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Issue 02/2017

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  • Bioplastics
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  • Biodegradable
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Agriculture/Horticulture PLA branches into agriculture New root trainers for rubber plants are biodegradable Fig. 1: Young rubbers planted in root trainers Fig. 2: Young rubbers planted in soil with root trainers Natural rubber is a key economic commodity for the countries of Southeast Asia. It is used in many different industries, ranging from auto manufacturing and sports to medical and marine applications, and consumer products. A biopolymer, natural rubber is derived from latex, a milky fluid that is tapped from the rubber tree (Hevea brasilliensis) and subsequently coagulates into rubber. In addition to natural rubber, synthetic rubbers have also been developed that are produced from petrochemicals. For the majority of applications, including tires, compounds of natural and synthetic rubbers are used. In 2016, demand for both natural and synthetic rubbers reached approximately 25 million tons. As only 12 million tonnes of natural rubber were produced, this meant that the shortfall had to be made up by synthetic rubbers. Nonetheless, demand for natural rubber continues to rise, not only because of its biobased origins, but also because of its superior quality, which makes it the material of choice in high-performance products such as aircraft tires. The natural rubber supply, however, is limited by the suitability of both land and climate for rubber production. Natural rubbers are exported mainly from the four Southeast Asian countries of Thailand, Indonesia, Malaysia and Vietnam. Combined, these four countries produce some 70 % of the world’s natural rubber supply. Thailand is the biggest producer, accounting for 40 % of global production. These four natural rubber-producing countries implement massive replanting programs on a yearly basis. Rubber trees have a service life of 25 years, after which the latex yield becomes too low and they are cut down. The farmers then replant with higher-yielding clones. Each year, the trees that have reached the end of their economic life are taken out and replaced. Replanting involves cultivating the young rubber seedlings in nurseries for about six months before outplanting in the plantations. The rubber seedlings in the nurseries are grown in plastic bags or in plastic cones called root trainers. Rubber trees grown from root trainers have service lives that are about 5 years longer than those grown in bags; in other words, the productive life of the tree is extended to 30 years. Farmers not only enjoy the benefits of 5 additional years of productivity, the costs of replanting are also reduced. In the past, root trainers were made from polypropylene, which does not biodegrade in soil. This meant that the farmers were required to extract the young trees from the root trainer in order to replant these in the plantation, resulting in damage to the root systems and, consequently, a higher rate of dead trees. This disadvantage jeopardized the benefit provided by the added years of productivity. As the country with the largest replanting program - a program in which 70-90 million new Fig. 3: Root trainers degraded after 4 months in soil 24 bioplastics MAGAZINE [02/17] Vol. 12

Buss Laboratory Kneader MX 30-22 By: Nopadol Suanprasert President Global Biopolymers Co., Ltd. Bangkok, Thailand trees are replanted each year -Thailand has been exploring the use of new materials for root trainers that could be buried in the soil with the young trees, thus eliminating potential root damage. This material would have to be able to degrade in soil to allow roots to penetrate out to the soil. Corbion Purac, headquartered in the Netherlands, and Global Biopolymers of Thailand have now jointly developed a new root trainer made from PLA compounds. The cone-shaped product is injection molded. As a test, young rubber trees were planted in the new root trainers (Fig 1) and kept in a nursery for 6 months. While in the nursery they were stored in racks for good ventilation. No degradation of the root trainers occurred during the period in the nursery. After 6 months, the young rubber trees were outplanted in the plantation without removing them from the root trainers (Fig. 2). After 4 months in the soil, the PLA root trainers had degraded, allowing the roots to penetrate and grow in vertical direction controlled by the root trainer (Fig. 3). This test was conducted in Thailand’s government rubber plantation in Rayong province. Rayong is where Corbion’s lactic acid plant is located and the site of the new Total Corbion PLA plant, currently under construction, for the production and marketing of PLA polymers and lactide monomers. The use of root trainers made from PLA to cultivate rubber seedlings is therefore a classic case of circular economy in the local host country. The lactic acid is produced in Thailand from local agricultural raw materials. PLA made from this lactic acid is used to produce root trainers for growing rubber, another agricultural economic crop. The technical benefits are a longer service life and higher productivity, and these are accompanied by lower costs and a higher financial return. From a socio-economic point of view, both the farmers producing the lactic acid raw materials and the rubber farmers gain from better economic returns for their crops. Additionally, eliminating the use of PP root trainers helps farmers to operate more sustainably. Although the research and development of root trainers is still ongoing, other tests are planned in larger areas with different climatic conditions. The initial test results in Rayong have indicated the practicality of growing rubber in PLA root trainers. Due to a longer life of the rubber trees the projected economic benefits of PLA root trainers translate to approximately EUR 850 per tree additional income from more harvested latex for the farmer. The application of PLA root trainers is just one example of bioplastics in agriculture. The same concept could be applied to other economic crops, fruit trees, and reforestations. Buss Kneader Technology Leading Compounding Technology for heat and shear sensitive plastics For more than 60 years Buss Kneader technology has been the benchmark for continuous preparation of heat and shear sensitive compounds – a respectable track record that predestines this technology for processing biopolymers such as PLA and PHA. > Uniform and controlled shear mixing > Extremely low temperature profile > Precise temperature control > High filler loadings Buss AG Switzerland bioplastics MAGAZINE [02/17] Vol. 12 25

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