scholarly journals Characterization of Polyhydroxybutyrate-Based Composites Prepared by Injection Molding

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4444
Author(s):  
Marcos M. Hernandez ◽  
Nevin S. Gupta ◽  
Kwan-Soo Lee ◽  
Aaron C. Pital ◽  
Babetta L. Marrone ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Injection Molding ◽  
Carbon Fibers ◽  
Mechanical And Thermal Properties ◽  
Minimal Impact ◽  
Molecular Weights ◽  
Single Use ◽  
Injection Molded ◽  
Composite Samples

The waste generated by single-use plastics is often non-recyclable and non-biodegradable, inevitably ending up in our landfills, ecosystems, and food chain. Through the introduction of biodegradable polymers as substitutes for common plastics, we can decrease our impact on the planet. In this study, we evaluate the changes in mechanical and thermal properties of polyhydroxybutyrate-based composites with various additives: Microspheres, carbon fibers or polyethylene glycol (2000, 10,000, and 20,000 MW). The mixtures were injection molded using an in-house mold attached to a commercial extruder. The resulting samples were characterized using microscopy and a series of spectroscopic, thermal, and mechanical techniques. We have shown that the addition of carbon fibers and microspheres had minimal impact on thermal stability, whereas polyethylene glycol showed slight improvements at higher molecular weights. All of the composite samples showed a decrease in hardness and compressibility. The findings described in this study will improve our understanding of polyhydroxybutyrate-based composites prepared by injection molding, enabling advancements in integrating biodegradable plastics into everyday products.

Water Debinding for Zirconia Powder Injection Molding

2008 ◽  
Vol 368-372 ◽  
pp. 732-735 ◽  
Author(s):  
Zhi Peng Xie ◽  
Lin Lin Wang ◽  
Xian Feng Yang ◽  
Zhen Ting Zhang
Keyword(s):  
Polyethylene Glycol ◽  
Injection Molding ◽  
Powder Injection ◽  
Major Fraction ◽  
Zirconia Powder ◽  
Sintered Ceramic ◽  
Molecular Weights ◽  
Minor Fraction ◽  
Ceramic Injection Molding ◽  
A Minor

Water debinding is an important debinding technique for ceramic injection molding. However cracks or blisters usually generate during water extraction. In this paper, two types of multi-component binder systems were studied: (1) a major fraction of polyethylene glycol (PEG), and a minor fraction of polyvinyl butyra (PVB) and other additives. (2) a major fraction of PEG, and a minor fraction of polymethyl methacrylate (PMMA) and other additives. Mechanism of defects generation was investigated, and PEGs with various molecular weights were introduced to avoid cracks or blisters during the process. Further more, the compatibilities of PEG/PVB and PEG/PMMA were studied. The results showed that PEG and PMMA exhibited better compatibility, with the feedstock more homogeneous and sintered ceramic parts higher strength.

Characterization of Feedstocks for Injection Molded SiCp-Reinforced Al-4.5 wt.%Cu Composite

2011 ◽  
Vol 383-390 ◽  
pp. 3234-3240 ◽  
Author(s):  
Tapany Udomphol ◽  
Benchawan Inpanya ◽  
Nutthita Chuankrerkkul
Keyword(s):  
Injection Molding ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Solid Loading ◽  
Aluminium Powder ◽  
Twin Screw ◽  
Injection Molded ◽  
Hardness Values ◽  
Potential Use

Characterization of feedstocks for powder injection molding of SiCp-reinforced aluminium composite, as potential use for automotive and light-weight applications, has been studied in this research. Al-4.5 wt.% Cu powder, SiCp and polymeric binder were pre-mixed and compounded using a twin screw extruder at 170oC prior to powder injection molding at 170 oC. Effects of varied solid loadings at 52, 55 and 58% on green properties of the feedstocks have been investigated. Experimental results showed that compounding followed by powder injection molding allowed uniform distribution of SiCp surrounding the aluminium powder. It was found that higher solid loading improved bulk density while hardness values were observed to be similar. Molded specimens of 55% solid loading provided the optimum bend strength and strain at failure. Moreover, it was observed that the opposing abrasive property with angular shape of SiCp resulted in SiCp scratching effect, leading to irregular surface of aluminium powder after injection molding. This consequence and molding porosity were expected to be responsible for relatively low density of the molded specimens, giving the difficulty in molding at higher solid loading.

Synthesis and Characterization of Novel Amphiphilic Helical Copolymer

2011 ◽  
Vol 239-242 ◽  
pp. 1711-1716 ◽  
Author(s):  
Dong Mei Yue ◽  
Dong Zhao ◽  
Ting Yu ◽  
Wei Min Wang ◽  
Li Qun Zhang
Keyword(s):  
Polyethylene Glycol ◽  
Optical Activity ◽  
Monomethyl Ether ◽  
Synthesis And Characterization ◽  
Glycol Monomethyl Ether ◽  
Amplification Effect ◽  
Molecular Weights ◽  
Chiral Amplification ◽  
Environmental Stimulation

The new comb-copolymers [polyacetylene–MPEG (polyethylene glycol monomethyl ether)] were synthesized with (nbd)Rh+[η6-C6H5B- (C6H5)3] as catalyst. The copolymers with moderate molecular weights (Mn) (13000-170000) and yields (31.6-47.3%) exhibited higher optical activities compared with chiral monomer, which accorded with the “Chiral Amplification” effect. The optical activity of the copolymers gradually decreased as the amount of MPEG increased. The maximum amounts of MPEG for successful copolymerization and optical activity of copolymers were 40%, 30%, 20%(mol%) as the Mn of MPEG was 350, 750,1900, respectively. The optical activity of copolymers could change at external environmental stimulation, e.g., decreased as methanol content increased.

Replication, Characterization and Simulation of Micro Injection Molded Microlens Arrays Using Technical Amorphous Polymers

2013 ◽  
Vol 562-565 ◽  
pp. 458-464 ◽  
Author(s):  
Lei Chen ◽  
Stefan Kirchberg ◽  
Bing Yan Jiang ◽  
Lei Xie ◽  
Qing Jun Qiu ◽  
...  
Keyword(s):  
Injection Molding ◽  
Microlens Array ◽  
Amorphous Polymers ◽  
Experimental Methods ◽  
Microlens Arrays ◽  
Ultra Precision ◽  
Injection Molded ◽  
Micro Optics ◽  
Lens Radius

Novel results relating to the characterization of microlens array production by simulation and micro injection molding were examined to produce precise micro-optics from Polymethylmethacrylate (PMMA), Polycarbonate (PC) as well as Polystyrene (PS). The microlens arrays show 100 lenses in a 10×10 array with a lens radius of 271 µm and a lens depth of 45 µm. The pitches between the lenses are fixed at 800 µm. The surface of the ultra-precision diamond end-ball milled microlens array mold was polished to reduce the surface roughness of the injection molded specimen. The injection molding parameters were optimized to get precise lens geometries with high shrinkage uniformity by simulation and experimental methods. The injection molding results show precise injection molded microlens arrays and PC microlens array shows the best geometrical results compared to the microstructured insert.

scholarly journals Characterization of Hermetically Sealed Metallic Feedthroughs through Injection-Molded Epoxy-Molding Compounds

2021 ◽  
Vol 2 (4) ◽  
pp. 976-995
Author(s):  
Mehmet Haybat ◽  
Thomas Guenther ◽  
Romit Kulkarni ◽  
Serhat Sahakalkan ◽  
Tobias Grözinger ◽  
...  
Keyword(s):  
Injection Molding ◽  
Electronic Devices ◽  
Injection Molding Process ◽  
Molding Process ◽  
Process Step ◽  
Molding Compounds ◽  
Single Process ◽  
Injection Molded ◽  
Molding Tool

Electronic devices and their associated sensors are exposed to increasing mechanical, thermal and chemical stress in modern applications. In many areas of application, the electronics are completely encapsulated with thermosets in a single process step using injection molding technology, especially with epoxy molding compounds (EMC). The implementation of the connection of complete systems for electrical access through a thermoset encapsulation is of particular importance. In practice, metal pin contacts are used for this purpose, which are encapsulated together with the complete system in a single injection molding process step. However, this procedure contains challenges because the interface between the metallic pins and the plastic represents a weak point for reliability. In order to investigate the reliability of the interface, in this study, metallic pin contacts made of copper-nickel-tin alloy (CuNiSn) and bronze (CuSn6) are encapsulated with standard EMC materials. The metal surfaces made of CuNiSn are further coated with silver (Ag) and tin (Sn). An injection molding tool to produce test specimens is designed and manufactured according to the design rules of EMC processing. The reliability of the metal-plastic interfaces are investigated by means of shear and leak tests. The results of the investigations show that the reliability of the metal-plastic joints can be increased by using different material combinations.

scholarly journals Effect of Injection Molding Melt Temperatures on PLGA Craniofacial Plate Properties during In Vitro Degradation

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Liliane Pimenta de Melo ◽  
Gean Vitor Salmoria ◽  
Eduardo Alberto Fancello ◽  
Carlos Rodrigo de Mello Roesler
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Melt Temperature ◽  
In Vitro Degradation ◽  
Molecular Weights ◽  
Ft Ir ◽  
Injection Molded ◽  
Higher Temperature ◽  
Lower Temperature

The purpose of this article is to present mechanical and physicochemical properties during in vitro degradation of PLGA material as craniofacial plates based on different values of injection molded temperatures. Injection molded plates were submitted to in vitro degradation in a thermostat bath at 37 ± 1°C by 16 weeks. The material was removed after 15, 30, 60, and 120 days; then bending stiffness, crystallinity, molecular weights, and viscoelasticity were studied. A significant decrease of molecular weight and mechanical properties over time and a difference in FT-IR after 60 days showed faster degradation of the material in the geometry studied. DSC analysis confirmed that the crystallization occurred, especially in higher melt temperature condition. DMA analysis suggests a greater contribution of the viscous component of higher temperature than lower temperature in thermomechanical behavior. The results suggest that physical-mechanical properties of PLGA plates among degradation differ per injection molding temperatures.

Electron Microscope Study of RNA's of Paramyxoviruses

1972 ◽  
Vol 30 ◽  
pp. 196-197
Author(s):  
Ruchama Baum ◽  
J.T. Seto
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Microscope Study ◽  
Sendai Virus ◽  
Sodium Dodecyl ◽  
Rna Molecules ◽  
Virus Particles ◽  
Molecular Weights ◽  
Length Measurements

The ribonucleic acid (RNA) of paramyxoviruses has been characterized by biochemical and physiochemical methods. However, paramyxovirus RNA molecules have not been studied by electron microscopy. The molecular weights of these single-stranded viral RNA molecules are not known as yet. Since electron microscopy has been found to be useful for the characterization of single-stranded RNA, this investigation was initiated to examine the morphology and length measurements of paramyxovirus RNA's.Sendai virus Z strain and Newcastle disease virus (NDV), Milano strain, were used. For these studies it was necessary to develop a method of extracting RNA molecules from purified virus particles. Highly purified Sendai virus was treated with pronase (300 μg/ml) at 37°C for 30 minutes and the RNA extracted by the sodium dodecyl sulfate (SDS)-phenol procedure.

EXELFS Studies of Carbon Fibers

1990 ◽  
Vol 48 (2) ◽  
pp. 72-73
Author(s):  
V. Serin ◽  
K. Hssein ◽  
G. Zanchi ◽  
J. Sévely
Keyword(s):  
Carbon Fibers ◽  
Energy Analysis ◽  
Electron Excitation ◽  
Complex Structures ◽  
High Modulus ◽  
Promising Technique ◽  
X Ray ◽  
Fine Structures ◽  
X Ray Absorption

The present developments of electron energy analysis in the microscopes by E.E.L.S. allow an accurate recording of the spectra and of their different complex structures associated with the inner shell electron excitation by the incident electrons (1). Among these structures, the Extended Energy Loss Fine Structures (EXELFS) are of particular interest. They are equivalent to the well known EXAFS oscillations in X-ray absorption spectroscopy. Due to the EELS characteristic, the Fourier analysis of EXELFS oscillations appears as a promising technique for the characterization of composite materials, the major constituents of which are low Z elements. Using EXELFS, we have developed a microstructural study of carbon fibers. This analysis concerns the carbon K edge, which appears in the spectra at 285 eV. The purpose of the paper is to compare the local short range order, determined by this way in the case of Courtauld HTS and P100 ex-polyacrylonitrile carbon fibers, which are high tensile strength (HTS) and high modulus (HM) fibers respectively.

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