scholarly journals A Dyciandiamine-Based Methacrylate-Epoxy Dual-Cure Blend-System for Stereolithography

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3139
Author(s):  
Manuel Romeis ◽  
Dietmar Drummer
Keyword(s):  
Material Properties ◽  
Thermal Reaction ◽  
Thermal And Mechanical Properties ◽  
Active Components ◽  
Uv Curable ◽  
Additional Degree ◽  
Mechanical Measurements ◽  
Calorimetric Measurements ◽  
Epoxy Curing ◽  
Specific Material

In this research, an epoxy-based dual-cure system is developed and characterized for SLA additive manufacturing. Dual-cure systems consist of UV-curable acrylates and thermal active components. The second curing step offers an additional degree of freedom to design specific material properties. In this study, a blend of varying concentrations of an epoxy/curing agent mix, respectively, DGEBA, DICY and photocurable methacrylate, was used to create a material that is printable in the SLA process into a UV-cured or green part and subsequently thermally cured to achieve superior thermal and mechanical properties. Calorimetric measurements were performed to determine the reactivity of the thermal reaction at different concentrations of epoxy. The fully cured specimens were tested in mechanical and dynamic mechanical measurements, and the results showed a significant improvement in tensile stress and glass transition temperature with rising epoxy concentrations. Fractured surfaces from tensile testing were investigated to further characterize the failure of tested samples, and thermal degradation was determined in TGA measurements, which showed no significant changes with an increasing epoxy concentration.

Effects of infill patterns on the strength and stiffness of 3D printed topologically optimized geometries

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nadim S. Hmeidat ◽  
Bailey Brown ◽  
Xiu Jia ◽  
Natasha Vermaak ◽  
Brett Compton
Keyword(s):  
Material Properties ◽  
Failure Modes ◽  
Mechanical Anisotropy ◽  
Failure Behavior ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Orthotropic Composite ◽  
Material Extrusion ◽  
Specific Material ◽  
Strength And Stiffness

Purpose Mechanical anisotropy associated with material extrusion additive manufacturing (AM) complicates the design of complex structures. This study aims to focus on investigating the effects of design choices offered by material extrusion AM – namely, the choice of infill pattern – on the structural performance and optimality of a given optimized topology. Elucidation of these effects provides evidence that using design tools that incorporate anisotropic behavior is necessary for designing truly optimal structures for manufacturing via AM. Design/methodology/approach A benchmark topology optimization (TO) problem was solved for compliance minimization of a thick beam in three-point bending and the resulting geometry was printed using fused filament fabrication. The optimized geometry was printed using a variety of infill patterns and the strength, stiffness and failure behavior were analyzed and compared. The bending tests were accompanied by corresponding elastic finite element analyzes (FEA) in ABAQUS. The FEA used the material properties obtained during tensile and shear testing to define orthotropic composite plies and simulate individual printed layers in the physical specimens. Findings Experiments showed that stiffness varied by as much as 22% and failure load varied by as much as 426% between structures printed with different infill patterns. The observed failure modes were also highly dependent on infill patterns with failure propagating along with printed interfaces for all infill patterns that were consistent between layers. Elastic FEA using orthotropic composite plies was found to accurately predict the stiffness of printed structures, but a simple maximum stress failure criterion was not sufficient to predict strength. Despite this, FE stress contours proved beneficial in identifying the locations of failure in printed structures. Originality/value This study quantifies the effects of infill patterns in printed structures using a classic TO geometry. The results presented to establish a benchmark that can be used to guide the development of emerging manufacturing-oriented TO protocols that incorporate directionally-dependent, process-specific material properties.

Inflammation and biomaterials: role of the immune response in bone regeneration by inorganic scaffolds

2020 ◽  
Vol 8 (41) ◽  
pp. 9404-9427 ◽  
Author(s):  
Joanna M. Sadowska ◽  
Maria-Pau Ginebra
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Bone Regeneration ◽  
Material Properties ◽  
Specific Material

The design of inorganic scaffolds able to instruct the immune system, eliciting adequate feedback by tuning specific material properties, has become an emerging field of research.

scholarly journals Polylactide (PLA) and Its Blends with Poly(butylene succinate) (PBS): A Brief Review

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1193 ◽  
Author(s):  
Shen Su ◽  
Rodion Kopitzky ◽  
Sengül Tolga ◽  
Stephan Kabasci
Keyword(s):  
Material Properties ◽  
Chemical Structure ◽  
Building Blocks ◽  
Processing Parameters ◽  
International Standards ◽  
Butylene Succinate ◽  
Reactive Compatibilization ◽  
Application Potential ◽  
Specific Material

Polylactide (PLA), poly(butylene succinate) (PBS) and blends thereof have been researched in the last two decades due to their commercial availability and the upcoming requirements for using bio-based chemical building blocks. Blends consisting of PLA and PBS offer specific material properties. However, their thermodynamically favored biphasic composition often restricts their applications. Many approaches have been taken to achieve better compatibility for tailored and improved material properties. This review focuses on the modification of PLA/PBS blends in the timeframe from 2007 to early 2019. Firstly, neat polymers of PLA and PBS are introduced in respect of their origin, their chemical structure, thermal and mechanical properties. Secondly, recent studies for improving blend properties are reviewed mainly under the focus of the toughness modification using methods including simple blending, plasticization, reactive compatibilization, and copolymerization. Thirdly, we follow up by reviewing the effect of PBS addition, stereocomplexation, nucleation, and processing parameters on the crystallization of PLA. Next, the biodegradation and disintegration of PLA/PBS blends are summarized regarding the European and International Standards, influencing factors, and degradation mechanisms. Furthermore, the recycling and application potential of the blends are outlined.

Material and Structural Properties for Creating High Performance Concrete Structures

2014 ◽  
Vol 629-630 ◽  
pp. 21-27
Author(s):  
György L. Balázs
Keyword(s):  
Structural Properties ◽  
Material Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Structural Elements ◽  
Design Rules ◽  
Existing Structures ◽  
New Codes ◽  
Specific Material

HPC and UHPC concretes are finding their ways both to new structures and to retrofitting of existing structures. Herein specific material properties as well as structural examples are discussed. New Codes and Recommendations provide description of material properties and design rules for HPC/UHPC structures and structural elements.

Direct Mechanical Measurements Reveal the Material Properties of Three-Dimensional DNA Origami

Nano Letters ◽  
2011 ◽  
Vol 11 (12) ◽  
pp. 5558-5563 ◽  
Author(s):  
Dominik J. Kauert ◽  
Thomas Kurth ◽  
Tim Liedl ◽  
Ralf Seidel
Keyword(s):  
Material Properties ◽  
Three Dimensional ◽  
Dna Origami ◽  
Mechanical Measurements

scholarly journals Archaeology, anthropology and the stuff of time

2015 ◽  
Vol 22 (1) ◽  
pp. 31-36
Author(s):  
Thomas Yarrow
Keyword(s):  
Material Properties ◽  
Absolute Dating ◽  
Specific Material

Lucas's discussion of contemporaneity makes an important contribution to archaeological understandings of chronology and dating and to broader debates about temporality. Extending his earlier work on time (Buchli and Lucas 2001; Lucas 2001; 2005), Lucas's central insight is that contemporaneity is not a function of a shared unit of time but of the specific relations through which objects are imbricated. The approach is likely to have profound implications for archaeological approaches to chronology. Whether or not it undermines the current preoccupation with absolute dating, it should certainly give renewed impetus to those branches of archaeology that make it possible to examine time as a matter of the specific material properties of artefacts. This is important, first, because it opens up the possibility of more nuanced empirical understanding of the very stuff of time (literally how it is materially manifest) and, second, because such empirical understandings enable conceptual refinement and extension of the categories through which time is understood. Of broader interest for non-archaeological readers are the ramifications of this discussion of contemporaneity for the ways in which time is investigated and conceptualized. Writing as an anthropologist, interested but with no expertise in archaeological dating, it is these latter considerations that I want to pursue in my comments, as these relate to contemporaneity and to the broader investigation of time.

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