Effect of coir fibers and their acid hydrolyses on properties of thermoplastic starchpoly(Lactic acid)coir fiber composites

Name: Patra Chotiprayon.

LCSH: Kasetsart University -- Theses. M.S. (Packaging Technology) 2019.

Classification :.LCCS: TP1180.B55

LCSH: Kasetsart University. -- Department of Packaging and Materials Technology -- Theses.

LCSH: Biodegradable plastics.

LCSH: Thermoplastics.

LCSH: Starch -- Thermal properties.

LCSH: Lactic acid.

LCSH: Hydrolysis.

Abstract: One alternative way to make a large amount of coconut waste more benefits is their coir fiber (CF) utilization as reinforcement for biodegradable plastics. The current thesis is divided into two parts. The first part aims to study the effect of CF on performances of thermoplastic starch (TPS)/polylactic acid (PLA) blend. TPS/PLA/CF composites, with a constant weight proportion of TPS:PLA of 60:40 and various concentrations of CF of 2.7 wt%, 5.5 wt%, 8.2 wt%, and 10.9 wt%, were fabricated using an extruder and then injection molded into dumbbellshaped specimens for property testing. The obtained TPS/PLA/CF composites possessed improved stiffness and hardness corresponding to the stronger hydrogen bond interaction between starch and PLA and/or starch and CF, and the increased PLA crystallinity. Due to the reinforcing effect, the composites showed lower extensibility, tensile strength and impact strength than the TPS/PLA blend. Incorporating CF also caused reduced melt flow ability, increased shear viscosity, and decreased shear thinning effect of the blend. The second part focuses on the acid hydrolysis of CF to produce smaller fibers for improving the properties of TPS/PLA blend. Different types of acid, including sulfuric acid, hydrochloric acid, and nitric acid were applied to hydrolyze delignified coir fibers (DCF) and the effects of acid type, acid concentration, and hydrolysis time on characteristics and properties of CF and DCF were investigated. Sulfuric acid-hydrolyzed coir fibers (SDCF) showed the reduction of fiber length for more than 90 %, but nearly constant diameter. In contrast, hydrochloric acid- (HDCF) and nitric acidhydrolyzed coir fibers (NDCF) became smaller (88–93% diameter reduction) and shorter (41–91% length reduction) as compared with DCF. The highest aspect ratio, narrow size distribution and higher crystallinity of NDCF are the reasons to choose for further adding into TPS/PLA blend. The blends filled with CF, DCF, and NDCF (1, 5, and 10 wt%) were prepared using the same above methods. Although TPS/PLA/NDCF composites showed poorer mechanical properties than TPS/PLA/DCF composites, high melt flow ability, crystallinity, thermal stability, and nucleating effect were advantages for TPS/PLA/NDCF composites particularly at high NDCF concentrations of 5 wt% and 10 wt%. The TPS/PLA/coir fiber composites are potentially used to produce biobased and biodegradable injectionmolded products.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Rangrong Yoksan.

Role: Thesis Advisor

Name: Amporn Sane.

Role: Thesis Co-Advisor

Created: 2019

Modified: 2025-06-23

Issued: 2025-06-23

วิทยานิพนธ์/Thesis

วิทยานิพนธ์/Thesis

application/pdf

URL: https://kasetsart.idm.oclc.org/login?url=https://www.lib.ku.ac.th/KUthesis/2562/patra-cho-all.pdf

CallNumber: TP1180.B55.P37

eng

Level: Master's Degree

Descipline: Packaging Technology

Grantor: Kasetsart University

DegreeName: Master of Science

©copyrights Kasetsart University

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