Moldable Wood Plastic Composite (WPC)

Those who like to work with wood must have noticed how this activity generates a lot of waste! And you certainly wondered if there wasn't an alternative use for so much wasted wood. In the steps of manufacturing a wooden artifact, a lot of waste, such as sawdust and wood chips, is generated. These wastes vary in size and quantity, and can be used to form so-called WPCs (wood and plastic composites).

In this tutorial you will learn not only how to recycle the waste generated in your logging activity, but also the possibility of using other cellulose residues such as sisal fibers, piassava, paper etc. Usually the so-called WPC (wood and plastic composites) are manufactured in expensive processes using plastic extruders and injectors, where previously selected sawdust residues are mixed with plastic pellets that, when heated, allow their mixing. However, there are advanced polymer recycling processes where this can be done without the use of machines and at much lower temperatures using the polymer solubilization technique. Of course, you can use thermosetting polymers such as polyester and epoxy, but a better and greener alternative would be to use plastic waste from packaging waste that is plentiful and of no commercial value, such as Styropor® (expandable EPS polystyrene), which otherwise it would pollute the environment or, at the most, be dumped in landfills. Whether to use it as a paste for your 3D printer, or as a moldable mass for sculptures, or for molding with molds, the interesting thing is that the residue of this material, when it exists by cutting, drilling or sanding, can have its residues used again to make more moldable wood mass.

The same manufacturing process can be used with plastics such as: ABS, HIPS, cellulose acetate and acrylic.

What you will see next in this tutorial is taken from my patents and research developed in my doctoral thesis on ecocomposites. PI 0100139-6 A2. This patent is available for didactic purposes and for artisans. For commercial uses, please contact the inventor.

REGISTER: 👉 https: //www.youtube.com/channel/UCaE1 ...

1- A lot of expanded polystyrene (EPS) or extruded (XPS) which is used in packaging and thermal insulation and is known by trade names like: Stiropor, Stiropor, Palstyrol, Polystyrol, Solarene, Styrofor , Stitol, Stirolan, StyroCal, Syrolution.

2- Sieved wood sawdust. While you can use sawdust mixed with different grain sizes, ranging from fine dust to wood shavings, we're going to use fine sawdust for the bench and a thicker one. The former can be used on the surface of your objects because it has a better finish and for the structural parts, for greater strength, use thicker chips and sawdust. To be aesthetically different, use different colored sawdust on each layer. I used piassava fiber on the top of my worktop, piassava is widely used in Brazil to make broom bristles and it is a very strong and resistant fiber.

3- To dissolve EPS, you need a solvent that softens the plastic, but without it becoming liquid or sticky. There are many options that solubilize EPS, but we need a partial solubilization and the ideal is the combination of a solvent and a non-solvent that combined make the plastic turn into a mass similar to gum. Therefore, I recommend using solvents used as paint thinners, such as the first or second thinner used for nitrocellulose based paints.

4- For the container where you are going to dissolve the EPS, use one bucket or pot made of plastic material resistant to solvents such as PP and PE.

5-If you use molds to put the dough to dry, give preference to plastic materials of PP and PE that would be discarded, so that it is not necessary to create molds and reuse materials that would go to waste.

To dissolve the Styrofoam you will need a glass jar or a solvent resistant plastic such as those made of PP and PE.

To avoid splashing, wear goggles. Wear a solvent resistant rubber or plastic glove, Protect your workplace with a solvent resistant plastic. Do this activity in an open and ventilated environment.

1- Put just a little solvent in the container

2- Then start to place pieces of Styrofoam until the solvent stops dissolving

3- A white mass that resembles chewing gum will form. remove it from the pot wearing gloves.

Now that you've dissolved the Styrofoam and you have something like modeling clay.

1-On a table covered with solvent-resistant plastic, add wood sawdust and work like a baker.

2- Add wood sawdust gradually and always knead the mass so that the plastic mass absorbs the sawdust. The more wood sawdust the mass absorbs, the faster it will dry afterwards, as it helps in evaporating the solvent from within the mass,
From time to time, use a little solvent to help the sawdust stick to the plastic putty.

Now that you have the moldable wood mass ready, you can experiment with making small sculptures or placing them in plastic or silicone molds.

Allow to dry for 2- to 4 days in a ventilated place and out of the sun. Once dry you can still drill, cut, sand and polish. The residues now generated in these operations are plastic with wood sawdust, and can be turned into mass simply by adding a little solvent. Here nothing is lost, everything is transformed.