Working with Biomaterial Composite

This week I chose to work with biomaterials!

Biomaterial Basics

The term biomaterials maybe overused.. or can be redundant.. but what I mean by biomaterial here is specifically an alternative material made out of organic substances that can be derived from organic waste, local agricultural resources, etc. Biomaterials now are argued as one of the solution for climate crisis as well as waste problem.

Forms of Biomaterial

All this time, I have been exploring many different kinds of biomaterials, starting from bioplastics, leather, foam, composite, etc. But in this assignment I’ll specifically focus on bio-composites.

How it works?

• binder
• substrate/filler
• complementary
  • plasticizer, e.g glycerin
  • solvent, e.g vinegar, alcohol, any reactant to binder
  • coating, e.g wax, alum
  • preservatives, e.g vinegar, citric acid, cinnamon, turmeric, etc
  • dye
  • etc

Binders

Types

Plant-derived

Animal-derived

Substrate/ Filler

Types of Biomaterial Fabrication

Designing for Bio-Composite Making

In this assignment I would like to focus on exploring bio-composites, using local waste, like seashells and eggshells. In this assignment, I’ll be making biomaterilas by ‘cooking’ and then using molding-casting method.

Because here, the new process that I’m trying is the process of making the biomaterial itself, so for the design for the mold, I will be using my previous mold design that I made on Week 12: Molding and Casting.

Designing on Onshape

• Start by making sketch

• Extrude

• Fillet Edges

Fillet the inner circle (radius value = 10 mm)

Fillet the outer circle (radius value = 5 mm)

Here, I experimented with the design by setting the fillet value quite high to make the shape more playful. Since I positioned the inner circle off-center, closer to the edge, applying the high fillet value resulted in uneven edge heights. This was unexpected but turned out beautiful!

• Final result Design

Digital Fabrication: 3D Printing the Mold with Surface Finishing Techniwue

For more details of the workflows of making 3D printed mold, you can follow the step by step process on my my week 12 page where I have explored in more details how to surface finish a FDM 3D printed mold.

Biomaterial Fabrication

Here’s the 3 different materials that I want to test for this wildcard week.

General Tools and Equipments

Prepare all the materials, tools and equipments for making biomaterials. The materials or ingredients you need are going to be dependent on what you want yo make. But below are some general tools that you will need:

• grinder/chopper
• digital scale
• measuring cup / spoon
• cooking utensils, e.g saucepan, spatula
• stove
• tray /mold (prepare one, but depend on what you want to make)
• gloves
• mask

Materials Ingredients:

For the materials, it will be again depends on your innovation. But if you are using raw material waste resources, ther emight be achance that you have to transform their form first into a powder-like form by using chopper/ grinder. Below I will elaborate you what are the materials needed to make eggshells-based composite and sea-shells-based composite along with its ratios.

I have experimented quite a lot with bio-composite using eggshells/seashells (calcium carbonate)-based material before. By far, the recipe that I found works best in my situation here in Indonesia is this Eggshell Biocomposite recipe by Sofia. You can try that as a starting point. However, the recipes I ended up using here have been improved and adjusted based on my personal experiences.

Process of Making Biomaterial (Case: Eggshells Composite)

Material Ingredients:

Eggshells-based Composite

• Eggshells waste (powder) : 24 gr –> thi is the amount that’s required to fill my mold
• Gelatin : 6 gr (datasheet)
• Palm Wax: 1 gr
• Water : 12 gr

Preparation

• Prepare all the tools and materials
• If you’re using a raw eggshell waste, you have to wash it until it’s clean and oven it / dry under the sun until it’s completely dry and crisp. Next, you want to grind it with a coffee/spice grinder until achieve the granule levels that you like. You may want to sieve it to achieve a fine powder level. In my case, in fab lab bali we already have ground eggshells powder.
• Measure all the ingredients with digital scale according to the recipe. make sure your scale is well-calibrated

• Once you have all your ingredients ready, mixed gelatin, eggshells waste, and water all together in a saucepan. There is not really good or wrong here… as this practice is also an emerging practice. Ideally, it is recommended to do it step by step, so you can make sure that the gelatin bond are made first before adding the filler/substance and you can observe the phase-state changes of the gelatin over time. However, from my experience, there’s not really a significant difference, so you can mix it right away.

Mixing/Cooking

• Turn on the stove and set it to low to medium heat.

❗ Important! Learn the technical specification of your ingredients!

Gelatin bond breaks easily in high temperature. I learned this through experience, but actually there is an explanation for that. It’s because each ingredient/material, especially biomaterial has their own specifications, such as melting point, gelling point, boiling point temperatures, aka thermal properties. Basically, you want to know their phase-state changes considerations & requirements.

Each gelatin might be different according to manufacturer/producer, but in general the melting point of gelatin is quite low, falls in the range of 30-40 degree celcius. Below that point, it will set to gel, and above that point it will melt and eventually break its bond (meaning it will split in water) at 100 celcius (boiling point).

What this implies? So that you know how to handle and manage / manipulate the heat when dealing with this ingredient. There are multiple occasions when I made material with gelatin and then I dried it under the sun in Indonesia, it turns out it’s melting..... You know, when working with agar or other binder, the melting point might be higher, thus can withstand such heat.

For a more detailed specification of gelatin, you can check/refer to this datasheet

It’s better to be aware of this prior to making biomaterials so you can mitigate / minimize errors and also you know what to expect out of your material.

• Stir the mixture well in one direction, try to do it patiently to avoid not making any bubbles (unless that’s the quality that we want to achieve)

  

• Once it turns to gel-like consistency, add palm wax to the mixture. Stir it again until there’s no clump.

• Keep stirring until achieving a slurry consistency. Don’t doo this process too long tho, remember what I mentioned, too long in the heat might broke the bond, which means the mixture will turn to liquid again.

• You can sense when your mixture is about to be ready, when the solution starts to shimmer.

Forming

• Pour the eggshells mixture inside the mold. Make sure to stir again before you pour, because the powder tends to get left in the bottom of the saucepan.

• Wait for 5-10 minutes until it’s set/cure.

Drying

• Once it is set, it’s time dry it.
• Now, again, you should remember of the temperature constraint! We can’t dry gelatin with high heat like putting it in the oven. Even, putting it under the sun directly might melt it. So, there are various ways that you can try: (1) using dehydrator: quite self-explanatory, but this is an ideal one as what you want is just continuously air-dried it with very minimum heat. SO if you have one, you can try using it. But I don’t have one and we dont have it in the lab as well. (2) we can air-dry it, put in a good air-flow area, you can accelerate the process by using fan or hair-dryer as well

• But if using this two techniques, with the context of using a mold, it will take a very long time for it to dry. So another trick that I learn from that Materiom recipe, to accelerate the drying process, you can put it in freezer for 15-20 minutes. And then Demold it. And then air-drying it.

  

  demolding

  Next, air dry it in a place with good airflow. Direct morning sunlight is still okay. It usually takes 1-2 day for it to be fully dried without additional dryer / dehydrator.

  

This is by far the workflow that works best and produced best result, consistency, and composition for me.

Result

Seashells-based Composite

For the seashells, you can follow the same workflow as above, since the binder is the same, and seashells is also calcium-carbonate. The difference would be using seashells might result in heavier material weight.

Seashells-based Composite

• Seashells powder: 24 gr –> thi is the amount that’s required to fill my mold
• Gelatin : 6 gr (datasheet)
• Palm Wax: 1 gr
• Water : 12 gr

As seashells is much harder to break than eggshells, so if you would like to use raw (ungrounded) seashell, you would require a much more durable grinder (coffee grinder would not be able to do it..)

Making Process

Result

Sawdust Composite

Sawdust-based Composite

• Sawdust powder: 24 gr –> thi is the amount that’s required to fill my mold
• Gelatin : 6 gr (datasheet)
• Palm Wax: 1 gr
• Water : 12 gr + additional water to wet the sawdust first

Sawdust tend to shrink a lot! So, the volume of a 24 gr sawdust would seems like very much. But once you soak it in water, they will shrink immediately. So, for sawdust it’s suggested to first make it wet (spray/pour some water in it) to make all the sawdust fit in the molds, becaus it tends to expand in size when cooking but then result in heavy shrinking

Making Process

Soon after demolded:

Result

Reflections

• Biomaterials tend to shrink, resulting in smaller size

  especially because I took the approach of freeze it first before demolding, so when it went to drying process, there’s no ‘scaffolding’ that holds the shape and size in place. So it will shrink from 360 degree direction. Resulting in smaller size.

  This might be also due to some unprecise measurement in the recipe or process when making the biomaterial itself. But assuming the composition was right, as you can see the sawdust is the one that shrinks the most… probably because it is basically fibres so it contracts a lot when drying.

• Biomaterials texture

  With gypsum or the wax, I believe if there’s some dirts, or still there are printing line in your mold, it will be much more visible. BUt in the case of biomaterial, such slight bumps would not affect much.

• Always learn and understand the datasheet of the material you’re working with!

  Gladly biomaterials ingredients I’m working on are not that hazardeous, because basically they are all kitchen and cooking ingredients.. which supposed to be safer. But if you’re working with material hat you’re not sure of… especially biological material that might need special disposal system, always check for the specifications in the datasheet, so you know how to handle it and protect yourself from harmful situation

Design Files

• Incense Holder/Trinket Dish - 3D Design (Onshape)
• Incense Holder/Trinked Dish (.STEP)