<html><head></head><body><p dir="ltr">Composite material performance can be approximated by weight averaging the mechanical properties of each component in proportion to its volume fraction within the composite. In general, it is advantageous to minimize the matrix (resin) volume in a composite, whether fiber or micro/macro sphere reinforced. This is why multiple sizes of spheres are recommended - to preferentially fill the interstitial spaces between the largest spheres with additional spheres and not simply matrix material.</p>
<p dir="ltr">The spheres provide the required density reduction, but are brittle. The resin adds ductility / toughness to the composite, to carry mechanical loads applied to the composite part, and distribute the load across the sphere surfaces. Packed spheres with no matrix material would still withstand the hydrostatic pressure loads, but any additional mechanical loading would point-load the spheres at their points of contact.</p>
<p dir="ltr">The requirement for glass spheres is really only derived from the strength and density requirements of the application. Using an air entrained resin exclusively may be sufficiently strong, but you may find it difficult to achieve a low enough density, both because of the maximum possible bubble size you can manufacture, and because of the fact that consistently sized air bubbles will never pack as densely as using various different sizes of e.g. glass spheres.</p>
<p dir="ltr">Sean</p>
<br><br><div class="gmail_quote">On June 11, 2017 8:24:36 AM MDT, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px"><div id="yui_3_16_0_1_1497190369061_3501"><span>Greg,</span></div><div id="yui_3_16_0_1_1497190369061_3501" dir="ltr"><span>There has to be good reason to make foam by other means than standard practices. Cost would be the biggest reason, and using wax will probably work, but is there a saving? Using wax </span>means you have to use a deeper rated sphere to offset the loss of reinforcement provided by the resin. I have no idea what the cost difference would be. Maybe the cost is still much better. When I look at Cliff's report, the resin is not the expensive part. Perhaps the direction should be, to look for a replacement for the spheres. In Cliff's report it shows the resin triples the sphere's performance. That implies that the true strength comes from the resin. Maybe a sawdust resin or a
styrofoam granule resin is worth looking at also. Maybe it is a simple as air entrained resin?</div><div id="yui_3_16_0_1_1497190369061_3501" dir="ltr">Fun to think about anyways.</div><div id="yui_3_16_0_1_1497190369061_3501" dir="ltr">Hank</div> <div class="qtdSeparateBR"><br /><br /></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 13px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"><font size="2" face="Arial"> On Sunday, June 11, 2017 6:22 AM, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br /></font></div> <br /><br /> <div class="y_msg_container"><div id="yiv0445916215"><div><div style="color:#000;background-color:#fff;font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px;"><div><span>Hi
Scott,</span></div><div><span>Thanks for the offer, but I need foam for 3,000 feet.</span></div><div><span>Hank</span></div> <div class="yiv0445916215qtdSeparateBR"><br clear="none" /><br clear="none" /></div><div class="yiv0445916215yahoo_quoted" style="display:block;"> <div style="font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px;"> <div style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div class="yiv0445916215yqt0903242652" id="yiv0445916215yqt14923"><div dir="ltr"><font size="2" face="Arial"> On Saturday, June 10, 2017 9:03 PM, Scott Waters via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br clear="none" /></font></div> <br clear="none" /><br clear="none" /> <div class="yiv0445916215y_msg_container"><div id="yiv0445916215"><div><div>Hank,</div><div><br clear="none" /></div><div>Hola from Costa Rica!</div><div><br clear="none" /></div><div>Depends on if
they are glass or carbon fiber spheres and what size they are. They are all pretty durable. We are actually cutting up the foam on Pisces and reattaching it to get the shapes we want. </div><div><br clear="none" /></div><div>I do have a ton of syntactic foam that is cert to 400m that I'd sell you for super cheap. Like all of it for $200</div><div><br clear="none" /></div><div>Thanks,</div><div>Scott Waters</div><div><br clear="none" /></div><div><br clear="none" /></div><div><br clear="none" /></div><div id="yiv0445916215composer_signature"><div style="font-size:85%;color:#575757;">Sent from my U.S. Cellular® Smartphone</div></div><div><br clear="none" /></div><div class="yiv0445916215yqt4119055720" id="yiv0445916215yqt61652"><div style="font-size:100%;color:#000000;"><div>-------- Original message --------</div><div>From: hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> </div><div>Date: 6/10/17 12:38 PM (GMT-06:00) </div><div>To: Personal
Submersibles General Discussion <personal_submersibles@psubs.org> </div><div>Subject: [PSUBS-MAILIST] syntactic foam. </div><div><br clear="none" /></div></div><div style="color:#000;background-color:#fff;font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px;"><div id="yiv0445916215yui_3_16_0_1_1497115959959_2837">I have an idea, but not sure if it will work. My idea is to fill a neutrally buoyant container with macro and micro spheres. After the container is as full as possible, then fill with an environmentally friendly oil. This would be more buoyant than using a resin and less complicated and cheaper. My concern is, how well will the spheres stand up against breaking from being in contact with the other spheres and the container. Are these spheres delicate? </div><div id="yiv0445916215yui_3_16_0_1_1497115959959_2837">Hank</div></div></div></div></div><div class="yiv0445916215yqt4119055720"
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