Preparation and properties of terpolymers of ethylene, vinyl acetate and vinyl alcohol

Abstract

Several terpolymers of ethylene, vinyl acetate and vinyl alcohol have been prepared by controlled transformation into hydroxyls of the acetate groups of an ethylene‐vinyl acetate copolymer (with 28 wt.‐% in vinyl acetate). The degree of transformation has been determined by 1H NMR. Samples covering the entire range of transformations have been obtained, and their properties have been analyzed by DSC and X‐ray diffraction. The results show a marked increase of both melting temperature and crystallinity as the degree of transformation increases, owing to the fact that the vinyl alcohol units are able to cocrystallize in the polyethylene lattice, while the acetate groups are excluded.

Diffusion and sorption of nitroplasticizers in vinyl copolymer elastomer and its composites

“…It is worth noting that the NP isotherms of the VCE polymer and VCE composites at ambient temperature are noticeably different from these obtained at the elevated temperature. The DSC data suggests that the vinyl‐acetate component of the polymer typically softens and melts above 37°C . The VCE terpolymer, contains ∼43% of this group.…”

Influence of processing on the ethylene-vinyl alcohol (EVOH) properties: Application of the successive self-nucleation and annealing (SSA) technique

“…They are prepared commercially by transesterification (saponification) of Ethylene-vinyl acetate copolymers (EVA). They could be considered, then, as complex copolymers of ethylene, vinyl alcohol and some vinyl acetate units, if the saponification process is not 100% complete [1][2][3]. In addition, owing to the free-radical nature of the EVA copolymerization, the resulting EVOH copolymers posses a certain degree of short chain branching, which, according to Vanderhart et al [4] are rejected from the crystalline region.…”

Thermal and chemical stabilization of ethylene/vinyl acetate/vinyl alcohol (EVA‐OH) terpolymers under nitroplasticizer environments

“… Possible degradation mechanisms of the cross‐linker removal and continued degradation in the EVA‐OH under moisture and acidic environment . [Color figure can be viewed in the online issue, which is available at http://wileyonlinelibrary.com.…”

“…Upon the X‐linker removal, the degradation of EVA‐OH is very similar to that of EVA. Based on the literature, some possible thermal degradation mechanisms are highlighted in Scheme . When EVA is thermally oxidized, many fragments containing >CO and CO are formed.…”

“…Clearly, the main structure of uncured EVA‐OH is almost the same as that of EVA. The thermal aging of EVA at the high temperature (>200°C) has been well studied . Researchers concluded that the deacetylation typically occurs at the first degradation and results in the loss of acetic acid and unsaturated materials.…”