A series of Ti/Mg supported catalysts are prepared by using ball-milled mixtures of MgCl2-ethanol adducts and NaCl as supports, and 1-hexene polymerizations catalyzed by the novel catalysts are studied. It is found th...A series of Ti/Mg supported catalysts are prepared by using ball-milled mixtures of MgCl2-ethanol adducts and NaCl as supports, and 1-hexene polymerizations catalyzed by the novel catalysts are studied. It is found that the molecular weight distribution of poly(1-hexene) becomes apparently narrower when catalysts with doped supports are used, indicating that changing the structure of the support is an effective way to regulate the active center distribution of heterogeneous Ziegler-Natta catalyst.展开更多
Spherical polyethylene/polypropylene (PE/PP) in-reactor blend granules with various ethylene/propylene molar ratios and high porosity were synthesized using a high yield TiCVMgCl2 supported catalyst. A solution of ben...Spherical polyethylene/polypropylene (PE/PP) in-reactor blend granules with various ethylene/propylene molar ratios and high porosity were synthesized using a high yield TiCVMgCl2 supported catalyst. A solution of benzoyl peroxide (BPO)/maleic anhydride (MAH)/xylene (interfacial reagent) or BPO/MAH/St (comonomer) was absorbed onto the PE/PP in- reactor blend granules, and solid phase graft polymerization of MAH on PE/PP was conducted. The amount of grafted MAH on PE/PP was measured through chemical titration. The results showed that solid phase graft polymerization of MAH in PE/PP in-reactor blend granules produced graft copolymer with high amount of grafted MAH, and the amount of grafted MAH was raised slightly when St was introduced as comonomer. The graft in-reactor blend was fractionated into five fractions through temperature-gradient extraction fractionation (TGEF), and the fractions were analyzed by FTIR. The results revealed that MAH is mainly grafted on the PE segments, whereas MAH was predominantly grafted on the PP segments when St was present in the graft polymerization system. In addition, the final product is still in the form of regular spherical granules, which is beneficial for industrial processing.展开更多
The polyamide 6(PA6)/SiO_(2) nanocomposites were prepared by in situ polymerization and the rheological behaviors were investigated.The morphology of resultant materials was characterized by scanning electron microsco...The polyamide 6(PA6)/SiO_(2) nanocomposites were prepared by in situ polymerization and the rheological behaviors were investigated.The morphology of resultant materials was characterized by scanning electron microscopy(SEM)and the rheological behaviors were characterized by capillary rheometer.The results showed that the SiO_(2) particle size was around 50 nm and the particles dispersed evenly in PA6 matrix.The nanocomposites were pesudoplastic fluids and the apparent viscosities of nanocomposites increased initially and then decreased with the increase in nano-SiO_(2) content at the same temperature.The non-Newtonian indexes of nanocomposites were smaller than those of pure PA6.With the increase in nano-SiO_(2) content the apparent viscous activation energies of nanocomposites increased initially and then decreased.The rheological behaviors revealed that there were strong interactions between PA6 macromolecule chains and nano-SiO_(2) particles.展开更多
基金This work was supported by the National Natural Science Foundation of China (grant No. 20174034, 20274037).
文摘A series of Ti/Mg supported catalysts are prepared by using ball-milled mixtures of MgCl2-ethanol adducts and NaCl as supports, and 1-hexene polymerizations catalyzed by the novel catalysts are studied. It is found that the molecular weight distribution of poly(1-hexene) becomes apparently narrower when catalysts with doped supports are used, indicating that changing the structure of the support is an effective way to regulate the active center distribution of heterogeneous Ziegler-Natta catalyst.
基金This work was supported by the Special Fund for Major State Basic Research Projects (Grant no. G1999064803).
文摘Spherical polyethylene/polypropylene (PE/PP) in-reactor blend granules with various ethylene/propylene molar ratios and high porosity were synthesized using a high yield TiCVMgCl2 supported catalyst. A solution of benzoyl peroxide (BPO)/maleic anhydride (MAH)/xylene (interfacial reagent) or BPO/MAH/St (comonomer) was absorbed onto the PE/PP in- reactor blend granules, and solid phase graft polymerization of MAH on PE/PP was conducted. The amount of grafted MAH on PE/PP was measured through chemical titration. The results showed that solid phase graft polymerization of MAH in PE/PP in-reactor blend granules produced graft copolymer with high amount of grafted MAH, and the amount of grafted MAH was raised slightly when St was introduced as comonomer. The graft in-reactor blend was fractionated into five fractions through temperature-gradient extraction fractionation (TGEF), and the fractions were analyzed by FTIR. The results revealed that MAH is mainly grafted on the PE segments, whereas MAH was predominantly grafted on the PP segments when St was present in the graft polymerization system. In addition, the final product is still in the form of regular spherical granules, which is beneficial for industrial processing.
基金This paper is financially supported by the National Natural Science Foundation of China(Grant No.10672197).
文摘The polyamide 6(PA6)/SiO_(2) nanocomposites were prepared by in situ polymerization and the rheological behaviors were investigated.The morphology of resultant materials was characterized by scanning electron microscopy(SEM)and the rheological behaviors were characterized by capillary rheometer.The results showed that the SiO_(2) particle size was around 50 nm and the particles dispersed evenly in PA6 matrix.The nanocomposites were pesudoplastic fluids and the apparent viscosities of nanocomposites increased initially and then decreased with the increase in nano-SiO_(2) content at the same temperature.The non-Newtonian indexes of nanocomposites were smaller than those of pure PA6.With the increase in nano-SiO_(2) content the apparent viscous activation energies of nanocomposites increased initially and then decreased.The rheological behaviors revealed that there were strong interactions between PA6 macromolecule chains and nano-SiO_(2) particles.
