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FAIR-CT95-1195
A Static Mixer Reactor for Starch Graft Polymerisation (StaMiStAP) |
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Proposal No: | FAIR-CT95-1195 |
| Date Prepared: | November 2001, July 2001, November 1999, April 1998 | |
| Source: | Final Report Annual Progress Report September 2000 Abstract and Scientific Synthesis Report Annual Progress Report September 1999 First Annual Progress Report |
Annual Progress Report 2000 - Scientific Synthesis Report
Annual Progress Report 2000 - Abstract
Source: Progress Report September 2000
Consortium: This project was co-ordinated by the department of Chemical Engineering, University of Groningen, Groningen (The Netherlands), in partnership with AVEBE BA, Foxhol (The Netherlands), the department of Materials Science and Metallurgy, University of Cambridge, (UK) and BASF Aktiengesellschaft, Ludwigshafen (Germany)
Abstract
Objectives
The main aim of the project is to graft (meth)-acrylates onto starch, with a continuous static mixer reactor. The interest in such starch based products originates from the fact that they are useful as super absorbing materials, detergent compounds and in products for the paper industry. As starch is a biodegradable/renewable material, the use of these products to replace the non-degradable/renewable materials, used at this moment, is of interest. In more detail, the project aimed to:
The project is focused on processing methodologies and scale-up of grafted starch-acrylic copolymers (S-g-A polymers), which are known at laboratory scale and seem attractive for the use as superabsorbents or co-builders. To develop a continuous process for these starch polymerisation reactors objectives of the project are:
To achieve these objectives the research is sub-divided in three tasks:
Progress
During the fourth year of the project the following tasks had to be performed:
Some of these tasks were undertaken within the original time schedule set up at the beginning of the project. However, some tasks have been delayed as a result of problems encountered, that include difficulties in analytical procedures and construction of the CSMR.
During the fourth year the last drawbacks of the analytical procedure were solved, such that it is now possible to determine the percentage of grafting of acrylic acid on starch, the amount of free acrylic acid and the amount of homopolymer formed during the reaction. However, the development of an exact and accurate expression for the kinetic rate equations may still not be possible due to the relatively large errors in the analysis. Therefore an extensive literature search was carried out in order to identify feasible kinetic equations for the competitive reactions of grafting and homopolymerisation.
Some major problems concerning the operation of the CSMR with acrylic acid had to be solved. This included acquisition of an alternative acrylic acid pump was acquired.
As a result of these improvements the first reaction samples have been produced. Rheological measurements on the gelatinised starch and the reaction mixture (starch, AA and initiator) have been completed. These give an indication of the rheological behaviour of the material in the SMR. The results have been used to construct a model that can be used to define the complete reaction process in the Static mixer.
Conclusion
The remaining problems associated with the analytical procedure have been solved and hence the amount of polyacrylic-acid can be determined.
The static mixer reactor is operational for reaction runs.
A complete rheological characterisation of the gelatinised starch and the reaction mixture has been obtained.
Future actions
For the next reporting period the main tasks will be:
Introduction
Grafted starch-acrylic copolymers (S-g-A-polymers) are known at laboratory scale to have attractive properties that enables their use for products such as super-absorbents and detergents. Research activities are increasing in this area as indicated by the large number of available patents, some of which are held by the industrial partners of this project. However, research has not yet been focused on processing methodologies and scale up of such processes. Such process engineering is important as part of an overall estimation of the potential market viability of the new products. Hence, the StaMiStAP project aims remedy this by developing a continuous static mixer reactor (CSMR) for the production of grafted starch (meth)acrylic acid copolymers(S-g-A polymers). This type of reactor is attractive because of its:
The second area of activity is to test the application and biodegradation of products resulting from the new, continuous static-mixer process. Grafting of (meth)acrylic acid onto starch can result in promising products, such as super absorbing non-wovens, detergents or products for the paper industry.
Objectives
The aim is to develop this continuous process for these starch polymerisation reactors, applying the static mixer reactor and to optimise the final product properties. The project intends to undertake process development of the CSMR through an independent study of the reaction kinetics and hydrodynamics of the reactor as well as by prediction and analysis of the material properties of the S-g-A polymers as a function of the molecular structure.
Activities
To achieve these goals, the research is sub-divided in three tasks:
Progress
In the third year-of the project the following tasks were to be performed:
In addition, due to the problems encountered in the previous activities, the following tasks had to be completed.
After encountering several difficulties, a working analytical procedure has been achieved. The technique is based on the separation of the components, starch (grafted and ungrafted), poly-acrylic acid and free acrylic acid, with an acetone-water mixture. After the separation the starch fraction is quantitatively analysed by NMR. The amount of acrylic acid is analysed by HPLC. Unfortunately no PAA could yet be detected. An analytical procedure was developed that enabled sufficient data to be obtained to enable the project to continue.
Rheological measurements on the gelatinised starch and the reaction mixture (starch, AA and initiator) have been performed.
Once the analytical techniques were established, the kinetic experiments could be performed. Based on experimental results, the partners decided to use Fentons' reagent, (NH4)2Fe(SO4)2,6H20/H202, as the initiator system to be used. It gave the highest percentage of grafting at the most suitable temperature for reactor operation. However, insufficient information was obtained to set up a kinetic model. To obtain these results it will be necessary to perform extra measurements and experiments.
The construction of the CSMR was complete this year. Initial runs have been carried out to test the reactor. These runs went very well, revealing only some minor construction problems that had to be solved.
It is anticipated the first product samples from this reactor will be produced in late 1999. This will enable the various partners to continue with their tasks of product definition and analysis.
Achievements
The key project milestones reached are as follows:
Future activities
For the next reporting period the main tasks will be:
Objectives:
The project's object is to graft (meth)-acrylates
onto starch, with a continuous static mixer reactor. The interest in products of
starch, grafted with (meth)acrylates, originates from the fact that they are
useful as super absorbing materials, detergent compounds and in products for the
paper industry. As starch is a biodegradable material, the use of these products
to replace the non-degradable materials, used at this moment, becomes
interesting. Considering these aspects StaMiStAP aims to:
Activities:
StaMiStAP focuses on processing methodologies and
scale-up of grafted starch-acrylic copolymers (S-g-A polymers), which are known
at laboratory scale and seem attractive for the use as e.g. super-absorbents or
co-builders. To develop a continuous process for these starch polymerisation
reactors, e.g. applying a static mixer reactor and to optimise the final product
properties the goals of the project are:
To achieve these goals, the research is sub-divided in three tasks:
State of progress:
In the first year of the project the
following tasks had to be performed:
At the University of Groningen, initial experiments with the grafting reaction were performed. With native starch and acrylic acid as the reaction components, several aspects were researched:
The samples of the experiments were analysed by the University of Cambridge for composition and graft efficiency. An analytical procedure was developed from literature and discussions with the partner industries involved. After testing the procedure proved to be inaccurate towards the separation of the different components (PM homopolymer, free AA, grafted starch and ungrafted starch). Therefore a new analytical procedure was setup which is currently being tested for its accuracy in separating the components and determining the grafting efficiency. Although the first analytical procedure was inaccurate, trends could be deduced concerning the performance of the initiator systems. Based on these results and the applicability of the systems for the target products, a selection of initiators could be made.
The static mixer reactor was designed based on literature data, information from BASF and AVEBE, and experiments. The SMR for the grafting reaction should consist of the following parts:
The specific demands of the reaction necessitated the design of a special gelatinization section and special mixing sections for the acrylic acid and the second initiator part. Therefore the design of the static mixer reactor took considerably more time as expected.
Achievements:
Initiator systems, suitable for the grafting
process, were selected.
A new analytical procedure was set up, which is currently being tested for its applicability to the S-g-A-polymer reaction mixtures. A continuous static mixer reactor was designed for the grafting reaction of starch with acrylates.
Future activities:
For the next reporting period the main tasks
will be:
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