Search

Heterogeneous nucleation is the main path to ice formation on Earth. The ice nucleating ability of a certain substrate is mainly determined by both molecular interactions and the structural mismatch between the ice and the substrate lattices. We focus on the latter factor using molecular simulations of the mW model. Quantifying the effect of structural mismatch alone is challenging due to its coupling with molecular interactions. To disentangle both the factors, we use a substrate composed of water molecules in such a way that any variation on the nucleation temperature can be exclusively ascribed to the structural mismatch. We find that a 1% increase in structural mismatch leads to a decrease of ∼4 K in the nucleation temperature. We also analyze the effect of orientation of the substrate with respect to the liquid. The three main ice orientations (basal, primary prism, and secondary prism) have a similar ice nucleating ability. We finally assess the effect of lattice flexibility by comparing substrates where molecules are immobile to others where a certain freedom to fluctuate around the lattice positions is allowed. Interestingly, we find that the latter type of substrate is more efficient in nucleating ice because it can adapt its structure to that of ice. [ABSTRACT FROM AUTHOR]

NaNbO 3 -based glass-ceramics have garnered considerable attention owing to their high dielectric constant (ε r), low dielectric loss (tan δ), excellent chemical stability and tunable dielectric properties. Nonetheless, one major obstacle restricting the applications of NaNbO 3 -based glass-ceramics in energy-storage capacitors is their low breakdown strength (BDS) caused by interface polarization. In this work, the grains of glass-ceramics turn into fine and uniform from agglomeration via adding nucleating agent analogue HfO 2 to Na 2 O–Nb 2 O 5 –CaO–SiO 2 –B 2 O 3 (NNCBS–H) glass matrix. Thus, the long-range migration of space charge is frozen by the refined grains, which is conducive to diminishing the interfacial polarization of glass-ceramics. Moreover, the band gap energy (E g) of NNCBS-H glass-ceramics elevates from 3.21 eV to 3.30 eV with the incorporation of HfO 2 with wide band gap, enhancing its insulating performance. Ultimately, NNCBS-H4 glass-ceramics achieve a remarkable energy storage density (W rec) of 3.8 J/cm3, establishing an effective approach and precedent for developing glass-ceramic materials with high energy storage properties. [ABSTRACT FROM AUTHOR]

The dimensional accuracy of injection molded parts plays an increasingly significant role in the plastics processing industry, as is the utilization of recycled raw materials. To obtain the desired dimensions and properties of injection moldings, various material modification methods are used simultaneously. The conducted research aimed to assess the impact of hybrid modification of non-nucleated heterogeneously isotactic polypropylene using recovered phosphogypsum and a chemical blowing agent on the shrinkage value and mechanical properties of injection molded parts. Additionally, changes in dimensions and properties of composites with solid and porous structures that occur within 1000 hours of their removal from the injection mold were determined. The research showed that the filler used acts as a nucleating agent causing an increase in the shrinkage of the parts, up to 10 wt%. Similar changes were observed in the case of tensile strength. The increase in the value of this parameter at the lowest phosphogypsum contents used was most likely the result of changes in the crystalline structure of polypropylene. Changes in the mechanical properties of the molded parts that occurred during conditioning are correlated with shrinkage changes that occur from the moment the molded parts are removed from the injection mold. Young's modulus and tensile strength increased linearly for both solid and porous moldings. However, the rate of stiffness increases as a function of shrinkage changes with the filler content. Nevertheless, the opposite tendency was observed in the case of changes in impact strength, the values of which decreased as a function of shrinkage to the greatest extent in the case of unfilled polypropylene. [ABSTRACT FROM AUTHOR]

As a highly effective nucleating agent, layered zinc phenylphosphonate (PPZn) is incorporated into polylactic acid (PLA) to investigate the epitaxial crystallization of PLA on PPZn in this study. The corresponding lattice spacing change, crystalline morphology, and crystalline structure are emphasized to reveal the epitaxial crystallization mechanism. As a result, with the increase of PPZn content and the annealing time, the increasing lattice spacing of PPZn and the formation of mutually perpendicular rodlike crystals are observed through x‐ray diffraction (XRD) and polarized optical micrograph (POM) measurements, implying that the interlayer spacing of PPZn crystals is expanded as the PLA α‐form crystals epitaxially grow on its surface, that is, epitaxial crystallization. To be specific, "edge on" lamellae epitaxial grow on the PPZn crystals along the [010] and [100] directions under two excellent lattice matchings, which possess acceptable mismatching of 0.347% and 7.5%, respectively. With the support of the epitaxial crystallization mechanism, the occurrence of the filamentous structure observed in the fracture morphology of PLA/PPZn composites suggests strong interfacial adhesion between PLA and PPZn, which makes the impact toughness of the PLA/PPZn composites increase by 53.6% compared with pure PLA. [ABSTRACT FROM AUTHOR]

Polylactic acid/poly(methyl methacrylate) (PLA/PMMA) composite fibers with high performance were fabricated using melt spinning technique. The crystallization, lamellae orientation and physical properties of composite fibers were investigated systematically. The addition of PMMA (0–20 wt%) has improved the hydrolysis resistance of composite fibers by preventing water molecules from penetrating and diffusing through the fibers, but the strength and heat resistance were reduced at the same time. The stereocomplex crystallites (SC) formed before spinning by introducing poly(D‐lactide) (PDLA) (3 wt%) in poly(L‐lactide) (PLLA) matrix and acted as nucleating agents to enhanced the crystallization and lamellae orientation of PLLA matrix, which improved the physical properties of PLA composite fibers resultful. The tensile strength of PLA fibers with 3 wt% PDLA and 5 wt% PMMA was increased 31% as well as the boiling water shrinkage and the hydrolysis rate were decreased 30% and 33% in relation to PLLA fibers. Finally, the hydrolysis resistance was further enhanced on the basis of realizing high strength and heat resistance, which is of great significance for preparing durable PLA fiber materials and expanding their application. [ABSTRACT FROM AUTHOR]

In this paper, a morphologically stable composite phase change material (CPCM) suitable for use in the field of building energy conservation was developed using Na2HPO4∙12H2O (DHPD) as the phase change material, Na2SiO3∙9H2O (SSNH) as the nucleating agent, and silica aerogel (SA) as the carrier. The results showed that the incorporation of 25 wt% SA resulted in the as-prepared DHPD-SSNH/SA CPCM with a phase change temperature of 30.4 °C, an enthalpy of 163.4 J/g, and a low supercooling degree of 1.3 °C, which also solved the corrosion problem of reinforcing bars caused by the hydrated salt PCM. Meanwhile, DHPD-SSNH/SA CPCM had good shape stability and low thermal conductivity (0.1507 W/(m·K)). The phase change temperature was basically unchanged, and the enthalpy only decreased by 4.8% after 200 cold-heat cycles. In addition, the thermal performance evaluation of CPCM showed that the indoor thermal comfort time of the testing system loaded with PCM board accounted for 50.75%, which was 43.38% higher than that of the one without PCM board (7.37%). The results suggest that the obtained CPCM had a good energy saving effect and great potential in the field of building energy conservation. [ABSTRACT FROM AUTHOR]

In the present work, the development of nanocomposites was carried out by processing the nanofillers viscogel clay B8 and vanadium oxide with the polycaprolactone (PCL) matrix, through a twin-screw extruder. The evaluation of the nanomaterial obtained by X-ray diffraction technique showed that the addition of nanoparticles caused change in the crystallization process and in the crystallinity index, due to the action of them as a nucleating agent. Evaluation of thermogravimetric analysis, it was observed an increase in the thermal stability of nanocomposites containing clay. Analyzing the SEM micrographs, it was observed that there was a good dispersion and distribution of nanofillers in the matrix. The differential scanning calorimetry and X-ray diffraction technique, showed the possibility of nanoparticles are acting as a nucleating agent, in some mixtures there was change in the values of crystallinity index. Through nuclear magnetic resonance analysis, it was evaluated a good homogeneity of the nanofiller in the matrix due to the intermolecular interaction promoting a better dispersion and distribution of the nanoparticle in the polymer. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) was a very practical and important thermoplastic, which was widely used in various fields due to its low cost, universal, and corrosion resistance. However, the moderate mechanical and heat resistance properties of PP limited its application in some special fields. In this paper, nucleating agents NP‐657 were added to further improve its mechanical and heat resistance performances of PP (300H). Furthermore, the heterogeneous nucleation of NP‐657 reduced the crystal size and increased the crystal density of 300H. With the rise of NP‐657 content, the crystallization rate of different PP systems increased significantly, such as the t1/2 of 300H‐0.2 reduced by 31.9 min in comparison with that of 300H at 140°C. At the same time, the crystallinity of 300H‐0.05 with 0.05 wt.% NP‐657 increased by about 5.96% compared with 300H. In addition, 300H‐0.05 has the highest tensile strength (23.9 ± 0.6 MPa), flexural modulus (1273.3 ± 67.3 MPa), and the highest thermal deformation temperature (88.5 ± 7.7°C) in different PP systems. In general, this paper provided a reference for the fabrication of PP with satisfactory mechanical and heat resistance performances. Highlights: 300H‐0.05 had a maximum crystallinity of 40.8 ± 0.2% in different PP systems.The flexural modulus of 300H‐0.05 was 434 MPa higher than that of 300H.The tensile strength of 300H‐0.05 increased to 23.9 ± 0.6 MPa.300H had the highest thermal deformation temperature of 88.5 ± 7.7°C. [ABSTRACT FROM AUTHOR]

In this work, poly(L-lactide) (PLLA)/poly(D-lactide) (PDLA)/carbon fiber (CF) composites with different PDLA content were prepared by simple melt blending. The stereocomplex (SC) crystallites were in situ formed. The effects of CFs and SC crystallites on the morphology, crystallization, rheological behaviors, mechanical properties, heat resistance, thermal and electrical conductivity of composites were investigated. The SC crystallites acted as nucleating agents of PLLA to accelerate the crystallization of PLLA, improve the degree of crystallinity, and refine spherical crystals, which led to a more homogeneous and dense dispersion of CFs. For the PLLA/PDLA/CF composite with 10 wt% PDLA, attributing to the synergistic effect of CFs and SC crystallites, vicat softening temperature (VST) was increased by about 100 ℃ over neat PLLA. The thermal conductivity increased from 0.21 W (mK)−1 of neat PLLA to 0.47 W (mK)−1, and surface resistivity decreased dramatically by about 8 orders of magnitude. More importantly, an increases of 156% and 29.2% were achieved in the tensile modulus and strength of composite with 10 wt % PDLA compared to neat PLLA. Melt viscosity and elasticity were also significantly improved with the addition of CFs and PDLA. The unusual combination of the improved mechanical and rheological performances, thermal resistance, thermal and electrical conductivity established in the degradable composites meets the properties required for a wider range of PLLA applications. [ABSTRACT FROM AUTHOR]

Magnesium slag (MS) and fly ash (FA) are industrial wastes that must be utilized in a clean, effective, and massive method to avoid environmental pollution. In this study, the preparation of diopside-augite-based glass-ceramics was theoretically analyzed and experimentally conducted by disposal of MS and FA with chromium oxide (Cr 2 O 3) as a nucleating agent. The thermodynamics analysis first indicated that pyroxene could be the main crystal phase of the target glass-ceramics for the co-utilization of both wastes. The experimental results indicated that the main phase in prepared glass-ceramics samples was diopside ([Ca(Mg, Fe, Al)(Si, Al) 2 O 6 ], and the degree of glass network polymerization was enhanced with the FA in raw material increasing from 50 wt% to 65 wt%. Plus, the crystal size of the prepared glass-ceramics was gradually refined by increasing the FA. The optimized conditions were given as controlling nucleation at 790 °C for 2 h and crystallization at 929 °C for 2 h of the parent glass that derived from 40 wt% MS and 60 wt% FA as raw materials, 1 wt% Cr 2 O 3 as nucleating agent. The resulting glass-ceramics had excellent properties and chemical stability, such as a density of 3.11 g cm−3, bending strength of 101.98 MPa, acid resistance of 98.34 %, and alkali resistance of 99.53 %. This study provided a route to produce eco-friendly glass-ceramics material for architectural decoration by high-efficiency utilization of MS and FA. [ABSTRACT FROM AUTHOR]

Blast furnace slag glass–ceramics were prepared by melting using rare-earth-containing blast furnace slag (REBFS) as the main raw material and Fe 2 O 3 and Cr 2 O 3 as composite nucleating agents. By adding different TiO 2 contents, the study comprehensively revealed the effects of high field strength ions on the glass network structure, crystalline properties, elemental distribution and physicochemical properties. Raman spectroscopy and differential scanning calorimetry revealed that TiO 2 acted primarily as a network modifier in the glass network. The appropriate TiO 2 content disrupted the glass network, decreasing the crystallization activation energy (E C) of the glass–ceramic. However, excess TiO 2 repaired the network structure, thereby increasing the E C. The combined effect of the Cr and Ti substantially improved the crystallization characteristics of the glass-ceramics. Cr 2 O 3 induced the formation of spinel, which promoted the crystallization of the main crystalline augite phase. The self-aggregation of the high field strength Ti4+ ion induced the formation of a titanium- and cerium-containing titanite phase, which also contributed to grain refinement. This titanite phase effectively increased the Vickers hardness and acid and alkali resistances of the glass-ceramics to 9.16 GPa and over 98.5 %, respectively. The excellent physicochemical properties render REBFS glass–ceramics as being promising materials for various construction applications. This research provides theoretical support for comprehensively utilizing blast furnace slag and provides theoretical guidance for preparing slag glass–ceramics possessing desirable physicochemical properties. [ABSTRACT FROM AUTHOR]

This study introduces a flexible, sensitive, and cost-effective hybrid piezoelectric nanogenerator (PENG) by integrating MnAl-alloy nanoparticles into a poly (vinylidene fluoride) (PVDF) nanocomposite film. The MnAl-alloy nanoparticles serve as a nucleating agent for promoting the formation of the electroactive β-phase. It is observed that the electroactive β-phase, dielectric permittivity, saturation polarization, and output performance of the device improve with the incorporation of the MnAl-alloy nanoparticles up to 7.5 wt. % in the PVDF matrix. Hence, in this work, we report a MnAl-alloy-based optimized piezoelectric nanogenerator device using a free-standing nanofiber mat (7.5 wt. % MnAl-alloy) prepared by the electrospinning technique. The as-fabricated piezoelectric nanogenerator effectively channels charges generated by mechanical stress to the electrodes, resulting in an impressive output voltage of approximately 16 V and an output current of around 7.1 μA, yielding a power of 47 μW across 4.5 MΩ resistor. Furthermore, energy harvesting from human movements such as jogging, knee bending, and walking is demonstrated for practical application. A piezo potential of approximately 8 V generated during walking showcases the development of a self-powered pedometer. Furthermore, tapping the PENG charges a capacitor of 0.1 μF up to approximately 1 V, demonstrating the potential application for the power up of small portable electronic devices. [ABSTRACT FROM AUTHOR]

The widespread use of traditional petroleum‐based plastics is causing significant environmental pollution for example microplastics issues, due to its non‐biodegradability. Poly (lactic acid) (PLA) as a representative biodegradable polymer is a promising candidate to replace petroleum‐based plastics in some fields of disposable packaging materials and tableware. In this work, in order to improve the poor crystallization, mechanical and heat resistance performances of PLA, styrene–acrylonitrile‐glycidyl methacrylate (SAG) as a chain extender and octamethylenedicarboxylic dibenzoylhydrazide (ST‐NAB3) as a heterogeneous nucleating agent (HNA) were added simultaneously into PLA matrix. The chain‐extended PLA (CPLA) with branch structures had smaller crystal sizes and higher crystal density, compared with those of pure PLA. In addition, thanks to the nucleation effect of ST‐NAB3 and the development of "shish‐kebab", this tendency became more pronounced in CPLA/HNA systems. It was worth mentioning that, CPLA with the ST‐NAB3 content of 1 wt% (CPLA‐1) possessed the highest crystallinity of 43.6%. Meanwhile, CPLA‐1 had the best impact strength and heat deformation temperature of 38.9 kJ/m2 and 91.3°C respectively, which had increased by 11.3 kJ/m2 and 32.4°C contrast to pure PLA. On the whole, this study proposed a simple and effective method, which provided a new possibility for PLA modification research. [ABSTRACT FROM AUTHOR]

Passive cooling techniques have gained widespread use in everyday life and various industries by utilizing sunlight reflection to cool objects without requiring additional energy input. Porous polymer materials possess the unique ability to provide both thermal insulation and solar reflection due to their inherent multiphase structure. In this study, we developed a porous polypropylene (PP) with a hierarchically structured surface layer using a simple and efficient solvent treatment method based on recrystallization. As a result, the porous structure and hierarchically structured surface significantly increase the solar reflectance from 11 to 86%. We found that by manipulating the recrystallization process and using reflective additives, solar reflectivity can be further improved. With the use of TiO2 and BaSO4 additives, a solar reflectance of 90% was achieved, while a solar reflectance of 93% was achieved with nucleating agents. In practical terms, these improvements result in significant temperature reductions in cooling performance tests compared to extruded PP sheets: 17, 19, and 22 °C for porous PP, porous PP/TiO2 or PP/BaSO4, and porous nucleated PP, respectively. The modification method introduced could help PP offer new possibilities for developing low-cost chemically resistant and thermally insulating layers in thermal management applications. [ABSTRACT FROM AUTHOR]

The development of poly(lactic acid) (PLA) nanocomposites incorporating urchin-like WO3 particles through a cost-effective solution-casting method has led to significant enhancements in structural, thermal, optical, and rheological properties. The incorporation of these WO3 particles up to 7 wt% resulted in the formation of an irregular honeycomb-like morphology with broad pore sizes ranging from 14.1 to 24.7 µm, as confirmed by SEM and EDX analysis. The urchin-like WO3 particles acted as effective nucleating agents, increasing the crystallinity of PLA from 40% to 50% and achieving an impressive overall crystallinity rate of 97%. Differential scanning calorimetry (DSC) revealed an 11 K reduction in the crystalline phase transition temperature while maintaining stable melting (Tm) and glass transition (Tg) temperatures. Thermal analysis indicated a significant decrease in the onset of degradation and maximum thermal stability (Tmax), with a reduction of 21 K due to the incorporation of the WO3 particles. Optical measurements showed enhancement of UV-blocking properties from 9% to 55% with the WO3 particle loading. Rheological tests demonstrated substantial improvements in viscoelastic properties, including a remarkable 30-fold increase in storage modulus, suggesting enhanced gel formation. Although the nanocomposites showed minimal antibacterial activity against Escherichia coli and Staphylococcus aureus, they exhibited significant antifungal activity against Candida albicans. These results underscore the potential of the PLA/WO3 nanocomposites for advanced material applications, particularly where enhanced mechanical, thermal, optical, and antifungal performance is required. [ABSTRACT FROM AUTHOR]

Prevention of aseptic loosening, the main reason for secondary surgery of bone implants, is of great crucial clinical importance. As a promising bioactive material to promote bone regeneration, the piezoelectric materials for preventing aseptic loosening has not been reported. Here, a surface coating is presented for implants based on piezoelectric poly(L‐lactic acid) (PLLA). The coating ingeniously utilizes zoledronic acid (ZA), a drug used to treat osteoporosis, as a nucleating agent to enhance the piezoelectricity of PLLA. The coating can not only provide a continuous porous piezoelectric environment to stimulate osteogenic differentiation without intervention, but also effectively inhibit the osteolytic activity of osteoclasts through the slow release of ZA, achieving long‐term effectiveness with a single implantation. The rat femur cavity implantation experiment suggests that, the PLLA/ZA coating can rapidly initiate osseointegration of the implant and effectively mitigate the risk of aseptic loosening, even in the presence of metal submicroscopic particles that induce aseptic loosening. This strategy of piezo‐enhanced PLLA drug‐loaded coating may provide a new idea for the surface modification of bone implants. [ABSTRACT FROM AUTHOR]

Inorganic particles dispersed in the polymer matrix can enhance the strength of polymers. In this paper, 3-Glycidyloxypropyltrimethoxysilane (KH560) and 2-Amino-1,3-propanediol were used to surface modify Zirconium dioxide (ZrO2) to prepare modified Zirconium dioxide (ZrO2), denoted as ZrO2-g. The modified ZrO2-g was characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic hydrogen (1HNMR) spectroscopy, and the results showed that the modification was successful. Then the PBAT/ZrO2-g composites were synthesized by grafting ZrO2-g into poly (butylene adipate-co-terephthalate) (PBAT) molecular chain segments using in situ copolymerization. The results showed that ZrO2-g acted as a nucleating agent and improved the crystallinity of poly (butylene adipate-co-terephthalate) (PBAT). The rheological behavior analysis showed that the composite viscosity, storage modulus and loss modulus of PBAT/ZrO2-g composites were improved compared to PBAT. The ZrO2-g content had a significant effect on the tensile properties of the composites, and the composites had the highest tensile strength and elongation at break when the ZrO2-g content was 1% wt, reaching 23.27 MPa and 888.89%, respectively, which were increased by 60% and 38%, respectively, compared with PBAT. When the content of ZrO2-g exceeds 1.5 wt%, aggregation phenomenon occurs, which rather reduces the performance of the composites. Meanwhile, the thermal stability of the composites decreases with the increase of ZrO2-g incorporation. [ABSTRACT FROM AUTHOR]

Over the past decades, the use of polyethylene terephthalate (PET) has seen significant growth, particularly in the packaging industry. However, its long decomposition time poses serious environmental challenges. The aim of this research was to develop a process for the foaming of large quantities of recycled PET (rPET) using endothermic and exothermic foaming agents. Various formulations with different ratios of endothermic and exothermic foaming agents were prepared, as well as their mixtures. The study found that the endothermic–exothermic hybrid foaming process resulted in a finer cell-size distribution and enhanced mechanical properties, making the foams highly suitable for widespread applications. The results support the potential use of exothermic foaming agents as nucleating agents in a hybrid foaming system. In particular, the ratio of 3% endothermic and 1% exothermic foaming agents proved optimal in terms of achieving a balance between porosity and mechanical strength, thereby enabling broad industrial applicability. [ABSTRACT FROM AUTHOR]

Organophosphates nucleating agents are widely used in the plastics industry. Nucleating agents with different morphologies have various effects on the resin materials. The micro‐jetting technique is shown to be a promising tool for the controlled preparation of micro‐and nano‐sized particles. Therefore, in this paper, controllable preparation of sodium 2,2'‐methylene‐bis‐(4,6‐di‐tert‐butylphenyl) phosphate (NA11) is achieved by the micro‐jetting technique. The study focused on the impact of various parameters on its shape and size. Hexagonal, rhombic, rod‐shaped, and needle‐shaped micro‐sized NA11 crystals are prepared. The results show that the decrease in the polarity of the organic solvents added in the antisolvent water led to the transformation of NA11 from bulk hexagon to plate‐like rhombus and finally to needle‐shaped crystals. The addition of surfactants can regulate the crystal growth rates and orientations, thereby facilitating the formation of rod‐shaped crystals. Based on rod‐shaped crystals, the crystal size is studied. Crystals with average particle sizes in the range of 40–100 µm can be obtained with coefficients of variation as low as 4% by varying the relevant experimental parameters such as the supersaturation, the solution homogeneity in the crystal growth environment, and the mixing intensity. This study provides references for designing functional materials. [ABSTRACT FROM AUTHOR]

PLA was melt-blended with a chain extender (CEAX8840) and a nucleating agent (ST-NAB3) by using a torque rheometer, and the microstructure, crystallization behavior, mechanical properties, and heat resistance of the modified PLA were characterized by suing scanning electron microscope, hot-plate polarizing microscope, differential scanning calorimeter, thermal deformation meter, universal testing machine, and impact tester. The results indicated that the modified PLA obtained the smallest crystal size at CEAX8840 and ST-NAB3 contents of 6 and 1 wt%, respectively; however, its crystal density was the highest. Moreover, the crystallization temperature and crystallinity degree of the modified PLA were increased to 123. 9 °C and 44. 9 %, respectively. In addition, its impact strength and thermal deformation temperature were increased to 64. 7 kJ/m² and 84. 9 °C, respectively. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) is regarded as a recyclable material for high-voltage direct current (HVDC) cable insulation due to its high melting point and electrical resistivity. This work focuses on the effect of the β-nucleating agent content on the electrical tree growth characteristics in isotactic PP (iPP) insulation. The results demonstrate that adding β-nucleating agents promotes the growth of β-crystals while limiting the α-crystal content. The crystallinity improves with the reduction in the average size of spherulites due to the addition of a β-nucleating agent with 0.1 wt% content. Electrical tree experiments show that the electrical tree growth rate declines as the nucleating agent content rises from 0 to 0.1 wt%. Meanwhile, the expansion coefficient increases with higher nucleating agent content. Continuous increases in the nucleate agent content result in the upward growth rate of electrical trees. When the nucleating agent content is below 0.1 wt%, the α–β-crystal interface introduced by the agent suppresses carrier migration and limits impact ionization, leading to the slower growth rate of the electrical tree. Further addition of the nucleate agent induces a β–β-crystal interface with weak coupling in carriers. It is concluded that β-nucleating agent-modified PP with 0.1 wt% content has potential application in HVDC cable insulation. [ABSTRACT FROM AUTHOR]

This study investigated the microstructure, mechanical properties, and nucleation mechanism of acicular ferrite (AF) present in hot-rolled Ti deoxidized steel. In our experiments, the impact toughness of Ti deoxidized steel is significantly increased to 144 J at −20 °C, while those Mn and Al deoxidized steels are only 9 J and 18 J, respectively. Interlocked AF is the primary microstructure of Ti deoxidized steel. The second-phase particles of the core–shell-type structure, in which Ti2O3 is the nucleus and TiO is the outermost shell, act as effective nucleating agents to stimulate AF nucleation. The low lattice disregistry between TiO and AF is the main factor contributing to the production of AF. It is also revealed that Ti2O3 and MnS fulfill the particular orientation relationship, contributing to the formation of an Mn-depleted zone (MDZ) adjacent to MnS, proposed to be one of the possible mechanisms for promoting AF nucleation. [ABSTRACT FROM AUTHOR]

We herein report the enhancement of thermal, electrical, electromagnetic interference (EMI) shielding, and mechanical performance of polyethylene (PE) nanocomposites by the introduction of non‐covalently modified multi‐walled carbon nanotube (MWCNT) and ethylene‐glycidyl methacrylate (EGMA) copolymer. For this purpose, benzylacetic acid‐functionalized MWCNT (BA‐M) is prepared by ball milling, and it is melt‐mixed with EGMA to prepare a masterbatch. The masterbatch is then melt‐compounded with neat PE to manufacture a series of PE/EGMA/BA‐M nanocomposites with 0.5–5 wt% MWCNTs. Electron microscopic and spectroscopic analyses confirm the successful fabrication of non‐covalently functionalized BA‐M, the uniform dispersity of MWCNTs in the PE matrix, and the chemical reactions between the carboxylic acid groups of BA‐M and the epoxy group of EGMA in the nanocomposites. Scanning calorimetric data reveals that BA‐M acts as an efficient nucleating agent for the crystallization of PE. The excellent dispersity and robust interfacial bonding of BA‐M in the PE matrix result in improved electrical and EMI shielding properties in PE/EGMA/BA‐M nanocomposites. Furthermore, the tensile strength, initial modulus, and impact strength of the nanocomposites gradually rise as the BA‐M content increases. Thus, the PE/EGMA/BA‐M nanocomposite containing 5 wt% MWCNT achieves excellent performance of EMI shielding effectiveness of ~14.7 dB/mm, tensile strength of ~34.5 MPa, initial modulus of ~295.7 MPa, and impact strength of ~539.9 J/m, which represent enhancements of ~265%, ~40%, ~82%, and ~452%, respectively, compared to pristine PE. Highlights: Non‐covalently modified MWCNT (BA‐M) was prepared by facile ball milling.PE nanocomposites with BA‐M and EGMA were prepared by masterbatch melt‐mixing.Excellent dispersity and interfacial bonding of MWCNT in the PE matrix were attained.Tensile strength and initial modulus of the nanocomposites were highly improved.EMI shielding effectiveness of the nanocomposite with 5 wt% MWCNT was ~14.7 dB/mm. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) has been widely studied because of its various crystal phase transformations as well as its special dielectric, piezoelectric, and other electrical properties. In this study, a temperature gradient (T-gradient) was constructed for studying the temperature dependence of the crystallization behavior of PVDF and the heterogeneous nucleation effect of multiwall carbon nanotubes (MWCNTs). The nanoscale structure of PVDF was investigated through three different dimensions using FTIR for the surface, WAXD/SAXS for the bulk and AFM for the cross-section. The results showed that low temperature and a heterogeneous nucleating agent were both conducive to the formation of the γ phase of PVDF. The distance of MWCNT nucleation effect is about 15 μm, and it is more significant in 0–5 μm. The content of the γ phase reached 77% when Tc was lower than 61 °C. The higher content and lower crystallite size of the γ phase lead to a higher dielectric constant, which can lay a foundation for its future application in the field of dielectrics. [ABSTRACT FROM AUTHOR]

AbstractPhase change energy storage materials are the core of phase change energy storage technology. Phase change hysteresis can cause phase change materials not to store and release thermal energy as expected, and most studies have not focused on this. A low-temperature eutectic phase change material CaCl2·6H2O–MgCl2·6H2Omaterial prepared was investigated, and some influencing factors of the phase change hysteresis phenomenon and its regular characteristics were aspired to be obtained. The melting-solidification curves were obtained using a step-cooling test bench, and the latent heat values and heat absorption and exothermic curves of materials with different proportions were measured by a differential scanning calorimeter. The experimental results show that the temperature difference of the phase change hysteresis tended to increase gradually with the increase of the mass fraction of the nucleating agent, and the hysteresis temperature difference increases from the initial 3.9 °C–15.02 °C when SrCl2·6H2O was added by 2.4%. The temperature difference of the phase change hysteresis increased gradually with the increase of the mass fraction of the thickener. This paper provides a new idea for optimizing the properties of phase change energy storage materials and provides a possibility for realizing the parametric control of phase change hysteresis factors. [ABSTRACT FROM AUTHOR]

Polyvinylidene difluoride (PVDF) membranes have low surface tension and strong hydrophobicity in water treatment process, and are easily polluted by organic substances. Blending modification can effectively improve the hydrophilicity. The surface of modified membranes are easy to form hydrophilic layer to prevent contact between pollutants and membranes, thus improving the anti-pollution properties. Two amphiphilic block copolymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) radical polymerization. The block copolymers and PVDF were mixed by blending method to form hydrophilic modified membranes. The membranes hydrophilicity, surface PAA coverage, and anti-pollution properties increased with increasing ratios of block copolymers/PVDF and PAA in block copolymers. The anti-pollution properties depended more strongly on membranes surface hydrophilicity when block copolymers chemical structures, that was, the PAA ratios, were changed, rather than the ratios change of block copolymers/PVDF. The block copolymers improved crystallization performance of PVDF because of the role of nucleating agent of block copolymers. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is currently the largest volume of production and application of synthetic biodegradable polymer via bio-derived materials. However, the relaxation characteristics and very low crystallization rate determined by the hand- structure of PLA chains result in low heat-resistance temperature and troublesome demold behavior for fast extrusion and/ or injection molding process. It is well known, by introducing of nucleating agent and crystal growing accelerator, the crystallization properties of PLA materials can be improved efficiently. In the paper, the isothermal crystallization behaviors of PLA, which include the rate and temperature of crystallization, crystallinity, crystals morphologies, were systemically shown. Meanwhile, a serious of regulation strategies of isothermal crystallization kinetics of PLA materials, such as adding of biodegradable polymers, different dimension of fillers, various chain-reconstruct for PLA, processing flow fields and post-treatment, were comprehensively summarized. Additionally, the regularity strategies and next study points for PLA isothermal crystallization behavior were also presented. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is one of the most widely used biodegradable materials at present due to its excellent reproducibility and degradability. However, PLA still suffers from poor crystallinity, which seriously affects its development and application. Therefore, PLA/cellulose nanocrystalline (CNC)‐polyethylene glycol (PEG) composite (PLA/CNC‐PEG) was prepared by melt blending using CNC as nucleating agent and PEG as compatibilizer. The effect of PEG with different molecular weights (MW) on the properties of PLA/CNC‐PEG composite was investigated. The experimental results shown that the crystallization properties of PLA were greatly improved under the synthetic action of CNC and PEG. With the increasing MW from 400 to 20,000 of PEG, the crystallinity of PLA/CNC‐PEG composite decreased from 32.1% to 13.3%. In addition, the crystallization model of PLA/CNC‐PEG was constructed to explore the mechanism of crystallization growth of PLA, effectively guiding the reduction of crystallization activation energy of PLA. Furthermore, it was found that PLA/CNC‐PEG exhibited good thermal stability, mechanical properties, and hydrophilicity with the addition of CNC and PEG400. Therefore, the synthetic action of CNC and PEG well regulated the performance of PLA. The proposed work is of hopeful to expand the application of PLA in production and life. [ABSTRACT FROM AUTHOR]

A novel thermoplastic elastomer, kernel resin (KN), α‐nucleating agent (HPN), and β‐nucleating agent (DCHT), which acted as toughener and nucleating agents (NAs), were used to improve the mechanical properties and crystallization behaviors of isotactic polypropylene (PP). The impact strength of the PP/KN blends increased significantly with increase in KN concentration. Surprisingly, the impact strength of PP/KN/NA blends improved further upon addition of NA. The toughening effect of DCHT was stronger than that of HPN. The maximum impact strength of PP/KN/DCHT blend reached 69.2 kJ/m2 when the DCHT content was 0.05%, which was six times higher than that of neat PP. The SEM images of fractured surfaces of the blends showed a change from brittle fracture to ductile fracture. Moreover, the WAXD results showed that the incorporation of HPN promoted the formation of the α form of crystalline PP. Addition of DCHT induced the generation of α‐β crystal transition of PP. Furthermore, differential scanning calorimetry showed that the crystallizability and the overall crystallization rate of PP were enhanced by the addition of KN and NA. The half‐crystallization time of PP at 128°C decreased from 5.52 (neat PP) to 0.34 min (PP/KN/DCHT‐0.3). [ABSTRACT FROM AUTHOR]

The iron oxide nanoparticles (IONs), coated with different materials, are synthesized and utilized as nucleating agents to prepare magnetic multi‐modal porous scaffolds of poly (lactic‐co‐glycolic acid)/IONs using the supercritical carbon dioxide (ScCO2) foaming process. The effects of the modification materials, including citric acid, polycaprolactone, and polyvinyl acetate, on the foaming process and properties of the magnetic scaffolds are systematically investigated. The results indicate that the solubility and diffusion ability of CO2 in the foaming materials played a vital role in the foaming process. The use of CO2‐philic materials and high pressure proves beneficial in generating micropores. The scaffolds with multi‐modal porous structures can be obtained at relatively low pressure for the ScCO2 foaming systems evaluated in this study. Furthermore, the prepared scaffolds exhibit high porosity and a good compressive modulus (higher than 0.4 MPa), satisfying the requirements of tissue engineering for soft tissue scaffolds. [ABSTRACT FROM AUTHOR]

Polyethylene (PE) foams are widely used for the advantages of light weight and reducing energy consumption. So, the preparation of environmental friendly and efficient blowing agent is essential. The use of supercritical carbon dioxide (CO2) as physical blowing agent requires harsh experimental conditions such as high‐pressure and temperature. In this study, CO2 was captured by 1, 2‐cyclohexanediamine (TRK) under atmospheric pressure, and reversibly released under heating as a blowing agent with nanosponges (NS) used as the carrier (NS:TRK‐CO2). Furthermore, three ethoxy silane coupling agents were selected to improve the compatibility between heterogeneous nucleating agent (cyclodextrin nanosponges, NS) and PE, so as to improve the nucleation effect of NS and the comprehensive properties of PE composites. Analyses showed that triethoxyvinyl silane (VTES) was a suitable candidate for improving the compatibility of NS and PE. The addition of NS:TRK‐CO2@VTES not only improved the crystallization performance, but also improved the complex viscosity and storage modulus, and enhanced the thermal properties of PE composites. The optimal cell morphology was obtained by introduction of NS:TRK‐CO2@VTES with 5 wt%, the minimum cell diameter was 50 μm, and the maximum cell density was 9.4 × 104 cells/cm3. Compared with the other PE composites, PE/NS:TRK‐CO2@VTES composites showed excellent mechanical, thermal, and sound insulation properties. The maximum impact strength was 7.62 KJ/m2, which was two times higher than pure PE. The thermal conductivity was 0.054 W/m k, the sound absorption coefficient was 0.836 at 1500 Hz. [ABSTRACT FROM AUTHOR]

In the present study, a novel crystalline nucleating agent for isotactic polypropylene (PP) comprising the calcium salt of 4‐methyl‐cyclohexane‐1,2‐dicarboxylic acid (MHPA‐Ca) is developed. The performance of the nucleating agent is evaluated by determining the crystallization temperature and isothermal crystallization period of the PP by differential scanning calorimetry, and comparing them with those obtained using the calcium salt of cyclohexane‐1,2‐dicarboxylic acid (HHPA‐Ca), which is one of the most effective nucleating agents for PP. The results demonstrate that the nucleating ability of MHPA‐Ca is much stronger than that of HHPA‐Ca. Consequently, an injection‐molded plate containing MHPA‐Ca has a high degree of chain orientation. [ABSTRACT FROM AUTHOR]

The technology for the resourceful utilization of electrolytic manganese residue (EMR) in the production of superior performance glass-ceramics has garnered significant interest for its potential to maximize the consumption of waste residues in the Mn metal industry. In this study, utilizing the unique chemical composition of high-Mn EMR, superior performance glass-ceramics were prepared via a melting method, with TiO 2 utilized as a nucleating agent. The influence of the TiO 2 doping amount on the crystalline characteristics, microstructure and properties of the glass-ceramics were systematically evaluated. Additionally, the curing mechanism of Mn in glass-ceramics was scrutinized. The results show that TiO 2 enhances the precipitation of Ca(Ti,Mg,Al) (Si,Al) 2 O 6 predominant crystalline phase in the glass-ceramics. This phase transitions from a spherical to an interlocking and dense dendritic morphology. The glass-ceramics containing 10 wt% TiO 2 , which was heat-treated by nucleation at 750 °C for 2 h followed by crystallization at 900 °C for 3 h, exhibits enhanced mechanical properties and chemical stability. Its bending strength exceeds 40 MPa, with a water absorption of 0.11 %. Additionally, the acid resistance of glass-ceramics is rated at higher than 97 %, while the alkali resistance is over 99.7 %. Notably, the superior performance in Mn leaching toxicity is achieved in T10 (1.39 mg/L), which is attributable to the fact that Mn is physically coating between the crystalline and glassy phases. This technology has the potential to address the issue of heavy metal release from EMR, and provides a theoretical foundation for the industrial production path of glass-ceramics from high-Mn EMR. [ABSTRACT FROM AUTHOR]

Thermal resistance of expanded polystyrene (EPS) insulation boards are investigated in terms of foam extrusion process equipped with an underwater pelletizer. This method has been used by several companies as an alternative process to obtain EPS beads from suspension polymerization of styrene. In this process either polystyrene granules with no cellular microstructure (general purpose polystyrene) or polystyrene beads with closed cell structure or both together can be used. Therefore, in this study, commercial general purpose polystyrene and expandable polystyrene materials were blended with either carbon black or graphite powder through foam extrusion process to obtain effective thermal resistance values. In order to make a fair comparison, materials were prepared similar to commercial recipes which include flame retardant and nucleating agent. It was observed that the compatibility of graphite powder with general purpose polystyrene was better than expandable polystyrene in terms of glass transition temperatures and thermal insulation values. The density of the prepared materials increased with the addition of carbon black to all samples. The best glass transition temperature was measured as 107.5 °C while the best thermal conductivity value was recorded as 0.2997 W/m.K which is fairly good when compared to commercial polystyrene insulation boards. [ABSTRACT FROM AUTHOR]

In this study, the crystallization behavior of a CaO–MgO–Al 2 O 3 –SiO 2 based glass ceramics with Nb 2 O 5 addition was investigated by using DSC, XRD and TEM techniques. It was found that three crystalline phases, namely, CaNb 2 O 6 , diopside and Gehlenite (Ca 2 Al 2 SiO 7), were formed from the glass matrix during the crystallization heat treatment. The CaNb 2 O 6 phase was the first to precipitate from the glass matrix at around 850 °C, acting as a nucleating agent that facilitated the formation of Gehlenite (Ca 2 Al 2 SiO 7) at 900–950 °C. The TEM observation revealed a consistent orientation relationship between the CaNb 2 O 6 and the Gehlenite (Ca 2 Al 2 SiO 7) phases, indicating that CaNb 2 O 6 could induce the epitaxial growth of Gehlenite (Ca 2 Al 2 SiO 7). This result provides a new insight into the preparation of Gehlenite epitaxial films and glass ceramics. [ABSTRACT FROM AUTHOR]

The impact of adding ethylene vinyl acetate copolymer (EVA 80) and 1 wt% TiO2 nanoparticles on the morphology and crystallization behavior of poly(lactic acid) blends was investigated using DSC, SEM, and POM. Thermal analysis revealed the enhancement of crystallinity of PLA in the presence of TiO2 and higher EVA 80 content in the blend. The PLA and EVA 80 components showed compatibility, as evidenced by the shift of the glass transition temperatures of the PLA phase in the blend to lower values compared to neat PLA. The lower temperature shift of the cold crystallization of the PLA and the formation of the small spherulites of the PLA in the blends indicated that the EVA 80 and TiO2 act as a nucleating agent for crystallization. The non-isothermal crystallization parameters of the composites were evaluated using Avrami's modified model, the MO approach, and Friedman's isoconversional method. The Avrami's modified rate constant (K) and the effective activation energy values significantly increased with the incorporation of EVA 80 and TiO2 nanoparticles. Furthermore, the thermogravimetric analysis (TGA) showed improved thermal stability of PLA by adding EVA 80 and TiO2. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) is known to exhibit slow crystallization. Therefore, post‐process annealing is often performed, at which structure change is inevitable. In this paper, the structure development during annealing of PLA containing N,N′‐ethylenebis(12‐hydroxystearamide) (EBHS) is studied using extruded strands. First, EBHS, which acts as a nucleating agent, is dissolved in molten PLA, and then segregates with a fibrous shape during cooling. Next, the PLA containing EBHS is extruded, which causes EBHS fibers in the strand to orientate with the flow direction. When the strand is annealed at 100°C, amorphous PLA chains initially lose their orientation. Then, the chain orientation in the PLA strand develops because of transcrystallization from the surface of EBHS fibers that are aligned with the flow direction. As a result, the Hermans orientation function increases from 1.8 × 10−3 (before annealing) to 6.0 × 10−3 (after annealing). Moreover, the annealed PLA/EBHS strand shows less shrinkage (0.80 ± 0.19%) than the annealed PLA strand (2.04 ± 0.27%). The promotion of PLA chain orientation induced by the presence of aligned EBHS fibers can be used to control the structure and dimensional change of PLA products during annealing. [ABSTRACT FROM AUTHOR]

In this study, styrene-ethylene-butene-styrene block copolymer (SEBS) is blended with polypropylene (PP) to improve the melt strength of PP. Azodicarbonamide (AC) is used as a chemical foaming agent to prepare PP foaming materials with good mechanical properties by moulding foaming. The melt strength of the material, the content of the nucleating agent and the concentration of the foaming agent will affect the foaming effect of the material. Orthogonal optimization experiments are designed for these three factors to explore the best ratio of foaming materials. The results show that when PP:SEBS = 85:15, the addition amount of nano-SiO2 is 3%, and the content of AC foaming agent is 5%, the cell structure of the foaming material is the best. The cell structure is observed by SEM,the average cell diameter is reduced to 45.73 μm, and the cell density is increased to 4.12 × 106 cells cm−3. The apparent density of the material is measured to be 0.62 g cm−3, which is 32% lower than that of pure PP (0.91 g·cm−3). The tensile strength of PP/SEBS foamed composites is lower than that of pure PP and pure PP foamed materials, but its elongation at break is 124.3% higher than that of pure PP, and 238.8% higher than that of pure PP foamed materials. The bending strength of PP/SEBS foamed material is lower than that of pure PP and pure PP foamed material. The impact strength of PP/SEBS is only 8.4 % lower than that of pure PP, and 60.8 % higher than that of pure PP foamed material. [ABSTRACT FROM AUTHOR]

Highlights Currently, toughening poly(lactic acid) (PLA) without reducing its strength and modulus is still challenging. Fortunately, this problem could be addressed by incorporating cellulose nanocrystals grafted with epoxidized soybean oil (CNCs‐g‐ESO) into the PLA matrix. The percolation threshold for uniform dispersion of the CNCs‐g‐ESO in the PLA matrix was about 0.8 wt%. The loading made the elongation at break and tensile fracture energy of the PLA composite film increase to 26.5 and 11.26 from 3.7% and 0.96 MJ.m−3, respectively, concerning the neat PLA. Meanwhile, it also resulted in a 4.7% and 12.4% increase in the tensile strength and Young's modulus, respectively. Additionally, the initial decomposition temperature (T5%) of the PLA composite increased to 334.9 from 316.1°C after incorporating the CNCs‐g‐ESO. Therefore, the CNCs‐g‐ESO, acting as an ESO‐like plasticizer and a CNCs‐like nucleating agent, is a potential nanofiller for reinforcing and toughening PLA. Cellulose nanocrystal grafted with epoxidized soybean oil (CNCs‐g‐ESO) The CNCs‐g‐ESO acting as both plasticizer and nucleating agent The CNCs‐g‐ESO decreasing the spherulite size, but increasing the CrI of PLA The CNCs‐g‐ESO enlarging the window for thermal process of PLA Simultaneous reinforcement and toughness of PLA [ABSTRACT FROM AUTHOR]

Isocyanates are critical components that affect the crosslinking density and structure of polyurethane (PU) foams. However, due to the cost and hazardous nature of the precursor for isocyanate synthesis, there is growing interest in reducing their usage in polyurethane foam production—especially in rigid PU foams (RPUF) where isocyanate is used in excess of the stoichiometric ratio. In this study, lignin-containing nanocellulose fibrils (LCNF) were explored as mechanical reinforcements for RPUF with the goal of maintaining the mechanical performance of the foam while using less isocyanate. Different amounts of LCNF (0–0.2 wt.%) were added to the RPUF made using isocyanate indices of 1.1, 1.05, 1.0, and 0.95. Results showed that LCNF served as a nucleating agent, significantly reducing cell size and thermal conductivity. LCNF addition increased the crosslinking density of RPUF, leading to enhanced compressive properties at an optimal loading of 0.1 wt.% compared to unreinforced foams at the same isocyanate index. Furthermore, at the optimal loading, LCNF-reinforced foams made at lower isocyanate indices showed comparable stiffness and strength to unreinforced foams made at higher isocyanate indices. These results highlight the reinforcing potential of LCNF in rigid polyurethane foams to improve insulation and mechanical performance with lower isocyanate usage. [ABSTRACT FROM AUTHOR]

Basalt fiber reinforced polypropylene composites with two initial fiber lengths (3.2 and 6.4 mm) were fabricated using twin‐screw extrusion compounding. In the case of composites with smaller initial fiber length, basalt fibers predominantly served as nucleating agents for polypropylene thereby resulting in an increase in the degree of crystallinity. The addition of polypropylene‐g‐maleic anhydride (PP‐g‐MA) caused the matrix to become amorphous, which was due to the establishment of a fiber–matrix interphase. This behavior was different for the composites with relatively larger initial fiber length especially at higher fiber content. The reduction in fiber length in the composites caused a decrease in crystallinity, as this hindered the ability of the polypropylene matrix to form crystals. Addition of PP‐g‐MA established a fiber–matrix interphase thereby synergistically contributing to the increased matrix amorphousness of the basalt fiber reinforced polypropylene composites with 6.4 mm initial fiber length. Reduced fiber length due to processing also accelerated the thermal degradation of the composites with an initial fiber length of 6.4 mm. However, the reduction in fiber length due to processing resulted in increased fiber orientation, which contributed to the improvement in tensile and flexural properties of the basalt fiber reinforced polypropylene composites with an initial fiber length of 6.4 mm. At 30% fiber content, the tensile strength and modulus of basalt fiber reinforced matrix modified polypropylene composites with 6.4 mm initial fiber length improved by 18% and 13% as compared with the composites with 3.2 mm initial fiber length. [ABSTRACT FROM AUTHOR]

In this study, hollow nanospheres of titanium dioxide (TiO2) are prepared and utilized as potential nucleating agents in supercritical carbon dioxide (scCO2) foaming process of thermoplastic polyurethanes (TPUs) at different foaming temperatures and saturation pressures. To produce the hollow nanospheres of titanium dioxide (TiO2), well-defined spheres of polystyrene (PS) with a diameter of about 300 nm are first synthesized as templates using surfactant-free emulsion polymerization. A layer of titanium tetraisopropoxide (TTIP) is then uniformly coated on the PS spheres followed by calcination in a furnace to convert the titania layer to the titanium oxide layer. Hollow nanospheres of titanium dioxide with a well-defined morphology are prepared by calcination at high temperatures, as the PS spheres completely decompose. Interestingly, highly porous structures, which give rise to high surface area for trapping scCO2, are generated on the surface of the TiO2 nanoparticles during the thermal treatment. The dispersion of TiO2 nanospheres in the TPU matrix is successful, serving as heterogeneous nucleating agents that influence the cell density and morphology of the extended TPU in the foaming process. In this study, hollow nanospheres of titanium dioxide (TiO2) with unique porous surface are prepared and utilized as potential nucleating agents in supercritical carbon dioxide (scCO2) foaming process of thermoplastic polyurethanes (TPUs) to control various foaming parameters including foaming ratio, cell size, cell density etc. [ABSTRACT FROM AUTHOR]

In this study, a twin-screw extruder was used to fabricate poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends and blend-based nanocomposites with carbon nanotube (CNT) or nanocarbon black (CB) as nanofillers. The fabricated samples were subsequently treated with supercritical carbon dioxide (scCO2) to fabricate the corresponding foams. Bi-phasic morphology and selective distribution of CNTs or CBs in the PBAT phase were observed in the blends/composites through scanning electron microscopy. After the scCO2 treatment, the selective foaming of the PBAT phase in the prepared blends/composites was confirmed. The cellular structure of PBAT phase in scCO2-treated blends is similar to the size/shape of PBAT domains in untreated blends or treated neat PBAT foam. The addition of CNTs or CBs in the blends led to a slight reduction in cell size of the foamed PBAT phase, demonstrating CNT/CB-induced cell nucleation. Differential scanning calorimetry (DSC) results showed that CNTs and CBs played as nucleating agents and increased the initial crystallization temperature up to 14 °C compared with neat PBAT for PBAT in different composites during cooling. The scCO2 treatment induced the bimodal stability of PBAT crystals in different samples, which melted mainly in two temperature regions in DSC studies. Thermogravimetric analyses revealed that compared with parent blends, the addition of CNTs or CBs increased the temperature at 80 wt.% loss (degradation of PBAT portion) up to 6 °C. The electrical resistivity decreased by more than six orders of magnitude for certain CNT- or CB-added composites compared with the parent blends. The hardness of the blends slightly increased after forming the corresponding composites and then declined after the scCO2 treatment. [ABSTRACT FROM AUTHOR]

Microcellular foams of polyphenylene oxide/high-impact polystyrene (PPO/HIPS) with high strength are prepared using supercritical CO2 foaming technology. The study focuses on examining the influence of polytetrafluoroethylene (PTFE) and polystyrene–butadiene block (SEBS) polymers in PPO/HIPS blends. Compared with the pure PPO/HIPS blend, the PPO/HIPS blend with 1 phr PTFE exhibits higher impact strength (7.62 kJ/m²), and the foam compressive strength is 5% larger. The PPO/HIPS foams with 1 phr PTFE (as a nucleating agent) and 5 phr SEBS (as a toughening agent) display a small cell diameter (13.73 μm) and the highest cell density (2.02 × 109 cells/cm³) compared to the pure PPO/HIPS blend. Moreover, the compressive strength of the PPO/HIPS/PTFE-1/SEBS-5 foam (1.63 MPa at a 5% strain) demonstrates a remarkable increase of 92% compared to that of the PPO/HIPS/PTFE-1 foam. [ABSTRACT FROM AUTHOR]

Single (TiO2) and complex (TiO2 and ZrO2) nucleating agents were added in CaO–Al2O3–SiO2–ZnO–Na2O–K2O‐based multicomponent glass to investigate its crystallization behavior and physical properties according to the types and amounts of nucleating agents. Nonisothermal analysis revealed crystallization behavior with an activation energy (E) of 165.176–518.985 kJ/mol and Avrami constant (n) of.73–2.12 with the complex nucleating agent. X‐ray diffraction was used to observe the titanite and zircon crystalline phases in glass when using complex nucleating agents, and the crystallinity was found to be 43%–55%. Scanning electron microscopy and energy‐dispersive x‐ray spectroscopy were used to observe the plate‐shaped titanite and column‐shaped zircon crystalline phase in the glass matrix, and the glossiness was found to be decreased owing to the crystallization of the glass. The glass‐ceramic showed a higher hardness and fracture toughness value of 6.45–6.7 GPa and 1.54–3.35 MPa∙m1/2 when using the complex nucleating agent rather than when using the single nucleating agent. [ABSTRACT FROM AUTHOR]

Zinc stearate (Znst) was physically blended with the sodium 4-[(4 chlorobenzoyl) amino] benzoate (SCAB) to obtain the SCAB-Znst composite nucleating agent. Znst was used to improve the dispersion property of SCAB and exert a lubricating effect on the PP matrix. The scanning electron microscopy and the fracture surface morphology of the PP/SCAB composite illustrated that the addition of Znst greatly reduced the aggregation phenomenon of SCAB in the PP matrix. The result of the rotary rheometer indicated that Znst exhibits internal lubrication in PP. The DSC result illustrated that the crystallization properties of PP were improved. Compared with pure PP, the Tc of the PP/SCAB composite increased by 1.44 °C (PP/Znst), 13.48 °C (PP/SCAB), and 14.96 °C (PP/SCAB-Znst), respectively. The flexural strength of pure PP, PP/SCAB, and PP/SCAB-Znst were 35.8 MPa, 38.8 MPa, and 40.6 MPa, respectively. The tensile strength of the PP/SCAB and PP/SCAB-Znst reached the values of 39.8 MPa and 42.9 MPa, respectively, compared with pure PP (34.1 MPa). The results demonstrated that Znst can promote the dispersion of SCAB in the PP matrix while exerting a lubricating effect, which enabled the enhancement of the crystalline and mechanical properties of PP. [ABSTRACT FROM AUTHOR]

Transparent ZnO–MgO–Al 2 O 3 –SiO 2 (ZMAS) glass-ceramics comprising ZrO 2 and SnO 2 as nucleating agents were prepared via melting and two-step heat treatment. The effects of varying the SnO 2 concentration (1–3 mol%) on the crystallization behavior, microstructures, and mechanical properties of the glass-ceramics were investigated. Increasing the SnO 2 content promoted the precipitation of spinel and gahnite because SnO 2 improved the formation of ZrO 2 nanocrystals, which provided nucleation sites for subsequent crystallization. When the SnO 2 content was varied between 2 and 3 mol%, the crystallization behavior of the ZMAS glass-ceramics showed little difference, and SnO 2 crystals precipitated from the glass at a relatively low crystallization temperature. In addition, glass-ceramics containing 2 and 3 mol% SnO 2 exhibited average grain sizes of ∼26 and ∼29 nm, respectively, but their transmittance decreased to ∼52% and ∼50%, respectively, owing to grain aggregation. The best overall performance was achieved when the SnO 2 content of the glass-ceramic was 3 mol% and heat treatment was conducted at 780 °C for 3 h and 960 °C for 2 h, with the resulting glass-ceramic exhibiting a bending strength of ∼187 MPa and a Vickers hardness of ∼845 kgf/mm2. [ABSTRACT FROM AUTHOR]

In this paper, the effects of four different types of nucleating agents, namely, α-nucleating agent CH-6N, HPN-715, TMP-7 and β-nucleating agent TMB-5, as well as the effects of compounding of different types of nucleating agents on the mechanical, optical and crystalline properties of polypropylene were investigated. The results show that the nucleating agent can effectively increase the crystallization temperature and crystallinity. α-nucleating agent CH-6N has the best rigidity effect. The bending modulus and bending strength of polypropylene are 2 390 MPa and 60.6 MPa respectively with the addition of 0.2% CH-6N. The α nucleating agent can reduce the toughness of polypropylene. Adding 0.2% CH-6N, the impact strength of polypropylene is only 2.7 kJ/m². The β -nucleating agent TMB-5 can effectively improve the toughness of polypropylene, but reduce the rigidity. The toughening effect of 0.1 % TMB-5 is the best. The impact strength of polypropylene is 20.7 kJ/m2, and the elongation at break is 530%. In terms of optical properties, α nucleating agent CH-6N has the best modification effect, and after the addition of 0.1% CH-6N, the yellow index of polypropylene is only 0.46. The combination of α nucleating agent and β nucleating agent can not only improve the toughness of polypropylene, but also improve its rigidity, and achieve the balance of rigidity-toughness. The compound modification effect of 0.1% CH-6N and 0.1% TMB-5 is good, and the impact strength of polypropylene is 5.5 kJ/m², the bending modulus is 2 140 MPa, and the tensile strength is 41.1 MPa. [ABSTRACT FROM AUTHOR]

Using benzoyl hydrazide and benzoyl chloride with different end-capping structures, three kinds of organic hydrazide nucleating agents, 1, 4-dibenzoyl p-phenylhydrazide (BTAD), 1, 4-bis(4-methylbenzoyl) p-phenylhydrazide (BTAD-CH3) and 1, 4-bis(4-tert-butylbenzoyl) p-phenylhydrazide [BTAD-(CH3)3], were prepared by coupling reaction. Their effects on crystallization behavior, mechanical properties and heat resistance of polyethylene terephthalate (PET) were also discussed. The results show that when the addition of nuclearing agents BTAD, BTAD-CH3 and BTAD-(CH3)3 are 1.0%, the crystallization peak temperature (Tc) of PET is increased by 51, 53, 56 °C, respectively, and the crystallinity (Xc) is increased from 18.1% to 26.3%, 26.9% and 29.7%, respectively. BTAD-(CH3)3 can further refine the size of PET spherulite and show better nucleation effect. When BTAD-(CH3)3 is added at 2.0%, the bending modulus of PET composites is increased to 2 675 MPa, with an increase of 22%, and the Vicat softening temperature and thermal deformation temperature are increased by 60 °C and 10 °C, respectively, compared with PET, and the mechanical properties and heat resistance are improved. [ABSTRACT FROM AUTHOR]

Biodegradable poly(butanediol succinate-co-L-lactate) (PBSLA) copolyesters were modified using organic modified montmorillonite (OMMT) and Mica layered silicate inorganic fillers in solution blending method. The thermal properties, crystallization properties, barrier properties and mechanical properties of PBSLA/laminosilicate composites were studied. The results show that when the mass fraction of the layered silicate filler is less than 4%, its dispersion in copolyester matrix is good. The inorganic filler acts as the heterogeneous nucleating agent, which improves the crystallization property of the matrix material to some extent. In terms of mechanical properties, a certain amount of layered silicate filler plays an enhanced role. When the addition of OMMT and Mica is 2% and 3%, respectively, the tensile strength of the composites reache the maximum value, and can be increased by 18.4% and 34.4% compared with PBSLA, respectively. The layered structure effectively increases the zigzag path of gas molecules. With the increase of filler content, the water vapor and oxygen permeability coefficients of the composite show a downward trend. Therefore, the addition of layered silicate fillers can improve the barrier properties of PBSLA matrix materials. [ABSTRACT FROM AUTHOR]