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Showing 1 to 18 of 18 for “"semi-crystalline polymers"”.
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Multiscale Modeling of the Deformation of Semi-Crystalline Polymers
The mechanical and physical properties of polymers are determined primarily by the underlying nano-scale structures and characteristics such as entanglements, crystallites, and molecular orientation. These structures evolve in complex manners during the processing of polymers into useful articles. …
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A model treating tensile deformation of semi-crystalline polymers
Semi-crystalline polymeric solids are usually in a state being built up of crystallites and an amorphous phase. A complex structure changing occurs in the polymer materials during the extension process. Uniaxial stretching of a semi-crystalline polymer sample causes the initial spherulitic …
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Thermoelectric and Charge Transport in Doped Semi-Crystalline Polymers
In recent years, organic semiconductors (OSCs) have generated many research interests from both academia and industry due to the exotic properties and potential applications in flexible displays, light-emitting diodes, solar cells as well as thermoelectrics. Compared with their inorganic …
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Process/Structure/Property Relationships of Semi-Crystalline Polymers in Material Extrusion Additive Manufacturing
… in most typical MEX processes, only amorphous polymers are being used as feedstock material owing to their smaller dimensional shrinkage during cooling and well-stablished process/structure/property (P/S/P) relationship. Semi-crystalline polymers, with their crystalline nature, possess unique …
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Determining the constants for an analyzing the predictive capabilities of a gas sorption model for semi-crystalline polymers
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992.
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Application of Diagnostic Methods to Assess Ageing Processes in Polymers
… to the understanding and assessment of ageing in semi-crystalline polymers through destructive and non-destructive tests, and to study the feasibility of acoustic means to be utilized for future age-monitoring systems. This called for a thorough evaluation of the governing material properties that …
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Relationships between micromorphology and impact properties of injection moulded isotactic polypropylene
… and properties of injection moulded semi-crystalline polymers can be significantly modified by changes in the injection moulding parameters and the design of mould. Further modifications to the microstructure and properties occur following the incorporation of additives into a …
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NMR studies of conduction mechanisms in electrolyte materials for fuel cells
… polyaniline are examined. Both amorphous and semi-crystalline polymers are analysed by 19F and 1H NMR relaxometery and show similar dependence on the dimensionality of charge carriers through the heterogeneous regions of the material. The dimensionality of this motion is shown to be dependent …
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Modeling Heat Transfer and Densification during Laser Sintering of Viscoelastic Polymers
… relationships for LS of viscoelastic polymers. A one-dimensional closed-form analytical solution for heating of a semi-infinite body, with a convective boundary condition, by a moving surface heat flux was developed. This solution approximates the shape of the Gaussian energy …
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Polymer Crystallization: Micro- and Nano- Filler Effects on Isotactic Polypropylene
… of the application field. Since the features of semi-crystalline polymers depend on the crystallinity degree and crystallite morphology, studies about the effects of fillers on the crystallization behavior of composites are of great interest. Nucleated crystallization has been the subject of …
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Designing Functionality into Step-Growth Polymers from Liquid Crystallinity to Additive Manufacturing
… of a wide range of industrially applicable polymers, such as polyesters and polysulfones. The choice of backbone and end group structure within these polymers drastically impacts the final material properties and processability emphasizing the necessity for thorough understanding of …
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Understanding Heterogeneous Nucleation Mechanisms in Polyolefins
… of polyolefins are among the most widely used semi-crystalline polymers in the modern world, with many of their desirable properties due to their microstructure formed during crystallization. While processing conditions have a large impact on crystallization, an additional tool is the use of …
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Hot-melt mixing of partially miscible active pharmaceutical ingredient-polymer mixtures
… to a great extent by converting drugs from crystalline to amorphous form. HME can be carried out at two process temperature regimes: one where T_{process} > T_m of the drug and the T_g of the polymer (or the T_m for the case of semi-crystalline polymers); the other at T_m > T_{process} > T_g …
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Crystallization Behavior, Tailored Microstructure, and Structure-Property Relationships of Poly(Ether Ketone Ketone) and Polyolefins
… and chemical properties of fast crystallizing polymers. The primary objectives were to 1) utilize advanced methodologies to accurately determine the fundamental thermodynamic value of equilibrium melting temperature (Tmo) for the semi-crystalline polymer poly(ether ketone ketone) (PEKK), 2) …
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Synthesis and Characterization of Wholly Aromatic Semicrystalline Polyimides Based Upon Bis(4-Aminophenoxy) Benzenes
Semicrystalline thermoplastic polyimides based upon bis(4-aminophenoxy)benzene and related "triphenyl ether" diamines were synthesized via the classical two step amic acid route. More specifically, polyimides were derived from para linked 1,4-bis(4-aminophenoxy)benzene, or TPEQ (triphenyl ether …
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Supramolecular polymer additives to improve the crystallization behavior and optical properties of polybutylene terephthalate and polyamides
… the property profile of commercial thermoplastic polymers. The physico chemical properties of semi crystalline polymers depend to a large extend on the crystal structure and spherulite size, which can be controlled by nucleating agents. These additives can increase the crystallization temperature …
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Additive manufacturing of polyolefins via powder bed fusion
… the molten polymer together to form each layer. Semi-crystalline polymers are the most common thermoplastics processed in this AM process and powder is heated during the printing process to retard crystallization in the material. When crystallization happens too rapidly, warpage of a layer, which …
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Property-Process-Property Relationships in Powder Bed Fusion Additive Manufacturing of Poly(phenylene sulfide): A Case Study Toward Predicting Printability from Polymer Properties
… be a suitable processing technique for all semi-crystalline polymers, the polyamide family currently occupies around 90% of the commercial market for polymer PBF. This commercial dominance of polyamides is mirrored in the focus of research publications. The lack of chemical variety in …