The majority of materials used in rotational moulding (or molding) are MDPE and HDPE (although they are commonly known as LLDPE for the rotational moulding process). The materials are widely recycled using technology available around the world. While most of the recycled material goes into the blow moulding industry more and more products are being developed to put rotational moulding material back into rotationally moulded (or molded) products such as water systems bunding pallets cattle troughs and other "non potable" applications.
These classifications of the material are very important for recycling so they can be classified in the right density range and used appropriately in different applications. The majority of rotational molding resins is in a density range of 0.933 g/cc to 0.945 g/cc which puts them in the classifications of MDPE and HDPE. The majority of blow molding recycle is in the range of 0.940 to 0.960 g/cc with a fractional melt index. It is very easy to blend roto grades into blow molding grades; however the reverse is not so easy and can lead to very poor performance.
The density classifications are (ASTM 4976) g/cc
• Ultra-Low Density ULDPE < 0.910
• Low Density LDPE > 0.910 – 0.925 (also LLDPE, low pressure)
• Medium Density MDPE > 0.925 – 0.940
• High Density HDPE > 0.940 – 0.960
• High Density HDPE > 0.960
THE RECYCLING PROCESS
RECYCLED MATERIALS ARE WIDELY AVAILABLE
An extensive range of plastic resin grades colours and quantities both prime and recycles in either granules or rotational moulding (molding) powders can currently be provided.
Using recycled resin is both environmentally and economically responsible. Recycled resins generally cost only 60% as much as prime resin. Grades commonly offered include HDPE LDPE MDPE LLDPE PP GPPS. HIPS and ABS. Supplied in multicolour black and natural (limited) in 25kg or bulk bags. Providers can also provide resins with specific additives e.g. antioxidants UV stabilizers process aids and colourants to customer specification.
OUR FAVOURITE SUSTAINABLE PROJECTS
There's some fantastic products currently being made from this recycled material and some market leading manufacturers helping consumers to recycle even large products such as water tanks. Managing products from inception through recycling and into new forms is known as product stewardship and there's an increasing amount of companies ensuring their stewardship is of the highest calibre.
Australian industry embraces sustainable design By Kate Tilley
PLASTICS NEWS CORRESPONDENT
MELBOURNE AUSTRALIA (November 17 3:10pm ET) - The Australian plastics industry is embracing an initiative by one of the nation's environmental agencies to promote sustainable product design and recycling.
Industry peak body the Melbourne-based Plastics and Chemicals Industries Association (PACIA) has joined forces with Victorian Government agency Sustainability Victoria to promote the concept of design for sustainability.
PACIA Chief Executive Officer Margret Donnan said design for sustainability shorthanded to D4S recognised that the environmental benefits and impacts of any product are "locked in" at its design stage.Donnan said a new program D4S with Plastics involves developing and publishing on the PACIA website 12 sustainability guides for between now and March 2009.She said that the guides will be used as reference material by designers and manufacturers to ensure sustainability is taken into account over the full lifecycle of a product - from the materials used to make it to its potential for recycling.
Topics covered by the guides will include the design of building products and furniture plastics recycling packaging design degradable polymers and the implications of a carbon-constrained economy."This program is important because plastics and chemicals are at the hub of every production chain " Donnan said."In addition product design will increasingly become the biggest opportunity to deliver significant improvement in our response to pressing challenges like climate change and water scarcity."
Manager of Sustainable Products and Services with Sustainability Victoria Diana Gibson said because the D4S guides will be published on the Internet they will be accessible by designers and those involved in the plastics industry throughout Australia.She said the D4S with Plastics program highlights the importance of collaboration across every stage of the product chain."Our research shows many groups are involved in making decisions about a product's design including manufacturers suppliers retailers brand owners recyclers consumers and designers " Gibson said."All these groups have the power to influence the design and therefore the sustainability of a product " she said.
Gibson said the design guides will highlight the long-term environmental and economical benefits of D4S.Examples include products being wrapped in lighter packaging so they are more efficient to transport products such as durable plastic water tanks that enable us to conserve water and shorter-life products that have been assembled in such a way that they can be recovered and dismantled for recycling " she said.
For more information on this article including D4S with Plastics see: Pacia Quick Start Documents
If you would like to find out more about recycling in the rotational moulding industry click on any of the links below for more information on projects that other companies are pursuing:
•Drum Bunds - Products made from 100% Australian Recycled Polyethylene
Association of Rotational Moulders Australasia, Inc.
National Telephone: (07) 3812 1450
Copyright 2013 - Association of Rotational Moulding Australasia