A Process to Engineer and Manufacture Medium to High Value 3D Products Using Mixed Polymer Recyclate

Periodic Report Summary 2 - PRIME (A Process to Engineer and Manufacture Medium to High Value 3D Products Using Mixed Polymer Recyclate)

Project Context and Objectives:

The PRIME (Plastic Recyclate Impression Moulding Engineering) process is aimed to produce sandwich panels of two outer layers (referred to as skins) and a core which is composed of mixed plastic recyclate. The reuse of mixed waste plastics is appropriate for low to medium value products such as building materials, flood barriers, temporary structures, flooring and marine products.

The project aims are the following:

• Capability to manufacture complex three dimensional components from a combination of virgin polymer, mixed recycled polymer and reinforcing materials. The overall aim is to achieve mechanical strength/stiffness adequate to replace aluminium alloys for some applications without excessive increases in cross section (strength to weigh ratio etc).
• Capability to uniformly apply a virgin polymer skin layer in a mould profile that deviates by more than 20° from the horizontal plane
• The option of being able to incorporate either discrete reinforcing materials or composite skins without compromising recyclability
• Capability to produce components that are resistant to UV, Ozone, water, fire and other environmental degradation mechanisms
• Development of design tools that will enable accurate computation of mechanical properties of an arbitrary PRIME material cross section as a function of skin thickness, reinforcement, core thickness and second moment of area.
• Development of a rapid heating/cooling system to optimise heat transfer and reduce cycle times

The Overall strategy is based on a number of technical work packages:

WP1 Preparatory Research.
WP2 Development of PRIME process.
WP3 Mould heating system design
WP4 Design tool and knowledge base.
WP5 Integration of pilot PRIME production system
WP6 Flood barrier product design.
WP7 Validation of knowledge base and design tools.

After Period 2 work packages 1 – 4 are complete and 5 -7 will be completed in Period 3

For the 2nd Period of the PRIME project there was one scientific objective to be met:

Development of an electrostatic technique to apply a polymer skin layer to the 3-D moulds halves.

The Scientific Objective was tried in P1 and was reported that this was not viable; this was also approved in the P1 review

There were also two technical objectives to be met:

1. Development of a process to incorporate fibre or other reinforcement into the skin layer.
2. Development of a mould heating system based on sprayable conductive ceramic heating elements and infrared radiative heating.

Both of these technical objectives have been fully met

1. Skins have been trialled and chosen that a) can have reinforcement added or b) can be purchased with reinforcements already added, all of these have been taken forward to board manufacture in P3.
2. Both sprayable conductive ceramic heating elements and infrared radiative heating were trialled and a gas catalytic infrared radiative heating system has been chosen to take forward as the preferred heating system. The mould heating system has been designed and is being produced for use in P3.

Project Results:

The recognition that increasing the re-use of mixed post-consumer plastics waste is an excellent opportunity to reduce the impact of high raw material prices and also help reduce Europe's growing plastics waste problem. The reuse of mixed waste plastics is appropriate for low to medium value products such as building materials, flood barriers, temporary structures, flooring and marine products. Enabling this segment to reduce materials costs will lower demand for virgin polymers which will have a downward effect on raw material prices. Simultaneously, the increased demand for recyclate will help the polymer recycling industry.

The PRIME (Plastic Recyclate Impression Moulding Engineering) process is aimed to produce sandwich panels of two outer layers (referred to as skins) and a core which is composed of mixed plastic recyclate. The reuse of mixed waste plastics is appropriate for low to medium value products such as building materials, flood barriers, temporary structures, flooring, road side furniture, marine products and other uses are still being investigated.

In P1 basic research was carried out. A series of panels were made consisting of different skin and core and tested for flexural test (3 point bend), impact test (Charpy and Drop), density, water absorption and thermal expansion. The results of all the different tests v skin core combinations were analysed and materials chosen for further trials. An extensive literature survey with regards to the process of environmental degradation and fire resistance of the proposed materials was undertaken. Full environmental and fire resistance testing will be carried out in P3.

The development of PRIME process was completed. A study was carried out to determine the feasibility of employing electrostatic methods to apply a polymer skin to a mould tool prior to fusing the outer skins with the core material in the PRIME process; however limitations imply that electrostatic techniques are unfeasible in view of the objectives of this project. PRIME samples of both reinforced and none reinforced were manufactured and tested. Combinations of mixed waste core materials and different skins have been identified for different product specifications.

A simplified mould / polymer heat transfer model was been carried out in P1 and further developed for both the sprayable ceramic element and gas catalytic heating system and concluded that the energy required increases linearly with panel area and core thickness. Also that the time required is essentially constant with panel area but increases exponentially with core thickness.

The Gas IR heating systems has been chosen. The benefits are that it is highly efficient and different wavelengths of IR can be used with the system to finally tune the sintering process. The Ceramic sprayable element was evaluated. Although this appears an exciting process the rate of heating was to slow to be a viable process.

The reinforcement strategies examined in P1 a) reinforcement of the skin layer and b) design (by modelling) was further developed. It was concluded that a flat panel using the reinforced skins can meet the required specifications. Modelling of the PRIME beam, using standard beam theory and corresponding analytical formulas was carried out and this work led to the development of a design tool able to quickly provide quantitative data on the performance of the PRIME composite panels. The software uses a "traffic signal" style indicator. Green, yellow and red colours mean respectively that both, one or none of the mechanical conditions have been satisfied.

The mould heating methodology has been designed and the prototype system is in the process of being ordered for use in P3. In order to design the integrated mould for the mould heating methodology a stress/strain modelling based on FEA has been carried out. The modelled support design using I beams keeps the aluminium mould deformation below the tolerance level.

Potential Impact:

The overall objective of PRIME is to give the plastics conversion and recycling industry some leverage over raw materials costs by enabling them to substitute low cost mixed recyclate for a wide range of applications.

It will achieve this by: i) increasing the demand and utility of recycled mixed waste polymers; ii) decreasing demand for virgin polymers, metals and timbers for low to medium value engineering applications; iii) decreasing feedstock costs for plastic converters. The benefits of achieving these targets are economic as well as environmental. Currently there is very little demand for mixed waste polymer and this contributes to about 60% of all collections. It is believed that this could provide new business opportunities for our members operating in the polymer recycling industry.

This will decrease demand for other materials such as virgin polymer which will have a downward pressure on virgin polymer prices. Furthermore, the ability to produce low cost and mechanically robust recycled materials will enable the direct substitution of metals and timbers for applications such as building products and flood defence systems.

Hence, PRIME will have a significant impact on both polymer processing and polymer recycling industries whilst simultaneously reducing the amount of waste mixed polymer going to landfill. Further benefits will accrue to companies that currently require metals or timber for low-to-medium value products such as building materials, flood defence systems, temporary structures etc. These companies, such as our partners Caro FDS, Mikrolin and APM will be able to access PRIME components that are more cost-effective and sustainable.

The advantages of PRIME are not limited to the material itself; an important benefit is the capital cost of equipment for PRIME production compared to conventional conversion processes. A comparable aluminium panel (same structural integrity) will cost ~€200/ m². Hence, replacing for example an aluminium flood barrier system with a PIM equivalent would save up to €125/ m². Moreover, product weight will be reduced by 20-30% which provides significant user benefits. Also, it will enable use of larger components without causing OH&S issues. Furthermore, 3DPIM can be easily and cost-effectively recycled which means that damaged materials can be re-used. Polymer converters can thus use the 3DPIM process to diversify or reengineer their products so that they can use 20-98% recycled plastics. Hence, plastics converters will potentially be able to save between 20-50% on material costs without reducing the functionality or aesthetics of their products.

PRIME will enable a further reduction in the amount of mixed waste plastics going into landfill. This is very relevant as current near zero prices have almost brought the market for mixed waste plastics to a standstill. This is leading to serious storage problems as local authorities are stockpiling mixed waste plastics. If the price does not recover quickly there will be no storage space and the materials will have to be dumped on already scarce landfill sites.

The proposed PRIME heating system is also predicted to be more efficient in both reduced energy costs and improved production rates.

Hence, PRIME is very relevant and will contribute significantly to efforts required to comply with existing landfill legislation and EC directives such as WEEE, WFD and EC Packaging Waste Directives. Furthermore, substituting virgin polymers or aluminium will significantly reduce CO2 emissions per life cycle of the material. As substituting an aluminium panel with a PRIME panel will save 10.3 kg of CO2 per kg of material. Compared to virgin plastics such as PE or HDPE this is 8 kg of CO2 per kg.

List of Websites:

www.fp7prime.eu

Periodic Report Summary 2 - PRIME (A Process to Engineer and Manufacture Medium to High Value 3D Products Using Mixed Polymer Recyclate)

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