Preparation And Properties Of Novel Unsaturated Organic Acid Functionalized Polypropylene

In this work,1-acryloy-L-yrrolidine-2-carboxylic acid (L-APCA) functionalizedpolypropylene (PP) was prepared through solid phase grafting by using styrene ascomonomer. The chemical structure of L-APCA was characterized using nuclear magneticresonance (NMR) and Fourier transform infrared spectroscopy (FTIR), and the graftingdegree was measured by chemical titration. The properties of the functionalizedpolypropylene were studied by differential scanning calorimetry (DSC), polarized lightmicroscopy (PLM), Gel permeation chromatograph(GPC), FTIR, water contact angle andplatelet adhesion. The grafting mechanism was investigated by high performance liquidchromatography/time of flight-mass spectrometry (HPLC/TOF-MS).The monomer L-APCA was synthesized in alkali aqueous solution, then, purified byrecrystallization, and the results of NMR and FTIR proved that pure monomer wasacquired.PP-L-APCA/St with different grafting degree was prepared by solid state grafting ofL-APCA to the backbone, using Benzoyl peroxide (BPO) as initiator, styrene (St) ascomonomer, xylene as swelling reagent. Effects of concentration of the total monomers,ratioes of the two monomers, the amounts of initiators, temperature and reaction time ongrafting degree were investigated. It was found that in the range of90~110oC，the highertemperature gained the higher degree of grafting, the grafting degree increased firstly withthe increasing of reaction time, until reaching a limit. The highest grafting degree14.27%was obtained when the ratio of the two monomers L-APCA/St was3/7, the amount ofinitiator was0.67g, and reacted for30~40min at110oC. PP-L-APCA/St with welldistributed L-APCA functional group was observed through infrared imaging technology,the wettability and biocompatibility was improved according to the test of water contactangle and platelet adhesion, respectively.The mass-to-charge ratioes of small molecules generated during the grafting reactionprocess was measured by HPLC/TOF-MS and the reaction mechanism was analysed.During the reaction process of solid phase grafting, formed macroradicals of PP mightchiefly involve in the following reactions: reconbimation, grafting only with St orL-APCA, grafting with both St and L-APCA, and β-scission of the tertiary macroradicals. When both St and L-APCA were grafted on PP, it was found that St might react with themacroradical of PP firstly, and then the L-APCA grafted to the St-PP macroradicals,because St was more active than L-APCA during the reaction process.