| Poly-(arther-ether-ketone) is a type of high performance polymer which have outstanding thermal property, corrosion resistance and mechanical properties, these polymers and their composites materials have found many applications in aerospace, automotive, electronic and nuclear industry, especially the poly-(ether-ether-ketone)(PEEK) based composites beome the most popular engineering thermal plastic. Besides good thermal property, corrosion resistance and outstanding mechanical property, its wear resistance is superb, it is the performance that used most widely in its application. PEEK can be used in no lubrication, high temperature, wet or corrosion conditions. However, with the developing of new technology, traditional PEEK can’t satisfy the industial application any longer. So, the improvement of PEEK’S wear resistance becomes the concentrated research.The present study aims to promote PEEK thermal property by chemical modification and improve the wear resistance of PEEK materials via an in situ synthesis process. This paper is concerned with the evaluation of the effects of addition of EG as filler on the conversion degree of polymerization, melting temperature Tm, decompose temperature Td, crystallinity and morphology of composites and wear resistance of these composites.The study results indicate that,1. PEEK was synthesized via nucleophilic polycondensation of phenol with4,4’ difluoro benzophenone in the presencse of potassium carbon. The effects of reaction temperature, reaction time to molecular weight were studied, the influence on the molecular weight by the reaction time indicating that the molecular weight mounted up with the increase of the reaction time, reaction was carried out at320℃and a time of4h was the best condition, this reaction condition can get the highest molecular weight ([η]=0.858) and the highest melt temperature(Tm=333℃). Then, expanded graphite (EG) was adopted as fillers, PEEK/EG was synthesized via in-situ polymerization and researched the effects of EG to PEEK in in-situ reaction. The results indicated that EG did affect PEEK molecular weight dramatically, with the increasing EG content, PEEK molecular weight got reduced. And the chemical and crystal structure wasn’t influenced by EG, the crystal degree was increased from35%to37.5%when EG content was0.5wt%but decreased when EG content was higher than0.5wt%. Moreover, the wear rate of PEEK/EG was decreased to3.992×10mm2/Nm at high load and sliding speed (200g,300r/min), it’s5times lower than PEEK. 2. In order to satisfy the harsher application environment requirements, this study introduced biphenyl-into PEEK polymer chain to get wear resistance composites with original decomposition temperature higher than500℃. DPEEK was synthesized via nucleophilic polycondensation of biphenol with4,4’-difluoro benzophenone. The effects of reaction temperature, reaction time to molecular weight were studied, The effects of reaction temperature, reaction time to molecular weight were studied, the influence on the molecular weight by the reaction time indicating that the molecular weight mounted up with the increase of the reaction time, reaction was carried out at320℃and a time of4h was the best condition, this reaction condition can get the highest molecular weight ([η]=0.574) and highest melt temperature(Tm=418℃). Then, expanded graphite (EG) was adopted as fillers, DPEEK/EG was synthesized via in-situ polymerization and researched the effects of EG to DPEEK and in in-situ reaction. EG did affect DPEEK molecular weight dramatically, with the increasing EG content, DPEEK molecular weight got reduced. And the chemical and crystal structure wasn’t influenced by EG, the crystal degree was increased from22%to25%when EG content was0.5wt%but decreased when EG content was higher than0.5wt%. Moreover, the wear rate of DPEEK/EG was decreased to0.142×10-6mm2/Nm mm2/Nm at high load and sliding speed(200g,300r/min), it’s3times lower than DPEEK and27times lower than PEEK/EG at the same test condition. |
PDF Full Text Request