scholarly journals Comparative study of the effect of TiO2 and ZnO on the crystallization of PHB

2017 ◽  
Vol 22 (4) ◽  
Author(s):  
Nichollas Guimarães Jaques ◽  
Ingridy Dayane dos Santos Silva ◽  
Manoel da Cruz Barbosa Neto ◽  
Rayane Karoline Melo Diniz ◽  
Renate Maria Ramos Wellen ◽  
...  
Keyword(s):  
Crystallization Rate ◽  
Nucleating Agent ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Dsc Studies ◽  
Heating And Cooling ◽  
Internal Mixer ◽  
Zno And Tio2 Nanoparticles ◽  
Fractured Surface ◽  
Scanning Electron

ABSTRACT PHB/TiO2 and PHB/ZnO compounds were prepared in a laboratory internal mixer. Crystallization was investigated by differential scanning calorimetry (DSC) with heating and cooling rates ranging from 5 to 30 °C/min. Fractured surface of selected samples was analysed by scanning electron microscopy (SEM). From the SEM images, it was observed that ZnO and TiO2 nanoparticles were properly dispersed in the PHB matrix. DSC studies revealed that the addition of TiO2 and ZnO changed the temperature and crystallization rate but did not affect the total crystallinity significantly. In general, TiO2 behaved as nucleating agent greatly influencing the PHB crystallization.

Morphology and thermal properties of clay based biocomposites

2018 ◽  
Vol 38 (8) ◽  
pp. 785-793 ◽  
Author(s):  
Leila Bounabi ◽  
Naima Bouslah Mokhnachi ◽  
Amar Djadoun ◽  
Nabila Haddadine ◽  
Regis Barille
Keyword(s):  
Crystallization Rate ◽  
Layered Silicate ◽  
Nucleating Agent ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Low Weight ◽  
The Matrix ◽  
Poly Ethylene ◽  
Temperature Melting

Abstract Carboxymethylcellulose/poly(ethylene glycol) (CMC/PEG) blend and CMC/PEG/montmorillonite (MMT) nanocomposites were produced by the solvent casting method. The clay, a sodium MMT, was incorporated in the polymer matrix at low weight loadings (from 1 wt% to 7 wt%). The MMT dispersion in the matrix was evaluated by X-ray diffraction, which revealed an intercalated structure of the nanocomposites. Different levels of intercalation have been detected. The changes in morphology caused by the addition of layered silicate on CMC/PEG blend were investigated by scanning electron microscopy (SEM). The SEM images of CMC/PEG blend containing 5% of MMT displayed more homogenous morphology than CMC/PEG blend. The compatibilizing performance of the filler was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. The effect of the introduction of the clay on the crystallization temperature, melting temperature and crystallization degree of CMC/PEG revealed that clay behaved as a nucleating agent and enhanced the crystallization rate of PEG. Furthermore, it was demonstrated that the addition of a small percentage of montmorillonite (1%) was enough to improve the thermal stability of the nanocomposites.

Thermal properties of polybenzoxazine exhibiting improved toughness: Blending with cyclodextrin and its derivatives

2021 ◽  
pp. 095400832110130
Author(s):  
Hailong Li ◽  
Sipei Zhao ◽  
Li Pei ◽  
Zihe Qiao ◽  
Ding Han ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Hydrogen Bonds ◽  
High Performance ◽  
Practical Application ◽  
Scanning Calorimetry ◽  
Thermoset Resins ◽  
Chemical Structures ◽  
Microscopy Techniques ◽  
Fractured Surface ◽  
Scanning Electron

Polybenzoxazines are emerging as a class of high-performance thermoset polymers that can find their applications in various fields. However, its practical application is limited by its low toughness. The cyclic β-cyclodextrin and a newly synthesized derivative (β-cyclodextrin-MAH) were separately blended with benzoxazine to improve the toughness of polybenzoxazine. The results revealed that the maximum impact strength of the blend was 12.24 kJ·m−2 and 14.29 kJ·m−2 when 1 wt.% of β-Cyclodextrin and β-Cyclodextrin-MAH, respectively, were used. The strengths were 53% and 86% higher than that of pure polybenzoxazine. The curing reaction, possible chemical structures, and fractured surface were examined using differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques to understand the mechanism of generation of toughness. The results revealed that the sea-island structure and the presence of hydrogen bonds between polybenzoxazine and β-cyclodextrin and β-cyclodextrin-MAH resulted in the generation of toughness. Furthermore, the curves generated during thermogravimetric analysis did not significantly change, revealing the good thermal properties of the system. The phase-separated structure and the hydrogen bonds present in the system can be exploited to prepare synergistically tough polybenzoxazine exhibiting excellent thermal properties. This can be a potential way of modifying the thermoset resins.

PP/MWCNTs composites: Effects of length of MWCNTs on isothermal crystallization behaviors, crystalline structure, and thermal stability

2017 ◽  
Vol 52 (4) ◽  
pp. 503-517 ◽  
Author(s):  
Zheng-Ian Lin ◽  
Ching-Wen Lou ◽  
Yi-Jun Pan ◽  
Chien-Teng Hsieh ◽  
Chien-Lin Huang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Crystalline Structure ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Scanning Calorimetry ◽  
Crystallization Behaviors ◽  
Walled Carbon Nanotubes ◽  
Thermal Stability Of

This study adopts the melt compounding method to prepare /mutli-walled carbon nanotubes composites. The effects of different lengths of the mutli-walled carbon nanotubes on the isothermal crystallization behaviors, crystalline structure, and thermal stability of the polypropylene/mutli-walled carbon nanotubes composites are examined. The PLM results show that the combination of mutli-walled carbon nanotubes prevents the growth of polypropylene spherulites, and thus results in a small size of spherulites. The differential scanning calorimetry results show that the short (S-) or long (L-) mutli-walled carbon nanotubes can function as the nucleating agent of polypropylene, which accelerates the crystallization rate of polypropylene. Avrami theory analyses indicate that the addition of short-mutli-walled carbon nanotubes particularly provides polypropylene/mutli-walled carbon nanotubes composites with a high crystallization rate. The X-ray diffraction results show that the combination of mutli-walled carbon nanotubes does not pertain to the crystal structure. The TGA test results show that long-mutli-walled carbon nanotubes outperform short -mutli-walled carbon nanotubes in improving the thermal stability of polypropylene, and both can significantly improve it.

scholarly journals Effects of annealing parameters on phase, structure and thermochromic properties of VO2 (M) derived from nanostructured VO2(B)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hamdi Muhyuddin Barra ◽  
Soo Kien Chen ◽  
Nizam Tamchek ◽  
Zainal Abidin Talib ◽  
Oon Jew Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
X Ray ◽  
Thermogravimetric Analyzer ◽  
Different Temperatures ◽  
Thermochromic Properties ◽  
Scanning Electron

Abstract Synthesis of thermochromic VO2 (M) was successfully done by annealing hydrothermally-prepared VO2 (B) at different temperatures and times. Conversion of the metastable VO2 (B) to the thermochromic VO2 polymorph was studied using thermogravimetric analyzer (TGA) under N2 atmosphere. Moreover, the phase and morphology of the synthesized samples were studied using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively. Accordingly, the XRD scans of all the annealed samples exhibited the presence of monoclinic VO2 (M), while the FE-SEM images of the samples showed the formation of nanorods and nanospheres, particularly those heated at high temperatures (650 °C and 700 °C). Meanwhile, differential scanning calorimetry (DSC) was used to measure the phase transition temperature (τc), hysteresis, and enthalpy of the prepared VO2. Based on these results, all samples displayed a τc of about 66 °C. However, the hysteresis was high for the samples annealed at lower temperatures (550 °C and 600 °C), while the enthalpy was very low for samples heated at lower annealing time (1.5 h and 1 h). These findings showed that crystallinity and nanostructure formation affected the thermochromic properties of the samples. In particular, the sample annealed at 650 °C showed better crystallinity and improved thermochromic behavior.

Preparation and Characterization of Hydrogels Based on Chitsoan/Polyvinyl Alcohol Blends

2015 ◽  
Vol 1105 ◽  
pp. 203-207
Author(s):  
Mohammed Amine Zitouni ◽  
Sofia Borsali Kara Slimane
Keyword(s):  
Weight Ratio ◽  
Poly Vinyl Alcohol ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
Intermolecular Hydrogen Bonds ◽  
Sem Images ◽  
Structure Morphology ◽  
Ft Ir ◽  
Scanning Electron

In this study, a series of poly (vinyl alcohol) (PVA)/chitosan (CS) hydrogels with different weight ratio of PVA to CS were prepared by freezing-thawing (F-T) method. The structure, morphology, and crystallinity of hydrogels were investigated by Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). FTIR demonstrated the presence of strong intermolecular hydrogen bonds between CS and PVA molecules. SEM images showed that the higher the chitosan, the greater the porous size of the hydrogel and DSC confirmed that crystallinity is higher when PVA is more in hydrogel. The mechanical properties of these hydrogels were studied by rheometry. The study of swelling ability demonstrated that the hydrogel developed with PVA and Cs was more swellable than that with PVA only because of its cross-linking interaction with PVA.

Non-isothermal crystallization kinetics of poly (lactic acid)/graphene nanocomposites

2013 ◽  
Vol 33 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Yanhua Chen ◽  
Xiayin Yao ◽  
Qun Gu ◽  
Zhijuan Pan
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Graphene Nanocomposites ◽  
Solution Blending ◽  
Transmission Electron ◽  
Graphene Nanocomposite

Abstract Poly(lactic acid) (PLA)/graphene nanocomposites were prepared by solution blending and the dispersibility of graphene in the PLA matrix was examined by transmission electron microscopy (TEM). The non-isothermal crystallization behaviors of pure PLA and PLA/graphene nanocomposites from the melt were investigated by differential scanning calorimetry (DSC). The results showed that the graphene could play a role as a heterogeneous nucleating agent during the non-isothermal crystallizing process of PLA, and accelerate the crystallization rate. The non-isothermal crystallizing data were analyzed with the Avrami, Ozawa and Mo et al. models and the crystallization parameters of the samples were obtained. It is demonstrated that the combination of the Avrami and Ozawa models developed by Mo et al. was successful in describing the non-isothermal crystallization process for pure PLA and its nanocomposite. According to the Kissinger equation, the activation energies were found to be -154.3 and -179.5 kJ/mol for pure PLA and PLA/0.1 wt% graphene nanocomposite, respectively. Furthermore, the spherulite growth behavior was investigated by polarized optical microscopy (POM) and the results also supported the DSC data.

Structure and Performance of PP Porous Membrane Prepared with Adipic Acid and NA-40 as Nucleating Agent via TIPS

2016 ◽  
Vol 848 ◽  
pp. 733-737
Author(s):  
Hui Xia Xuan ◽  
Chun Ju He
Keyword(s):  
Adipic Acid ◽  
Water Flux ◽  
Nucleating Agent ◽  
Porous Membrane ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Thermally Induced ◽  
Cooling Temperature ◽  
And Performance

Polypropylene (PP) membranes were respectively prepared using adipic acid (APA) and Sorbitol (NA-40) as nucleating agent via thermally induced phase separation (TIPS) method. The effects of nucleating agent content and cooling temperature on the structure and performance of membrane were investigated using scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). WAXD spectrogram indicates that three kinds of α, β and γ-form crystal were formed in this preparation process and the relative content of β-form crystal in membrane prepared by NA-40 system is higher than that of membrane formed by adipic acid. SEM images show that porous structure and cellular structure were observed on the surface and cross-section of membrane. The water flux, tensile strength and elongation increase with the addition of nucleating agent content and decrease with cooling temperature rising. This paper aims to choose proper nucleating agent NA-40 and coagulation temperature to improve the properties of PP membranes.

The Mechanical Properties and Thermodynamic Study on Polypropylene/Talc Composites

2014 ◽  
Vol 915-916 ◽  
pp. 751-754
Author(s):  
Shao Hui Wang
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Tensile Strength ◽  
Electron Microscope ◽  
Impact Strength ◽  
Scanning Electron Microscope ◽  
Stearic Acid ◽  
Crystallization Rate ◽  
Scanning Calorimetry ◽  
Scanning Electron

The composites of PP/Talc modified by stearic acid were prepared and its effect on the properties of PP/Talc composites was investigated in this paper. The tensile strength and impact strength of PP/Talc composites increased about 15% and 30% compared with pure PP respectively. Based on surface analysis by scanning electron microscope (SEM), the Talcparticles buried well in PP matrix when the Talc was coated with the stearic acid. At the same time, it was found that Talc significantly increased the crystallization temperature and crystallization rate of PP by differential scanning calorimetry (DSC).

Plasticizer effect on melt blending of polylactide stereocomplex

e-Polymers ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 409-416 ◽  
Author(s):  
Yottha Srithep ◽  
Dutchanee Pholharn
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Crystallization Rate ◽  
Wide Angle ◽  
Melt Blending ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Neat Plla ◽  
Internal Mixer

AbstractPoly(l-lactide) (PLLA)/poly(d-lactide) (50/50) with plasticizer contents ranging from 2% to 16% w/w were prepared by melt blending using an internal mixer. Wide-angle X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry results confirmed that complete stereocomplex polylactide crystallites without any homocrystallites were produced. Compared to neat PLLA, the melting temperature of the stereocomplex polylactide and its plasticized samples was approximately 55°C higher. Higher plasticizer contents decreased glass transition temperature of the stereocomplex, which implied higher flexibility and enhanced the crystallization rate. However, the plasticizer in the stereocomplex reduced the thermal stability.

scholarly journals From Waste to Reuse: Manufacture of Ecological Composites Based on Biopolyethylene/Wood Powder with PE-g-MA and Macaíba oil

2021 ◽  
Author(s):  
Fabiano Santana da Silva ◽  
Carlos Bruno Barreto Luna ◽  
D D Siqueira ◽  
Eduardo Ferreira ◽  
Edcleide Maria Araujo
Keyword(s):  
Water Absorption ◽  
Interfacial Adhesion ◽  
Softening Temperature ◽  
Wood Powder ◽  
Temperature Differential ◽  
Scanning Calorimetry ◽  
Torque Rheometry ◽  
Heat Deflection Temperature ◽  
Internal Mixer ◽  
Scanning Electron

Abstract This work aimed to investigate the biopolyethylene (BioPE)/wood powder (WP) composites compatibilized with polyethylene-grafted maleic anhydride (PE-g-MA), using macaíba oil (OM) as a processing aid. The composites were prepared, initially, in an internal mixer and, later, the crushed flakes were molded by injection. Mechanical properties (impact, tensile, flexural and Shore D hardness), heat deflection temperature (HDT), Vicat softening temperature, differential scanning calorimetry (DSC), thermogravimetry (TG), water absorption, torque rheometry and scanning electron microscopy (SEM) were evaluated. The addition of 30% wood powder to the BioPE matrix increased the elastic modulus (tensile and flexural), Shore D hardness and heat deflection temperature (HDT), compared to neat BioPE. These properties were improved when 10% of the PE-g-MA compatibilizer was added, compared to neat BioPE and the non-compatibilized composite. There was a significant reduction in the torque of the composites with the addition of macaíba oil, indicating that it improved the processability. In addition, the incorporation of macaíba oil into the composites helped to reduce water absorption, as well as to increase impact strength. SEM micrographs illustrated a greater degree of interfacial adhesion when PE-g-MA and macaiba oil were added.

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