Synthesis And Properties Of PDCPD Nanocomposites

Polydicyclopentadiene （PDCPD） is a novel engineering plastic since1990s,which processes high elastic modulus, high impact strength and excellent thermalstability. The current research on PDCPD is mainly focused on the improvement ofmechanical and flame retardant properties utilizing inorganic filler. Because of thepoor dispersity of inorganic additives in PDCPD matrix, they do not exert thefounction of inorganic additive, but often decrease the mechanical properties ofPDCPD composites. Actually it can’t improve the overall performance of PDCPDcomposites effectively. Therefore, improving the dispersion of inorganic fillers inpolymer matrix became one of the most important and difficult aspects for reinforcingand toughening polymers.In this work, SiO₂and MoS₂nanoparticles were selected as filler, PS/SiO₂andPS/MoS₂nanometer microspheres with core-shell structure were successfully preparedby two step method, which have good compatibility with PDCPD; and then wereadded into dicyclopentadiene （DCPD） monomer, and the two-component catalyst wereadopted to prepare PDCPD nanocomposites. First the influence of fillers on thepolymerization was discussed and the optimum reaction conditions were determined.Then PDCPD/PS/SiO₂nanocomposites were prepared using the reaction injectionmolding（RIM） device by in-suit polymerization method.Fourier-Transform Infrared Spectroscopy（FT-IR）, Ultraviolet visible spectroscopy（UV-Vis）, Field Emission Scanning Electron Microscope（FESEM）, Energy DispersiveSpectroscopy （EDS）, Transmission electron microscope （TEM） and dispersion testwere employed to characterize structure, morphology, ingredient, size and thedispersion in the dicylopentadiene （DCPD） of the PS/SiO₂and PS/MoS₂nanopowders;The morphology, structure, mechanical properties, tribological properties and themicrostructure of friction surface of PDCPD/PS/SiO₂nanocomposites werecharacterized and tested by FT-IR, SEM, FESEM, EDS, TEM, three-dimensional surface profile meter, universal material testing machine, Hang beam impactexperiment machine, and QG-700high-temperature atmosphere friction/wear tester.The results showed that PS had been successfully introduced into the surface ofSiO₂and MoS₂nanopowders, core-shell structure of PS/SiO₂and PS/MoS₂nanometermicrospheres, were obtained, which were formed by inorganic nanoparticles as thecore and PS as the shell. The well dispersion of PS/SiO₂and PS/MoS₂nanometermicrospheres in DCPD monomer were successfully achieved. The maxmum amount ofthe nanopowders reached6%（mass fraction） in DCPD, and the nanopowers could stillstay in the DCPD for more than30min. Then PS/SiO₂microspheres as filler wereadded into DCPD to prepare PDCPD/PS/SiO₂nanocomposites. And the best reactionconditions of PDCPD/PS/SiO₂nanocomposites were determined by the ampule tests:the polymerization temperature was70℃, and the mole ratio of n（DCPD）: n（W）: n（Al）was1200:1:25. Then a series of different PDCPD-based nanocomposites wereprepared under the best reaction conditions. The SEM and TEM images showed that agood interfacial compatibility exsited between PS/SiO₂nanometer microspheres andPDCPD matrix, and PS/SiO₂could disperse uniformly in PDCPD matrix. Themechanical and tribological properties tests showed that PDCPD/PS/SiO₂nanocomposites have the best comprehensive properties when the content of PS/SiO₂nanopowers was4wt.%. Compare to the pure PDCPD, the tensile strength and tensilemodulus were increased by92.8%and103.4%, respectively; the flexural strength andflexural modulus were increased by70.5%and81.2%, respectively; the impactstrength increased by112%; the friction coefficient and weight loss were reduced by16.9%and36.4%, respectively; and the wear rate in volume and weight weredecreased by92.9%and29.9%, respectively. The strengthening and tougheningmechanisms and friction and wear mechanisms were also discussed forPDCPD/PS/SiO₂nanocomposites in this paper. The well interfacial compatibility ofPS/SiO₂nanometer microspheres in PDCPD matrix is the important reason for thePDCPD/PS/SiO₂nanocomposite with good mechanical and wear properties in the lowPS/SiO₂addition.