Study On The Maleic Anhydride/Divinylbenzene Functional Modified Isotactic Polybutene-1

The maleic anhydride(MAH)/divinylbenzene(DVB) melt grafting of isotactic polybutene-1(iPB-1) was prepared(iPB-g-MAH-co-DVB) in torque rhemeter using dicumyl peroxide(DCP) as an initiator and DVB as comonomer. The effects of DVB concentration, reaction temperature, DCP concentration, MAH concentration, and reaction time on the grafting degree(Gd), grafting efficiency(Ge), and melt flow rate(MFR) of the iPB-g-MAH-co-DVB were researched respectively. It is significantly that DVB can improve the grafting degree, and when the reaction temperature was 180 centigrade degree, DCP and MAH concentration were 0.6 and 6 phr respectively, the ratio of DVB and MAH was 4/6, the grafting degree was 3.4%.The surface polarity of i PB-g-MAH-co-DVB increased with increasing grafting degree. Compared with iPB-1, the width of crystallization peak of iPB-g-MAH-co-DVB apparent narrowed, which indicated that the crystal speed was more fast than iPB-1. The melting and crystallization temperature of samples increased gradually with increasing graft degree, indicating the existence of(MAH-co-DVB) side chain could promote crystallization of iPB-1. Study on non-isothermal crystallization showed that, the crystallization peak of iPB-1 and iPB-g-MAH-co-DVB tend to move lower temperature with increasing cooling rate, and iPB-g-MAH-co-DVB need less time to complete crystallization than iPB-1. The non-isothermal crystallization kinetics was analyzed by Avrami, Ozawa, and Mo method, the results showed that it was not appropriate to analyze crystallization mechanism according to Avrami exponent values(n) under non-isothermal conditions, but it was suitable for the analysis crystallization mechanism through Ozawa and Mo method, because the two method could get a good linear curve. The isothermal crystallization process of iPB-1 and iPB-g-MAH-co-DVB was analyzed by polarizing optical microscopy(POM), in the same crystallization temperature(95 centigrade degree), the crystallization nucleation points of iPB-1 was few and the spherulites size was big, while the spherulites size of iPB-g-MAH-co-DVB was small due to a number of heterogeneous nucleation points existed in crystallization process.The iPB-1/iPB-g-MAH/OMMT(organically modified montmorillonite) composites were prepared by melt intercalation method in torque rheometer using iPB-g-MAH as compatibilizer. The effects of iPB-g-MAH and OMMT concentration on the structure melt crystallization behavior and mechanical properties of composites were investigated respectively. The results showed that, the tensile strength and elongation at break of the composites decreased with the addition of iPB-g-MAH-co-DVB and iPB-g-MAH-co-St compatibilizer. With the increasing compatibilizer, the mechanical properties of the composites decreased gradually when using iPB-g-MAH-co-DVB, but the using iPB-g-MAH-co-St showed an inverse tread. The POM of composites indicated that the OMMT and compatibilizer provided plenty of nucleating sites for crystallization of iPB-1, which resulting in the number of spherulites increased and the dimension reduced. It was evidenced by DSC that the crystallization properties of the composites could be improved by adding two kinds of compatibilizers.In the two kind of compatibilizers system, the tensile strength and elongation at break of the composites had a decrease tread with the increase of the amount of OMMT. The amount of OMMT had little influence on the melting temperature and crystallization temperature of the composites, but the relative crystallinity of the composites decreased gradually. The OMMT provided adequate nucleation sites for the heterogeneous nucleation of iPB-1, and the OMMT layers limited the spherulite growth of iPB-1, a large number of crystallization nuclei growed in a limited space, which resulting in the site of spherulites decreased gradually.