Study On Engineering Technology Of PVC

Based on the reviews with plenty of references about the engineering technology of general plastics, nanoparticles/polymer composites, the crystallization behavior of poly(vinyl chloride)(PVC), modifying PVC by the way of blending with another polymer and mixing with nanometer CaCO₃ (nanoCaCO₃) , the new idea that engineering PVC materials may be prepared because of the effect of self-plasticization, self-toughening and self-reinforcement of nanocrystalline PVC on PVC is raised. Other new idea that high performance PVC/nanoCaCO₃ composites may be prepared through in-situ preparing nanoCaCO₃ is also raised. The three engineering technology of modifying by crystallization, blending with polyamide 6(PA6) grafted styrene-maleic anhydride (SMA) (PA6-g-SMA) and compositing with in situ prepared nanoCaCO₃ were studied respectively. The structure, morphology, composition and properties of modified PVC compounds and composites were investigated systematically. The main results obtained can be summarized in 15 parts as follow:(1) SMA can be grafted to molecular chain of PA6 by reaction between PA6 and SMA in phenol solution. The maximal grafting ratio of PA6-g-SMA can reach 5.12% when PA6 are reacted with 60% SMA for 8 hour at 100℃.The melting point of PA6-g-SMA decrease when it's grafting ratio increase. The melting point of PA6-g-SMA with 5.12% grafting ratio is 197℃. PA6-g-SMA can mix with PVC at 185℃ to prepare PVC/PA6-g-SMA compounds, it is said that, the problem of no way of PVC mixing with PA6 is solved.(2) PA6-g-SMA can toughen and reinforce PVC. The impact strength of PVC/PA6-g-SMA compound can reach 64.7kJ/m², which is 61.7% higher than that of pure PVC when the use level of PA6-g-SMA whose grafting ratio is 5.12% is 15%. The tensile strength of above mentioned materials can reach 55.0MPa, about 48.6% higher than that of pure PVC. Cocrystalline can found in PVC/PA6-g-SMA materials, it is suggested that PA6-g-SMA can used as nucleating agent of PVC and induce PVC crystallize.(3) After appropriate heat treated, unregulated PVC can crystallize when modified nylon uses as out-of-phase nucleating agent. The maximal crystallinity of PVC reaches 30.4% when raw PVC mixed with 2% modified nylon and heated for 2hr at 110℃.(4) Crystalline PVC can be crashed by improved flow clash crashing machine to prepare crystalline PVC micro powder effectively. The grain size of nanocrystalline in crystalline PVC micro powder is 80 nm. The melting point of nanocrystalline PVC is 128℃. The mechanism anddecisive factor of forming nanocrystalline PVC can be simulated by the crashing broken principle schematic plan of crystalline region model and shearing slip principle schematic plan of crystal plate model.(5) Nanocrystalline PVC has obvious effect of self-plasticization, self-toughen and self-reinforcement on PVC. Nanocrystalline PVC can also improve the heat-resisting property of PVC. The impact strength of PVC/nanocrystalline PVC materials can reach 70.3kJ/m2, at the same time;the glass transition temperate of the composite can reach 90 °C when 10% nanocrystalline PVC are dispersed to PVC matrix. The tensile strength of PVC/nanocrystalline PVC composite can reach 57.3MPa when 5% nanocrystalline PVC are dispersed to PVC matrix. The mechanism and decisive factor of self-plasticization can be simulated by being relieving from wrapping model and inducing molecular to relief from wrapping through generating velocity gradient model. The mechanism and decisive factor of self-toughen but self-reinforcement also improving the heat-resisting property of PVC can be simulated by out-of-phase nucleating of crystal nucleus model.(6) Microporous PVC with pore size of 0.2-2micron can be obtained by foaming of suspension PVC powders using the solution of 2, 2'-azo-bis-iso-butyronitrile in butanone when heated in 112°C oil bath for 8min. The pore of microporous PVC can be used as reactors to in-situ restricted prepare nanoCaCO3(7) It is found that macromolecular surface-activator and chelating agent of citric acid play a key role in the formation of CaCO3 nanoparticles through affecting the yield and particle size of in-situ prepared nanoCaCO3 The maximal yield can reach 10% when 18% Ca(OH)2, 0.18% macromolecular surface-activator and 0.5% citric acid are used and CO2 aerates for 15min at the velocity of 0.25L/min.(8) It is found that in-situ nanoCaCC>3 has obvious effect of toughen and reinforcement on PVC and can also increase the glass transition temperate of PVC. The impact strength of PVC/in-situ nanoCaC03 composites can reach 90.6kJ/m2, which is 93% higher than that of pure PVC when 5% in-situ nanoCaCO3 are dispersed to PVC matrix. The tensile strength of above mentioned PVC/in-situ nanoCaC03 composites can reach 70.2 MPa, which is 63% higher than that of pure PVC. The glass transition temperate of above mentioned PVC/in-situ nanoCaCO3 composites can reach 89.4°C.(9) It is found that in-situ nanoCaCO3 and nanocrystalline PVC have obvious synergistic effect of toughen and reinforcement on PVC and can also increase the glass transition temperateof PVC. The impact strength of nanocrystalline PVC/PVC/in-situ nanoCaC03 composites can reach 96.5kJ/m2, which is 105% higher than that of pure PVC when 10% nanocrystalline PVC and 5% in-situ nanoCaCO3 are dispersed to PVC matrix. The tensile strength of above mentioned nanocrystalline PVC/PVC/in-situ nanoCaC03 composites can reach 95.0 MPa, which is 121% higher than that of pure PVC. The glass transition temperature of above mentioned nanocrystalline PVC/PVC/in-situ nanoCaC03 composites can reach 105.68 °C(10) PVC plastics can be used as sectional material and tubular product when PVC is modified by both nanocrystalline PVC and in-situ nanoCaCO3 The maximal impact strength of PVC sectional material can reach 85kJ/m2;its maximal tensile strength can reach 78MPa when 10% nanocrystalline PVC and 5% in-situ nanoCaC03 are dispersed to PVC matrix. The maximal impact strength of tubular product material can reach 83kJ/m2;its maximal tensile strength can reach 75MPa when 10% nanocrystalline PVC and 5% in-situ nanoCaCO3 are dispersed to PVC matrix. The vicat softening point of sectional material and tubular product can reach 110 °C.