Preparation And Treatment Of Calcium Sulfate Whiskers In The Presence Of Fe³⁺ Study On The Effect Of Polypropylene Structure And Properties

In this paper,Fe³⁺-based calcium sulfate whiskers?TCSW?were prepared by choosing hydrothermal method and using industrial waste phosphogypsum?PG?as the main raw material.In the preparation process,the effects of reaction temperature,slurry concentration,slurry initial p H value,reaction time and Fe³⁺-based crystal type agitator on the preparation and morphology of calcium sulfate whisker were studied in detail.Confirm the results of the experiment the optimum conditions were as follows: reaction temperature 130 ?,slurry concentration 6%,slurry initial pH4.0,reaction time 4h,Fe₂?SO₄?₃ and MgSO₄ ratio of 1.25.Under these conditions,Fe³⁺-based calcium sulfate whisker products?TCSW-3?with an average diameter of 2 m and an aspect ratio of35.3 were prepared.The FTIR and XRD analysis show that the whiskers synthesized under these conditions are calcium sulfate hemihydrate whiskers.In addition,the TCSW with different aspect ratio could be prepared under different conditions,the phosphogypsum and the TCSW with different aspect ratio were using to blend with polypropylene respectively to prepare the necessary composites.Then analyzing the property of effects and the law of changes in PP crystallization by adding these fillers and their quantities.The study found:PG,Fe³⁺-based superfine calcium sulfate whisker?TCSW-4?and he average aspect ratio of the Fe³⁺-based whiskers is 5?TCSW-2?have little effect on the Heterogeneous nucleation effect of PP,and the quantities of which can promote the conversion of PP from ?-crystal to?-crystal are about 13%.The heterogeneous nucleation effect of PP is relatively obvious by TCSW-3 and the average aspect ratio of the Fe³⁺-based whiskers is 1?TCSW-1?.When the addition amount is the 5% TCSW-3,the content of ? crystal is as high as 91.82%,which can be used as an effective nucleating agent of polypropylene ?.The main components of the modified PP filler are S?sulfur?element and other impurities,so the infrared absorption peak of the composite material is obviously enhanced.After ultrasonic modification of TCSW-4,it can accomplish heterogeneous nucleation of PP,and promote the conversion of PP from ?-crystal to ?-crystal.The content of ?-crystal increases with the increase of UTCSW content.After the addition of suberic acid?SA?and ultrasonic modification of TCSW-4,the crystallization temperature of the composites increased which improved the crystallization rate of the composites,promote the growth of ?-crystal of PP.