Crystallization Behavior of the Graft Copolymers of PP
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Maleic zinc was successfully grafted on polypropylene powder by solid-phase grafting technology.The crystallization behavior of PP and its graft copolymers was studied by WAXD,PLM and DSC.The results indicate that the graft group can induce PP to form β type crystal,and its spherulite become smaller and imperfect.The graft copolymers are easy to crystallize at higher temperature.The isothermal crystallization kinetics indicate that the graft group can accellerate the crystallization rate of PP,and doesn`t affect the nucleation behavior.Keywords:
Spherulite (polymer physics)
Polypropylene
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The influence of surface grafting modified nano-silica on the isothermal and non-isothermal crystallization kinetics of isotactic polypropylene (IPP) was investigated by DSC.The silica particles were pre-grafted with styrene,methyl methacrylate,ethyl acrylate and butyl acrylate,respectively.The experimental results show that the addition of nano-silica into PP has an obvious nucleating effect on the crystallization of PP,resulting in higher crystallization temperature and melting point,as well as higher crystallinity and the overall rate of crystallization,but lower crystalline regularity.The surface grafting treatment of the nanoparticles promotes the nucleating effect due to the increased miscibility between the particle and the matrix.The nucleating effect of the particles is also related with their dispersion state in the polymer matrix.The melting behavior of neat PP is different to that of the PP filled with nano-silica.The later has a more uniform crystal structure because the fillers act as nucleates.However,a faster isothermal crystallization process of the PP filled with nano-silica results in a lower equilibrium melting point,implying that the crystalline structure is less perfect in this case.
Tacticity
Polypropylene
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Abstract Polypropylene (PP)/wasted poly(ethylene terephthalate) (PET) fabric composites and these composites modified by maleic anhydride grafted polypropylene (PP‐ g ‐MA) and reactive monomers were prepared with a twin‐screw extruder. The crystallization morphology, nonisothermal crystallization and melting behavior, crystallization kinetics, and isothermal crystallization kinetics were investigated with differential scanning calorimetry. The results indicated that the wasted fabric (WF) had a heterogeneous nucleation effect on PP in the composites, and this increased the crystallization temperature and induced PP to form transcrystallinity. PP‐ g ‐MA further increased the crystallization temperature; however, the reactive monomers weakened the heterogeneous nucleation effect of WF. Also, the premelting temperature affected the crystallization and melting behavior of the composites significantly. The Avrami equation and the Mo method provided a fairly satisfactory description of the crystallization kinetics. The crystallization activation energy, nucleation constant, and folding surface free energy of PP were markedly reduced in the PP/waste PET fabric composites and the compatibilized composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 00: 000–000, 2011
Polypropylene
Maleic anhydride
Avrami equation
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Polypropylene
Morphology
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The non-isothermal crystallization kinetics of polypropylene solid grafted Ethyl methacrylate (PP-g-EMA) at different cooling rate was studied by means of DSC, and the data were analyzed by using Jeiorny, MO and Kissinger methods. The results showed that solid grafted EMA could play a role of heterogeneous nucleating agent in PP, raising the crystallization temperature and crystallinity of PP. Mo method was very suitable to describe the non-isothermal crystallization kinetics of the system. The grafted EMA accelerated the crystallization rate of PP, also changed the mode of the nucleation and the growth of the crystallites. The crystallization activation energies of PP and PP-EMA were calculated by means f Kissinger method. It was found that the grafted EMA increased the crystallization activation energy of PP, hindered the motion of the molecular chain of PP during the crystallization.
Polypropylene
Isothermal process
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Copolymerization is an effective strategy to regulate the molecular structure and tune crystalline structures. In this work, novel butene-1 copolymers with different polyethylene glycol (PEG) grafts (number-average molecular weight Mn = 750, 2000, and 4000 g/mol) were synthesized, for the first time introducing long-chain grafts to the polybutene-1 main chain. For these PEG-grafted copolymers, crystallization, melting, and phase transition behaviors were explored using differential scanning calorimetry. With respect to the linear homopolymer, the incorporation of a trimethylsilyl group decreases the cooling crystallization temperature (Tc), whereas the presence of the long PEG grafts unexpectedly elevates Tc. For isothermal crystallization, a critical temperature was found at 70 °C, below which all polyethylene glycol-grafted butene-1 (PB-PEG) copolymers have faster crystallization kinetics than polybutene-1 (PB). The subsequent melting process shows that for the identical crystallization temperature, generated PB-PEG crystallites always have lower melting temperatures than that of PB. Moreover, the II-I phase transition behavior of copolymers is also dependent on the length of PEG grafts. When form II, obtained from isothermal crystallization at 60 °C, was annealed at 25 °C, PB-PEG-750, with the shortest PEG grafts of Mn = 750 g/mol, could have the faster transition rate than PB. However, PB-PEG-750 exhibits a negative correlation between transition rate and crystallization temperature. Differently, in PB-PEG copolymers with PEG grafts Mn = 2000 and 4000 g/mol, transition rates rise with elevating crystallization temperature, which is similar with homopolymer PB. Therefore, the grafting of the PEG side chain provides the available method to tune phase transition without sacrificing crystallization capability in butene-1 copolymers.
Polybutene
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Polypropylene
Toughening
Poly ethylene
Ethylene propylene rubber
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The non-isothermal crystallization behaviors of polypropylene graft poly(vinyl acetate) (PP-g-VAc) with two grafting degrees were studied by differential scanning calorimetry.The kinetics of PP and PP-g-VAc under non-isothermal crystallization conditions were analyzed by Reziorny method and R-t method.The results showed that both Reziorny method and R-t method described the crystallization behaviors successfully,VAc side chains didn't change the nucleation and growth patterns,but decreased the crystallization rate and ability: t_1/2 increased and Z_c decreased,nucleation rate of grafted PP at high graft percentage ( GP) increased,crystallization enthalpy decreased and crystallization parameter F(T) increased with GP.
Polypropylene
Isothermal process
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The cross-linked grafts of polypropylene with high grafting levels and polarity were prepared from isotactic polypropylene (iPP) reacting with maleic anhydride (MAH) and triallyl isocyanurate (TAIC) in solid phase. Rheological characteristic, crystallization and melting behavior, and crystal morphology of the grafts were studied. Addition of TAIC during reaction makes the molecular structure of PP stable and the molten viscosity increases significantly. The crystallization peaks, melt temperatures, crystallinity and crystallization rates of the grafted PP are lower compared to pure PP. But the nucleating ability of the cross-linked graft with higher grafting level is strongest, and the behavior of isothermal crystallization is different from that of PP and MPP. Its nucleation and growth mechanism is two-dimensional growth of crystallites from instantaneous nucleation.
Tacticity
Maleic anhydride
Polypropylene
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Crystal (programming language)
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Non-isothermal crystallization kinetics of polypropylene/polypropylene grafted 2-acrylamido-2-methylpropanesulfonic acid(PP-g-AMPS) at different cooling rates was studied using differential scanning calorimetry.Jeziorny and Mo methods were used to analyze the DSC data.It showed that both methods described the crystallization behaviors successfully.AMPS side chains did not change the crystallization behaviors obviously,however,increased the crystallization rate.The crystallization activation energy of grafted PP was increased.
Polypropylene
Isothermal process
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