Oriented Structure Formation Of PAcr/MPS-SiO₂ Composite Particle In Shear Flow Field

Oriented filling one-dimensional materials in micron chemical fiber to give them enhancement,conduction,fluorescence,catalysis,magnetic response,temperature response and structure chromaticity effects is an important proposition in the production of fiber modification and chemical fiber differentiation,and also a kind of important development direction of developing functional fibers and intelligent fibers.Carbon nanotubes,carbon fiber with high-strength and high-conductivity are the first choice of one-dimensional materials,but these fibers are difficult to disperse in the melt whether modification or not,a small amount of addition will dramatically increase the viscosity of the compound system,which is difficult to molding.Inorganic nanoparticles have a series of excellent properties which is different from large particles,addition it to textiles can greatly improve the strength,elasticity,abrasion resistance,light stability and thermal stability of textiles,but the existing addition methods have shortcomings of esistant poor wash ability and easy to aggregation.Preliminarily encapsulation of the surface-modified inorganic nanoparticles in the polymer latex particles by in-situ polymerization to prepare pomegranate-like composite colloids.And then take the high inorganic content pomegranate-like composite particles as pre-dispersed masterbatch,and by the strong shear effect of the molten blending field to realize the one-dimensional oriented filling of inorganic nanoclaves in the fiber to solve the problem of agglomeration and also give excellent performances of the materials.And to carry out the relevant basic research,one need to complete the following works:?1?Prepared a series of different size,inorganic nano-particle content,graft crosslinking structure wihch can be significantly controlled pomegranate-like PAcr/MPS-SiO₂ composite particles;?2?To optimize the shear flow field processing technology and conditions;?3?To specific research the formation law of the orientation structure of the pomegranate-like PAcr/MPS-SiO₂ composite colloidal particles in shear flow field.In this paper,we choose nano-SiO₂ as representative inorganic nano-particles,hard monomer methyl methacrylate?MMA?and soft monomer butyl acrylate?BA?as representative monomer,3-?methyl Acryloyloxy?propyltrimethoxysilane?MPS?as representative active silane coupling agent,a series of pomegranate-like PAcr/MPS-SiO₂ composite particles with different SiO₂ size,SiO₂ content and crosslinked structure were prepared by MPS coupling modification of SiO₂,monomer substitution and in situ micro-suspension polymerization.The effects of the free MPS,SiO₂ surface anchoring of MPS and SiO₂ content on the grafting and crosslinking structure of composite colloid were evaluated by the combination of extraction test and 3D video microscope.Then by observing the morphological structure of the composite particles in the matrix by TEM to reveal the formation laws of the orientation structure of the PAcr/MPS-SiO₂ in the Shear flow field.First,using SiO₂ ethanol dispersion prepared by St?ber method as basis nanopartilcles,SiO₂ was modified by silane coupling agent MPS to obtain a series of SiO₂ ethanol dispersions with different coupling densities.The methyl methacrylate monomer dispersion with different content of MPS was prepared by centrifugation or medi ?m replacement.The methyl methacrylate monomer dispersion and butyl acrylate were used as monomer,a series of PAcr/MPS-SiO₂ composite colloids with different cross-linking structures were prepared by single change the SiO₂ content,surface anchored MPS content and free MPS content.Then,the grafted cross-linked structures of the composite colloids were assessed by combination the size change of colloidal particles in its good solvent observed by 3D video microscopy system and the Soxhlet extraction test measured gelatinization rate of rubber particles.The effects of the content of SiO₂ particles,the degree of coupling modification and the content of free silane coupling agent MPS on the degree of crosslinking of the composite colloid were focused investigated.It was found that the double cross-linking structure with SiO₂ particles and MPS oligomer molecules as the crosslinking point could be constructed simultaneously in the composite colloid by conventional in-situ micro-suspension polymerization.These two cross-linking forms have different scales and effects on the molecular chain motility,which can produce synergistic effect on the shearing orientation behavior of the colloidal particles under certain conditions.Secondly,by studying the effect of shear rate,shear temperature and shear time on the formation of oriented arrangement structure of the pomegranate-like PAcr/MPS-SiO₂ composite particles,the optim ?m process conditions were determined.It was found that pomegranate-like PAcr/MPS-SiO₂ composite particles could form a perfectly aligned structure in the matrix at shear rate of 65r/min,shear temperature of 180 ? and shear time of 12 min under the shear flow of HAAKE torque rheometer.Finally,on the basis of the above work,the effect of the size and cross-linked structure of pomegranate-like PAcr/MPS-SiO₂ composite particles on the orientation structure were studied.Through the morphology of PAcr/MPS-SiO₂ composite particles observed by TEM and the statistic aspect ratio of the oriented structure,we have found that the size of the composite particles has an important effect on the oriented structure.Too large size of the composite particles lead to easy dissociation,and too small size not produce oriented structure.When the size of the composite colloid is about 1 3 ?m,the composite particles can form a well alignment structure.At the same time,the degree of cross-linking of composite particles is too high or too low are both not suitable for orientation,low easy break down at low degree,and difficult to orientation at high degree.When the Keq value?swelling degree?of the composite particles is 1.46,the composite particles can form a wellr alignment structure.In this work,the PAcr/MPS-SiO₂ grafted composite particles prepared by in-situ micro-suspension polymerization were used as pre-dispersed masterbatch,by adjusting the size and crosslinked structure of the composite particles and using the strong shearing action of melt blending to make the PAcr/MPS-SiO₂ grafted composite partickes deformed and oriented with different degrees,and then the SiO₂ particles in the matrix will appear in the ellipsoid,spindle-like,micro-fiber-like nano-level of the one-dimensional orientation structure.The research results can provide a new process sight for modification and differentiated production of fibers.