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Study on Preparation and Properties of PAI Materials Containing Trifluoromethyl in Side Chain
Haiyang Yang,Duxin Li,Jun Yang,Jin Wang,Shunchang Gan,Kaikai Cao,Yufeng Liu 한국고분자학회 2021 Macromolecular Research Vol.29 No.10
Polyamide-imide (PAI) materials with good heat resistance, excellent friction, wear properties, and low water absorption were prepared by acyl chloride process with diamine monomer containing trifluoromethyl in the side chain. The results showed that PAI prepared from 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]- 4,4'-diamine without flexible hinge group had the best heat resistance, with T g as high as 302.6℃ and T d5% as 490.1℃. With the increase of the proportion of flexible hinge groups in diamine monomer, the thermal properties of PAI materials would decrease. The wear mechanism of PAI prepared from 2,2'-bis(trifluoromethyl)- [1,1'-biphenyl]-4,4'-diamine was mainly adhesive wear. With the increase of the proportion of flexible hinge groups in diamine monomer, the wear mechanism would change from abrasive wear, slight adhesive wear to severe adhesive wear. The friction coefficient and wear loss of PAI prepared by 1,4-bis(4-amino-2-trifluoromethylphenoxy) benzene were the smallest, which were 0.4706 and 3.5, respectively. PAI synthesized by diamine monomer containing trifluoromethyl had low water absorption and high water contact angle. With the increasing flexibility of monomer containing trifluoromethyl diamine, the elongation at break and tensile strength of the material increased gradually.
Qi Zhang,Duxin Li,Dengwang Lai,Baoli Ou 한국고분자학회 2015 Macromolecular Research Vol.23 No.9
In order to increase the spacing between clay layers and study the effects of processing on the morphology and properties of PI/organoclay composites, polyimide (PI) composites containing multi-step procedure-modified sericite mica were prepared via in situ polymerization and solution intercalation. The structure-property relationships of the composites were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS). The results of XRD patterns revealed d002-spacing of clay was expanded from 0.99 to 2.77 nm. TEM photographs indicated majority of the organoclay exhibited an exfoliated morphology in composites prepared by in situ polymerization. TGA summarized the composites prepared by solution intercalation and in situ polymerization had a 9 and 29 oC increment in T5 compared with pristine PI respectively. XPS indicated the interaction of organoclay and polymer matrix in composites prepared by in situ polymerization was stronger than other types of composites. The glass transition temperature (Tg) and storage modulus of the composites prepared via in situ polymerization was much higher. Especially the Tg of this composites revealed a 33 oC increase compared with pure PI.