Synthesis And Properties Of Novel Crosslinkable Poly (Arylene Ether Sulfone)

Poly(arylene ether sulfone)s (PAES) comprise a class ofmaterials used as engineering thermoplastics. Because of theirexcellent properties, such as high Tg and superior thermo-oxidativestability, which have been well reviewed, the synthesis andcharacterization of these amorphous aromatic polymers have beeninvestigated for numerous applications. Further more, compared topoly(aryl ether ketone)s, they are considerably more fluid at hightemperatures and thus are molded and processed more easily.However, Poly(arylene ether sulfone)s still have some undesirablefeatures. For example, they are solvent sensitive, especially understress, and as is typical for thermoplastics, undergo some creep whenunderload at elevated temperatures (>175oC). These shortcomingspreclude their use when solvent resistance and high-temperaturedimensional stability are requirements. To solve above problems we synthesized the poly (arylene ethersulfone)s, which cannot only resist to those industry solvents, but alsoheld the excellent properties the traditional PAESs have. A noveldiallyl-diphenol and a novel PAES with di-propylene pendant unitsare prepared by aromatic nucleophilic condensation. We expect thenovel PAES has some other many excellent properties: 1. Easy process above the Tg or in the solvent, 2. Simpler synthesis route than before, 76吉林大学硕士学位论文 3. Broad process window resulting from the larger range from polymer's Tg to onset crosslinking temperature, To prove our assumption, at first we characterized and analyzedthe monomer and polymer through MS, FTIR, DSC, H-NMR and 113C-NMR. The final results are consistent with our prediction . Secondly, we carried out further research about the polymer'scrosslinking properties .The polymer was procured with differenttime and temperatures respectively, and was measured their Tgs andGel percent. Based on the equation of the published literature, wecalculated the Tg∞ ( Tg∞ means Tg when the Gel percent is 100)by using the data of gel percent and their corresponding Tgs, and thecalculated result was 282oC. At the same time, we investigated other factors such as thecuring time, temperature and curing atmosphere how to influence thecrosslinking rate. The result was that the crosslinking degree wasincreased with the elevating curing temperature; the similar situationappeared in the relationship between crosslinking degree and curingtime. When we changed the curing atmosphere, the Tgs of thepolymers cured in air condition were a bit higher than Tgs of thosecured in nitrogen atmosphere. Thirdly, we employed FTIR instrument to trace the crosslinkingreaction. The absorption of vinyl groups at 966cm-1 was faded awaywith longer curing time and higher curing temperature, which could 77吉林大学硕士学位论文prove that the crosslinking reaction had occurred. Finally, the comparisons of polymer before and after curingwere performed. The glass transition temperature(Tg) and solubilityof polymer changed greatly after fully crosslinked (curing at 280oCfor 8 hours), in another word, we got a solvent-resistant PAES withhigh Tg after curing. However the thermo stability of polymer onlychanged slightly after crosslinking, but the TGA curve of crosslinkedpolymer was divided into two stages: the first one is the thermodecomposition of the aliphatic residues, and the second one is thedecomposition of aromatic residues. In sum, we successfully synthesized a novel crosslinkablepoly(arylene ether sulfone), which shows some advantages such asthe easy process before crosslinking, solvent resistance and high glasstransition temperature after crosslinking and so on. We also carriedout a serious of detail studies about the polymer's crosslinkingbehaviors, which provide a theoretical base for future researches.