Poly(imide‐siloxane) films with controlled thickness

Abstract Although thermoplastic poly-imide (TPI) gears do not have sufficient strength for power transmission, carbon fiber reinforcement greatly improves the strength of TPI gears. Previous experimental research showed that although standard specimens made from carbon fiber reinforced (CFR) TPI has 2.4 times strength in static bending than specimens made from natural TPI, gears made from CFR-TPI yields bending fatigue strength about 10 times greater than gears made from natural TPI. The present paper explains this phenomenon using viscoelastic tooth root stress analysis. The experiments indicated that the natural TPI gears showed much larger viscoelasticity than the CFR-TPI gears. Thus, tooth root stresses were calculated for cases of large and small viscosity moduli. These calculations showed tooth root stress increased with the increase in the viscosity modulus. Also, viscoelasticity may induce heat due to hysteresis loss, and this heat should reduce gear durability. The increase in tooth root stress and the heat due to hysteresis loss must make the durability of the natural TPI gears very small. Therefore, the CFR-TPI can yield much more durable gears than the natural TPI.

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Preparation and properties of propargyl ether-terminated poly(imide siloxane)s and their composites

High Performance Polymers ◽

10.1177/0954008320954523 ◽

2020 ◽

pp. 095400832095452

Author(s):

Qing Ye ◽

Qiaolong Yuan ◽

Farong Huang

Keyword(s):

Flexural Strength ◽

Thermomechanical Analysis ◽

Proton Nuclear Magnetic Resonance ◽

Aromatic Diamine ◽

The Novel ◽

H Nmr ◽

Chemical Structures ◽

Propargyl Ether ◽

Poly Imide ◽

Thermal Stability Of

The novel propargyl ether-terminated oligo(imide siloxane)s (PTISs) based on 2,2’-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), aminopropyl-terminated polydimethylsiloxane (APPS), 4,4’-diaminodiphenylmethane (MDA) and p-aminophenyl propargyl ether (APPE) were synthesized. The chemical structures of PTISs were characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR). The PTISs exhibited excellent solubility in organic solvent and had broad processing window. The T300 carbon fabric was used to reinforce the PTIS matrices and prepare the composites (T300CF/PTISs). The thermal stability of the cured PTISs was analyzed by thermogravimetric analysis (TGA). The dynamic thermal mechanical properties of the composites were measured by dynamic thermomechanical analysis (DMA). The results show that the temperature at 5% weight loss (Td5) and residual yield at 800°C (Yr800°C) of the cured PTISs in N2 increase with incorporation of the aromatic diamine, whereas the Yr800°C of the cured PTISs in air decreases with introduction of the aromatic diamine. The elasticity of the composite increases with incorporation of the aromatic diamine, and the peak temperature of loss factor for the composites are higher than 300°C. The flexural strength, tensile strength and interlaminar layer shear strength (ILSS) of the T300CF/PTIS composite display the values of 439 MPa, 427 MPa and 32 MPa at room temperature, respectively. The retention of the flexural strength and ILSS for the T300CF/PTIS composite are above 80% at 250°C.

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