Preparation Of Polypropylene/Calcium Carbonate Composites And Analysis Of Its Viscoelasticity And Micromechanics

The two factors that influence the mechanical properties of prepared PP/CaCO₃composites were systematically discussed by perspectives of mechanics theory in this paper,which are aiming at the changing tendency of mechanical behavior in different test rate based on identical PP/PP-g-MAH/CaCO₃ composites,as well as aiming at the influence of CaCO₃content on the properties of different PP/PEPA-g-PHS/CaCO₃ composites in identical test condition.The analytical methods are extended based on the viscoelastic mechanics and micromechanics for engineering situations.In the discussion that the mechanical behavior of identical composite is influenced by different test rate:（1）Based on experiment,an optimized composite was obtained by method of two-factor optimal selection,whose prescription is 57.55wt%PP,35.56wt%CaCO₃,6.60wt%polypropylene grafted maleic anhydride（PP-g-MAH）,0.29wt%Antioxidant 1010.（2）In theory,the viscoelastic constitutive equation is extended for the simulation of geometric nonlinearity.Two respective relationships between average true stress/strain and normal stress/strain as well as a homogenizing constitutive equation are established.Furthermore,combined with the conditions of the two tests respectively,both uniaxial tension and three-point bending model are established.（3）The relationships between material constants and test rate are given.The theory coincides with experiments,which shows that the strain-stress curve of PP/CaCO₃ composite is owing to the outcome of competition between stress-increasing of extension and stress-decreasing of relaxation.In the discussion that the properties of composites in identical test rate are influenced by different CaCO₃ contents:（1）Based on experiment,for expanding the discussion range of CaCO₃ content and preparing high content composites,a hyper-dispersant of polyethylene polyamine grafted poly（12-hydroxy stearate）（PEPA-g-PHS）was designed and synthesized to obtain composites up to 70wt%CaCO₃ content.Dosage of PEPA-g-PHS is just 5wt%of CaCO₃ content.（2）In theory,a tensor independent on filler-contents is suggested by the combined self-consistent method to obtain an anisotropic general solution.Furthermore,the general solution is simplified and verified for the requirement of discussion in experiment.There is a close contact between combined self-consistent method and Mori-Tanaka method,which shows the theoretical significance of the combined method.（3）The relationships between material constants and filler content are given.The theory coincides with experiments,which shows the effectiveness of combined self-consistent method to estimate the properties of composite with irregular fillers.