QLK5-1999-01298 BIOFOAM: Bio-source based recyclable poly (ester-co-amide)s and poly (ester-co-urethane)s for industrial foam applications

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Contract No:	QLK5-1999-01298
Source:	Mid-term Report - April 2002 - Executive Summary
	Progress Report - April 2003 - Summary

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Progress Report -April 2003 - Summary

The BIOFOAM project aims at developing foams from aliphatic segmented poly(ester-co-amide) and poly(ester-co-urethane) block copolymers synthesised with chemicals obtainable from renewable feedstock. In the first three years of the four years project, the RTD activities focused on developing flexible open cell foams from segmented poly(ester-co-amide) (PEA) block copolymers. The specific focus on PEA was imposed by the need to converge to a manageable RTD activity and the constraints on the ultimate polymer required in terms of renewable feedstock and intrinsic properties. Furthermore, the timeline dictated finding a balance between what is practically possible and ultimately desirable in terms of foam applications.

In the first instance the renewable feedstock selection required very specific target chemicals. Secondly, the polymer synthesis needed to be scalable in order to provide sufficient materials for foaming trials. The synthesis process needed to offer a sustainable perspective balancing an economically viable polymer manufacturing with the required environmental and polymer performance properties. Thirdly, making polymeric foam needed to be feasible either through the classic polyurethane foaming route allowing a fluid to spontaneously foam or through the foaming action of a physical blowing agent introduced into a polymer melt.

The current objectives of the project are still in line with those defined at the outset but have been refined into a very specific set of goals and targets in line with the challenges of the RTD findings. The refined project focus substantially advanced the RTD progress and allowed setting well defined renewable chemical and polymer synthesis pathways to achieve the project goals through the life cycle management modelling.At this stage of the project all workpackages (WP's) are still being addressed.

Significant progress has been made in the definition of the renewable feedstock options and the associated chemistry routes that provide the basic elements for the synthesis of PEA. Very detailed literature and experimental validation of these routes either via conventional chemistry or biotechnological routes have been carried out. This information is essential for the Life Cycle Management Analysis that supports the overall decision making and combines and evaluates the three aspects of:

• sustainability
• environmental impact
• economic and societal impact

All data are captured into the newly developed software GaBi4 allowing 'what if' scenario evaluations and enable the cost of production of the material to be estimated. Costs of up to 5 euro per kg may be reduced substantially in view of varying feedstock pricing and selected routes for their synthesis, while the overall environmental and societal impact of the PEA is considered to be positive.

On a laboratory scale various types of PEA polymers have been synthesised. The variables are type of "hard segment" and concentration of the "hard segment". The subsequent "hard segment" is then further reacted. The complete reaction thus consists of two steps, making first the "hard segment" and second, reacting the "hard segment" with the other chemicals to make the polymer via a step-growth reaction. The chemical composition and associated intrinsic PEA properties are then determined. The scaling up of the hard segment proved to he very straightforward. A mayor step forward is made making this synthesis solvent free. However, the second step, the PEA polymerisation process proves to be difficult. Several approaches have been tried but so far the molecular mass achieved is limited. Surprisingly, the relatively low molecular mass polymer shows very interesting characteristics. It has a low shear rate independent viscosity (<20 Pa,s at 160 ^oC) and a solid state tensile behaviour comparable with low density (LDPE) or linear low density polyethylene (LLDPE). The resilience and paintability are significantly better than for PE. The next step is to evaluate the foaming behaviour of these polymers as well as the polymer and foam application biodegradability and reecyclability.

In addition to the polymer investigations, some of the oligomeric PEA and extended laboratory scale PEA have been used to explore conventional polyurethane foaming routes. The incorporation of the PEA is anticipated to be beneficial when reducing the foam density as it introduces additional stiffness.

Significant advances have been made in the foam modelling effort, in both the microscopic as well as macroscopic foam process simulation. Multiple bubbles either homogeneously or heterogeneously nucleated can he simulated to expand and coalesce. Realistic foam structures are simulated in generalised Newtonian fluids under non-isothermal conditions. This is only possible through a major breakthrough in the finite element simulation techniques used. In addition to the bubble growth technology, macroscopic foam front evolutions arc simulated reflecting the growth of the entire foam as defined by the individual bubbles. It reflects a major advance in the simulation of foam dynamics with important applications into the field of injection moulding.

At the start of the BIOFOAM project's fourth year, the consortium is a strong team of complementary players with clearly defined goals, and dedicated and motivated individuals. The collaboration between the partners is outstanding. Despite a number of unanticipated RTD results challenging the initial expectation level the overall objectives of the project are expected to be reached. Moreover, some significant RTD advances are already achieved in terms of renewable feedstock, Life Cycle Management Analysis and foam modelling. The unexpected performance of relatively low molecular mass PEA suggests a number of potential applications well beyond the originally foreseen foams and its applications.

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Mid-term Report -April 2002 - Summary

This project aims to develop closed and open cell foams from segmented aliphatic poly(ester-co-amide) and poly(ester-co-urethane) block copolymers. The strategic intent of the project is to develop an isocyanate free foam that has comparable or better properties than the classic flexible polyurethane foam. The chemistry to achieve this is different and should be considered as an alternative. The envisaged advantage is the application of such foam into higher added value markets in order to compensate for the potentially higher renewable feedstock cost. Alternatively to the synthesis of high polymers, the use of lower oligomeric molecules is envisaged to function as building blocks in existing PU type foaming processes. This can lead to hybrid PU foams with potential improved performance properties functioning as an intermediate step towards fully renewable foams. The selected monomers to synthesis these biodegradable polymers are to be obtained from a renewable feedstock.

Objectives

The overall project objectives are:

• Define and use a renewable bio-source based feedstock for the synthesis of recyclable aliphatic block-co-polyesters with an emphasis on Poly(ester-co- amide)s and Poly (ester-co-urethane)s.
• Chemically synthesise with high efficiency a range of block co-polyesters that meet the processing and intrinsic property requirements of a foam application at a cost of less than one Euro per kg.
• Develop industrially important biopolymer foams that contribute to the efficient and cost effective recyclability of waste streams. At least one novel biopolymer for a high value, foam market application currently dominated by Polyurethane, Polystyrene and Emulsion polymers.
• Develop a numerical model that allows quantitative 3-D predictions of a foaming process for chemical and physical blowing agents and that takes into account the novel biopolymer rheology and processing conditions.
• Develop a Life Cycle Management Analysis (LCMA) method that integrates economic, environmental and societal considerations to direct the renewable bio- source, biopolymer and biofoam developments.
• Integrate the methodology into a software package to provide European Work-process guidelines for new product developments.

Results

The first two years of the four years project that started in March 2000, focussed on identifying and exploring potential renewable feedstock, laboratory scale synthesis of the segmented block copolymers, their characterisation, and exploring ways to scale-up their manufacturing. In addition, initial foaming experiments were carried out and significant progress made in developing an efficient methodology for 3-D modelling of multiple bubble growth simulating the foaming process. Initial data for the Life Cycle Management Analysis were gathered and consolidated into a software tool to facilitate decision-making.

During this period, particular attention has been paid to identifying renewable feedstock and to defining efficient routes to obtain the specific eight monomers (ethanediol, butanediol, ethylenediamine, butanediamine, adipic acid, suberic acid, delta- valerolactone and eta-caprolactone) that compose the segmented block copolymers. A significant body of literature has been examined and reported. The most promising routes are being explored experimentally. Simultaneously, using petrochemical based monomers a systematic lab-scale synthesis of poly-ester-amide (PEA) polymers with varying amide content was completed including the structural and physical characterisation of the samples.

The lab-scale synthesis experience formed the basis for exploring the scale-up from gram to kilogram samples of one specific PEA (having about 25 mol % amide content). Alternative routes for scale up were explored in order to improve the production cost. At present about 500 g quantities have been prepared of amide "hard-segment" and segmented PEA oligomer up to a molecular weight of about 2500 g/mol.

Cost estimates have been made for the base polymer based on current market monomer pricing. Extended calculations for renewable feedstock monomers indicated a significant higher price up to 2 to 3 times more. These numbers suggest that it will be possible to obtain foams of the target price.

In order to explore the foaming of segmented PEA resins in the absence of kilogram quantities foaming experiments with super critical C0₂ using commercially available random polyester-amide copolymers were performed in an autoclave and on a twin screw extruder. These polymers are expected to behave similarly in the molten state as the segmented PEA resins of this project. The foam target is set to a density of preferably 30 kg/cubic m, being flexible and with an operational temperature window between -50 to 140 degrees C. The flexibility and temperature requirements are considered reachable, but so far only closed cell foams of about 80 kg/cubic m have been made.

In parallel to the synthesis activities, the first results for a full 3D simulation of multiple growing bubbles in a viscoelastic liquid has been completed. The software framework operates on a PC and is based on existing commercial software REM3D.

In addition significant advances have been made in the area of Life Cycle Management Analysis (LCMA), with development of the overall software framework to perform detailed comparisons of selected options based on environmental, social and labour implications. This forms the basis for guiding the monomer feedstock and process selection.