Effects of gamma irradiation on PTFE

Chipara, Mircea; Chipara, Mircea

doi:10.1016/0141-3910(92)90093-k

Cited by 20 publications

(17 citation statements)

References 5 publications

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“…As described in section Radiation Grafting in Presence of Homo-Polymerization Inhibitor above noticeable grafting was observed at dose $3 kGy indicating that by this dose significant increase in crystallinity of the PTFE would have taken place in the pristine PTFE and latter grafting took place on PTFE which was more crystalline than the PTFE started with. Our observation of crystallinity increase with radiation dose is similar to that reported by earlier workers [35,36] where increase in crystallinity on irradiation under aerated atmosphere has been reported. However, similar extent of increase in crystallinity has been reported at much higher does [35] and at much lower dose [36] than observed by us.…”

Section: Dsc Studies Of Ptfesupporting

confidence: 94%

“…Our observation of crystallinity increase with radiation dose is similar to that reported by earlier workers [35,36] where increase in crystallinity on irradiation under aerated atmosphere has been reported. However, similar extent of increase in crystallinity has been reported at much higher does [35] and at much lower dose [36] than observed by us. Probably the crystallinity of the sample initially and changed irradiation ambiance have role for this discrepancy observed among our work and work reported earlier.…”

Section: Dsc Studies Of Ptfesupporting

confidence: 94%

See 1 more Smart Citation

Teflon scrap based cation exchanger by radiation grafting: Process parameter standardization and characterization

Chaudhari¹,

Paul²,

Panicker³

et al. 2011

Env Prog and Sustain Energy

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High-energy gamma radiation from 60 Co-gamma radiation source has been used to covalently link acrylic acid to teflon by mutual radiation grafting technique. Effect of various experimental parameters viz, dose, dose rate, monomer concentration, backbone thickness effect of additives on grafting extent was investigated in order to optimize the conditions for grafting acrylic acid onto teflon to optimum levels. The grafting extent decreased with increasing dose rate and thickness of the substrate while it increased with concentration of acrylic acid and optimum concentration of Mohr's salt. The grafted product was characterized for grafting yield, surface morphology, bulk morphology, and crystallinity change. The SEM studies indicate significant difference in bulk and interface due to change in thickness of the teflon backbone. Dynamic contact angle measurement studies of the grafted and radiation treated teflon showed that initial grafting as well as radiation treatment of teflon enhances its hydrophilicity.

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Section: Dsc Studies Of Ptfesupporting

confidence: 94%

Section: Dsc Studies Of Ptfesupporting

confidence: 94%

Teflon scrap based cation exchanger by radiation grafting: Process parameter standardization and characterization

Chaudhari¹,

Paul²,

Panicker³

et al. 2011

Env Prog and Sustain Energy

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“…y-Irradiation The DSC method was used to investigate changes in melting behavior in dependence on the irradiation conditions. Our measurements were carried out using a Mettler DSC 20, which was calibrated with In and Pb standards (temperature range of measurements, 200-400°C; cycle 1, heat to cool; cycle 2, heat; scanning rate, 10 K/min; sphere, pure nitrogen; sample weight, about 10.0 mg for irradiated micropowders). For the qualitative estimation of the change in molecular weight M w of irradiated PTFE, we used the correlation between heat of recrystal- from data of cooling thermograms in the temperature range between 247 and 322°C.…”

Section: Methodsmentioning

confidence: 99%

“…Investigations concerning crystallinity and dependence of the thermal expansion coefficients on irradiation dose at constant dose rate have been performed by Subrahmanyan." Rabolt12 investigated the influence of y-irradiation to unsintered Teflon 7A; he found a decrease of crystallinity with rising irradiation dose in the dose range of 500- 10,000 kGy. This effect is connected with a strong low-temperature shift of the phase transition at 19OC and therefore can be observed using Raman spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Studies on ?-radiation treatment of poly(tetrafluoroethylene) powder

Lunkwitz

Brger

Geiler

et al. 1996

J. Appl. Polym. Sci.

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SYNOPSISy-Irradiation of poly(tetrafluoroethy1ene) (PTFE) in the presence of air results in degradation of polymer chains by insertion of oxygen. At first, in the low-dose range below 400 kGy, a rise in crystallinity can be observed due to main chain scission in the amorphous part of the macromolecules. Dose increase up to approximately 1000 kGy causes progressive degradation of molecular weight as well as a growing degree of carboxylation of PTFE and increased concentration of trifluoromethyl groups in near-surface regions. At constant irradiation temperature, the properties of irradiated PTFE hardly depend on dose rate and starting material. The degree of carboxylation of the irradiated unsintered PTFE is appreciably lower in comparison with electron-irradiated PTFE under comparable conditions.

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“…Furthermore, the formation of vinyl end groups were identified under ␥-radiation in the presence of oxygen atmosphere. [17][18][19][20][21][22] However, high-energy radiation under vacuum showed the characteristics of olefin formation in the polymer chain and was responsible for the possible branching or crosslinking reactions. 23 The changes in thermal expansion coefficient, 24 thermal conductivity, 25 and dielectric properties 26 of PTFE were also studied when PTFE was exposed to ␥-irradiation.…”

Section: Introductionmentioning

confidence: 98%

?-Irradiated poly(tetrafluoroethylene) particle-filled low-density polyethylene. I. Effect of silane coupling agents on mechanical, thermal, and morphological properties

Akinay

Ti̇nçer

1999

J. Appl. Polym. Sci.

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Poly(tetrafluoroethylene) (PTFE) scraps were recovered as a filler material for low-density polyethylene (LDPE) after they were degraded by Co-60 ␥-rays under atmospheric conditions to make small-size powder. The powder PTFE, which was called secondary PTFE (2°-PTFE), was melt mixed with LDPE and then extruded to obtain 200 m films. The mechanical and thermal properties and also the morphology of the fractured surface of these 2°-PTFE-filled LDPE were studied. It was found that the addition of 2°-PTFE resulted in thermofilm property of LDPE but it slightly decreased the thermal oxidative temperature of LDPE. The tensile strength and ultimate elongation of LDPE were found to decrease with the addition of 2°-PTFE. However, when it is compared to the addition of virgin PTFE into LDPE, 2°-PTFE shows better mechanical properties due to the presence of oxy groups which are capable of interacting with the main matrix. A further improvement in mechanical properties was achieved by silane coupling agent treatment of 2°-PTFE. Silane coupling agents were found to enhance the interfacial adhesion between 2°-PTFE and LDPE. The study on the fractured surfaces by scanning electron microscope revealed this adhesion between these two polymers.

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Effects of gamma irradiation on PTFE

Cited by 20 publications

References 5 publications

Teflon scrap based cation exchanger by radiation grafting: Process parameter standardization and characterization

Teflon scrap based cation exchanger by radiation grafting: Process parameter standardization and characterization

Studies on ?-radiation treatment of poly(tetrafluoroethylene) powder

?-Irradiated poly(tetrafluoroethylene) particle-filled low-density polyethylene. I. Effect of silane coupling agents on mechanical, thermal, and morphological properties

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