Polytives GmbH, a specialized manufacturer of unique polymer additives, has presented test results confirming the possibility of significant optimization of processing Plexiglas-type PMMA compounds using the bFI A 3745 process additive. The use of hyperbranched PMMA that is chemically identical to the polymer matrix enables a marked reduction of melt viscosity and an increase in melt volume rate, shorter cycle times, and lower processing temperatures and pressures, while maintaining the transparency and mechanical stability characteristic of Plexiglas, also under long-term service conditions.
Scope of the study and additive characteristics
The study covered PMMA compounds based on standard Plexiglas injection molding grades 6N, 7N and 8N. These materials were modified with the polymer additive bFI A 3745 at loadings of up to 7%. This additive is hyperbranched PMMA and is therefore chemically identical to the polymer matrix of the base material.
Incorporating an additive of the same chemical nature as the base polymer makes it possible to modify processing properties without introducing foreign phases that could impair transparency or weatherability. In practice, this translates into the ability to significantly improve melt rheology and processing parameters while maintaining the required optical properties of the finished part.
Optimization of processing parameters
According to data presented by Polytives, the use of bFI A 3745 enabled substantial improvement of key processing parameters for the tested PMMA compounds:
- a significant reduction in melt viscosity,
- a pronounced increase in MVR (melt volume rate) values, in some cases by more than 100%,
- cycle time reductions of more than 20%,
- a reduction in processing temperature, in some cases by up to 35 °C,
- a decrease in processing pressures by up to 50%.
Such far-reaching changes in processing parameters are usually associated with the risk of deterioration of the optical or mechanical properties of PMMA parts. In the case of compounds modified with bFI A 3745, however, the manufacturer reports that optical properties remain unchanged. This applies both to transparency and clarity of the material, which is crucial in applications with high optical requirements.
The reduction of melt viscosity and the increase in MVR support easier mold filling, which is important for complex part geometries. Lower processing temperatures and pressures can reduce energy consumption and lower the load on injection molding machines or extruders, which in the longer term may affect operating costs and the service life of production equipment.
Long-term stability and weather resistance
To assess the durability of materials modified with the bFI A 3745 additive, xenon weathering tests were carried out in accordance with DIN EN ISO 4892-2, method A, over a period of 10,000 hours. These tests are designed to simulate prolonged exposure to radiation and conditions similar to those in service.
The results confirm the high durability of the material. No significant changes in light transmission were observed in the wavelength range 400–800 nm, and the color changes determined by the yellowness index according to ASTM E313 remained clearly below critical thresholds, even at additive contents of up to 7%.
This means that the polymer additive bFI A 3745 does not impair, and in practice preserves, the optical properties and stability of Plexiglas compounds even under long-term exposure to weathering. This is particularly important in outdoor applications and wherever lasting transparency and resistance to light-induced ageing are required.
Impact on costs and application design
The use of the bFI A 3745 additive in PMMA compounds has both technological and economic implications. On the one hand, improved flow behavior and shorter cycle times can increase the output of production cells. On the other hand, lower processing temperatures and pressures offer potential for reducing energy demand. Combined with the preservation of material performance, this may result in a more favorable cost balance in many applications.
Oliver Eckardt, managing director at Polytives, states: "The combination of optimized processing and stable material properties opens up new possibilities for development and innovation for raw material manufacturers, compounders and processors. Especially in applications with high optical requirements, long cycle times or complex geometries, this allows for previously unimagined efficiency gains without having to compromise on material quality."
The reported test results suggest that PMMA compounds modified with the bFI A 3745 additive can be used wherever design freedom, energy efficiency and process efficiency are crucial. This applies, among others, to lighting technology, components for the automotive industry, electronics parts and the high-end consumer goods segment.
Polytives reports that further detailed technical data and graphs illustrating the test results are available in a dedicated technical article and in the latest post on the company's blog.
