Polymer Library

Recycling of Rubber - September 2015

This month we are focussing on recycling rubber and the issues around this.

The recycling of rubber has been a problem for some time and the environmental implications of this situation mean that a great deal of research is carried out in this field, whether it be finding alternative uses for recycled/reclaimed rubber, or methods of devulcanisation (depolymerisation) processing the vulcanised rubber back to the non-polymerised monomer state so that it may be used again.

Recycling rubber has huge advantages, despite the difficulties in doing so. Cost is one big advantage. It can be as little as half the price of new natural or synthetic rubber, partly due to the lower levels of energy required for processing and some recovered rubber, surprisingly, has some properties that are better than with virgin rubber. There are also advantages in the form of the conservation of the feedstock of natural petroleum products required to manufacture new synthetic rubber.

Why not read some of the latest literature in this area? There is a selection of abstracts from the Polymer Library on this subject below.

Abstracts

These abstracts were highlighted in the September Newsletter and found in the Polymer Library.

Click on the 7-digit accession numbers to find out about ordering a copyright-cleared full text copy of the items shown.

1206024 - Recycling of natural rubber-based waste tyres - a green environment for the future
The recycling of NR-based scrap tyres is dealt with in this chapter. Sections are included on types of scraprubber recycling methods, recycling technologies (grinding, microwave reclaiming, pyrolysis and burning of scrap tyres for energy), reaction mechanisms for reclaiming of vulcanised rubber, applications of reclaimed rubber and technical and economic barriers to the recycling of scrap tyres. 48 refs.
Recycled polymers: chemistry and processing, volume 1, Shawbury, Smithers Information Ltd, 2015, p.205-238, ISSN: 978-1-90903-096-1; 978-1-90903-097-8; 978-1-90903-098-5
Prasanth R; Liehui Ge; Joyner J; Xifan Wang; Owuor P; Thakur V K

1198925 - Waste management through life cycle assessment of products (OPEN ACCESS - FREE ACCESS TO FULL TEXT)
The rapid growth of a population in a country can contribute to high production of waste. Municipal waste and industrial waste can bring unhealthy and unpleasant environment or even diseases to human beings if the wastes are not managed properly. With increasing concerns over waste and the need for 'greener' products, it is necessary to carry out Life Cycle Assessments of products and this will help manufacturers take the first steps towards greener designs by assessing their product's carbon output. Life Cycle Assessment (LCA) is a process to evaluate the environmental burdens associated with a product, process or activity by identifying and quantifying energy and materials used and wastes released to the environment, and to assess the impact of those energy and material used and released to the environment. The aim of the study was to use a life cycle assessment approach to determine which waste disposal options that will substantially reduce the environmental burdens posed by the Polyethylene Terephthalate (PET) bottle. Several important observations can be made. Recycling of the PET bottle waste can significantly reduce the energy required across the life cycle because the high energy inputs needed to process the requisite virgin materials greatly exceeds the energy needs of the recycling process steps. Greenhouse gases can be reduced by opting for recycling instead of landfilling and incineration. Quantity of waste emissions released from different disposal options was identified. Recycling is the environmentally preferable disposal method for the PET bottle. Industry can use the tools and data in this study to evaluate the health, environmental, and energy implications of the PET bottle. LCA intends to aid decision-makers in this respect, provided that the scientific underpinning is available. Strategic incentives for product development and life cycle management can then be developed. 5 Refs.
IOP Conference Series: Materials Science and Engineering, 81, 2015, paper 012085, pp.7, ISSN: 1757-8981, DOI:10.1088/1757-899X/81/1/012085
Borodin Y V; Aliferova T E; Ncube A

1194315 - A novel industrial technique for recycling ethylene-propylene-diene waste rubber
Recycling waste rubber has gained importance in recent years. Ethylene-propylene-diene rubber (EPDM) is used to manufacture various automotive parts. Reclaiming EPDM rubber waste is a major problem. Waste powder from discarded EPDM automotive parts was devulcanised using an industrial autoclave which provided both heating and high pressure steam. To aid the devulcanisation process, 2-mercaptobenzothiazoledisulphide (MBTS) and tetramethylthiuram disulphide (TMTD) devulcanising agents, and aromatic and aliphatic oils were also used. A portion of the virgin EPDM rubber in a common formulation for the automotive rubber strips was replaced with the devulcanised product to produce blends, which were revulcanised using a semi-efficient (SEV) vulcanisation system. The viscosity, cure and mechanical properties of the blends were subsequently determined. This study showed that the oils had different effects on the devulcanisation of the waste powder and MBTS was more efficient than TMTD. Replacing 60 wt% of the virgin rubber in the automotive rubber strips with the devulcanised powder had no adverse effect on the scorch and optimum cure times, crosslink density, rate of cure, and viscosity. Also, when 20 wt% of the virgin rubber was replaced, the hardness, compression set, and modulus at 20% elongation were unaffected. It was concluded that the reclaimed rubber could be used in low percentage in order not to extremely deteriorate the mechanical properties of the virgin rubber. This provided a new effective recycling route for the waste EPDM powder in the automotive rubber strips. 50 refs.
Polymer Degradation and Stability, 111, No.1, 2015, p.114-123, ISSN: 0141-3910, DOI: 10.1016/j.polymdegradstab.2014.11.003
Mohaved S O; Ansarifar A; Nezhad S K; Atharyfar S

1200759 - Effects of silica on properties of reclaimed butadiene rubber/polyolefin thermoplastic vulcanizate
The reclaimed butadiene rubber (RBR)/polyolefin (POE) thermoplastic vulcanisate (TPV) was prepared by dynamic vulcanisation technology, and the curing characteristics of sulphur curing system and the effect of silica on the physical properties and dynamic mechanical properties of RBR/POE TPV were investigated. The results showed that RBR/POE TPV could be further vulcanised with the sulphur curing system. The modulus at 300% elongation and tensile strength of RBR/ POE TPV increased as the addition level of silica increased, while the elongation at break and tensile permanent set decreased. Moreover, the modulus at 300% elongation, tensile strength and storage modulus of RBR/POE TPV filled with Si69 modified silica were higher compared with those of RBR/ POE TPV filled unmodified silica, respectively, while the elongation at break and tensile permanent set were lower.
China Rubber Industry, Original Language: Chinese, 62, No.3, 2015, p.154-157, ISSN: 1000-890X
Liu Su-su; Liu Guang-yong; Ji Chang-Yuan; Qiu Gui-xue

1192266 - Production of thermoplastic elastomer foams based on recycled rubber
Recycled EPDM was blended with PP with and without a coupling agent (PP-g-MA) to produce thermoplasticelastomers and the processing, morphology and mechanical properties of the blends investigated. The effects of blend composition and feeding strategy (order and position along the extruder screw) were investigated to optimise blend properties. The optimised blends were then used to produce thermoplastic elastomer foams by injection moulding and the effects of recycled EPDM content and chemical blowing agent concentration on the density, hardness, morphology and mechanical properties of the foams investigated. 28 refs. (Blowing Agents and Foaming Processes, 13-14 May 2104, Vienna, Austria, iSmithers)
TPE Magazine International, 7, No.1, 2015, p.40-45, ISSN: 1868-8055
Mahallati P; Rodrigue D

1189704 - Asphalt gets cooler, greener (Short Article)
The results of a survey of asphalt mix producers conducted by NAPA under contract to FHWA in mid-2014 are briefly reported. According to this survey, 106.4 million tons of WMA was produced in 2013 and about 73.5 million tons of reclaimed asphalt pavement and 1.7 million tons of reclaimed asphalt shingles were used in new asphalt pavements mixes in the USA in 2013.
Scrap Tire News, 29, No.2, Feb. 2015, p.13

1186197 - Brief history of rubber recycling
A brief history of the recycling of rubber is presented, looking at the development of reclaiming processes in the 19th century and the impact of World War II, the oil crisis of the 1970's and the advent of environmental legislation and environmental awareness throughout society on rubber recycling. The future of rubber recycling and its sustainability and economic viability are also briefly considered. 8 refs.
Recycling and re-use of waste rubber, Shawbury, Smithers Information Ltd, 2014, p.11-15, ISSN: 978-184735-682-6; 978-184735-684-0
Forrest M

DON'T FORGET!

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The Recycling of Rubbers Polymer Bulletin is available with 20% off until 10 November 2015.

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