I hope this article can help some friends in scientific research. I am very proud of our efforts over the past few months and hope to 6600-40-4 help many people in the next few years. Product Details of 6600-40-4.
One of the major reasons for studying chemical kinetics is to use measurements of the macroscopic properties of a system, such as the rate of change in the concentration of reactants or products with time. 6600-40-4, Name is (S)-2-Aminopentanoic acid, formurla is C5H11NO2. In a document, author is Pai, Alex Y., introducing its new discovery. Product Details of 6600-40-4.
Effect of High Temperature Annealing on Thermal Expansion Behavior of Poly(amide-imide) Films with Ultralow Coefficient of Thermal Expansion
A kind of representative poly(amide-imide) (PAI) films derived from 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) and amide-containing diamine i e N,N’-(1,4-phenylene)bis(4-aminobenzamide) (PABA) were prepared via thermal imidization, and then annealed at various high temperatures including 350, 375, 400 and 425 degrees C, respectively. With the increase of annealing temperature, the heat-resistance of PAI films were improved with higher T-g values, whereas their thermal decomposition stabilities were reduced to some extent especially when annealed above 400 degrees C. All of these PAI films exhibited ultralow thermal expansion with negative coefficient of thermal expansion (CTE) values from -6.87 ppm/degrees C to -3.84 ppm/degrees C even in a wide temperature range of 30 – 400 degrees C. It was noted that the CTE values of PAI films were increased to around zero as annealing temperature elevated. The annealing effect on aggregation structures and thermal expansion behavior was further investigated by birefringence (Delta n), FTIR, WAXRD and WAXS. The birefringence of PAI films was extraordinarily larger than that of aromatic polyimide films, indicating that PAI molecular chains were more oriented in the in-plane direction. Their Delta n values ranged from 0.2438 to 0.2621 as annealing temperature increased from 350 degrees C to 425 degrees C. The hydrogen bonding interactions were proved to be maintained even at high temperature as the main reason for the dimension stabilities of PAI films. It was also found that annealing at high temperature could contribute to the enhanced intermolecular interactions. In addition, the intermolecular chain distance of PAI films was observed to be reduced with the increasing temperature, suggesting that molecular chains were packed more densely. Furthermore, the interchain distance in the film thickness direction was more affected by annealing with large variation than that of in-plane direction. PAI-425 film showed significantly negative thermal expansion mainly because of its expanding out-of-plane interchain distance. Based on high temperature annealing, the relationship between thermal expansion behavior and aggregation structures of PAI films was established to be used for the regulation and control of thermal expansion. It provided a new strategy to prepare heat-resistant polymer films with ultralow CTE values by the structure design and high temperature annealing.
I hope this article can help some friends in scientific research. I am very proud of our efforts over the past few months and hope to 6600-40-4 help many people in the next few years. Product Details of 6600-40-4.