HMC Funds University Research

HMC Polymers is constantly seeking new material options for customers to enable them to stay at the leading edge. The company sponsors a number of long-term programs and research relationships investigating new materials, processes and additives.

The results of one such HMC research project at the Chulalongkorn University (Bangkok, Thailand) looking at new material benefits based on the use of chitosan as a polypropylene additive, has now been published.

Chulalongkorn University is the oldest university in Thailand comprising twenty faculties, and has an international reputation as one of the best learning and advanced technology-based research institutions in East Asia with more than thirty-five research centres within the university.

The key subject of the research was chitosan which is a natural polysaccharide derived from the chitin component of the shells of crustacean, such as crab, shrimp and cuttlefish.

Research into chitosan has found that it can offer cost effective and renewable advantages as a natural filler for thermoplastics particularly for the production of isotactic polypropylene (iPP) fibres.

In addition, chitosan has high oxygen barrier properties and may offer possible future benefits in the development of renewable additives for packaging materials and other applications.

HMC manufactures a significant volume of isotactic polypropylene for the synthetic fibres and textiles market.

The properties of iPP fibres can be enhanced by melt mixing with fillers including particulates such as pigments, antioxidants, nucleating agents and clarifying agents and fibrous materials as well as by melt blending with other polymers.

Natural fillers are one of candidates offering the advantages of cost effectiveness and renewability. Dr. Kawee Srikulkit, the project team leader, said “chitosan is a promising candidate due to biodegradability, non-toxicity and antimicrobial activity.”

However, due to the abundance of hydrophilic groups, melt mixing chitosan with thermoplastic polymers presented a key challenge for Dr. Srikulkit. In order to solve this problem, the chitosan particle surface was changed using modified soybean oil.

The successful solution prepared in Dr. Srikulkit's laboratory was based on chitosan encapsulated with soybean oil. As a result, Dr. Srikulkit has reported that homogenous dispersion of hydrophobic chitosan in polypropylene matrix by melt mixing is now indeed possible.

The research phases for the development of a polypropylene/soy oil grafted chitosan (PP-SO-CTS) composite were:

First: The surface modification of chitosan particles by reacting chitosan powder with functionalized soybean oil.

Second: The resulting SO-CTS powder was mixed with PP resin using a twin-screw extruder to obtain a masterbatch containing 10 wt% SO-CTS.

Third: The dog-bone shaped samples with the final loadings of 1 wt%, 2 wt% and 4 wt% SO-CTS were prepared using a twin screw extruder. The mechanical properties evaluated included tensile strength, elongation at break, impact and flexural strength. Heat distortion temperature (HDT) was also measured.

And finally: Testing of the antimicrobial activity of the composite was performed and tabulated.

These first encouraging steps offer insight into future possibilities for our customers in fibers, packaging and other markets. We thank Dr. Srikulkit for his research as part of our broader effort to bring new and differentiated additions to the HMC product portfolio.