scholarly journals Composites Based Green Poly(L-Lactic Acid) and Dioctyl Phthalate: Preparation and Performance

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Yan-Hua Cai ◽  
Li-Sha Zhao ◽  
Yan-Hua Zhang
Keyword(s):  
Lactic Acid ◽  
Mechanical Performance ◽  
Dioctyl Phthalate ◽  
X Ray Diffraction ◽  
Elongation At Break ◽  
X Ray ◽  
Melt Index ◽  
Neat Plla ◽  
Tensile Tester ◽  
And Performance

The effects of dioctyl phthalate (DOP) on performances of poly(L-lactic acid) (PLLA) were investigated in detail using optical depolarizer, X-ray diffraction, melt index instrument, and electronic tensile tester. Crystallization performance showed that the half time of overall PLLA crystallizationt1/2decreased with increasing of crystallization temperature (80°C to 105°C), but thet1/2of PLLA/DOP composites firstly decreased and then increased, andt1/2of PLLA/DOP exhibited minimum value at 85°C. Compared to neat PLLA, 20%DOP made thet1/2decrease from 7258.3 s to 265.4 s. X-ray diffraction experiment further confirmed that DOP could accelerate the crystallization of PLLA. The fluidity of PLLA/DOP composites indicated that the melt mass flow rate firstly decreased and then greatly increased with increasing of DOP content. The mechanical performance showed that DOP could improve the general mechanical performance, and the elongation at break of PLLA/25%DOP was about 30 times longer than that of neat PLLA.

scholarly journals Preparation and Physical Performance of Green Poly(L-lactic acid) Composition by Blending with Starch

2017 ◽  
Vol 11 (1) ◽  
pp. 22-28
Author(s):  
Yan-Hua Cai ◽  
Qian Zheng ◽  
Wen-Jiang Guo
Keyword(s):  
Lactic Acid ◽  
Crystallization Rate ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Temperature Zone ◽  
X Ray ◽  
Melt Index ◽  
Neat Plla ◽  
Maximum Value ◽  
Green Polymer

Objective: To develop more green polymer composites and further know the performance of green composites, the composites based on green poly(L-lactic acid) (PLLA) and starch were fabricated by a counter-rotating mixer. And effect of starch on the fluidity and nucleating performance of PLLA was investigated using melt index instrument, optical depolarizer and wide angle X-ray diffraction instrument, respectively. Method and Conclusion: The fluidity of PLLA/starch composites showed that, compared to the neat PLLA, the addition of starch made the fluidity of PLLA increase significantly and the melt mass flow rate of PLLA/5%starch sample had the maximum value 13.36 g/10min. In addition, the introduction of starch could also increase the crystallization rate of PLLA through isothermal crystallization measurement and x-ray diffraction analysis, the maximum value of crystallization rate of PLLA/starch composites appeared in low crystallization temperature zone, and 10 wt% starch could make the t1/2 of PLLA decrease from 3999.4s to 421.4s.

Stereocomplex formation in injection-molded poly(L-lactic acid)/poly(D-lactic acid) blends

2019 ◽  
Vol 39 (3) ◽  
pp. 279-286
Author(s):  
Yottha Srithep ◽  
Dutchanee Pholhan ◽  
Lih-Sheng Turng ◽  
Thiptida Akkaprasa
Keyword(s):  
Lactic Acid ◽  
Injection Molding ◽  
Melting Peak ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Neat Plla ◽  
Stereocomplex Formation ◽  
Injection Molded ◽  
Complex Crystal

AbstractPoly(L-lactic acid)/poly(D-lactic acid) (PLLA/PDLA) blends were prepared by hand mixing, followed by injection molding at 210°C to produce tensile specimens. Thermal properties, crystalline structure, and mechanical properties were measured by differential scanning calorimetry (DSC), thermogravimetric analysis, wide-angle X-ray diffraction (XRD), and tensile testing. From the DSC tests of blends ranging from 10% to 30% PDLA in PLLA, the PDLA melting peak was absent and was replaced by a stereocomplex melting peak at 210°C, which was ~50°C higher than that for neat PLLA or PDLA. The reverse blending of PLLA into PDLA showed a similar behavior. Surprisingly, three melting peaks (for PLLA, PDLA, and the complex crystal) appeared in the 1:1 PLLA:PDLA pellet blends. However, the PLLA and PDLA powders (ground to less than 200 μm) and hand mixed, prior to injection molding, showed only small amounts of homocrystals and much higher fractions of stereocomplex crystals (18–44%). Compared to the hand mixed un-ground pellets, molded specimens from the PLLA and PDLA powders also exhibited higher tensile strengths (33–48 MPa) and moduli (1100–1250 MPa). Moreover, the stereocomplex formation was found to enhance the thermal stability compared with those of the pure PLLA and PDLA.

Preparation and Characterization of Poly(Lactic Acid) / Montmorillonite Nanocomposites via a Masterbatching Method

2011 ◽  
Vol 335-336 ◽  
pp. 1493-1498 ◽  
Author(s):  
Ying Ning He ◽  
Kai Guo ◽  
Jin Zhou Chen ◽  
Ming Jun Niu ◽  
Wan Jie Wang ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Layer Structure ◽  
Poly Lactic Acid ◽  
Index Test ◽  
X Ray Diffraction ◽  
Elongation At Break ◽  
Melt Index ◽  
Transmission Electron ◽  
Average Grain Size

To improve the toughness of PLA, Poly(lactic acid) (PLA)/organically modified montmorillonite (OMMT) nanocomposites were prepared via a masterbatching method. Melt index test indicated that nanocomposites had a better processability compared with pure PLA. When the loading of MMT was 3 wt%, the nanocomposites showed the maximum tensile strength (63.81MPa), and its elongation at break increased by 2.6 times compared with pure PLA. The thermal properties and crystallization behaviors of pure PLA and nanocomposites were studied by Differential Scanning Calorimeter (DSC). With OMMT loaded, the crystallinity of PLA in nanocomposites increased from 7.34% to 16.66%. The microstructure and morphology were studied by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). It revealed that the average grain size reduced compared with pure PLA, and most of layer structure of OMMT was exfoliated.

scholarly journals (S)-1-(Ethoxycarbonyl)ethyl(2R,5S)-2,5-dimethyl-1,3-dioxolan-4-one-2-carboxylate

Molbank ◽  
10.3390/m1178 ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. M1178
Author(s):  
R. Aitken ◽  
Oliver Haslett ◽  
Alexandra Slawin
Keyword(s):  
Lactic Acid ◽  
Title Compound ◽  
Ethyl Pyruvate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Methods

The title compound was obtained in low yield in the condensation of ethyl pyruvate and lactic acid. Its structure is determined by NMR methods and x-ray diffraction and the mechanism for formation of this 1:2 adduct from the initial 1:1 adduct is considered.

scholarly journals Functional Bionanocomposite Fibers of Chitosan Filled with Cellulose Nanofibers Obtained by Gel Spinning

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1563
Author(s):  
Sofia Marquez-Bravo ◽  
Ingo Doench ◽  
Pamela Molina ◽  
Flor Estefany Bentley ◽  
Arnaud Kamdem Tamo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Cellulose Nanofibers ◽  
Microstructural Characterization ◽  
Fiber Formation ◽  
Fiber Direction ◽  
Composite Fibers ◽  
X Ray Diffraction ◽  
Gel Spinning ◽  
X Ray

Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anhydrous chitosan allomorph. The spinning process combining acidic–basic–neutralization–stretching–drying steps allowed obtaining CHI/CNF composite fibers of high crystallinity, with enhanced effect at incorporating the CNFs. Chitosan crystallization seems to be promoted by the presence of cellulose nanofibers, serving as nucleation sites for the growing of CHI crystals. Moreover, the preferential orientation of both CNFs and CHI crystals along the spun fiber direction was revealed in the two-dimensional X-ray diffraction patterns. By increasing the CNF amount up to the optimum concentration of 0.4 wt % in the viscous CHI/CNF collodion, Young’s modulus of the spun fibers significantly increased up to 8 GPa. Similarly, the stress at break and the yield stress drastically increased from 115 to 163 MPa, and from 67 to 119 MPa, respectively, by adding only 0.4 wt % of CNFs into a collodion solution containing 4 wt % of chitosan. The toughness of the CHI-based fibers thereby increased from 5 to 9 MJ.m−3. For higher CNFs contents like 0.5 wt %, the high mechanical performance of the CHI/CNF composite fibers was still observed, but with a slight worsening of the mechanical parameters, which may be related to a minor disruption of the CHI matrix hydrogel network constituting the collodion and gel fiber, as precursor state for the dry fiber formation. Finally, the rheological behavior observed for the different CHI/CNF viscous collodions and the obtained structural, thermal and mechanical properties results revealed an optimum matrix/filler compatibility and interface when adding 0.4 wt % of nanofibrillated cellulose (CNF) into 4 wt % CHI formulations, yielding functional bionanocomposite fibers of outstanding mechanical properties.

scholarly journals In situ observation of phase changes of a silica-supported cobalt catalyst for the Fischer–Tropsch process by the development of a synchrotron-compatible in situ/operando powder X-ray diffraction cell

2018 ◽  
Vol 25 (6) ◽  
pp. 1673-1682 ◽  
Author(s):  
Adam S. Hoffman ◽  
Joseph A. Singh ◽  
Stacey F. Bent ◽  
Simon R. Bare
Keyword(s):  
High Pressure ◽  
Elevated Pressure ◽  
Phase Changes ◽  
In Situ Observation ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
X Ray ◽  
And Performance ◽  
Co Nanoparticles

In situ characterization of catalysts gives direct insight into the working state of the material. Here, the design and performance characteristics of a universal in situ synchrotron-compatible X-ray diffraction cell capable of operation at high temperature and high pressure, 1373 K, and 35 bar, respectively, are reported. Its performance is demonstrated by characterizing a cobalt-based catalyst used in a prototypical high-pressure catalytic reaction, the Fischer–Tropsch synthesis, using X-ray diffraction. Cobalt nanoparticles supported on silica were studied in situ during Fischer–Tropsch catalysis using syngas, H2 and CO, at 723 K and 20 bar. Post reaction, the Co nanoparticles were carburized at elevated pressure, demonstrating an increased rate of carburization compared with atmospheric studies.

scholarly journals Effect of Film Formation Method and Annealing on Crystallinity of Poly(L-Lactic Acid) Films

2011 ◽  
Author(s):  
Shan-Ting Hsu ◽  
Y. Lawrence Yao
Keyword(s):  
Drug Delivery ◽  
Lactic Acid ◽  
Film Formation ◽  
Solvent Casting ◽  
Crystalline Morphology ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lamellar Structures ◽  
Coating Methods ◽  
Formation Method

Poly(L-lactic acid) (PLLA) has been shown to have potential medical usage such as in drug delivery because it can degrade into bioabsorbable products in physiological environments, and its degradation is affected by crystallinity. In this paper, the effect of film formation method and annealing on the crystallinity of PLLA are investigated. The films are made through solvent casting and spin coating methods, and subsequent annealing is conducted. The resulting crystalline morphology, structure, conformation, and intermolecular interaction are examined using optical microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It is observed that solvent casting produces category 1 spherulites while annealed spin coated films leads to spherulites of category 2. Distinct lamellar structures and intermolecular interactions in the two kinds of films have been shown. The results enable better understanding of the crystallinity in PLLA, which is essential for its drug delivery application.

scholarly journals Design and Evaluation of an Ultrahigh-Strength Coral Aggregate Concrete for Maritime and Reef Engineering

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5871
Author(s):  
Jinming Liu ◽  
Boyu Ju ◽  
Wei Xie ◽  
Huang Yu ◽  
Haiying Xiao ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Autogenous Shrinkage ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
X Ray ◽  
Ultrahigh Strength ◽  
Marine Concrete ◽  
Marine Engineering ◽  
Reactive Powder ◽  
Economical Alternative

In this paper, an ultrahigh-strength marine concrete containing coral aggregates is developed. Concrete fabricated from marine sources is considered an effective and economical alternative for marine engineering and the construction of remote islands. To protect sea coral ecosystems, the coral aggregates used for construction are only efflorescent coral debris. To achieve the expected mechanical performance from the studied concrete, an optimal mixture design is conducted to determine the optimal proportions of components, in order to optimize the compressive strength. The mechanical properties and the autogenous shrinkage, as well as the heat flow of early hydration reactions, are measured. The hydration products fill up the pores of coral aggregates, endowing our concrete with flowability and self-compacting ability. The phases in the marine concrete are identified via X-ray diffraction analysis. The 28-day compressive and flexural strength of the developed marine concrete achieve 116.76 MPa and 18.24 MPa, respectively. On account of the lower cement content and the internal curing provided by coral aggregates, the volume change resulting from autogenous shrinkage is only 63.11% of that of ordinary reactive powder concrete.

scholarly journals PolyProc: A Modular Processing Pipeline for X-ray Diffraction Tomography

2019 ◽  
Vol 8 (3) ◽  
pp. 388-399 ◽  
Author(s):  
Jiwoong Kang ◽  
Ning Lu ◽  
Issac Loo ◽  
Nancy Senabulya ◽  
Ashwin J. Shahani
Keyword(s):  
Three Dimensional ◽  
Valuable Insight ◽  
Diffraction Tomography ◽  
Computationally Efficient ◽  
X Ray Diffraction ◽  
Orientation Data ◽  
Bulk Specimen ◽  
X Ray ◽  
Data Alignment ◽  
And Performance

Abstract Direct imaging of three-dimensional microstructure via X-ray diffraction-based techniques gives valuable insight into the crystallographic features that influence materials properties and performance. For instance, X-ray diffraction tomography provides information on grain orientation, position, size, and shape in a bulk specimen. As such techniques become more accessible to researchers, demands are placed on processing the datasets that are inherently “noisy,” multi-dimensional, and multimodal. To fulfill this need, we have developed a one-of-a-kind function package, PolyProc, that is compatible with a range of data shapes, from planar sections to time-evolving and three-dimensional orientation data. Our package comprises functions to import, filter, analyze, and visualize the reconstructed grain maps. To accelerate the computations in our pipeline, we harness computationally efficient approaches: for instance, data alignment is done via genetic optimization; grain tracking through the Hungarian method; and feature-to-feature correlation through k-nearest neighbors algorithm. As a proof-of-concept, we test our approach in characterizing the grain texture, topology, and evolution in a polycrystalline Al–Cu alloy undergoing coarsening.

scholarly journals Mechanism and Performance of the SCR of NO with NH3 over Sulfated Sintered Ore Catalyst

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 90 ◽  
Author(s):  
Wangsheng Chen ◽  
Fali Hu ◽  
Linbo Qin ◽  
Jun Han ◽  
Bo Zhao ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Space Velocity ◽  
Acid Sites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffuse Reflectance Infrared Spectroscopy ◽  
And Performance ◽  
Diffuse Reflectance Infrared

A sulfated sintered ore catalyst (SSOC) was prepared to improve the denitration performance of the sintered ore catalyst (SOC). The catalysts were characterized by X-ray Fluorescence Spectrometry (XRF), Brunauer–Emmett–Teller (BET) analyzer, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared spectroscopy (DRIFTS) to understand the NH3-selective catalytic reduction (SCR) reaction mechanism. Moreover, the denitration performance and stability of SSOC were also investigated. The experimental results indicated that there were more Brønsted acid sites at the surface of SSOC after the treatment by sulfuric acid, which lead to the enhancement of the adsorption capacity of NH3 and NO. Meanwhile, Lewis acid sites were also observed at the SSOC surface. The reaction between −NH2, NH 4 + and NO (E-R mechanism) and the reaction of the coordinated ammonia with the adsorbed NO2 (L-H mechanism) were attributed to NOx reduction. The maximum denitration efficiency over the SSOC, which was about 92%, occurred at 300 °C, with a 1.0 NH3/NO ratio, and 5000 h−1 gas hourly space velocity (GHSV).

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