Jeziorny Method Research Articles

Study on the nonisothermal crystallization kinetics of ternary-monomer solid-phase graft copolymer of polypropylene

In order to discover how the grafted side chains affect the crystallization of the graft copolymers, the ternary-monomer solid-phase graft copolymers of polypropylene (PP; PPSM) were synthesized by solid-phase grafting of maleic anhydride, styrene and butyl acrylate onto PP. The Jeziorny and Mo methods were used to investigate the nonisothermal crystallization kinetics and polarizing microscope was used to study the crystalline morphology of PPSM. Results show that the grafted side chains not only promoted the heteronucleation of PP and reduced the size of spherulites but also hindered the growth of crystals resulting in the formation of imperfect crystallization region in PP. Due to the hindrance of the grafted side chains on the crystallization, the nonisothermal crystallization energy (ΔE) of PPSM calculated by the Kissinger equation is evidently higher than that of PP.

The Non-Isothermal Crystallization Kinetics of Dispersible Nano-SiO<sub>2</sub>/PA66 Composites

The PA66-based composites containing dispersible nano-SiO2 (DNS) were prepared in a twin-screw extruder by melt compounding. The microstructures of dispersible nano-SiO2/PA66 composites were investigated by means of TEM and XRD, and the non-isothermal crystallization behavior was studied through Jeziorny method and Mo method based on DSC analysis. The results showed that the dispersion of DNS was uniform in PA66 matrix, which could be related to surface structure of dispersible nano-SiO2. It was found from the study of the non-isothermal crystallization kinetics that dispersible nano-SiO2 possessed a heterogeneous nucleation capability in PA66 matrix, and its addition could hinder the motion of PA66 molecular chain, lower the crystallization temperature, and prolong the crystallization time of PA66. In addition, the activation energies for non-isothermal crystallization of neat PA66 and composites were also evaluated by the Kissinger method. The result showed that the activation energies of dispersible nano-SiO2/PA66 composites were higher than that of neat PA66.

Investigations of the Non-Isothermal Crystallization Behavior of Polyamide 6/Polyethylene-Octene/Organomontmorillonite Nanocomposites

The crystallization behavior of polyamide 6/polyethylene-octene/organomontmoril- lonite (PA 6/POE/OMMT) nanocomposites fabricated via melting intercalation route was investigated using differential scanning calorimeter (DSC). The crystallization kinetics under non-isothermal conditions was analyzed by Jeziorny method and Mo method, and the crystallization kinetics parameters were obtained. It was found that nano-clay acted as a heterogeneous nucleation agent and the semi-crystallization time was prolonged with the OMMT loading increasing. The activation energy for non-isothermal crystallization of such nanocomposites was calculated according to the Huffman-Lauritzen theory. The average size of the composite nanocrystals was reduced with introduction of OMMT to the synthetic system.

Crystallization behavior of bamboo shoot shell/high-density polyethylene composites

The BSS/HDPE (BSSP) composites with different BSS contents were prepared by melt-compounding method. The non-isothermal crystallization kinetics of HDPE and BSSP were investigated by DSC at various cooling rates. Jeziorny and Liu methods were employed to describe the non-isothermal crystallization process of HDPE and BSSP. The results showed that, when the relative degree X( t) of crystallinity is approximately 71.6% or more, the Jeziorny method is invalid to describe the non-isothermal crystallization process, while the Liu method is successful in doing so for HDPE and BSSP. The addition of BSS can accelerate the overall non-isothermal crystallization process of HDPE, but does not change the nucleation mechanism and dimension of spherulite growth of HDPE matrix. The crystallization rate for both HDPE and BSSP increases with the increasing cooling rate, but it is quicker for BSSP than HDPE at a given cooling rate. Moreover, the addition of BSS decreases the crystallization activation energy Ea calculated by Kissinger equation.

Polyethylene Glycol (<i>PEG</i>) - Polyvinyl Alcohol Graft Copolymer System of Non-Isothermal Crystallization Kinetics

The confined of PEG in PVA-g-PEG graft copolymers was investigated by differential scanning calorimetry. The crystallization kinetics was discussed by several methods. The results showed that the lower temperature peak (Tp) shifted to the lower temperature and its peak intensity also decreased with increasing the cooling rates, t1/2 decreased and G increased. The Tp of graft copolymers were lower than pure PEG and t1/2 of which were higher than pure PEG. The graft ratio had litter influence on t1/2. The results also showed that both Jeziorny method and the new method combing the Avrami equation described this system very well.

Non-Isothermal Crystallization Behavior of Poly(Ethylene Terephthalate)/Carbon Black Composite

Poly(Ethylene Terephthalate)(PET)/carbon black(CB) composite was prepared by melt blending using a separate feeding technique. The non-isothermal crystallization process of virgin PET and PET/CB composite were investigated by differential scanning calorimetry (DSC) and the different methods such as Jeziorny modified Avrami equation, Ozawa equation and the method developed by Mo were employed to analyze the non-isothermal kinetics of virgin PET and PET/CB composite. The results show that the CB particles dispersed in PET matrix act as heterogeneous nucleating agents, while CB particles hinder the movement of molecular chains of PET, meanwhile, the crystallization activation energy(⊿E) of PET/CB composite is much greater than that of virgin PET according to Kissinger formula, which is opposite to the low CB content condition. This indicates that CB particles reduce the rate of crystal growth. Whereas, the results obtained from the mentioned three methods simultaneously demonstrate the addition of CB greatly increases crystallization temperature and crystallinity and accelerates crystallization rate. Taking the two seemingly contradictory results, crystal growth has little effect on the crystallization rate and crystal nucleation dominate the crystallization process of PET/CB composite with very high CB content. According to Jeziorny method, the constant of crystallization rate (Zc) increases with the increment of cooling rate and Avrami index (n) doesn’t change significantly, but the Zc and n of PET/CB composite are greater than that of PET. Based on Ozawa method, lg[-ln(1-Xt)] and lgR don’t show a good linear relationship. The parameter F(T) increases significantly with the increasing of relative crystallinity and n is almost unchanged. Besides, the F(T) of PET/CB composite is less than that of PET, while a is greater than that of PET. Comparing with Ozawa and Avrami equation, Mo method can better describe the non-isothermal crystallization of PET and PET/CB composite.

Nonisothermal Crystallization Kinetics of HDPE/UHMWPE/n-HA Composites

The influence of compatibilizer and dispersant on the nonisothermal crystallization behavior of HDPE/UHMWPE/HA is investigated here by differential scanning calorimetry (DSC). It has been analyzed by Jeziorny method. For different composites, the Jeziorny plots shows the linear portion. The small deviations from linearity only appear at higher relative crystallinity because of the secondary crystallization. The value of Avrami parameter n is between 2.7 and 3.5. At the same temperature, Zc and Si become bigger after adding compatibilier and dispersant while tmax is decreasing. The activation energy of crystallization also have been studied by Kissinger equation. The result shows that the addition of compatibilizer and dispersant can decrease the activation energy. In addition, the compatibilizer and dispersant also improve the mechanical properties of composites.

Studies on the Nonisothermal Crystallization Behavior of Polypropylene/Multiwalled Carbon Nanotubes Nanocomposites

Polypropylene/multiwalled carbon nanotubes (PP/MWNTs) nanocomposites were prepared by a melt compounding process. The morphology and nonisothermal crystallization of these nanocomposites were investigated by means of optical microscopy, scanning electron microscopy, and differential scanning calorimetry. Scanning electron microscope micrographs of PP/MWNTs composite showed that the MWNTs were well dispersed in the PP matrix and displayed a clear nucleating effect on PP crystallization. Avrami theory, modified by Jeziorny and Mo's method, was used to analyze the kinetics of the nonisothermal crystallization process. It was found that the addition of MWNTs improved the crystallization rate and increased the peak crystallization temperature of the PP/MWNTs nanocomposites as compared with PP. The results show that the Jeziorny theory and Mo's method successfully describe the nonisothermal crystallization process of PP and PP/MWNTs nanocomposites.

Non-isothermal crystallization kinetics and melting behavior of EAA with different acrylic acid content

Non-isothermal crystallization kinetics and subsequent melting behavior for three kinds of ethylene-acrylic acid copolymer (EAA) are investigated via differential scanning calorimetry (DSC). From the Jeziorny method, the crystallization rate of the primary stage is significantly influenced by the competitive mobility of chains. While the crystallization rate in the secondary stage decreases in order of acrylic acid (AA) content in copolymers. Mo’s method can also provide a good fitting. Difference between the Jeziorny method and Mo’s method analysis is because of a higher effect of non-crystallizable chain ends. The effective activation energy is also determined via Kissinger’s method.

Crystallization behavior of poly(vinylidene fluoride)/montmorillonite nanocomposite

AbstractThe crystallization behavior of poly(vinylidene fluoride)/montmorillonite (PVDF/MMT) nanocomposite was investigated by using differential scanning calorimeter (DSC), polarizing optical microscope (POM), and X‐ray diffraction. The results showed that the crystallization behavior of PVDF was changed by adding MMT in PVDF matrix. The MMT layers in PVDF acted as effective nucleation agents. It is observed that the crystallization temperature of PVDF/MMT nanocomposite was higher than that of PVDF at various cooling rates. The value of half‐time of crystallization showed that the crystallization rate of PVDF/MMT nanocomposite was faster than that of PVDF at a given cooling rate. The addition of MMT hindered the growth of spherulite. Nonisothermal crystallization data was analyzed using Avrami, Ozawa, and Jeziorny method. The Jeziorny method successfully described the nonisothermal crystallization behaviors of PVDF/MMT nanocomposite. The MMT loading was favorable to produce the piezoelectric β phase in the PVDF matrix. The α phase coexisted with the β phase in the PVDF/MMT nanocomposite. For this polymorphic structure, a possible explanation was proposed based on the variable temperature X‐ray diffraction, DSC, and POM experiments. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Preparation and nonisothermal crystallization behavior of polypropylene/layered double hydroxide nanocomposites

Polypropylene (PP)/layered double hydroxide (LDH) nanocomposites were prepared via melt intercalation using dodecyl sulfate anion modified LDH and maleated PP as compatibilizing agent. Evidently the interlayer anions in LDH galleries react with maleic anhydride groups of PP-g-MA and lead to a finer dispersion of individual LDH layers in the PP matrix. The nanostructure was characterized by XRD and TEM; the examinations confirmed the nanocomposite formation with exfoliated/intercalated layered double hydroxides well distributed in the PP matrix. The nonisothermal crystallization behavior of resulting nanocomposites was extensively studied using differential scanning calorimetry (DSC) technique at various cooling rates. In nonisothermal crystallization kinetics, the Ozawa approach failed to describe the crystallization behavior of nanocomposites, whereas the Avrami analysis and Jeziorny method well define the crystallization behavior of PP/LDH nanocomposite. Combined Avrami and Ozawa analysis (Liu model) also found useful. The results revealed that very small amounts of LDH (1%) could accelerate the crystallization process relative to the pure PP and increase in the crystallization rates was attributed to the nucleating effect of the nanoparticles. Polarized optical microscopy (POM) observations also support the DSC results. The effective crystallization activation energy was estimated as a function of the relative degree of crystallinity using the isoconversional analysis. Overall, results indicated that the LDH particles in nanometer size might act as nucleating agent and distinctly change the type of nucleation, growth and geometry of PP crystals.

Synthesis and Non-isothermal Crystallization Behavior of PET/Surface-treated TiO 2 Nanocomposites

Poly(ethylene terephthalate) (PET)/TiO 2 nanocomposites were prepared by melt-blending PET and surface-treated TiO 2 . The crystallization behavior and the non-isothermal crystallization kinetics of these composites were investigated by differential scanning calorimetry (DSC). Jeziorny and Mo's methods were applied to describe the kinetics of the non-isothermal crystallization process. It was found that the PET matrix with incorporated surface-treated TiO 2 particles has lower crystallization temperature and melting point than that with incorporated pure nano-TiO 2 particles. Unlike plain TiO 2 , surface-treated TiO 2 particles showed less effect on the degree of crystallization of the PET matrix.

Effect of Nanoparticle Surface Treatment on Nonisothermal Crystallization Behavior of Polypropylene/Calcium Carbonate Nanocomposites

Polypropylene (PP)/CaCO3 nanocomposites were prepared by melt-blending method using a Haake-90 mixer. The CaCO3 nanoparticles were surface modified with a coupling agent before compounding. A fine dispersion of the modified nanoparticles in the nanocomposites was observed by transmission electron microscopy (TEM). Effects of surface treatment of CaCO3 nanoparticles on the nonisothermal crystallization behavior and kinetics of PP/CaCO3 nanocomposites were investigated by differential scanning calorimetry (DSC). Jeziorny and Mo methods were used to describe the nonisothermal crystallization process. It was shown that the crystallization temperature of the nanocomposites increased due to the heterogeneous nucleation of the surface-treated nanoparticles. It was found that the nanoparticles modified with a proper content range of coupling agent could facilitate the nonisothermal crystallization of the nanocomposites under certain conditions (the cooling rate and the relative degree of crystallinity). This may be a potential application for the crystallization controlling of composites in manufacturing. In addition, the activation energy of crystallization for the nanocomposites and the nucleation activity of the nanoparticle were estimated by using Kissinger and Dobreva's methods, respectively. It could be concluded that the surface-treated nanoparticles had a strong nucleating activity, which caused the decrease of the activation energy of the nanocomposites.

Influence of Adjustable Grafted Side Chains on the Non-Isothermal Crystallisation of a Ternary-Monomer Solid Phase Graft Copolymer of Polypropylene

A solid phase graft copolymer with an adjustable structure was prepared by grafting maleic anhydride, methyl methacrylate and butyl acrylate onto polypropylene (PP). How the grafted side chains affected the crystallisation of the graft copolymer was studied by differential scanning calorimetry and polarised optical micrographs. Results show that the grafted side chains not only promoted heterogeneous nucleation but also hindered the whole crystal growth of the copolymers. The Jeziorny method and Mo method were successful in describing the non-isothermal crystallisation kinetics. The Jeziorny method showed that the Avrami exponent ranged from 2 to 3, indicating that the crystal tended to grow in a three-dimensional mode. The Mo method showed that the graft copolymer (known here as PPTM) needed a lower crystallisation rate than PP to attain the same crystallinity at unit time, due to the hetero-nucleation of the grafted side chains. Meanwhile, the hetero-nucleation of the grafted side chains caused a decrease in the crystallisation half-time and in the spherulite size of PPTM. Hindrance of the grafted side chains was shown by the incomplete crystallisation images and by the increase in the non-isothermal crystallisation activation energy of PPTM.

The effect of attapulgite on crystallization behavior of Poly(ethylene terephthalate) (PET)/Attapulgite (AT) nano composites

AbstractPoly (ethylene terephthalate) (PET)/Attapulgite (AT) nanocomposites were prepared via in-situ polymerization. According to the observation of transmission electron microscopy (TEM), attapulgite is well dispersed in the PET matrix in a nanometer scale. The influence of attapulgite content on the nonisothermal crystallization kinetics was studied using a classical Avrami equation with Jeziorny method. The crystalline structures of the pure PET and PET/AT nanocomposites with different amount of AT (0.2%, 0.5%, 1%, 2%) were characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. It was found that the crystallization temperature for PET/AT nanocomposites with 0.2% and 0.5% content of AT were higher than pure PET and the rate of crystallization of all PET/AT nanocomposite samples increased significantly which indicated that attapulgite could be used as an effective nucleating agent in PET. However, with the addition of AT, smaller crystalline size, more crystalline defects and lower degree of crystallization was demonstrated.

Crystallization Behavior of Rare‐earth Doped Luminous Pigment/Polyamide 6 Composites

The crystallization behavior of well‐dispersed rare‐earth doped luminous pigment/polyamide 6 (PA6) composites prepared through in situ polymerization was investigated by DSC. The rare‐earth doped luminous pigments could accelerate the forming of γ form crystals and also had a great effect on the crystallinity and crystallization rate of PA6 composites. The Ozawa, Jeziorny, and Mo methods were used to analyze the non‐isothermal crystallization kinetics. It was found that the Ozawa method was unsuitable for non‐isothermal crystallization of PA6 composites. The results of Jeziorny analysis showed that the crystallization rates of PA6 composites increased when the luminous pigment content was larger than 5 wt.%. Mo's analysis also showed that the presence of the pigment shortened the crystallization time and accelerated the crystallization rate. Polarized optical microscopy showed that the spherulites became smaller with increasing of the luminous pigment amount due to the heterogeneous nucleation.

Influence of the amount of salts of rosin acid on the nonisothermal crystallization, morphology, and properties of isotactic polypropylene

AbstractThe nonisothermal crystallization of Isotactic polypropylene (iPP) containing different concentration of nucleating agent potassium dehydroabietate (DHAA‐K) or sodium dehydroabietate (DHAA‐Na) at the cooling rate of 10°C/min was investigated using differential scanning calorimetry (DSC) together with Jeziorny's method. It was found that the temperature at which the maximum rate of crystallization occurred shifted to a higher region by about 13.7–16.9°C, and the rate of crystallization became faster for iPP with DHAA‐K (PPK) or DHAA‐Na (PPNa) in comparison to the virgin iPP. Avrami exponent for virgin PP, PPK, and PPNa was about 3.1, 2.2, and 2.2, respectively, suggesting the change of the crystal growth mechanism of iPP with the addition of the nucleating agents. The morphology of iPP with and without nucleating agent examined by a cross polarized light microscope indicated that the size of spherulites marginally decreased, which then remained stable with the increase of the concentration of DHAA‐K or DHAA‐Na. The measurements of the optical and mechanical properties of iPP showed that the transparency, gloss, and flexural modulus increased with increasing nucleating agent before its optimal concentration. POLYM. ENG. SCI., 47:889–897, 2007. © 2007 Society of Plastics Engineers

Nonisothermal crystallization behavior of poly(ϵ‐caprolactone)/attapulgite nanocomposites by DSC analysis

AbstractNanocomposites based on biodegradable poly(ε‐caprolactone) (PCL) and attapulgite (AT) were prepared by solution mixing. The nonisothermal crystallization of the pure PCL and PCL/AT nanocomposites at different AT contents and different cooling rates were investigated by differential scanning calorimetry (DSC). There are significant dependence of nonisothermal crystallization behavior and kinetics of PCL/AT nanocomposites on the AT content and cooling rate. The Jeziorny method has been employed to analyze the DSC data. The results show that Jeziorny method could describe this system well. It can be concluded that AT can be used as an effective nucleating agent and has effects on the growth of crystallites in the crystallization process of PCL matrix. POLYM. ENG. SCI., 47:460–466, 2007. © 2007 Society of Plastics Engineers.

Crystallization behavior of PA66/SiO2 organic‐inorganic hybrid material

AbstractThe poly 2‐hydroxy propylmethacrylate‐methyl methacrylate (PHPMA‐MMA)/SiO2 composite, derived from 2‐hydroxy propylmethacrylate (HPMA), methyl methacrylate (MMA), and tetraethoxysilane (TEOS), was used to synthesize polyamide 66(PA66)/SiO2 organic‐inorganic hybrid material. X‐ray diffraction (XRD) was used to investigate the lattice spacing change of the PA66/SiO2 hybrid material. It was found that the addition of PHPMA‐MMA/SiO2 composite nearly did not change the crystal form of PA66. The nonisothermal crystallization kinetics of PA66 and PA66/SiO2 hybrid material was investigated by differential scanning calorimetry (DSC) with various cooling rates. At every given cooling rate, the start crystallization temperature of the PA66/SiO2 hybrid material was higher than that of PA66, while the crystallization temperature range was narrower than that of PA66. Avrami analysis modified by the Jeziorny method, the Ozawa method, and a method developed by Liu were employed to describe the nonisothermal crystallization process of the samples. The results showed that the Jeziorny method and the Ozawa method were not suitable to describe the nonisothermal crystallization process of PA66/SiO2 hybrid material; however, when the relative degree of crystallinity X (t) was less than 1 − 1/e, ln [− ln (1 − X (t))] was still linear to lnt. The Liu method was successful to describe the nonisothermal crystallization processes for both PA66 and the PA66/SiO2 hybrid material. It was confirmed that the presence of PHPMA‐MMA/SiO2 composite could increase the crystallization rate and had a hetero phase nucleation effect on the PA66 matrix. Moreover, the introduction of PHPMA‐MMA/SiO2 could improve the crystallization active energy ▵E calculated by the Kissinger equation, attributing to the strong interaction between the polyamide chains and the PHPMA‐MMA/SiO2 composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 810–817, 2006

Study on the nonisothermal crystallization behavior of poly(vinyl alcohol)/attapulgite nanocomposites by DSC analysis

AbstractAttapulgite (AT)‐reinforced poly(vinyl alcohol) (PVA) nanocomposite films were prepared by solution‐casting technique. The nonisothermal crystallization behaviors of PVA bulk and PVA/AT nanocomposites have been investigated by differential scanning calorimetry (DSC). It has been found that the uniformly dispersed AT nanorods in the matrix have great influence on the glass transition temperature and crystallization behavior of PVA matrix. The Jeziorny method has been employed to analyze the DSC data. The results show that Jeziorny method could describe this system very well. Comparing with the PVA bulk, PVA/AT nanocomposites have higher crystallinity Xt, shorter semicrystallization time t1/2, and higher crystallization rate constant Zc. It can be concluded that AT can be used as an effective nucleating agent and has effects on the growth of crystallites in the crystallization process of PVA matrix. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 534–540, 2006