Effects of water absorption on physical properties and degree of molecular orientation of poly (ethylene terephthalate)

Jabarin, S. A.; Lofgren, E. A.

doi:10.1002/pen.760260907

Cited by 65 publications

(44 citation statements)

References 14 publications

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“…3 Water effect was also observed in other hydrophilic polymers such as polyamides 4,5 and polyesters. 6 -8 Marked decreases in the glass transition temperatures (T g ) of Nylon 6 9 and poly(ethylene terephthalate) 6 (PET) caused by water sorption were measured. The concept of a hydrogen bond network in polyamides and the disruptive effects of water on this, with particular reference to water molecules becoming firmly bound to the polar groups in these polymers, is prevalent in the literature.…”

Section: Introductionmentioning

confidence: 99%

Water effect on the morphology of EVOH copolymers

Aucejo

Marco

Gavara

1999

J. Appl. Polym. Sci.

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ABSTRACT:The effect of water on the morphology of four ethylene vinyl alcohol copolymers (EVOH) with different ethylene contents was studied by differential scanning calorimetry (DSC). EVOH film samples equilibrated in controlled atmospheres at different relative humidities (RH) and 23°C were analyzed. Under dry conditions, the glass transition temperature (T g ) was unaffected by copolymer ethylene content. As RH increases, T g decreases. It seems that the presence of water within the polymer matrix results in plasticization of the polymer. T g varies from around 50°C (dry) to below room temperature. EVOH copolymers are glassy polymers when dry and rubbery polymers at high RHs. Fox and Gordon-Taylor's equations well describe T g depletion at low water uptake, although severe water gain results in a considerable T g decrease, which is not predicted by these theories. Melting temperature, T m , and enthalpy, ⌬H m , were also analyzed. When dry, T m decreases as ethylene content increases. No significant water effect was found on either T m or ⌬H m . Hence, crystallinity seems to be unaffected by water presence.

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Section: Introductionmentioning

confidence: 99%

Water effect on the morphology of EVOH copolymers

Aucejo

Marco

Gavara

1999

J. Appl. Polym. Sci.

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“…To determine the overall crystallization rate In addition to moisture that has a plasticizing effect, 8,9 substances such as epoxidized soybean and the activity of a nucleating agent, in addition to microscopic examination for spherulitic size, oil, neopentyl glycol dibenzoate, 10 aliphatic glycol phthalate, 11 and carbon dioxide at elevated presuseful parameters obtained from differential thermal analysis 6 include sures 12 have been suggested as plasticizers for PET. Addition of plasticizers results in an increased mobility of the polymer chains and a re-(a) The time needed to achieve a 50% crysduced glass transition temperature.…”

Section: Introductionmentioning

confidence: 99%

Effects of carbonate salts on crystallization kinetics and properties of recycled poly(ethylene terephthalate)

Xanthos

Baltzis

Hsu

1997

J. Appl. Polym. Sci.

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ABSTRACT:In this study, thermal and microscopic analyses were used to evaluate a variety of carbonate and bicarbonate salts (alkali, alkaline-earth, and other metals), having different thermal stability within the range of poly(ethylene terephthalate) (PET) processing temperatures, as nucleating agents for recycled bottle PET. In addition, the effects of the salts on the melt viscosity and MW of the resin after melt processing were investigated in attempts to determine their overall relative performance as potential nucleating agents during injection molding. It was found that among the additives tried sodium salts are the most effective nucleating agents for recycled PET crystallization with a concomitant relatively small reduction in molecular weight. All other salts were less effective nucleating agents and, in some cases, caused also significant resin degradation. Mechanisms explaining the behavior of the different salts are proposed. With regard to processability of recycled PET in injection molding, it was found that for certain additives temperatures below 100ЊC could be effectively used, resulting in short cycles that produced crystalline products with satisfactory mechanical properties.

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“…Also, earlier supplies of the AA brand were noticeably darker than those tested in follow-up simulations (The manufacturer suggested that this was due to the presence of more graphite in the earlier samples, and this seems to have an effect on the degradation properties of the AA product). All three aerogels contain fibers made with PETE, which is known to be hygroscopic (Jabarin and Lofgren 1986). Hydrolysis is a great factor in the deterioration of PETE and McMahon has studied the rate of hydrolysis as a function of temperature and RH (McMahon et al 1959).…”

Section: Follow-up Aging Simulation Tests On Aerogel Blanketsmentioning

confidence: 99%

Prediction of Long Term Degradation of Insulating Materials

Stephenson¹,

Heffron²,

Mehnert³

et al. 2015

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Advanced insulation materials provide resistance to heat flow. Properly insulating shelters can reduce heating and cooling costs, as well as improves comfort. However, the long-term performance of insulation materials is relatively unknown. This research investigated the long-term performance of five commercially available insulation materials including nonwoven insulation liner, aerogel blankets, closed cell spray polyurethane foam (ccSPF), extruded polysterene (XPS), and fiberglass batt. Accelerated aging simulation experiments were conducted in an environmental chamber. All materials were subjected to 5 weeks in the chamber and exposed to various temperature and humidity conditions. Thermal conductivity using a heat flow meter apparatus (HFMA) and corresponding Rvalues of each material were calculated. The results indicate that moisture absorption was a major contributor to changes in the thermal properties of the materials. Additional degradation in R-values in ccSPF was caused by loss of blowing agent over time. The results of this research are expected to help formulate an accelerated aging methodology that allows reliable prediction of long-term advanced insulation materials performance.

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Effects of water absorption on physical properties and degree of molecular orientation of poly (ethylene terephthalate)

Cited by 65 publications

References 14 publications

Water effect on the morphology of EVOH copolymers

Water effect on the morphology of EVOH copolymers

Effects of carbonate salts on crystallization kinetics and properties of recycled poly(ethylene terephthalate)

Prediction of Long Term Degradation of Insulating Materials

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