Background material properties of selected silicone potting compounds and raw materials for their substitutes

Flowers, G.L.; Switzer, S.T.

doi:10.2172/7032853

Cited by 10 publications

(9 citation statements)

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“…During our review of the literature, we found that the vast majority of studies used the low molecular weight Sylgard™ 184 PDMS polymer (Component A: M n = 5.8 × 10 3 Da; Component B: M n = 7.5 × 10 3 Da). Few studies looked at the behavior of the higher molecular weight Sylgard™ 186 polymer (Component A: M n = 4.8 × 10 6 Da; Component B: M n = 1.6 × 10 6 Da) [ 31 ]. Therefore, Sylgard™ 186 was chosen as the polymer matrix to provide a good guideline for tuning relevant properties with CF fillers.…”

Section: Introductionmentioning

confidence: 99%

Tuning Thermal and Mechanical Properties of Polydimethylsiloxane with Carbon Fibers

2021

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In order to meet the needs of constantly advancing technologies, fabricating materials with improved properties and predictable behavior has become vital. To that end, we have prepared polydimethylsiloxane (PDMS) polymer samples filled with carbon nanofibers (CFs) at 0, 0.5, 1.0, 2.0, and 4.0 CF loadings (w/w) to investigate and optimize the amount of filler needed for fabrication with improved mechanical properties. Samples were prepared using easy, cost-efficient mechanical mixing to combine the PDMS and CF filler and were then characterized by chemical (FTIR), mechanical (hardness and tension), and physical (swelling, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and coefficient of thermal expansion) analyses to determine the material properties. We found that hardness and thermal stability increased predictably, while the ultimate strength and toughness both decreased. Repeated tension caused the CF-filled PDMS samples to lose significant toughness with increasing CF loadings. The hardness and thermal degradation temperature with 4 wt.% CF loading in PDMS increased more than 40% and 25 °C, respectively, compared with the pristine PDMS sample. Additionally, dilatometer measurements showed a 20% decrease in the coefficient of thermal expansion (CTE) with a small amount of CF filler in PDMS. In this study, we were able to show the mechanical and thermal properties of PDMS can be tuned with good confidence using CFs.

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Section: Introductionmentioning

confidence: 99%

Tuning Thermal and Mechanical Properties of Polydimethylsiloxane with Carbon Fibers

2021

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“…The Pt-based catalyst found in PDMS (Sylgard 184) cross-links vinyl-terminated oligomers via a hydrosilylation mechanism . Tri-organophosphite, vinyl, maleate, fumarate, and β-alkynol can reversibly or irreversibly inhibit PDMS curing due to their strong affinity for the catalyst or by sequestering it in small droplets. − Moreover, 3D-printed objects release a variety of chemicals in solution, including polyethylene glycols, diethyl-phthalates, unreacted monomers, and phosphine-oxide photoinitiators, which can also inhibit the catalyst.…”

mentioning

confidence: 99%

PDMS Curing Inhibition on 3D-Printed Molds: Why? Also, How to Avoid It?

et al. 2021

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Three-dimensional (3D)-printing techniques such as stereolithography (SLA) are currently gaining momentum for the production of miniaturized analytical devices and molds for soft lithography. However, most commercially available SLA resins inhibit polydimethylsiloxane (PDMS) curing, impeding reliable replication of the 3D-printed structures in this elastomeric material. Here, we report a systematic study, using 16 commercial resins, to identify a fast and straightforward treatment of 3D-printed structures and to support accurate PDMS replication using UV and/or thermal post-curing. In-depth analysis using Raman spectroscopy, nuclear magnetic resonance, and high-resolution mass spectrometry revealed that phosphine oxide-based photo-initiators, leaching out of the 3D-printed structures, are poisoning the Pt-based PDMS catalyst. Yet, upon UV and/or thermal treatments, photo-initiators were both eliminated and recombined into high molecular weight species that were sequestered in the molds.

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“…Here a thin (~1 mm) layer of Sylgard-184® doped with 0.25 wt% Fe 2 O 3 (spherical, 44 microns) was poured into a Teflon® petri dish and placed in a vacuum to remove all air bubbles. Sylgard-184® has a number average molecular weight of 6,190 g/mol and a weight average molecular weight of 27,700 g/mol giving a polydispersity index (ratio of weight average to number average) of 4.47 [26]. The Fe 2 O 3 helps to provide contrast between the matrix and particle while using PCI [27] and is added after the Sylgard-184® is mixed, but before curing.…”

Section: Methodsmentioning

confidence: 99%

X‐ray Phase Contrast Imaging of the Impact of Multiple HMX Particles in a Polymeric Matrix

Kerschen

Drake

Sorensen

et al. 2020

Propellants Explo Pyrotec

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The initiation of high explosives (HEs) under shock loading lacks a comprehensive understanding: particularly at the particle scale. One common explanation is the hot spot theory, which suggests that energy in the material resulting from the impact event is localized in a small area causing an increase in temperature that can lead to ignition. This study focuses on the response of HMX particles (a common HE) within a polymer matrix (Sylgard‐184®), a simplified example of a polymer‐bound explosive (PBX). These PBXs consist of multiple HMX particles in a single polymer‐bound sample. A light gas gun was used to load the samples at impact velocities above 400 m/s. The impact events were visualized using X‐ray phase‐contrast imaging (PCI) allowing real‐time observation of the impact event. The experiment used two different types of samples (multi‐particle and two crystals) and found evidence of cracking and debonding in both sample types. In addition, it was found that the multiple particle samples showed similar evidence of damage at lower velocities than that of single particle samples. This is an expected result as the multiple particles add additional interfaces for stress concentration and frictional heating.

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Background material properties of selected silicone potting compounds and raw materials for their substitutes

Cited by 10 publications

References 0 publications

Tuning Thermal and Mechanical Properties of Polydimethylsiloxane with Carbon Fibers

Tuning Thermal and Mechanical Properties of Polydimethylsiloxane with Carbon Fibers

PDMS Curing Inhibition on 3D-Printed Molds: Why? Also, How to Avoid It?

X‐ray Phase Contrast Imaging of the Impact of Multiple HMX Particles in a Polymeric Matrix

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