Introduction

Student: Anezka Kristanova

I am a student coming from the Czech Republic and this academic year (2019/2020). I am finishing my Master’s degree at UCT Prague in Polymer materials. I came to Nancy in order to participate in research concerning polymer membranes at LCPM and to elaborate on my Master’s thesis. At the beginning of November, I joined the Green FabLab team for my six-month internship. During this time I will be working on the project which concerns designing, building and making first trial tests of the Melt Flow Index system for evaluating plastic waste for 3D printing. This project will be in collaboration with Joshua Pearce from Michigan University.

Open Source Melt flow Index

Rheological properties are one of the most important parameters in the quality assessment of the polymer materials. Viscosity and fluidity of the material are related to the polymer’s molecular structure, which is correlated to the process parameters to take into account in the injection or printing process . Therefore, the final quality of the fabricated object (e.g. resistance, surface finish, dimensional accuracy) are related to the initial state of the material. Melt Flow Index is one of the rheological properties to measure with the purpose to qualify the recycled material is for 3D printing process.

Melt Flow Index (MFI) is an indirect technique to measure the viscosity of polymers, which is also correlated with the and the molecular weight of a polymer. It is used in polymer technology as a product specification since this value gives an indication of the processing properties of the polymer. The polymer is heated in a small oven and a normal load is applied to the molten material. The melted material is extruded through an orifice and the weight of the extruded material over a 10-min period is recorded as the melt index (MI) value. The value of MFI is expressed as the mass of polymer melt pushed from the heated cylinder of the extrusion plastometer through its precision bore orifice by its piston in a period of time, the standard units of the value being grams per ten minutes (g/10 min). The weight used was 2.16 Kg and the temperature was 180.

Of all the family of capillary flow systems the Melt Flow Indexer is the cheapest and the most widely used. This test can be repeated at two different loads to determine the flow rate ratio (FRR). Flow rate may be determined as a function of applied load so that a qualitative indication of pseudoplasticity is readily obtained by comparing the ratios of flow rate at two different loads. The MI and FRR values provide correlations to the molecular weight and molecular weight distribution. Assuming all other things are equal, the lower the MI values, the higher the molecular weight and the higher the FRR, and the broader the molecular weight distribution.

This projects is in collaboration with MTU

Goals

The main goal of the project is to design, built and test an open source melt flow index system for the LF2L Moreover, to establish the quality and reproducibility of the test process with respect to the commercial test machines.

Specific goals

The main specific goals of this internship are:

  • Mechanical Design process considering the technical and user requirements
  • Fabrication considering the resources of a innovation space such as FabLabs
  • Realization of first trials test using virgin material (e.g. PLA) for calibration purposes.
  • Calibration test with regard to the commercial machines
  • Documentation of the prototype.
  • Establishment a protocol to use considering the user experience.

Expected elements to the end of the project

The following elements are expected as results:

  1. Benchmarking of the available open source testing machines taking to account the time, expertise, difficulty to maintain and cost.
  2. Development of technical features to consider. (e.g. Quality Function Deployment (QFD)?, Analyse de la valeur?)
  3. CAD models with the final version of the prototypes
  4. An on-line platform (e.g. a wiki, html page) for a complete documentation
  5. Bill of Materials (BOM)
  6. CAD model

Planning

First week

  • Introduction to the project
  • Print of the first object

Second week

-[X] Introduction to the project

November

December

January

February

Mars

April