Looks like plastic, made of molded bamboo!

Several years ago, I bought some dog dishes that look and feel like plastic, but they’re made with molded bamboo.

How can bamboo be made into something that so greatly resembles plastic?

Plastic is a family of different polymers, some of which are suitable for molding. An amazing number of products are made of molded plastic. I’m using a keyboard with molded plastic keys and a molded plastic mouse.

If you have any plastic table service, food preparation tools (such as measuring cups), containers for leftovers, etc. in your kitchen, they are all molded plastic. You might also have molded plastic chairs, toys, automotive parts, and all kinds of other things.

Industry uses eight basic molding techniques. Each one begins by heating plastic granules to a temperature where they become a thick liquid. Plastic is well entrenched, but many people are actively looking for plastic alternatives.

Molded bamboo has come along more recently. As far as I can tell, large corporations don’t make and market it. But it’s not like you can find it only on niche websites. I got my dog dishes at Petsmart. I also have a selection of molded bamboo products from Amazon at the bottom of this page.

In addition, 3D printing uses plastic. It can just as easily use bamboo alternatives to plastic.

Bamboo is actually a very versatile and fast-growing grass. Growing bamboo does not require fertilizers or pesticides. It grows from a rhizome, which means that harvesting it doesn’t kill it, and it grows back very quickly.

Therefore, it is a renewable resource, while plastic is made from oil. What’s more, bamboo powder is a waste byproduct of many other manufacturing processes. Using industrial waste to make molded bamboo products is therefore a kind of recycling.

Today’s molded bamboo: bamboo-plastic composite

 But molded bamboo products are mostly made from bamboo-plastic composite (BPC). In other words, bamboo fibers have been mixed with a matrix, most often epoxy resin.  

The matrix surrounds the fibers (known as the filler) and holds them together. Among its other advantages, BPC reduces the amount of plastic used to make a product. 

The process of using bamboo as a filler in a composite material is fairly new. The process of making plastic composites is not. In fact, Leo Bakeland patented the first mass-produced plastic in 1909. He called it Bakelite. He must have known it would be hard to market polyoxybenzylmethylenglycolanhydride!

Bakelite consists of a matrix made of phenol and formaldehyde and a filler such as wood flour or asbestos. It sounds like a horrible combination of poisons now, but Bakelite’s strength and low heat conductivity made it a revolutionary product. It soon found uses in kitchenware among many other applications. 

Environmental pros and cons of modern BPCs

BPCs essentially use bamboo fiber instead of the fillers Bakeland used. They can be based on any polymer matrix. BPC is 40% bamboo and 60% plastic. It uses less fossil fuels to make it. It’s lighter than any plastic. Therefore, molded BPC products use less energy to transport.

They do have some environmental drawbacks, however. 

• Composite kitchenware, for example, can react to heat and acidic foods and raise health concerns.
• It still uses plastic, which means it still requires fossil fuels. It’s not a complete substitute for plastic.
• It’s not necessarily biodegradable.

Biodegradability depends on the resin. Some plastics can biodegrade; others can’t. So-called bioplastics are made from crops, not oil. Some of the more biodegradable resins might release hazardous substances in the process of decomposing. Besides the chemistry of the resin, other variables in biodegradability include temperature, aerobic or anaerobic conditions, and what kinds of microbes are present.

Consumers can choose molded bamboo products, but it’s hard to know the matrix used for making them. And even in the case of biodegradable BPCs, it may require industrial composting to break them down. Recycling, while possible, remains uncommon. Not many facilities exist. 

Research on molded bamboo

We still need new plastic alternatives. Research has started on two improvements: how to make BPC on a biodegradable matrix and how to prepare bamboo powder for molding without it being part of a BPC.

It stands to reason that anything described in recent scholarly articles is not yet ready for commercial application. 

While considerable studies have been done on composites with traditional plastics, not many have concerned composites with polybutylene succinate (PBS), a biodegradable plastic. Experimentation with BPCs based on PBS show the necessity of adding other chemicals such as zinc oxide and silicon nitride. These substances appear to be eco-friendly.

Once a successful composite of bamboo and PBS becomes available, it should have all the advantages of standard BPCs yet be fully biodegradable and non-toxic. 

Molded bamboo without a plastic matrix

Molded bamboo as a complete substitute for plastic requires making it without a plastic matrix. A paper in Precedia Engineering explored injection molding of bamboo powder. Injection molding using only bamboo or other woody biomass is difficult. Part of the trouble is in achieving good flowability. Biomass that contains water flows well. The water softens and decomposes the fiber, but the water vapor produced by heating it for molding has a negative effect. 

Steaming the bamboo powder has the same effect as soaking it. Therefore, the team steamed bamboo powder and then attempted injection molding after it became oven-dry. They experimented with various temperatures of that powder and of the metal mold. Several conditions made it possible to make products by injection molding. 

The paper makes no mention of adding bamboo powder to resin. Therefore, it didn’t use the same techniques commercial injection molding uses. With more research, then, it should be possible to make molded bamboo without adding it to any kind of plastic. 

A paper in the Journal of Materials Science Research describes using bamboo powder for hot press molding. The experiment made objects at four different temperatures from 160-240ºC. The strength of products molded at the lowest temperature was  poor, but it increased with temperature. So did hardness. Products produced at high temperature had strength and hardness comparable to polyethylene. 

Molded bamboo made with BPC is more nearly sustainable than plastic. Molded bamboo made with only bamboo powder and no plastic matrix will be an even better plastic alternative. As it is, some manufacturers already claim to make fully biodegradable molded bamboo products. Natural Home Brands, for example, boasts that its plastic substitute is based entirely on plant-based materials.

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Sources:

Bamboo Plastic, is it Really Eco Friendly? / Pandabode. August 7, 2019
Fabrication of press-molded products using bamboo powder / Shinji Ochi. Journal of Materials Science Research 1 (January 2012): 156-66 
Injection Molding Using Only 200 °C Steamed Bamboo Powder by Controlling Metal Mold Temperature / Shohei Kajikawa and Takashi Iizuka, Procedia Engineering 81 (2014): 1186-119
Potential application of bamboo powder in PBS bamboo plastic composites / Shuaicheng Jiang et al., Journal of King Saud University 32 (January 2020): 1130-1134