Influence ofβ-nucleating Compound Agents on the Mechanical Properties and Crystallization Behavior of Polypropylene Random Copolymer

A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifier(TPE/WBG-2/CaCO_(3)).The effects of differentβ-nucleating agents and ternary compound modifier on the mechanical properties and crystallization behavior of PPR were analyzed.The results show that,compared with pure PPR materials,both WBG-2 and TMB-5 could significantly improve the impact strength of PPR.The crystallization temperature of PPR increased with the addition ofβ-nucleating agent.The modified PPR prepared with ternary compound modifier showed the most excellent comprehensive properties.

Effect of yttrium on thermal stability and crystallization behavior of Nd_(60)Fe_(20)Al_(10)Ni_(10) amorphous alloys

The effect of yttrium on the thermal stability and crystallization behavior of Nd-Fe-Al-Ni amorphous alloys was investigated using X-ray diffraction （XRD）, differential scanning calorimeter （DSC）, and transmission electron microscopy （TEM）.The results indicated that the as-cast Nd60Fe20Al10Ni10-xYx（X=-0, 2） amorphous alloys were fabricated with some quenched-in crystals, which could be restrained by Y. With the effect of yttrium, both the crystallization temperature and exothermic peak shifted to higher temperatures, illustrating that the thermal stability could be improved. The addition of Y changed the crystallization process and final crystallization results. Moreover, the crystallites in the amorphous matrix became more homogeneous and smaller. Meanwhile, Y was useful for the passivation of oxygen in chemistry and restrained the negative effect of oxygen. The activation energies of the start of crystallization and peaking were 1.21 and 1.16 eV, respectively, according to the Kissinger equation.

Influence of Carbon Nanofiber Addition on Mechanical Properties and Crystallization Behavior of Polypropylene

Carbon nanofiber （CNF）-reinforced polypropylene （CNF/PP） composites with different CNF contents were prepared by melt mixing, and the mechanical properties and crystallization behavior of the CNF/PP composites obtained were investigated. It was found that the tensile modulus of the composites was increased with the addition of CNFs, but their elongation at break and fracture strain energy were decreased, while the tensile strength of the composites was firstly increased and then decreased due to the agglomeration of CNFs at higher loading. Nonisothermal crystallization analysis showed that the CNFs played a role as nucleating agent in PP matrix, which led to increment in the crystallization rate and the degree of crystallinity of PP. Moreover, X-ray diffraction studies showed that the CNFs incorporated in the PP matrix favored the growth of （040）-oriented PP crystals. With the increase in the CNF content, the nucleating and orientation roles of the CNFs were obviously enhanced.

Effect of Rare Earth on the Crystallization Behavior of Li_2O-Al_2O_3-SiO_2 Glass-ceramic

X-ray powder diffraction and Fourier transform infrared spectroscopy were applied for characterization of Li2O-Al2O3-SiO2 glass-ceramic powders doped with Eu2O3,Gd2O3 and Er2O3,respectively,in the conditions of different heat-treatment temperatures and with various amounts.The powders were derived from the polyacrylamide gel method.The results show that,the wet gels prepared by polyacrylamide perform a unique crystallization behavior in the process of drying,comparing with some customary preparation such as melt processing.The main crystal phase and crystallization sequence of Li2O-Al2O3-SiO2 micro-powders have no distinct with addition of Eu2O3,Gd2O3 or Er2O3,while the crystallization temperature of the β-spodumene decreased and the amount of the β-spodumene increased.

Crystallization behavior of Fe_(78)Si_(13)B_9 metallic glass under high magnetic field

The effects of high magnetic field on the crystallization behavior of the Fe78Si13B9 metallic glass ribbon were studied. The samples were isothermal annealed for 30 min under high magnetic field and no field,respectively. Microstructure transformation during crystallization was identified by X-ray diffraction and transmission electron microscopy. It was found that the crystallizations of Fe78Si13B9 metallic glass processed under different conditions were that the precipitation of dendrite α-Fe（Si） and spherulite （Fe,Si）3B phases forms amorphous matrix and then the metastable （Fe,Si）3B phase transforms into the stable Fe2B phase. The grain size of the crystals is smaller and more homogeneous for the isothermal annealed samples under high magnetic field in comparison with that under no field indicating that the crystallization behavior of Fe78Si13B9 metallic glass is suppressed by high magnetic field.

Crystallization Behavior and Thermal Properties of PP/MgAl LDH Nanocomposites Prepared in Non-polar Solution

Polypropylene（PP）/MgAl layered double hydroxide（MgAl LDH） nanocomposites were synthesized by refluxing PP and dodecyl sulfate-intercalated MgAI LDH[MgAI（DS）] in non-polar xylene. Their structure, thermal and crystallization properties were studied via X-ray diffraction（XRD）, transmission electron microscopy（TEM）, thermogravimetric analysis（TGA）, differential scanning calorimetry（DSC）, and polarized light microscopy（PLM）. The nanoscaled dispersion of MgAI（DS） nanolayeres in the PP matrix was verified by the disappearance of the d（003） XRD diffraction peak of MgAI（DS） and observation of TEM image. The DSC data show that the SDS/LDH inorganic components negatively affect the crystallization properties of PP and decrease the size of PP sphcrulites because the inorganic components act as additional nuclei. The PP/MgA1 LDH nanocomposites have a faster charring progress in a temperature range of 250--430 ℃ and a better thermal stability above 320℃ than pure PP.

STUDIES ON THE MECHANICAL PROPERTIES AND CRYSTALLIZATION BEHAVIOR OF POLYETHYLENE COMPOSITES

The effects of interfacial modifier on the mechanical, dynamic mechanical properties and crystallization behavior of the polyethylene composites were investigated in the present paper. It was found that the interfacial modifer significantly improved the mechanical properties, influenced the dynamic mechanical spectra and slightly changed the crystallization behavior. The results showed that the interfacial modifier changed the dispersion state of dispersed phase of the composites, resulting in different phase structure, which was the major reason leading to different mechanical and crystallization properties.

MISCIBILITY AND CRYSTALLIZATION BEHAVIOR OF BIODEGRADABLE BLEND OF POLY(β—HYDROXYBUTYRATE)AND POLY(D,L—LACTIDE)—CO—POLY(ETHYLENE GLYCOL)

Studies on the miscibility of PHB/PELA blends showed that PHB and PELA were miscible in amorphous state.The crystallization behavior of PHB in the blend was strongly de- pendent on the addition of PELA component.

The Crystallization Behavior and Stability of Chromite Synthesized in Chromium-Containing Wastewater at Room Temperature

The ferrite process can not only purify wastewater containing heavy metal ions but also recycle valuable metals from wastewater. Therefore, it is considered a promising technology to treat chromiumcontaining wastewater. However, the process has not been extensively applied in industry due to its high synthesis temperature. In this paper, the feasibility of chromite synthesis at room temperature was comprehensively studied. The effects of critical factors on the effluent quality and the crystallization behavior and stability of the synthetic products were investigated. Results showed that the removal ratio of chromium from wastewater was over 99.0%, and the chromium concentration in the supernatant reached the sewage discharge standard after undergoing the ferrite process at room temperature. Increases in the aeration rate, stirring rate, and reaction time were favorable for the formation of stable chromite. The particles obtained by the ferrite process at room temperature were characterized by a compact structure, and the maximum size of the particles reached 52 μm. Chromium gradually entered the spinel crystal structure during the synthesis process, and the molecular formula of the synthetic chromite might be Fe3-xCrxO4, in which x was approximately 0.30. The path of the microscopic reaction was proposed to illuminate the synthesis mechanism of chromite under room temperature conditions. The present study has laid the foundation for the industrial application of the ferrite process in the purification and utilization of chromium-containing wastewater.

Crystallization Behavior of Polymer Derived Silicon Carbide Sintered Through Microwave Heating Technique

A self-crosslinkable liquid highly branched polycarbosilane（LHBPCS） with 5.07% vinyl group and a C/Si ratio of 1.33 was used as the precursor to prepare Si C ceramic material. Microwave heating technique and conventional heating method were applied for the heating treatment process. It was found that, compared with conventional heating method, microwave heating technique could enhance the crystallinity of Si C ceramic material with small grain size at much lower curing temperature and within shorter time. In addition, the SiO_2 additive could lead to less α-Si C and excess carbon, but worsen the crystallinity of β-Si C in the final samples.

Investigation on crystallization behavior between(Sc_(x)Yb_(1−x))O_(1.5)and CMAS:A new insight in the effect of Sc substitution

Environmental barrier coatings(EBCs)with thermomechanical robustness against calcium–magnesium–aluminum–silicate(CMAS)deposits are in high demand.The aim of this work was to clarify the influence of Sc^(3+)on the crystallization behavior of Yb-based coatings against CMAS deposits.The reaction products of solid solutions with compositions traversing the Sc_(2)O_(3)–Yb_(2)O_(3)system indicate that Sc^(3+)tends to form[BO_(6)]coordination polyhedra in the crystal structure to promote the formation of garnet and diopside,while Yb^(3+)occupies 7-,8-,and 9-coordinate sites to crystallize apatite and silicocarnotite.The transformation of crystalline products from apatite/silicocarnotite to garnet/diopside greatly improves the efficiency of CMAS melt consumption and facilitates the prevention of its further penetration and corrosion.Based on the commonality of cation occupancy in crystallography,an A(CaO+YbO_(1.5))–B(ScO_(1.5)+MgO+AlO_(1.5))–T(SiO_(2))pseudoternary phase diagram is established,which has great potential for describing phase equilibrium in coating-deposit systems and can provide guidance for the compositional design of corrosion-resistant coatings.

The Crystallization Behavior of L-Poly(lactic acid)/Polypropylene Blends:The Acceleration for Both L-Poly(lactic acid)and Polypropylene

For a polymer/polymer dismissible blend with two crystallizable components,the crystallization behavior of different components and the reciprocal influences between different crystals are interesting and important,but did not investigate in detail.In this study,the L-poly(lactic acid)/polypropylene(PLLA/PP)blends with different weight ratios were prepared by melt mixing and the crystallization behavior of the blends were investigated.Results showed that the crystalline structures of PLLA and PP were not altered by the composition.For the crystallization of PLLA,both the diffusion of chain segments and crystallization rate were enhanced under the existence of PP crystals.For the crystallization of PP,its crystallization rate was depressed under the existence of amorphous PLLA molecular chains.When the PP crystallized from the existence of PLLA crystals,although the diffusion rate of PP was reduced by PLLA crystals,the nucleation positions were obviously enhanced,which accelerated the formation of PP crystals.This investigation would supply more basic data for the application of PLLA/PP blend.

Formation and crystallization behavior of Fe-based amorphous precursors with pre-existingα-Fe nanoparticles-Structure and magnetic properties of high-Cu-content Fe-Si-B-Cu-Nb nanocrystalline alloys

Structure,crystallization behavior,and magnetic properties of as-quenched and annealed Fe_(81.3)Si_(4)O_(13)Cu_(1.7)(Cu1.7)alloy ribbons and effects of Nb alloying have been studied.Three-dimensional atom probe and transmission electron microscopy analyses reveal that high-number-density Cu-clusters and Pre-existing Nano-sized a-Fe Particles(PN-a-Fe)are coexistence in the melt-spun Cu1.7 amorphous matrix,and the PN-α-Fe form by manners of one-direction adjoining and enveloping the Cu-clusters.Two-step crystallization behavior associated with growth of the PN-a-Fe and subsequent nucleation and growth of newly-formedα-Fe is found in the primary crystallization stage of the Cu1.7 alloy.The number densities of the Cu-clusters and PN-a-Fe in melt-spun Fe8_(1.3-x)Si_(4)B_(13)Cu_(1.7)Nb_(x)alloys are gradually reduced with enriching of Nb,and a fully amorphous structure forms at 4 at.%Nb,although smaller Cu-clusters still exist.After annealing,2 at.%Nb coarsens the average size(D_(α-F)e)of theα-Fe grains from 14.0 nm of the Nb-free alloy to 21.6 nm,and 4 at.%Nb refines the D_(α-Fe)to 8.9 nm.The mechanisms of theα-Fe nucleation and growth during quenching and annealing for the alloys with large quantities of PN-α-Fe as well as after Nb alloying have been discussed,and an annealing-induced oc-Fe growth mechanism in term of the barrier co-contributed by competitive growth among the PN-a-Fe and diffusion-suppression effect of Nb atoms has been proposed.A coercivity(HC)αDα-Fe^(3)correlation has been found for the nanocrystalline alloys,and the permeability is inverse with the H_(C).

CRYSTALLIZATION BEHAVIOR AND MORPHOLOGY OF ONE-STEP REACTION COMPATIBILIZED MICROFIBRILLAR REINFORCED ISOTACTIC POLYPROPYLENE/POLY(ETHYLENE TEREPHTHALATE)(iPP/PET) BLENDS

One-step reaction compatibilized microfibrillar reinforced iPP/PET blends （CMRB） were successfully prepared through a ＂slit extrusion-hot stretching-quenching＂ process. Crystallization behavior and morphology of CMRB were systematically investigated. Scanning electronic microscopy （SEM） observations showed blurry interface of compatibilized common blend （CCB）. The crystallization behavior of neat iPP, CCB, microfibrillar reinforced iPP/PET blend （MRB） and CMRB was investigated by differential scanning calorimetry （DSC） and polarized optical microscopy （POM）. The increase of crystallization temperature and crystallization rate during nonisothermal crystallization process indicated both PET particles and mierofibrils could serve as nucleating agents and PET microfibrils exhibited higher heterogeneous nucleation ability, which were also vividly revealed by results of POM. Compared with MRB sample, CMRB sample has lower crystallization temperature due to existence of PET microfibrils with smaller aspect ratio and wider distribution. In addition, since in situ compatibilizer tends to stay in the interphase, it could also hinder the diffusion ofiPP molecules to the surface of PET phase, leading to decrease of crystallization rate. Two-dimensional wide-angle X-ray diffi：action （2D-WAXD） was preformed to characterize the crystalline structure of the samples by injection molding, and it was found that well-developed PET microfibrils contained in MRB sample promoted formation of t-phase of/PP.

Crystallization Behavior of Nd_2O_3 Doped Na_2O–CaO–SiO_2 Laser Glass-ceramics

For the desirable laser optical property, transition metals or rare-earths are always doped into parent glasses as active ions, and this doping will affect the crystallization of the precursor glasses inevitably. In this work, crystallization behavior of NaO-CaO-SiO2 system glasses doped with Nd2O3 was investigated. The crystallization kinetic parameters including the crystallization apparent activation energy （E） and the Avrami parameter （n） were also measured. The results show that the NaO-CaO-SiO2 system glassceramics with the NaxCa2Si3O9 crystal as primary phase can be highly crystalized as above 90%. The Nd2O3 doping has a significant influence on the crystallization apparent activation energy and the Avrami parameter, which affect the crystallization behavior and morphology of the transparent glass-ceramics of this system.

Confined Crystallization Behaviors of Cross-linked Comb-like Copolymers

Cross-linked PEG-based copolymers were obtained via synthesis of polyethylene glycol （PEG） and methoxy polyethylene glycol （MPEG） by the bridging and/or cross-linking agent of 2,4-tolylene diisocyanate （TDI） and/or hexamethylene-l,6-diisocyanate homopolymer （HDI trimer）. The effects on the crystallization behaviors of the samples could be found with the changes in molecular weight of MC-PEG and molecular weight of SC-PEG in certain cross-linked density. It is revealed that the samples appear not to crystallize when the molecular weight of MC-PEG and SC-PEG are 1000 g/mol or less than that. The samples begin to crystallize when the molecular weight of either MC-PEG or SC-PEG reaches 2000 g/mol. The crystallinity of crystallized MC-PEG decreases with the increasing molecular weight of uncrystallized SC-PEG and the crystallinity of crystallized SC-PEG declines with the rise of molecular weight of uncrystallizable MC-PEG. The chains of SC-PEG （M_n = 2000 g/mol） can fold and align easilier than those of MC-PEG （M_n = 2000 g/mol）, when the content of PEG is the same.

Effect of nanocomposite as pour point depressant on the cold flow properties and crystallization behavior of diesel fuel

The high effective nano-hybrid pour point depressant(PPD)has attracted extensive attention for its po-tential application in improving the cold flow properties of diesel fuel.In this paper,the nano-hybrid PPD was prepared by melt-blending method using three different alkyl chain lengths(i.e.,tetradecyl,hexade-cyl,and octodecyl)of n-alkyl methacrylate-maleic anhydride copolymers(R 1 MC-MA,R 1=C_(14),C_(16),C_(18))and SiO_(2)nanoparticles.The effect of those nano-hybrid PPDs on the cold filter plugging point(CFPP)and solidifying point(SP)depressing of diesel fuel were studied.Results indicated that nano-hybrid PPD showed much better performance on diesel fuel.The diesel fuel treated with 0.2 wt%C_(14)MC-MA/SiO_(2)nano-hybrid PPD exhibited the best depression in CFPP and SP by 6℃ and 18℃,respectively,which higher than that of single C 14 MC-MA.Viscosity-temperature curves and polarized optical microscopy were conducted to explore the performance mechanism;and results presented that nano-hybrid PPD of C_(14)MC-MA/SiO_(2)could effectively lower the low-temperature viscosity,and modify the crystallization behavior and crystal morphology of diesel.Therefore,the cold flow properties of diesel were significantly improved.

HYDROGEN-BONDING INDUCED CHANGE OF CRYSTALLIZATION BEHAVIOR OF POLY(BUTYLENE SUCCINATE) IN ITS MIXTURES WITH BISPHENOL A

In the present work, the blend of poly（butylene succinate） （PBS） and bisphenol A （BPA） was prepared by solution mixing, and the intermolecular interactions between the two components were characterized by a combination of nuclear magnetic resonance （NMR） and Fourier transform infrared spectroscopy （FTIR）. The results showed that intermolecular hydrogen-bonding forms between the carbonyl group of PBS and phenol hydroxyl of BPA. With the increase of BPA content, more hydrogen bonds were formed. The effect of hydrogen bonding on the crystallization behavior of PBS was investigated by differential scanning calorimetry （DSC） and polarized optical microscopy （POM）. The results showed that the overall isothermal crystallization kinetics and the spherulite growth rate of PBS decrease with the increase of BPA content, while the PBS spherulite size increases with BPA content.

Controllable Synthesis of a Well-defined Polypropylene grafted Silica Nanoparticles and Its Effect on Crystallization Behavior of Polypropylene

Well-defined polypropylene grafted silica nanoparticles(PP-g-SiO_(2))were prepared through the reaction of maleic anhydride grafted polypropylene(PP-g-MAH)with amino-functionalized silica(SiO_(2)-NH_(2))by the'grafting-to'method.The grafting density of PP-g-SiO_(2) is found to be controlled by the concentration of silane coupling agent 3-[2-(2-aminoethylamino)ethyl amino]propyl trimethoxy silane(TAMS).The maximum grafting density of grafted PP-g-MAH chains with molecular weight of 9100 g/mol could reach 0.34 chains/nm~2,when the critical concentration of TAMS was 0.0194 mol/L.The critical concentration of TAMS can be explained by the maximum amounts of primary amino groups,which can totally react with PP-g-MAH on the surface of SiO_(2)-NH_(2),when the silane monolayer is formed.The synthesized PP-g-SiO_(2)with different molecular weights was mixed with PP by solution mixing to form a series of nanocomposites.The crystallization temperature(T_(c))of nanocomposites increased significantly with the particle loading.The PP-g-SiO_(2) with high molecular weight of grafted chains exhibits a high nucleation ability at 1 wt%nanoparticle loading in PP/PP-g-SiO_(2)nanocomposites.In summary,we provide an effective method to synthesize the well-defined PP-g-SiO_(2)with controlled grafting density,which shows excellent nucleation ability.

Study on crystallization and microstructure of Li_2O-Al_2O_3-SiO_2 glass ceramics

Lithium aluminosilicate （LAS） glasses are generally difficult to prepare because of their high melting temperature. In this study, the preparation of LAS glasses was achieved at a relatively low melting temperature. The batch containing MgO-ZnO-LiEO- Al2O3-SiO2 was melted in a platinum crucible at 1550℃ for 2 h and was then followed by two- or three-step heat treatment processes for nucleation and crystal growth. The characterizations were carried out by differential thermal analysis, X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and UV-Vis-NIR scanning spectrophotometry. The hexagonal stuffed β-eucryptite solid solution crystallized at 840-960℃. Most of the hexagonal β-eucryptite solid solution transformed into the tetragonal β-spodumene solid solution at 1100℃. Almost all the aluminum atoms entered into the tetrahedral sites in the aluminosilicate network of the 6- eucryptite/β-quartz solid solution. All of the Al atoms did not belong to the aluminosilicate network of the β-spodumene solid solution. The glass ceramic with a mean grain size of 10-20 nm is transparent, the transmittance reaches -85% in the visible light wavelength.