Building Better Bottles

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Building Better Bottles - Nathaniel Mahowald - Fe 2 O 3 as an alternative to traditional glass colorants

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Current recycling practice includes glass separation by color before glass re-use because manufacturers use a cocktail of additives designed to change glass properties. The additives change the way the glass sets and the hue of the glass, while maintaining the structural integrity of the glass. For industrial process specifically, however, the change in the way glass sets is not necessary. Thus, the only reason for the cocktail of additives is to color the glass. The goal of this project was to examine how an increase in the Fe2O3 content of soda lime glass affects its strain resistance and color. Glass with Fe2O3 concentrations by weight of between 0.2% and 0.4% have comparable strength and hue with glass made using the standard cocktail of additives. Thus, Fe2O3 can be used in the place of the standard cocktail, solving the problem of glass separation in recycling.

Transcript of Building Better Bottles

Page 1: Building Better Bottles

Building Better Bottles

- Nathaniel Mahowald -

Fe2O3 as an alternative to traditional glass colorants

Page 2: Building Better Bottles

Personal Information

I am a junior at Mass Academy for Math and Science

I started research in glass in

September of 2013

All experimentation

was performed at my house

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The goal of this project was to examine how an increase in the Fe2O3 content of soda lime glass affects its strain resistance and color, because if Fe2O3 can be used as a substitute to current additives, then it will save recyclers money and open up new types of glass to be recycled.

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Background Information

•Additives That Commonly Change GlassIn boro-silicate glass Fe2O3

Increases densityIncreases the amount of green light absorbed by the glassHypothesized that increase in density is correlated to an increase in strength

•Cr2O3, Mn2O3, Fe2O3, Ni2O3, Y2O3, Ce2O3, Nd2O3 and Er2O3 •Selenium and chromium oxide colorants;

Large amount of Se and Cr are used •Defects are more common •Each of these has unique and often unpredictable effects•These colorants can be rare or expensive, especially ones with rare earth metals

Powdered Fe2O3

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Background Information

•Use of Multiple Additives Impair Single Stream RecyclingLimited amount of glass of colors and compositions other than the target composition can exist in the batch before problems ariseMore cullet = less energy taken by the glass recycling process

Energy costs drop 2-3% for every 10% cullet usedAll shattered glass must be exempt from the typical recycling process because it cannot be sortedThe cost of sorting glass greatly increases the cost of glass recycling

•Use of a single additive would alleviate this problemThe cullet would melt to a homogenous mixture Magnetic properties increased significantly (in boro-silicate glass)

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Background Information

•Industrial Container Production differs in its Requirements from other Settings for Production•Safety and color

Brand recognition purposes. Glass retailers sell glass that has been treated so that it expands and contracts as it cools at the same rate as the glass it will be molded with.

Use a slew of additives to augment this aspect of the glass, though the container manufacturers don’t need it

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Background Information

•Methods of Assessing Glass StrengthUse of fracture mechanics

Stress is defined as load over area, it is a key benchmark for determining the strength of a solidStrain is the change in length over the original lengthStructures under stress carry “strain energy,” or the amount of energy necessary to propagate a crack

A “test piece” is commonly used to generalize the material properties of a substance

The two main indicators of load bearing ability are plane stress and plane strainThe American Society for Testing and Materials has defined a limiting thickness standard for these types of tests

A common method for assessing the strength of

glass, called the drop weight method

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Background Information

•Methods for Hue Analysis of GlassOpen source software called Image J. allowed them to quantify qualitative data collected using computer analysis of their photos to identify patterns

Variables to control for in glass production•Quality of the glass is essential

•Foreign Phases” cause major problems•Inconsistent heating•Mishandling of glass while it cools•Allowing air to permeate the glass•Homogenization of additives is essential

The Kiln that I used to make my glass

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If the amount of Fe2O3 in soda lime glass is increased, then the hue of the glass will darken, and the strength of the glass will remain constant.If this hypothesis is confirmed, it would indicate Fe2O3 is a viable alternative

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Materials Required

1. Taylor Lithium brand scale2. Metal pan of dimensions 30.8x39.6cm with a lip3. 2 wooden planks of dimensions 64.9x2x15.4cm4. Metal broom handle diameter 2.1cm length at least 25cm5. 5 gallon water jug6. 2 5 gallon home depot buckets (with lids)7. Funnel small enough to fit the mouth of the jug8. 1 liter measuring cup9. Plastic container about 26.4x13.2x10cm10. Towels11. Ruler12. Camera13. Soda lime glass with incrementally increasing Fe2O3

content (between 0 (control) and 1 wt. %, at 0, .2, .4, .6, .8, and 1) produced using 6 hour batching at 2,300 degrees Fahrenheit and a cylindrical graphite mold of dimensions 2.54cm in height and 3.81cm in radius. (10 samples at each concentration, as well as 10 samples from green bottles)

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Obtaining the Glass

-The glass that used was batched in an Econo-Kiln-The batching period was 6 hours, at 2,300ºF-Each sample contained 200g of Soda Lime glass, samples of like composition were batched together-Batching started with a graphite crucible, but that melted, so a steel one was used in its place

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1. Take pictures of all samples in well lit environment against a white background

2. Lay towel down on work surface3. Place wooden planks parallel to each other 11cm apart on towels4. Fill plastic container with water5. Place sample perpendicular to the planks so that it rests on each and

crosses them6. Place broom handle parallel to the planks such that it rests on the

sample7. Place pan (lip up) centered on the broom handle8. Place Funnel in the mouth of the water jug9. Place jug (empty) on the pan10. Use measuring cup to add water, pouring slowly11. Pour until jug fills or samples break

If the jug fills, fill Home depot bucket with water in jug, place jug on top of bucket and continue to fillIf the sample breaks, use scale to weight all that rested on top of it at the point of breakage

12. Repeat steps 5-11 10 times and record masses13. Repeat step 12 4 times, using each sample

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Results•P value after conducting an ANOVA of less than .001. The strain capacity peaks when the concentration of additive is at .2, then drops

•The industry standard strength is not outside of the range of standard deviation of both the control and glass with .4% Fe2O3 by weight. Control is found not to be significantly different from the industry sample, with a p value of .62. .4% concentration and the industrial standard are significantly different (p value of .013)

Essentially identical - industrial standard glass was obtained from an industrially approved container. Glass with exclusively Fe2O3 is at least as strong if not stronger than current glass throughout the range between 0% and .4% additive by weight

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•P value after conducting an ANOVA of less than .001.

•Asymptotic increase in hue, •Industry standard additives not outside of the range of standard deviation of .2% through .6% Fe2O3 by weight

•Industrial sample when compared to the theoretical model posed in figure 6 has a percentage difference of 1.37% Percentage of all shades of green that can be safely achieved with this additive: 57.87%

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.4%  Fe2O3        Industry 

Resistance  (kg)


This figure shows how similarly the .4% Sample performed when compared to the

Industry Sample, showing that glass with .4% Fe2O3 would be comparable

when it comes to strength

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This graph shows the trend of color to

increase as the Fe2O3 increases, with .4%

Fe2O3 exactly in the range of the industrial


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•Imperfections, bubbles, and impurities in the glass were assumed to be fairly consistent

Low percentage relative standard deviation. The average percentage RSD was 3.223%, which constitutes high precision

•Another assumption was a consistent and high Young’s modulus for the glassNo bending was detected, and variations in the Young’s modulus were not reported

by other similar studies so it is unlikely that Fe2O3 changes the Young’s modulus in a way that would compromise the results

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The evidence supported the hypothesis that increasing the Fe2O3 concentration overall decreased glass strength and darkened hue, specifically green hue. The goal of the project in attempting to find a viable alternative to the cocktail of additives used by bulk glass manufacturers was also supported. Now that glass can be made with one additive only, it will no longer cause recycling problems and may even become 100% reusable, returning to a pure stage between uses.

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Future Applications/Extensions

•Between 0 and .4% Fe2O3 by weight, glass produced is at least as safe as glass found in manufacture today

Included in that spread are the colors most likely to be used in industry. A single additive could be used to augment the color of glass and in the process, solving the

problems of recycling.The cullet could melt down to a homogenous mixture of two componentsMagnetic properties could allow for 100% single stream recycling

•Identify the magnitude of propagation of magnetic properties specifically in soda lime glass,•Design of the process by which the additive could be safely extracted, especially because as the Fe2O3 becomes separated from the molecular structure of the glass, it loses its magnetic properties

•Procedure for batching glass that has exclusively FeeO3, to find the most efficient method for its re-use. Research about what the new tolerance for other types of glass in the batch becomes when only Fe2O3 is desired

•Changing emission of UV radiation of glass with increasing levels of the additive