Study On Phase Transition Kinetic Of Polybutene During Solvent Vapor Annealing

Polybutene-1(PB-1)is a polymorphic polymer,which has the advantages of abrasion resistance and chemical corrosion resistance,etc.It takes several days for PB-1 to transition from form II to form I at room temperature,which is a long and slow process,which is not conducive to production and product quality control.Research has found that solvent vapor annealing can accelerate the phase transition of PB-1,thereby shortening the production cycle and improving product quality.Therefore,this paper investigates the effect of solvent vapor treatment on the crystal transformation of PB-1.This paper mainly includes three parts of content.Firstly,the changes in crystallinity of PB-1 samples during isothermal crystallization at 30 ℃,40 ℃,and 50 ℃ for 10,20,and 30 minutes were studied.The isothermal crystallization of PB-1 samples at different temperatures and times was observed through WXRD in situ observation.The results indicate that at the same temperature,as time increases,the intensity of the diffraction peak of form II(200)crystal plane in the onedimensional X-ray diffraction pattern gradually increases,while the half width of the peak gradually decreases.And with the increase of time,the crystallinity of PB-1 sample gradually increases.Isothermal crystallization at 50 ℃ for 30 minutes resulted in the highest crystallinity,and there was a significant difference in the intensity of the diffraction peaks of form II(200)in the one-dimensional X-ray diffraction pattern.Secondly,the mechanism of PB-1 phase transition in the process of natural transformation/solvent vapor annealing phase transition was studied.PB-1 with form II obtained by isothermal crystallization in 50 ℃ water bath was taken as the research object,and it was characterized by wide-angle X-ray diffractometer and Fourier infrared spectrometer.Research has shown that: The longer the time the PB-1 sample is kept at room temperature after isothermal crystallization,the longer the time requires for completely disappearance of form II during solvent vapor annealing,the form I generated at room temperature hinders the continuous phase transition during solvent vapor annealing;When the PB-1 sample of isothermal crystallization is treated with solvent vapor annealing for different time,the longer the solvent vapor treatment time,the shorter the subsequent transformation time of the following phase.This shows that the residual solvent still has an accelerating effect on PB-1.FTIR study shows that it takes 100 min for the residual solvent to volatilize from PB-1;The isothermally crystallized PB-1 samples were kept at room temperature for different time,then treated with solvent vapor annealing for 30 min,and finally the following form II of PB-1 was phase-transformed at room temperature.It is found that the promotion effect of n-hexane molecules is far greater than that of form I produced at room temperature.Finally,the effect of nucleating agents on solvent vapor induced phase transition of PB-1 was studied.Nucleating agents can accelerate the crystallization rate of PB-1,but will slow down the phase transition rate of PB-1.Research has shown that when the amount of nucleating agent is constant,the longer the PB-1 sample is placed at room temperature,the longer it takes for the following phase transition to occur during solvent vapor annealing.The nucleating agent and the form I generated at room temperature both hinder phase transition during solvent vapor annealing.However,as n-hexane molecules enter the interior of PB-1,the nucleating agent and the form I generated at room temperature have a less inhibitory effect on phase transition than the promoting effect of nhexane.Finally,the PB-1 sample will completely complete phase transition;When the PB-1 sample was first subjected to solvent vapor annealing,the subsequent PB-1 form II did not completely complete phase transition at room temperature.This is because the continuous phase transition of PB-1 after solvent vapor annealing takes more than 100 minutes at room temperature,and the n-hexane in PB-1 has evaporated,making the blocking effect of nucleating agents increasingly apparent.The conversion rate of the phase transition of PB-1 will reach a plateau value,which is less than 1.