Spiga Nord > Polyglycerols for the bioplastics industry
Technical polyglycerol and polyol formulations based on glycerine and polyglycerols offer versatile solutions for developing bioplastics, starch-containing compounds, and thermoplastic starch-based materials, known internationally as Thermoplastic Starch (TPS).
Starch is a renewable and widely available raw material, but its crystalline structure prevents it from being processed directly like a common thermoplastic polymer. To convert it into TPS, it must undergo a gelatinisation and plasticization process that combines water, heat, mechanical energy, and plasticisers. In this process, polyols interact with the hydroxyl groups of the starch, modify chain interactions, and promote the molecular mobility necessary to obtain a material that can be processed using traditional polymer processing technologies.
Scientific studies conducted on starch-based systems have shown that, in addition to glycerine, diglycerol and polyglycerols can also be used as plasticisers in the preparation of TPS. Molecular weight, viscosity, hydrogen-bonding capacity, affinity for water, and oligomeric distribution influence the behaviour of the formulation during gelatinisation and subsequent processing.
Spiga Nord offers Refined Technical Polyglycerine and custom-formulated products created by combining different polyglycerols, glycerine, and, when required, water. This approach allows for the development of polyol systems tailored to the characteristics of the matrix, the extrusion conditions, and the objectives of the final product.
From oligomer distribution to compound performance: polyol systems developed to meet the needs of bioplastics.
Starch has a crystalline structure that cannot be processed directly like a conventional thermoplastic material. To convert it into thermoplastic starch (TPS), it must undergo a process that combines water, a plasticiser, heat, and mechanical shearing—typically generated during extrusion.
Under these conditions, glycerine and polyglycerols interact with the hydroxyl groups of the starch, reducing the interactions between its chains and promoting their mobility. The crystalline structure is thus progressively disrupted, making the material processable using traditional polymer processing technologies.
The system’s behaviour depends on the ratio of water, glycerine, and polyglycerols, the oligomeric distribution, viscosity, and process conditions. For this reason, Spiga Nord can develop customised polyol formulations, tailoring the composition to the characteristics of the matrix and the production facility.
Developing a bioplastic requires striking a complex balance among the source of the raw materials, industrial processability, and the stability and performance of the final material.
In systems containing starch, one of the main challenges is transforming a raw material that is naturally rigid and moisture-sensitive into a thermoplastic phase that is sufficiently homogeneous and processable. The plasticiser must allow the starch to gelatinise during the process, while maintaining behaviour compatible with the temperatures, residence times, and shear stresses generated by the system.
Glycerin is one of the most widely used plasticisers for TPS due to its effectiveness and availability. However, its low molecular weight can be a limitation in certain formulations, especially when greater stability at processing temperatures, lower sensitivity to moisture, or different behaviour within the matrix is desired.
In specific experimental formulations, TPS plasticised with polyglycerol exhibited lower moisture absorption and higher thermal stability compared to TPS plasticised exclusively with glycerine. The same studies highlighted good compatibility between polyglycerol and starch, as well as overall comparable mechanical properties in the analyzed TPS/polyethylene blends. These results depend on the composition, the type of polyglycerol, and the processing conditions, and cannot be automatically generalised to every formulation.
The challenge, therefore, is to identify the most suitable combination of:
The composition of the plasticiser system thus serves as a means of modulating the behaviour of TPS during compounding and the properties of the resulting material.
Refined Technical Polyglycerine is a refined technical polyglycerol characterised by a broad and controlled oligomeric distribution.
The presence of residual glycerine, diglycerol, triglycerol, and higher oligomers enables the production of a functional polyol for industrial formulations and thermoplastic starch-based systems.
Refined Technical Polyglycerine can be considered as a plasticising component in TPS-containing compounds, where the higher molecular weight of the oligomeric fractions may result in different behaviour compared to glycerine alone. Its actual performance must be evaluated based on the matrix, dosage, and processing conditions used by the customer.
The product features a controlled water content and a well-defined distribution of the main oligomeric fractions, providing a consistent foundation for formulation development. It is produced from GMO-free vegetable glycerine and is available with Kosher and Halal certifications.
Every starch-based formulation has different requirements. That is why Spiga Nord can develop customised polyol formulations by adjusting the composition to meet the customer’s technical objectives.
The preparations may include:
The ability to adjust the ratio of glycerine, diglycerol, and higher oligomers makes it possible to modify the average molecular weight and the profile of the plasticising system. Water can also be incorporated in controlled amounts when it serves as a functional parameter for the starch gelatinisation process.
A diluted preparation should therefore not be considered simply as a less concentrated version. In TPS systems, water plays a direct role in the gelatinisation process, influences the initial viscosity of the mixture, and promotes the penetration of the plasticiser into the starch granules. The most appropriate amount must be determined by considering the overall formulation and compounding conditions.
The specifications for custom formulations are agreed upon with the customer based on technically relevant parameters, such as oligomeric composition, glycerine content, water content, colour, and processing characteristics.
Choosing Spiga Nord means partnering with a manufacturer that specialises in the chemistry of glycerine and polyglycerols, capable of offering both standardised technical products and the ability to develop customised formulations.
Knowledge of the entire oligomer range makes it possible to adjust the polyol system composition by combining glycerine, diglycerol, and higher-chain polyglycerols according to customer needs. This represents a tangible advantage in the development of bioplastics, where raw material composition and process conditions are closely linked.
Spiga Nord can assist customers in defining the key parameters of the formulation, including oligomeric distribution, the ratio of glycerine to polyglycerols, and any water dilution.
Our approach is not to propose a one-size-fits-all solution, but rather to provide a flexible polyol platform that can be evaluated and optimised in collaboration with the compound manufacturer.
For Spiga Nord, every project in the bioplastics sector begins with an analysis of the matrix, the process, and the desired outcome. The goal is to transform the oligomeric distribution of polyglycerol into a formulative tool for the development of more advanced materials.
Our Products
Refined Technical Polyglycerine by Spiga Nord is a high-purity, multi-functional ingredient derived from vegetable glycerine.
It offers excellent lubricating, dispersing, and stabilizing properties, making it suitable for a wide range of industrial and technical applications.
Reliable and efficient, as PG-Ester or by itself, it supports improved process performance, product consistency, and formulation stability.