The Effect of Nanoclay on the Rheological Properties of Polylactic Acid/Polyhydroxybutyrate-Valerate Blends

2015 ◽  
Author(s):  
Haibin Zhao ◽  
Xiangfang Peng
Keyword(s):  
Injection Molding ◽  
Polylactic Acid ◽  
Strong Interaction ◽  
Rheological Behavior ◽  
Full Range ◽  
Complex Viscosity ◽  
Polymer Chains ◽  
Wide Range ◽  
Strong Shear ◽  
Microcellular Injection Molding

In this article, the effects of nanoclay (CN) on the rheological behavior of polylactic acid (PLA)/polyhydroxybutyrate–valerate (PHBV) blends was investigated. The rheological behavior of PLA/PHBV blends showed a Newtonian plateau that converted to strong shear thinning behavior over the full range of frequency by the incorporation of nanoclay. The results indicate that the storage modulus and complex viscosity of PLA/PHBV blends were sensitive to nanofillers. An obvious pseudo-solid-like behavior over a wide range of frequency in PLA/PHBV/CN nanocomposites showed that the strong interaction between the PLA/PHBV blend and the nanoclay restricted the relaxation process of the polymer chains. Therefore, the PLA/PHBV/CN nanocomposites possess a higher modulus and greater melt strength, which are desirable for creating an improved foamed structure when manufactured via microcellular injection molding.

The Major Transitions in Evolution

1997 ◽  
Author(s):  
John Maynard Smith ◽  
Eors Szathmary
Keyword(s):  
Full Range ◽  
Evolution Of Cooperation ◽  
Major Transitions ◽  
Insect Societies ◽  
Wide Range ◽  
Major Transition ◽  
Life Itself ◽  
History Of ◽  
Emergence Of Cooperation ◽  
Multicellular Organisms

Over the history of life there have been several major changes in the way genetic information is organized and transmitted from one generation to the next. These transitions include the origin of life itself, the first eukaryotic cells, reproduction by sexual means, the appearance of multicellular plants and animals, the emergence of cooperation and of animal societies, and the unique language ability of humans. This ambitious book provides the first unified discussion of the full range of these transitions. The authors highlight the similarities between different transitions--between the union of replicating molecules to form chromosomes and of cells to form multicellular organisms, for example--and show how understanding one transition sheds light on others. They trace a common theme throughout the history of evolution: after a major transition some entities lose the ability to replicate independently, becoming able to reproduce only as part of a larger whole. The authors investigate this pattern and why selection between entities at a lower level does not disrupt selection at more complex levels. Their explanation encompasses a compelling theory of the evolution of cooperation at all levels of complexity. Engagingly written and filled with numerous illustrations, this book can be read with enjoyment by anyone with an undergraduate training in biology. It is ideal for advanced discussion groups on evolution and includes accessible discussions of a wide range of topics, from molecular biology and linguistics to insect societies.

Oxford Studies in Medieval Philosophy Volume 7

2019 ◽  
Keyword(s):  
Late Antiquity ◽  
Full Range ◽  
Current Work ◽  
Medieval Philosophy ◽  
Original Essays ◽  
Wide Range ◽  
Extended Review

Oxford Studies in Medieval Philosophy annually collects the best current work in the field of medieval philosophy. The various volumes print original essays, reviews, critical discussions, and editions of texts. The aim is to contribute to an understanding of the full range of themes and problems in all aspects of the field, from late antiquity into the Renaissance, and extending over the Jewish, Islamic, and Christian traditions. Volume 6 includes work on a wide range of topics, including Davlat Dadikhuda on Avicenna, Christopher Martin on Abelard’s ontology, Jeremy Skrzypek and Gloria Frost on Aquinas’s ontology, Jean‐Luc Solère on instrumental causality, Peter John Hartman on Durand of St.‐Pourçain, and Kamil Majcherek on Chatton’s rejection of final causality. The volume also includes an extended review of Thomas Williams of a new book on Aquinas’s ethics by Colleen McCluskey.

scholarly journals Impact of Powder Properties on the Rheological Behavior of Excipients

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1198
Author(s):  
Pauline H. M. Janssen ◽  
Sébastien Depaifve ◽  
Aurélien Neveu ◽  
Filip Francqui ◽  
Bastiaan H. J. Dickhoff
Keyword(s):  
Flow Field ◽  
Rheological Behavior ◽  
Quality By Design ◽  
Filling Process ◽  
Dynamic Flow ◽  
Die Filling ◽  
Flow Characterization ◽  
Wide Range ◽  
Powder Properties ◽  
The Impact

With the emergence of quality by design in the pharmaceutical industry, it becomes imperative to gain a deeper mechanistic understanding of factors impacting the flow of a formulation into tableting dies. Many flow characterization techniques are present, but so far only a few have shown to mimic the die filling process successfully. One of the challenges in mimicking the die filling process is the impact of rheological powder behavior as a result of differences in flow field in the feeding frame. In the current study, the rheological behavior was investigated for a wide range of excipients with a wide range of material properties. A new parameter for rheological behavior was introduced, which is a measure for the change in dynamic cohesive index upon changes in flow field. Particle size distribution was identified as a main contributing factor to the rheological behavior of powders. The presence of fines between larger particles turned out to reduce the rheological index, which the authors explain by improved particle separation at more dynamic flow fields. This study also revealed that obtained insights on rheological behavior can be used to optimize agitator settings in a tableting machine.

scholarly journals Energy and Eco-Impact Evaluation of Fused Deposition Modeling and Injection Molding of Polylactic Acid

2021 ◽  
Vol 13 (4) ◽  
pp. 1875
Author(s):  
Emmanuel Ugo Enemuoh ◽  
Venkata Gireesh Menta ◽  
Abdulaziz Abutunis ◽  
Sean O’Brien ◽  
Labiba Imtiaz Kaya ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Injection Molding ◽  
Polylactic Acid ◽  
Fused Deposition Modeling ◽  
Plastic Injection Molding ◽  
Measurement Models ◽  
Fused Deposition ◽  
Dog Bone ◽  
Deposition Modeling ◽  
Plastic Injection

There is limited knowledge about energy and carbon emission performance comparison between additive fused deposition modeling (FDM) and consolidation plastic injection molding (PIM) forming techniques, despite their recent high industrial applications such as tools and fixtures. In this study, developed empirical models focus on the production phase of the polylactic acid (PLA) thermoplastic polyester life cycle while using FDM and PIM processes to produce American Society for Testing and Materials (ASTM) D638 Type IV dog bone samples to compare their energy consumption and eco-impact. It was established that energy consumption by the FDM layer creation phase dominated the filament extrusion and PLA pellet production phases, with, overwhelmingly, 99% of the total energy consumption in the three production phases combined. During FDM PLA production, about 95.5% of energy consumption was seen during actual FDM part building. This means that the FDM process parameters such as infill percentage, layer thickness, and printing speed can be optimized to significantly improve the energy consumption of the FDM process. Furthermore, plastic injection molding consumed about 38.2% less energy and produced less carbon emissions per one kilogram of PLA formed parts compared to the FDM process. The developed functional unit measurement models can be employed in setting sustainable manufacturing goals for PLA production.

Effect of Zeolite Addition on the Properties of Bioplastic Composites of Carboxymethyl Cellulose-Urea

2019 ◽  
Vol 948 ◽  
pp. 175-180 ◽  
Author(s):  
Indriana Kartini ◽  
Kukuh Handaru Iskandar ◽  
Chotimah ◽  
Eko Sri Kunarti ◽  
Rochmadi
Keyword(s):  
Tensile Strength ◽  
Hydrogen Bonds ◽  
Strong Interaction ◽  
Carboxymethyl Cellulose ◽  
Slow Release ◽  
Polymer Chains ◽  
Solvent Casting ◽  
Ammonium Ions ◽  
Petri Dishes ◽  
Urea Inclusion

Bioplastic composites based on carboxymethyl cellulose (CMC) and urea have been successfully synthesised at various amount of zeolites. Urea inclusion into the bioplastics was supposed to result in nitrogen slow-release composites. The bioplastic composites were prepared by solvent casting the precursor gel containing 0.5 % (w/w) urea in CMC in the petri dishes. The zeolites content was varied at 0.1, 0.5, 1.0, 2.0, and 3.0 % (w/w to CMC). It showed that the addition of zeolites to the bioplastic composites up to 0.5% increased their tensile strength. More addition of zeolites decreased the strain of the bioplastic composite. It could be due to the formation of hydrogen bonds between CMC and zeolites. The amount of urea absorbed in the bioplastics increased as the amount of zeolites increases. It is possibly to be due to the strong interaction between urea and zeolites. The ammonium ions may interact with interchangeable cations in the zeolite. This interaction will also extend the time for the bioplastics to biodegrade. The presence of zeolites in the CMC polymer chains is useful to give nitrogen slow-release composites.

Compressor Performance and Operability in Swirl Distortion

2010 ◽  
Author(s):  
Yogi Sheoran ◽  
Bruce Bouldin ◽  
P. Murali Krishnan
Keyword(s):  
Gas Turbine ◽  
Complex Geometry ◽  
Full Range ◽  
Axial Compressor ◽  
Cfd Model ◽  
Generator System ◽  
Sliding Mesh ◽  
Wide Range ◽  
Compressor Performance ◽  
The Impact

Inlet swirl distortion has become a major area of concern in the gas turbine engine community. Gas turbine engines are increasingly installed with more complicated and tortuous inlet systems, like those found on embedded installations on Unmanned Aerial Vehicles (UAVs). These inlet systems can produce complex swirl patterns in addition to total pressure distortion. The effect of swirl distortion on engine or compressor performance and operability must be evaluated. The gas turbine community is developing methodologies to measure and characterize swirl distortion. There is a strong need to develop a database containing the impact of a range of swirl distortion patterns on a compressor performance and operability. A recent paper presented by the authors described a versatile swirl distortion generator system that produced a wide range of swirl distortion patterns of a prescribed strength, including bulk swirl, twin swirl and offset swirl. The design of these swirl generators greatly improved the understanding of the formation of swirl. The next step of this process is to understand the effect of swirl on compressor performance. A previously published paper by the authors used parallel compressor analysis to map out different speed lines that resulted from different types of swirl distortion. For the study described in this paper, a computational fluid dynamics (CFD) model is used to couple upstream swirl generator geometry to a single stage of an axial compressor in order to generate a family of compressor speed lines. The complex geometry of the analyzed swirl generators requires that the full 360° compressor be included in the CFD model. A full compressor can be modeled several ways in a CFD analysis, including sliding mesh and frozen rotor techniques. For a single operating condition, a study was conducted using both of these techniques to determine the best method given the large size of the CFD model and the number of data points that needed to be run to generate speed lines. This study compared the CFD results for the undistorted compressor at 100% speed to comparable test data. Results of this study indicated that the frozen rotor approach provided just as accurate results as the sliding mesh but with a greatly reduced cycle time. Once the CFD approach was calibrated, the same techniques were used to determine compressor performance and operability when a full range of swirl distortion patterns were generated by upstream swirl generators. The compressor speed line shift due to co-rotating and counter-rotating bulk swirl resulted in a predictable performance and operability shift. Of particular importance is the compressor performance and operability resulting from an exposure to a set of paired swirl distortions. The CFD generated speed lines follow similar trends to those produced by parallel compressor analysis.

scholarly journals State of the Science in Dried Blood Spots

2018 ◽  
Vol 64 (4) ◽  
pp. 656-679 ◽  
Author(s):  
Jeffrey D Freeman ◽  
Lori M Rosman ◽  
Jeremy D Ratcliff ◽  
Paul T Strickland ◽  
David R Graham ◽  
...  
Keyword(s):  
Systematic Approach ◽  
Full Range ◽  
Dried Blood Spots ◽  
Blood Spots ◽  
Highly Sensitive ◽  
Wide Range ◽  
Potential Applications ◽  
Review Of Reviews ◽  
Near Term ◽  
State Of The Science

Abstract BACKGROUND Advancements in the quality and availability of highly sensitive analytical instrumentation and methodologies have led to increased interest in the use of microsamples. Among microsamples, dried blood spots (DBS) are the most well-known. Although there have been a variety of review papers published on DBS, there has been no attempt at describing the full range of analytes measurable in DBS, or any systematic approach published for characterizing the strengths and weaknesses associated with adoption of DBS analyses. CONTENT A scoping review of reviews methodology was used for characterizing the state of the science in DBS. We identified 2018 analytes measured in DBS and found every common analytic method applied to traditional liquid samples had been applied to DBS samples. Analytes covered a broad range of biomarkers that included genes, transcripts, proteins, and metabolites. Strengths of DBS enable its application in most clinical and laboratory settings, and the removal of phlebotomy and the need for refrigeration have expanded biosampling to hard-to-reach and vulnerable populations. Weaknesses may limit adoption in the near term because DBS is a nontraditional sample often requiring conversion of measurements to plasma or serum values. Opportunities presented by novel methodologies may obviate many of the current limitations, but threats around the ethical use of residual samples must be considered by potential adopters. SUMMARY DBS provide a wide range of potential applications that extend beyond the reach of traditional samples. Current limitations are serious but not intractable. Technological advancements will likely continue to minimize constraints around DBS adoption.

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