Research On Preparation Of High Melt Strength Polypropylene By Grafting Of Dual Monomers In Solid Phase

Polypropylene has a high cost performance,good mechanical properties and stability thermal properties,etc,which are widely used in industry,agriculture,health and daily life,etc,it's the largest and widest polymer material.However,due to the linear structure of the polypropylene,resulting in there are some defects in polypropylene melt processing,e.g.products will local thinning when thermo-forming,easy to sag when extruded sheet,curl at edges when high-speed extrusion coating,it is difficult to film blowing and preparation of foam products.These shortcomings of polypropylene greatly limit the scope of its application.Polypropylene with high melt strength can overcome the above disadvantages,so high melt strength polypropylene has aroused widespread concern.In this paper,a pure solid-phase method and organic swelling agent to assist the solid phase graft were used to prepare the high melt strength polypropylene.The influence of the monomer type,initiator dosage,and reaction conditions on the grafting reaction in pure solid-phase method were investigated.FTIR results confirmed that both 1,6-hexanediol diacrylate(HDDA)and styrene(St)were grafted onto PP.The grafted product with the maximum grafting percentage of 3.81%and melt strength of 2.15 kPa-s was received when mass ratio of PP/HDDA/St/AIBN/Xylene= 100/4/1.37/0.3/8.6,reacted at 80 ?for 2.5 h.The thermal stability of the grafted product was improved.Polypropylene was grafted with HDDA and St in solid state,after being swollen with an organic solution of monomers and initiator for some time.The influence of monomer amount,initiator amount,reaction conditions and impregnation conditions were investigated.Structure and properties of grafted products were analyzed using Fourier transform infrared spectroscopy and thermo gravimetric.It was founded that compared with non-swelled product the grafting percentage and melt strength were increased effectively.MS = 2.51 kPa.s(4.48 times of the pure PP)of the grafted PP was achieved under the optimal condition,i.e.being swollen in 6.6 g sweller at 40 °C for 3 h,and reacted at 85 ? for 2 h.when mass ratio of PP/HDDA/St/AIBN/Xylene=100/4/1.8/0.3/7.74.The thermal stability of grafted product was improved.