Preparation, Morphology And Properties Of Heat Resistant And Anti-impact Poly(Vinyl Chloride) Composites

Although the comprehensive performance of PVC resin is promising, the relatively low heat resistance and impact strength restrict its application. The attempts to promote the heat resistant property of PVC material usually deteriorate its processability and mechanical properties. The plasticization and toughening of PVC material can enhance the toughness, but meanwhile, sacrifice its heat resistant property. If the plasticizing molecules can be anchored on the surface of inorganic particles to form a core-shell structure and incorporated into the PVC matrix, their mobility in host material can be hampered and the dispensability of inorganic particles can be promoted. Additionally, such strategy can realize a simultaneous plasticizing, reinforcing and toughening, and enhance the heat resistance of PVC material. In this thesis, the kaolin and calcium carbonate particles with core-shell structure are prepared by liquid-like technique, intercalation inset technique and coating crosslink technique. These core-shell structured inorganic particles are mixed with PVC matrix to produce PVC/inorganic particle composites with high impact strength and heat resistance.The main contents and results are listed as follows:1. The dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride (DC5700) is used to modify the surface of kaolin. Then sodium nonylphenol polyoxyethylene ether sulfate (NPES) is used to achieve ion exchange reaction with kaolin organic ion salt to produce solvent-free kaolin fluid (SFKF). The Fourier Infrared Spectrometer analysis (FTIR), X-ray Diffraction (XRD), thermogravimetric analysis (TG) and transmission electron microscope (TEM) are used to analyze the structure of SFKF. The rheological property of SFKF is studied by electromagnetic rheometer. The results show that the surface of SFKF grafts43wt%long chain organic species. It can flow when the temperature achieves65℃, at which the kaolin particles are intercalated and partially exfoliated.2. The PVC/SFKF composites are prepared by mechanically mixing SFKF with PVC materials. The processability, micro-structure, dynamic mechanical behavior and mechanical properties of PVC/SFKF composites are studied by using torque rheometer, ultraviolet-visible spectroscopy (UV-vis), scanning electron microscope (SEM), dynamic mechanical analysis (DMA) and universal mechanical testing machine, respectively. The results show that SFKF has fine plasticization effect on PVC materials, and restrains the decomposition of PVC materials during melting process. SFKF can uniformly disperse in PVC matrix, and the interface adhesion between kaolin and PVC matrix is enhanced. The notched impact strength of the PVC/SFKF composite achieves4.08kJ/m2, which is33%higher than that of neat PVC materials. The Tg of the PVC/SFKF composite is93.6℃, which is4.4℃higher than that of neat PVC materials.3. The liquid macromolecular plasticizer (LMM-1) with nitrile end-group is used to intercalate kaolin on the surface, and thus the core-shell structured kaolin (LKL) is obtained. The PVC/LKL composites are prepared by melt blending LKL with PVC materials. The processability, micro-structure, dynamic mechanical behavior and mechanical properties of PVC/LKL composites are studied by employing torque rheometer, UV-vis, SEM, DMA and universal mechanical testing machine. The results show that LKL has good plasticization effect on PVC materials, and can restrain the decomposition of PVC materials during melting process. The intercalation of LMM-1can improve the dispersion of LKL in PVC matrix and the interface adhesion between LKL and PVC matrix is enhanced. The notched impact strength and Tg of the PVC/LKL composites achieve4.0kJ/m2and95.2℃, respectively, which are enhanced29%and6℃with respect to neat PVC materials.4. The core-shell structured CaCCO3(LCC) particles are prepared by coating LMM-1on the surface of CaCO3particles. The PVC/LCC composites are also prepared through melt blending LCC with PVC materials. The processability, micro-structure, dynamic mechanical behavior and mechanical properties of PVC/LCC composites are studied by using torque rheometer, UV-vis, SEM, DMA and universal mechanical testing machine. The results show that LMM-1and CaCO3particles have good synergistic plasticization effect on PVC materials, and can restrain the decomposition of PVC materials during melting process. The dispersion of LCC in PVC matrix is improved when the CaCO3particles are modified by LMM-1. The notched impact strength of PVC/LCC composite incorporated with optimum amount of LCC particles is4.95kJ/m2, which is59.7%higher than that of neat PVC materials. The Tg of the composite is93.0℃, which is3.8℃higher than that of neat PVC materials.5. The structure and properties of PVC material incorporated with CaCO3and LCC particles after UV aging are characterized using whiteness test, UV-vis, SEM and universal mechanical testing machine. The results show that LCC particles used as ultraviolet light screening agents can effectively improve the anti-aging properties of PVC matrix. Due to the coating of LMM-1on the surface of CaCO3particles, the compatibility between CaCO3particles and PVC matrix is significantly improved. The LCC particles can uniformly disperse in PVC matrix and effectively reflect ultraviolet light. Based on these premises, the LCC particles have better anti-aging properties than CaCO3particles for PVC matrix. The PVC/LCC composite has higher whiteness and mechanical property retention than PVC/CaCO3(PVC/CC) composite.6. The liquid macromolecular plasticizer (LMM-2) with double bond end-groups is used to modify CaCO3particles, and then the crosslinking agent is added to crosslink the LMM-2. The core-shell structured CaCO3particles with crosslinked coating layer (CLCC) are obtained. The PVC/CLCC composites are also prepared through melt blending CLCC with PVC materials. The processability, micro-structure, dynamic mechanical behavior and mechanical properties of PVC/CLCC composites are studied by using torque rheometer, UV-vis, whiteness test, SEM, DMA and universal mechanical testing machine. The results show that CLCC has fine plasticization effect on PVC materials, and can restrain the decomposition of PVC materials during melting process. CLCC significantly enhances the toughness and heat resistance of PVC materials. When the CLCC content reaches an optimum value, the crosslinked LMM-2forms three-dimensional network structure in PVC matrix, and the notched impact strength and Tg of the composite achieve5.8kJ/m2and104.6℃, respectively, which are much higher than that of neat PVC materials.7. The interface interaction between PVC matrix and CaCO3particles before and after modification is studied by using Pukanszky equation. The degradation mechanism and behavior of PVC/LCC and PVC/CLCC composites are investigated by using Friedman equation and Kissinger equation. The results show that the interface adhension between CaCO3particles and PVC matrix significantly enhances after the addition of LMM-1and LMM-2. The degradation mechanism of PVC, PVC/LCC and PVC/CLCC composites are consistent at the first stage of degradation. The addition of LCC and CLCC particles only changes the decomposition speed of PVC materials, but does not alter its degradation mechanism.