Radiation effects on liquid paraffins as polymer model compounds

Citation
Ys. Soebianto et al., Radiation effects on liquid paraffins as polymer model compounds, POLYM INT, 48(10), 1999, pp. 1010-1015
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
POLYMER INTERNATIONAL
ISSN journal
0959-8103 → ACNP
Volume
48
Issue
10
Year of publication
1999
Pages
1010 - 1015
Database
ISI
SICI code
0959-8103(199910)48:10<1010:REOLPA>2.0.ZU;2-6
Abstract
The effects of gamma rays on n-C16H34 and C30H62 have been studied under va cuum and oxygenated conditions. Aromatic compounds were dissolved in variou s liquids to investigate the protection mechanism. The radiolysis and prote ction mechanisms were explored from product analysis. Gas products were ana lysed by gas chromatography (GC),and combinations of GC, gel permeation chr omatography (GPC) and mass spectrometry (MS) were used to analyse the liqui d products. Hydrogen gas was the main component: of the gas product regardl ess of the irradiation conditions. Oligomerization was dominant under vacuu m, whereas chain-scission was dominant: under oxidation condition. Double b ond enrichment to the oligomeric products is the main source of HZ formatio n as shown by vacuum, radiolysis. The scission products under vacuum were s aturated alkanes, and the presence of O-2 during oxidation did not affect t he scission pattern. Energy (excitation and charge) transfer to the aromati c molecules reduces the solvent excitation that preceeds the formation of r adiolysis products. In vacuum radiolysis, reactions of additive-solvent mol ecules to form adduct compounds were observed. Mass analysis showed that th e adduct compounds had fewer double bonds due to hydrogenation, and the pro tection efficiency depended on the degree of aromaticity. The low OZ uptake [G(-O-2)approximate to 6.0] indicates that liquid oxidation does not exhib it chain kinetics. More than 90% of the consumed OZ was converted into the oxidation products in the liquid phase, mainly carboxylic acids. Hydroaroma tic compounds are energy- and charge-scavengers, but they are selectively o xidized leading to large OZ uptake and corresponding ketone formation. The G values of products in the vacuum radiolysis of liquid paraffins were hard ly comparable to those in the polymeric systems. However, similar tendencie s can be seen, and the comparable G(-O-2) in the radiation-induced oxidatio n indicates that the chemical reactions taken place in the liquid paraffins reflect those in the amorphous part of polymers. The results of mechanical testing on radiation-oxidized polypropylene (PP) matrix (stabilized and un stabilized) confirmed that alkane radiolysis and the protection mechanism a lso occurred in the practical application of polymers. (C) 1999 Society of Chemical Industry.