): a) poly(methyl acrylate) and poly(vinyl acetate) b) poly(1-butene) and poly(2-butene) c) poly(ethylene oxide) and poly(vinyl alcohol) d) poly(ethyl acrylate) and poly(methyl methacrylate)

Explanation / Answer

A) Miscibility behaviour of poly(methyl acrylate) (PMA) and poly(vinyl acetate) (PVAc) blends was investigated using dilute solution viscometry (DSV), differential scanning calorimetry (DSC) and fourier transform infrared (FTIR) spectroscopy. The viscometric parameter,  and the thermodynamic parameter, were determined at 25.0 for various PMA/PVAc compositions. Data obtained from the viscometry studies showed that PMA/PVAc blends are miscible at all compositions under investigation. Glass transition temperatures, Tgs for PMA and PVAc were observed at 14. and 40., respectively. For the blends of PMA/PVAc, only one Tg was observed indicating miscibility. FTIR spectra suggested interaction between PMA and PVAc. At the molecular level, the miscibility between PMA and PVAc is attributed to the inter-polymer hydrogen bondings.

b) Polybutene is similar to but different from polyisobutylene (PIB). Polybutene is typically made from cat cracker mixed C4s (after the stream is Merox treated to remove sulfur and amines, and contain 1-butene, 2-butene, and isobutylene. Ethylene steam cracker C4s are also used as supplemental feed for polybutene. On the other hand, PIB is produced from essentially pure isobutylene made in a C4 complex of a major refinery. The presence of isomers other than isobutylene can have several effects including: 1) lower reactivity due to steric hindrance at the terminal carbon in, e.g., manufacture of polyisobutenyl succinic anhydride (PIBSA) dispersant manufacture; 2) the molecular weight—viscosity relationships of the two materials may also be somewhat different.

The repeat unit is in case of 1-butene:

-[-CH2-CH(CH2CH3)-]n-

The repeat unit in case of 2-butene is:

-[-CH(CH3)-CH(CH3)-]n-

One of the end units in the polymer chain contains a double bond, allowing reactivity with other compounds to provide functional chemistry mainly for lubricant additives for engine oils, fuels, and greases.

C) To improve the drawability of poly(vinyl alcohol) (PVA) thermal products, poly(ethylene oxide) (PEO), a special resin with good flexibility, excellent lubricity, and compatibility with many resins, was applied, and the Fourier transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WXRD) were adopted to study the hydrogen bonds, water states, thermal properties, crystal structure, and nonisothermal crystallization of modified PVA. It was found that PEO formed strong hydrogen bonds with water and PVA, thus weakened the intra- and inter-hydrogen bonds of PVA, changed the aggregation states of PVA chains, and decreased its melting point and crystallinity. Moreover, the interactions among PVA, water, and PEO retarded the water evaporation and made more water remain in the system to plasticize PVA. The existence of PEO also slowed down the melt crystallization process of PVA, however, increased the nucleation points of system, thus made more and smaller spherulites formed. The weakened crystallization capability of PVA and the lubrication of PEO made PVA chains to have more mobility under the outside force and obtain high mechanical properties.

D) Poly(methyl methacrylate)-block-poly(ethyl acrylate) (PMMA-block-PEA) was synthesized by sequential group transfer polymerization (GTP) in tetrahydrofuran at 30°C using (1-methoxy-2-methyl-1-propenyloxy)trimethylsilane (MTS) as an initiator and tetrabutylammonium fluoride monohydrate (TBAF · H2O) as a catalyst. First, the PMMA macroinitiator was prepared in situin quantitative conversion and its lifetime was at least 15 min. In the second step, an equimolar amount of ethyl acrylate was polymerized with a conversion of 67–88% and PMMA-block-PEA with number-average molecular weight 5000 < Mn < 11 500 and polydispersity 1,4 < Mw/Mn < 2,1 was obtained. The number of chains almost does not change during the polymerization and the initiating efficiency of MTS was in both steps ca. 0,65–0,80. The diblock structure of the copolymer was confirmed by the 13C NMR spectrometric direct proof of the bond-linking of both blocks and by comparing the DSC behaviour of the copolymer with that of the corresponding blend of the homopolymers. No contamination of the block copolymer with the homopolymers was detected by the analytical methods used for the structural characterizations.

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