Development of hyper-branched polylactide and preparation of silica/polylactide biocomposites for use in packaging application

Name: Narisara Jaikaew

keyword: Packaging

; Polylactide

; Hyper-branched polymer

; Copolymer

; Composites

; Silica particles

; Polymeric composites

; Biopolymers

Abstract: This study is aimed to develop biocomposite materials from hyperbranched polylactide copolymers. The thesis is divided into two parts. The first part focuses on synthesis and characterization of hyper-branched poly (L-lactide) (hbPLLAs), and linear poly (L-lactide) (l-PLLA), and l-PLLA/hbPLLAs blended films. The second part is concentrated on the development of l-PLLA/silica composites. hbPLLAs are synthesized by copolymerization of l-lactide (LLA) using poly(ethylene imine) (PEI) as a macro-initiator. Effect of arm’s lengths on structures and properties of the copolymers are investigated by varying the PEI: LLA feed ratios. The synthesized products, which show interesting mechanical and rheological properties, are used in the properties modification of commercial l-PLLA resin by a melt blending process. Thermal, mechanical, and rheological properties of the blends, as a function of hbPLLAs structures and compositions, are examined. All blend samples exhibit lower glass transition temperature (Tg), crystalline melting temperature (Tm), and complex viscosity than those of l-PLLA resin, which can provide many advantages in processing of the materials. In term of mechanical properties, l-PLLA/hbPLLAs blended with long-branched structures (i.e. hbPLLA100) show an increased in the modulus with an increase of hbPLLA100 compositions. The blends properties can also be further optimized for specific applications by varying the branched structured compositions. In the second part, a preparation process for silica particles from rich husk ash (RHA) is developed and use as a filler in a preparation of l-PLLA/silica biocomposite films, in order to modify their mechanical property and gas permeability, for use as packaging materials. The silica materials are produced from a simple alkali extraction process of RHA, in which PLA-grafted-chitosan (PCT) copolymer is employed as a polymeric surfactant. PCT are synthesized by condensation polymerization of lactic acid with chitosan oligomer at 140 ºC. In the preparation of silica particles, PCT act as a surfactant for the formation of silica particles and also as a coating material which enhanced compatibility between the silica particles and l-PLLA matrix when they are employed in the preparation of composite materials. The l-PLLA/PCT-coated silica composites films show significant improvement in tensile modulus at 1.5%wt of PCT-coated silica contents. The gas permeability and selectivity of the composite films are enhanced in l-PLLA/PCT-coated silica composites films, which make the material a good candidate for packaging application.

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Pakorn Opaprakasit

Role: advisor

Created: 2015

Modified: 2021-10-14

Issued: 2021-10-14

วิทยานิพนธ์/Thesis

application/pdf

DOI: 10.14457/TU.the.2015.288

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Engineering and Technology

Grantor: Thammasat University

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