Melt-spun PLA liquid-filled fibers: physical, morphological, and thermal properties

PLA hollow fibers with different internal diameters were produced as a media for liquid encapsulation via high-speed melt-spinning process, changing important parameters (e.g. material type, polymer throughput, extrusion temperature, quench flow rate, drawing ratio, and winding speed). Morphological analysis showed 300% increment (linear mode) for internal and outer diameters by increasing the polymer throughput from 14.6 to 87.6 ml/min while raising the winding speed from 500 to 1500 m/min resulted in decreasing 70 and 75% for internal and external diameters, respectively. Quench flow rate and extrusion temperature showed lower effect on just internal diameter. XRD patterns indicated that using higher drawing ratio led to increase in the fiber crystallinity. According to the physical studies, although the linear density was duplicated about 10 times by increasing the polymer throughput, but the winding speed reduced 300%. Adding the polymer throughput, as the main factor, caused the tensile strength, elongation at break, modulus, tenacity, and fracture toughness to be changed approximately +650%,+217%, -68%, -58%, and +1500%, respectively. Other parameters also influenced (described in text) on tensile performances. Thermal analysis showed lower thermal stability for the fibers extruded at higher temperature. DSC results also confirmed the same trend in the degree of crystallinity of the melt-spun fibers. Melt-spun fibers were filled with glycerol as a model liquid using the previously developed microfluidic approach. Biodegradable liquid-filled fibers were conducted on composting test. Successful biodegradation is a promising result for potential applications such as agriculture pesticide and medical drug delivery.