Preparation Of Flexible Polypropylene For Nonwoven Fabric And Studies On Its Performances

The recent worldwide outbreak of COVID-19 highlights the importance of protective articles such as surgical masks and protection suits.As a result,the raw materials of non-woven fabrics used in surgical protective article manufacture are badly needed for epidemic prevention.A high proportion of nonwoven fabrics used for protective article manufacture are usually made of homopolymer polypropylene(PP)possessing high melt flow index by the method of spunbond nonwoven.However,the problem of insufficient flexibility in such fabrics leads to the reduction of the fit of the product.It has been found that the introduction of ethylene comonomer into the PP molecular main chain can reduce the regularity of the molecular chain and increase its flexibility.This research significantly improves the flexibility of the PP resin by the methods of blending elastomer and degradation of random propylene-ethylene copolymer(PPR).The processing properties,mechanical properties and flexibility of PP with high melt flow index prepared by the two methods are systematically studied.(1)Blending propylene-ethylene copolymer(PEC)elastomer with the homopolymer PP with high melt flow index makes the non-Newton index n of the blend increase,the viscous flow activation energy decrease,and the spinning stability increase;when the PEC content is low,PP/PEC blend fiber is not easy to break;after the introduction of PEC,the crystallization temperature of PP/PEC blend increases,which shortens the cooling and solidification time of the fiber;the Young's modulus and tensile strength of the PP/PEC blend decreased,meanwhile the impact strength increased significantly.(2)PPR with high melt flow index was also prepared by the degradation method.After degradation,the molecular weight of the PPR decreases and the molecular weight distribution narrows,the melt flow index of the material increase,and the apparent viscosity reduces,which is beneficial to the decrease in fiber fineness and improves the flexibility of the material.At the same time,the non-Newton index n of the PPR after degradation increases,providing good spinning stability;After degradation,the Young's modulus and tensile strength of PPR decreases,while the elongation at break increases.(3)Based on the above methods,the modulation of product flexibility has been realized,which is of guiding significance for industrial production.