April 28, 2014

PLA (polylactic acid) is kinder to the environment than other plastics as it is derived from corn stalks and not fossil fuels. Now a Chinese company has invented another eco-friendly material - straw based plastic - made from rice and wheat stalks and can be used in 3D printing, without sacrificing price or performance.

The straw based plastic is made from dried crops straw, such as wheat straw, rice straw, corn stalk etc, mixed with plastic and plastic additives, using company's patent pending technology.

Every year large amount of straw are generated from the production of crop plants such as wheat, rice, and cotton. In the past most of this biomass was burned resulting in air pollution and loss of a potential carbon feedstock for improving soil fertility. Due to these problems, straw burning in the field has been banned by the government.

Chinese company, Jiangsu Jinghe Hi-Tech Co.,Ltd, has developed a technology that can transfer crops straw into 3D printing material. The process started with shredding the straw to 1.5~2mm pieces. Then they mix the strawdust with polypropylene, adding silane coupling agent and ethylene bis(stearamide) as additives. The mixture is then extruded into granules using a twin screw extruder. After the transforming, the granules have even particle size and are more stable for further processing.

The plastic granules can be heated up to 160˜180° C for injection moulding. Using special filament extruders the company has turned these plastic granules into filament for 3D printers. The 3D printed object created using the straw based filament has the color of natural wood, and the texture of plant fiber on the surface. It has also nice surface finish and high strength.

According to Yan Wei, deputy general manager of Jinghe, the company has signed several cooperation agreement with villages in the area. In general, 1 ton of rice paddy produces 290 kg rice straw, currently the company pays the price of approximately 800-1000 RMB ($120~160) per ton for crops straw. Yan said this project has been supported by farmers. "This is a good way to get rid of straw wastes from our crops and still earn some income," said Mr. Pu, a local farmer.

Compared with traditional petroleum-based plastic, Jinghe's straw-based plastic has low production cost and fewer carbon emissions. According to the company, producing 14,000 tons of the straw-based plastic can reduce carbon dioxide emissions by 22,400 tons every year.

The ABS raw material costs around 15,000 RMB ($2,400) per ton in the market. PLA, as a natural green material, has more complex production process and costs more, around 20,000 RMB ($3200). Yan said their straw-based plastic material only costs about 10,000 RMB ($1,600) per ton. After processing, the price of straw based filament for 3D printing will be only half of the current PLA filament price.

If the material can plummet in price, it will be sooner for 3D printers to be in every home, Yan said.

Currently the company can process around 7,000 tons of straw annually. Jinghe has already signed a 2 billion RMB ($320K) contract with Shantou city government to provide straw based plastics for producing toys for European market.

 

Posted in 3D Printer Materials

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Peter L wrote at 5/9/2014 12:48:40 AM:

Is it available yet? If so, where to buy?

m.z. wrote at 5/2/2014 9:03:33 PM:

Because some people aren't clear on the concept, this is made from RICE STRAW, which is a WASTE PRODUCT from the rice harvest.

Davron wrote at 5/2/2014 10:03:55 AM:

This isn't made from the wheat or rice, it is made from the straw that is a byproduct. It sounds like the farmers can't use this for livestock or they would have been doing that instead of burning it prior to being forbidden. I don't know what the structural qualities of the material will be though, and it is bound to have worse issues with water than even PLA.

eastrises wrote at 4/29/2014 9:55:27 AM:

I accept all the above comments and ofcourse that is true that it will impact food chain. But on the other hand if it would have been invented similar to PLA from corn in a western country I believe the comments would have been in a strong positive sense... lol ;)

jd90 wrote at 4/29/2014 1:15:00 AM:

NoisyBlueJay - please read again. *stalks*.

NoisyBlueJay wrote at 4/28/2014 9:52:32 PM:

If this is made from rice, wouldn't the price of food rise? This sounds like the corn problem is the states...

Peter wrote at 4/28/2014 9:43:34 PM:

Straw is always in food chain, more better I'll be using Acetate Cellulose, it's derived from cotton plant and cotton plant do not cut during coltivation

jd90 wrote at 4/28/2014 8:07:11 PM:

I don't think polypropylene is a "green" material. I don't think I'll be supporting this process. Find a way to mix it with PLA, then maybe.

ThatGuy wrote at 4/28/2014 3:57:48 PM:

The cost of filament isn't in the raw materials, its in the mark up from pellet to filament. From the filament price comparo, the lowest price for filament is $19/kg, or $17,000+ per ton. You could get the raw plastics pellets for free and filament would still be expensive. Sure, it's good for the long term when the filament premium reduces and the raw material price becomes more dominant in driving the price.



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