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Micro - Preparation and Characterization of Nanometer SiC / polypropylene composites

Author: ChenHuiMin
Tutor: ZhangRui；ChenDeLiang
School: Zhengzhou University
Course: Materials Science
Keywords: Polypropylene (PP) Inorganic rigid particles Silicon carbide Composite Strengthening and toughening
CLC: TQ325.14
Type: Master's thesis
Year: 2009
Downloads: 43
Quote: 0
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Abstract


Polypropylene（PP） is widely used in automobiles and electrical equipments because of its unique processability,relatively high yield strength and low cost,when compared with other thermoplastics.However,owning to its low modulus and low heat deflection temperature,the applications of PP are still limited.PP,therefore,has to be strengthed and toughened.At present,modifying PP with rubber materials can improve the toughness while reducing the rigidity,dimensional stability and thermostability.Non-functional inorganic rigid particles can strengthen and toughen the PP composites but fail to endow PP with functional properties.For the purpose of "integration of structures and functions",we have chosen silicon carbide（SiC）,a functional semiconductor,as the modifier of PP,and expected that SiC has the ability to enhance the strength,toughness,modulus and antistatic properties of PP composites.Micro-sized and micro-/nanosized SiC particles were modified by silane （KH-550）,titanate（NDZ-201） coupling agents and their mixtures,respectively,and then the modified SiC particles were used as the fillers to fabricate SiC/PP composites. After blended and extruded,the mixtures of SiC and PP were injected and molded into standard specimens for measurements.The influences of the types and amounts of coupling agents,and the particle sizes of SiC powders on the properties of PP composites were systematically studied.The mainly results were shown as the followings:（1） Flexural strengths,flexural moduli,young’s moduli,and notched impact strengths of the SiC/PP composites have an obvious improvement with increases in the SiC content,while the tensile strengths decrease.When the mass fractions of SiC are 30%～40%,the flexural strengths,flexural moduli,and young’s moduli of the modified micro-/nanosized SiC/PP composites are enhanced by 40%,141%,142%, respectively,compared with the pure PP materials.The notched impact strength of the SiC/PP composite with 10%of the modified micro-/nanosized SiC filler is enhanced by 9%when compared with the pure PP materials,and enhanced by 15%compared with the SiC/PP composite with 10%of the modified microsized SiC filler.（2） The heat deformation temperature of SiC/PP composites has an obvious improvement along with the increase of the SiC content.The heat deformation temperature of the SiC/PP composite with 40%of the modified micro-/nanosized SiC filler is enhanced by 22%when compared with the pure PP materials,and enhanced by 4%when compared with SiC/PP composite with 40%of the modified microsized SiC filler.The DSC results show that SiC particles promot the crystal nucleation of PP, and increase the temperature and rate of crystallization of the PP composites. （3） The surface resistivity and volume resistivity of the SiC/PP composites with 40%of the modified micro-/nanosized SiC filler are 2.0×1012Ωand 4.5×1012Ω·m respectively,lower than those of the pure PP matrix(2.5×1015Ωfor the surface resistivity,7.4×1015Ω·m for the volume resistivity).SiC particles play a functional role in improvement of anti-static properties of the PP composites.（4） The SEM observations of the impact and tensile fractures of the modified micro-/nano-sized SiC/PP composites show that SiC particles homogeneously dispersed in the PP matrix,and the interface of SiC and the PP matrix bonded well. The improved interfacial bonding accounts for the strengthening and toughening of PP composites using SiC particles.（5） The SiC/PP composites with 30%～40%of the modified micro-/nanosized SiC fillers have the best overall properties.The modified micro-/nanosized SiC powders not only improve the mechanical and thermal properties of PP composites, but endow PP with anti-static properties.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > Polymer resin and plastic > Polyolefin plastic > Polypropylene
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