*Communication* **A Potential of New Untreated Bio-Reinforcement from** *Caesalpinia sappan* **L. Wood Fiber for Polybutylene Succinate Composite Film**

**Ekkachai Martwong <sup>1</sup> , Yvette Tran <sup>2</sup> , Nattawadee Natsrita <sup>3</sup> , Chaithip Kaewpang <sup>3</sup> , Kittisak Kongsuk <sup>3</sup> , Yeampon Nakaramontri <sup>4</sup> and Nathapong Sukhawipat 3,\***


**Abstract:** Natural cellulose-based *Caesalpinia sappan* L. wood fiber (CSWF) has been demonstrated to have significant promise as a new untreated bio-reinforcement of the polybutylene succinate (PBS) composite film. The morphology, mechanical characteristics, and biodegradation were investigated. The morphology, the fiber distribution, and the fiber aggregation has been discussed. The properties of the composite have been improved by the addition of CSWF from 5 phr to 10 phr, while with the addition of 15 phr, the properties were dropped. The result showed that CSWF could be used as a new reinforcement without any treatment, and 10 phr of CSWF was the best formulation of a new biocomposite film. The PBS/CSWF10 composite film had the highest mechanical strength, with a tensile strength of 12.21 N/mm<sup>2</sup> and an elongation at break of 21.01%, respectively. It was completely degraded by soil bury in three months. Therefore, the PBS/CSWF10 composite film has the potential to be a green with a promising short-term degradation.

**Keywords:** biocomposites; polybutylene succinate; polymer films; fiber; cellulose; bio-reinforcement
