Propylene Adipate Research Articles

Synthesis, characterization and thermal degradation mechanism of three poly(alkylene adipate)s: Comparative study

Three high molecular weight aliphatic polyesters derived from adipic acid and the appropriate diol – poly(ethylene adipate) (PEAd), poly(propylene adipate) (PPAd) and poly(butylene adipate) (PBAd) – were prepared by two-stage melt polycondensation method (esterification and polycondensation) in a glass batch reactor. Intrinsic viscosities, GPC, DSC, NMR and carboxylic end-group measurements were used for their characterization. Mechanical properties of the prepared polyesters showed that PPAd has similar tensile strength to low-density polyethylene while PEAd and PBAd are much higher. From TGA analysis it was found that PEAd and PPAd have lower thermal stability than poly(butylene adipate) (PBAd). The decomposition kinetic parameters of all polyesters were calculated while the activation energies were estimated using the Ozawa, Flynn and Wall (OFW) and Friedman methods. Thermal degradation of PEAd was found to be satisfactorily described by one mechanism, with activation energy 153 kJ/mol, while that of PPAd and PBAd by two mechanisms having different activation energies: the first corresponding to a small mass loss with activation energies 121 and 185 kJ/mol for PPAd and PBAd, respectively, while the second is attributed to the main decomposition mechanism, where substantial mass loss takes place, with activation energies 157 and 217 kJ/mol, respectively.

Novel random poly(propylene isophthalate/adipate) copolyesters: Synthesis and characterization

Poly(propylene adipate) (PPA) and poly(propylene isophthalate/adipate) (PPI–PPA) random copolymers of various compositions were synthesized in bulk and characterized in terms of chemical structure and molecular weight. Furthermore, the thermal behavior was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability. At room temperature they appeared as semicrystalline materials, except the copolymers containing 20 and 30 mol% of PI units: the main effect of copolymerization was a lowering in the amount of crystallinity and a decrease of melting temperature with respect to homopolymers. The crystalline phase of PPI and PPA was evidenced at high content of propylene isophthalate or propylene adipate units, respectively. Amorphous samples were obtained after melt quenching and an increment of T g as the content of PI units is increased was observed. This behavior was explained as due to the stiff phenylene groups in the polymeric chain. The Wood equation was found to describe well T g-composition data. Lastly, the presence of a rigid-amorphous phase was evidenced in the copolymers, differently from PPA homopolymer.

Correlation between interactions, miscibility, and spherulite growth in crystalline/crystalline blends of poly(ethylene oxide) and polyesters

Crystalline/crystalline blend systems of poly(ethylene oxide) (PEO) and a homologous series of polyesters, from poly(ethylene adipate) to poly(hexamethylene sebacate), of different CH 2/CO ratios (from 3.0 to 7.0) were examined. Correlation between interactions, miscibility, and spherulite growth rate was discussed. Owing to proximity of blend constituents' T g's, the miscibility in the crystalline/crystalline blends was mainly justified by thermodynamic and kinetic evidence extracted from characterization of the PEO crystals grown from mixtures of PEO and polyesters at melt state. By overcoming experimental difficulty in assessing the phase behavior of two crystalline polymers with closely spaced T g's, this work has further extended the range of polyesters that can be miscible with PEO. The interaction parameters ( χ 12) for miscible blends of PEO with polyesters [poly(ethylene adipate), poly(propylene adipate), poly(butylene adipate), and poly(ethylene azelate) with CH 2/CO = 3.0–4.5] are all negative but the values vary with the polyester structures, with a maximum for the blend of PEO/poly(propylene adipate) (CH 2/CO = 3.5). The values of interactions are apparently dependent on the structures of the polyester constituent in the blends; interaction strength for the miscible PEO/polyester systems correlate in the same trend with the PEO crystal growth rates in the blends.

Propionispora hippei sp. nov., a novel Gram-negative, spore-forming anaerobe that produces propionic acid.

A Gram-negative, spore-forming anaerobe, KS(T), was isolated from an enrichment culture that was set up for anaerobic degradation of the aliphatic polyester poly(propylene adipate). The strain had the cellular organization of Sporomusa, vibrio-shaped cells and terminal round spores, and fermented sugars and sugar alcohols to propionic and acetic acid. Based on the morphological and physiological features as well as on a 16S rRNA gene similarity of 98 %, it was grouped with Propionispora vibrioides. A relatively low DNA-DNA hybridization value with the type strain of this species (47 %), and differences in substrate utilization and spore morphology, suggested that the strain should be classified in a separate species, Propionispora hippei sp. nov., with KS(T) as the type strain (=DSM 15287(T)=ATCC BAA-665(T)).

Migration from plasticized films into foods. 6. Hydrolysis of polymeric plasticizers under simulated gastric and intestinal conditions.

The polymeric plasticizers poly(butylene adipate) and poly(propylene adipate), and a low molecular weight oligomer fraction from each, were exposed in vitro to simulated gastric and intestinal hydrolysis in order to study their likely fate after ingestion of foods contaminated by migration from plastics packaging. Analysis for loss of the parent compounds indicated that partial hydrolysis occurred under simulated gastric conditions, with the low molecular weight oligomers being the most susceptible. Analysis for one of the starting materials, adipic acid, revealed however that the hydrolysis did not result in a significant conversion to free monomer under either simulated gastric or intestinal conditions. This is explained on the basis of partial hydrolysis of the plasticizers to smaller oligomer units but with the more resistant ester linkages resisting complete breakdown to monomer.

Relation of Modulus of Urethan Rubber to Molecular Weight of Polyester

Abstract The modulus of polyurethan rubber prepared from poly(ethylene propylene) (70–30) adipate and diphenylmethane diisocyanate by chain extension and cross-linking with water is proportional to the reciprocal molecular weight of the polyester diisocyanate. The modulus at a given molecular weight is lowered by chain extension of the polyester with diisocyanate. The modulus is increased 40 per cent by change of the diisocyanate to 1,5-naphthalene diisocyanate and reduced 60 per cent by change to 2,4-toluene diisocyanate.

Hydrolytic Stability of Urethan Elastomers

Abstract Data have been presented bearing on the hydrolytic stability of a wide variety of urethan elastomers (Table III). It has boon shown that polyester based elastomers are considerably more susceptible to hydrolytic attack than polyether elastomers up to 158° F. The nature of the attack and results obtained are profoundly influenced by the temperature. At temperatures of 120° F and above the attack appears to be a “simple” hydrolysis consisting of scission of main chain ester groups resulting in reversion of the rubber. In this case aging over water and in water are similar. At temperatures below 120° F the attack cannot be rationally treated without considering the part played by fungi. In this case exposure over water yields drastically different results from immersion— the former being more severe by several orders of magnitude. Typically the attack over water involves a short term (two to three weeks) cracking of stressed or unstressed specimens and a gradual softening which takes place over a period of many months. The cracking seems to be connected with fungus attack. Resistance of polyesters to hydrolytic attack can be improved by the use of additives such as diisocyanates, fungicides, and carbodiimides. The latter are most useful and apparently scavenge the carboxylic acid resulting from hydrolytic breakdown of the polyesters thereby preventing autocatalysis. Their ability to react with carboxylic acids under these mild conditions has been reported. Differences among polyesters not only in inherent resistance to hydrolysis but also in response to inhibition are found. As has been seen the early cracking can be eliminated by use of sulfur cures, or inclusion of a fungicide but only at the expense of reduced resistance at 158° F. Accelerated tests have been shown to correlate reasonably well with outdoor exposures. Results on unstressed specimens correlate with the 158° F test while the stressed specimens yield results similar to exposure at 95 per cent R.H. and 100° F. Not all linear polyesters are susceptible to hydrolysis such as is poly (ethylene propylene adipate). The terephthalate polyesters, poly (ethylene terephthalate) and poly(1,4 cyclohexane diearbinyl terephthalate), have been exposed in the form of thin films over water at 158° F for 14 months and over water at 95 per cent R.H. and 100° F for 23 months without visible signs of deterioration. They are apparently stabilized by the presence of the aromatic rings or steric factors or a combination of these. In conclusion it must be said that although some progress has been made in protecting polyester urethan elastomers from hydrolytic failure under tropical and high humidity conditions, the problem has only partially been solved.

Monolayers of adipate polyesters at air-liquid interfaces

The surface pressure-area isotherms at 24.5 °C are reported for poly (ethylene adipate), poly(trimethylene adipate), and poly (propylene adipate), spread as monolayers at airaqueous interfaces. The monolayers were spread on distilled water and 0.01 N HC1, using benzene, chloroform, and acetone as spreading solvents. Poly (propylene adiptate) was the least compressible of the three, and poly (ethylene adipate) the most. Poly (propylene adipate) did not collapse at the highest pressure's studied. The spreading characteristics of both poly (ethylene adipate) and poly (propylene adipate) were independent of the amount of material used. The spreading of poly (trimethylene adipate) appeared to depend upon the spreading solvent. The effect of structure on the surface pressure—area isotherms and the specific areas for each polymer are discussed.