Nylon 18 18 and nylon 18 1,3-adamantanedicarboxylic acid (ADA) have been synthesized via melt polycondensation and characterized by thermal and spectroscopic techniques. Good film forming behavior combined with film toughness and flexibility indicate reasonable molecular weights for both. The higher aliphatic content of nylon 18 18 leads to increased resistance to common organic solvents over commercial nylons. Crystallization of nylon 18 18 combines hydrogen bonding of the amide units with a more significant contribution from van der Waals forces than possible for lower aliphatic content nylons due to the greater aliphatic chain lengths. Solid state 15 N CP/MAS NMR indicates a mostly amorphous polymer, with crystalline regions comprised of the thermodynamically stable a-form generally adopted by even-even nylons. Nylon 18 ADA as-produced is completely amorphous as determined by differential scanning calorimetry. However, solution cast samples of nylon 18 ADA shows some ordered structures that can grow into more stable crystals with annealing. These crystals, once melted, do not recrystallize possibly due to chain rearrangement inhibited by bulky adamantly-groups. V
ABSTRACT:The melting behaviors and crystal structures of a long alkyl chain polyamide and nylon 18 18, were investigated under annealing and isothermal crystallization conditions. Nylon 18 18 showed multiple melting peaks in differential scanning calorimetry (DSC) thermograms depending on thermal history of the samples. The origin of the multiple melting peaks may be a result of a melting and recrystallization mechanism during DSC scans. Wide-angle X-ray diffraction patterns showed two new diffraction peaks, which appeared at 0.44 and 0.37 nm, and are characteristic peaks of a-form (triclinic structure) of even-even nylons with increasing annealing temperature. The intensities of these peaks increased, and they split further apart, with elevated annealing temperatures. The solid-state 15 N CP/MAS NMR spectra of the nylon 18 18 samples that had been quenched and annealed also confirmed the a-crystalline form. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: [92][93][94][95][96][97][98] 2012
Summary: A soybean oil-based vegetable oil macromonomer (VOMM) was incorporated as a comonomer into an all-acrylic copolymer via semi-continuous emulsion polymerization. Structurally, VOMMs are comprised of long hydrocarbon fatty acid moieties with allylic double bonds which enable auto-oxidative crosslinking at ambient temperature. VOMMs facilitate low temperature film formation and the fatty acid chains tethered to the polymer backbone auto-oxidize upon film formation to yield crosslinked films. Latexes with varying VOMM levels were synthesized to elucidate the effect of VOMMs on the pre-cure and post-cure glass transition temperature (T g ) and minimum film formation temperature (MFT). Thermoplastic control latexes (without VOMM) were also synthesized via copolymerization of butyl acrylate and methyl methacrylate. This paper details the characterization performed to validate and quantify the VOMM allylic unsaturation retention before, during, and after polymerization, and to quantify and confirm the increase in T g resulting from auto-oxidative crosslinking via solid state 13 C nuclear magnetic resonance spectroscopy and differential scanning calorimetry.
A 12-membered cyclic diamide monomer for nylon 64 was successfully synthesized in fairly high yield (45%). The synthesis conditions were varied to see the effect of the diamine and succinyl chloride reactants on yield. Threefold excess of 1,6-hexamethylenediamine (HDA) gave the highest yield, while further increasing the amount of HDA decreased the yield. Using N,N-diisopropylethylamine as acid scavenger resulted in the formation of two different cyclic amides, which were fully analyzed by 1 H and 13 C solution nuclear magnetic resonance spectrometry and mass spectrometry. Copolymerization of cyclic amides with ecaprolactam via an anionic route gave a block copolyamide with a two distinct endotherms in the differential scanning calorimetry analysis. However, copolymerization by the hydrolytic route gave only nylon 6 with terminal 64 units. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52,[96][97][98][99][100][101][102][103]
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