Preparation And Study On The Perforanmance Of Polypropylene For Spun-bonded Nonwoven Grades

Spunbond nonwoven technology has become an indispensable part of nonwovens because of its short process,high production capacity,and versatility to produce a full range of products.Polypropylene(PP)is one of the most widely used raw materials in spunbond nonwovens.To meet the evolving needs of advanced technology,the demand for polypropylene material is also increasing.There are two ways to prepare spunbond polypropylene grades so far.One is the hydrogen initiated reaction which is used mainly in a large-scale of the petrochemical plant,and chemical degradation produces another one.Chemical degradation method adopted in this paper.The primary purpose of this study is to develop various spunbond grades polypropylene which has stable melt flow index and narrow molecular weight distribution.Chemical degradation process is introduced to solve the usual problems of hydrogen induced spunbond grade polypropylene such as a lack of mobility,unstable melt flow index,and wider molecular weight.Peroxide promoted degradation(chemical degradation process)can overcome those precise limitations and produce finer spunbond nonwoven grades.In this paper,the effects of various contents of a masterbatch degradation,processing temperature and main motor speed on the melting index and stability of polypropylene investigated.The mechanical properties,thermal properties,and rheological behavior of spunbond grade polypropylene analyzed by TG,DSC,and rheometer.The results showed that the melt flow rate of the polypropylene had increased with the increment of the degradation of that masterbatch and the processing temperature.The melt flow index of a material decreased with the increasing of machines' main motor speed and reduces the degradation time of the extruder.After degradation,the mechanical strength of material reduced due to the reduction in molecular weight,but the elongation at break increased,and the melting temperature and crystallization temperature went down.The deviation in the sensitivity of the shear rate indicated that the fluidity of the material is more stable and that the molecular weight and its distribution are narrower.Preparation of the spunbond grade polypropylene with better flow stability can be achieved by optimized process conditions like the degradation of master batch(molecular weight regulator content of 3%)dosage 50 phr ~ 60 phr,processing temperature 200? ~ 220?,feeder speed 144 rpm,main motor speed 70 rpm ~ 200 rpm.By this process,the melt flow index can be attained up to 40 ~ 50g/10 min or so,which is satisfied with spunbond grade polypropylene with desired material flow and stability requirements.