Disposable tableware has brought convenience to people's lives, especially with the development of the takeaway industry, the number of people's consumption of disposable tableware has surged. An environmental protection organization has conducted statistics on the amount of disposable tableware consumed by China's online food delivery platforms, and found that on average, 3.27 disposable plastic tableware will be consumed for each takeout order, so these platforms will consume nearly 80 million pieces of tableware every day, not including other platforms. and the consumption of traditional catering stores. From a global perspective, the world consumes about 16 billion disposable coffee cups every year, and discards 1 billion plastic straws every day. Such a huge consumption causes about 8 million tons of plastic waste to flow into the ocean every year. Conservative estimates of these plastic wastes are also It takes 450 years to degrade.

The research group of Zhu Hongli from Northeastern University blended short bagasse fibers with long bamboo fibers, and the two fibers were physically intertwined to form a highly intertwined network structure, and then the disposable tableware was prepared by cold pressing and hot pressing drying. It can completely replace plastic and traditional paper tableware.

Through electron microscopy, the researchers found that the melting of lignin in the hot-pressed fibers and the hydrogen bonding between the cellulose make the fibers tightly bonded together to form a 3D network, which improves the water resistance and strength of the product.

To study the biodegradability of tableware, the researchers buried them in soil and regularly checked for changes in shape and weight. It was found that after 20 days of burial, yellow fungi appeared on the surface of the tableware, began to deform after 30-45 days, and completely lost its shape and gradually disappeared after 60 days. And the weight of the cup dropped from 7.99 g to 4.18 g after 60 days, almost half of the degradation. In contrast, the polystyrene (PS) plastic tableware used as a comparison showed no change in appearance or shape after being embedded for 60 days.

Since it is used as tableware, it is necessary to ensure its safety first, especially the content of heavy metals such as Pb and As should not exceed the standard. According to European Food Contact Materials Regulation (EC) No. 1935/2004 and China National Food Safety Standard (Food Contact Paper and Cardboard Materials and Their Products) GB 4806.8-2016, 23, 24 The content of Pb and As should be lower than 3.0 mg/kg and 1.0 mg/kg. The researchers used inductively coupled plasma optical emission spectrometry (ICP-OES) to analyze the content of Pb and As in the mixed fiber tableware, and found that the content of Pb was 0.3633 mg/kg, only 1/8 of the standard value, and no As was detected. exist.

As tableware, oil resistance and water resistance are also critical. The contact angle of mixed fiber tableware to water reaches 127°, the contact angle of secondary fiber forming pulp SFMP and filter paper to water is 0°, and the commercial bagasse tableware is 93°. The mixed fiber material shows excellent hydrophobicity. Not only that, the water absorption of mixed fiber tableware is only 59.4%, while the commercial bagasse tableware is 77.5%, filter paper is 149.2%, and SFMP is 310%. Such low water absorption is due to the high hydrophobicity and dense structure of the mixed fiber. of.

In order to evaluate the oil resistance of tableware, the researchers analyzed according to the standard of Technical Association of Pulp and Paper Industry (TAPPI) 559 pm-96, and found that the oil resistance of mixed fiber tableware is 6, which is much higher than that of SFMP (1), commercial bagasse Cutlery (grade 4) and filter paper (grade 1), exhibiting excellent oil resistance.

The researchers compared the mechanical properties of the mixed fiber and PS tableware and found that the tensile strength was 35.0 MPa, which was at least 2 times higher than that of the PS plastic cup (15.6 MPa), and the Young's modulus was 3.25 GPa, which was much higher than that of the PS plastic cup of 1.40. GPa. A 7.9-gram mixed fiber paper cup can support a weight of 3 kilograms and still maintain its shape, a load that is 380 times its own weight.

97% lower CO2 emissions than plastic

The researchers estimated the amount of carbon dioxide emitted during the production of mixed fiber tableware. According to reports, the carbon dioxide emission of 1 kg of foamed PS plastic is 7.36 kg; according to the statistics of the European carton board manufacturers association (Pro-Carton), the emission of 1 kg of molded pulp products is 0.22 kg. As a result, the CO2 emissions of molded mixed fiber tableware are 97% lower than PS tableware and 65% lower than disposable paper and PLA plastic tableware.

Cost close to PS tableware

In addition to good performance, the material must be cheap to be king. By comparing the statistics from the Plastics Insight-Market Intelligence website, the researchers found that the cost of mixed fiber tableware was US$2,333/ton, which was only half that of PLA (US$4,750/ton) and close to that of PS tableware (US$2,177/ton).

In order to solve the increasingly serious problem of "white pollution", Zhu Hongli's research group from Northeastern University blended bamboo fiber and bagasse fiber → cold pressing → hot pressing to prepare a tableware that can be quickly degraded, which only takes 60 days. Degradation 48%; Pb content in tableware is 0.3633 mg/kg, only 1/8 of the standard; excellent water and oil resistance; tensile strength is 35.0 MPa, Young's modulus is 3.25 GPa, much higher than PS Plastic cup; the CO2 emission of producing 1 kg of product is 0.22 kg, which is 97% lower than that of PS tableware, and the cost is only US$2,333/ton, which is close to that of PS tableware (US$2,177/ton). From the comparative analysis of seven aspects of safety, odor, CO2 emission, cost, biodegradation, abundance and processability, it is not difficult to see that compared with other materials, the tableware made of this mixed fiber material is comparable in all aspects. Said to be perfect, if mass production is achieved, the solution of the world's "white pollution" problem is just around the corner.