The toughness and processability improvement of poly(lactic acid)/natural rubber blown film

การพัฒนาสมบัติด้านความเหนียวและสมบัติด้านการขึ้นรูปสำหรับฟิล์มเป่าพอลิแลคติกแอซิดผสมยางธรรมชาติ

Name: Peerapong Chanthot

keyword: Poly(lactic acid)

; Natural rubber

; Peroxide

; Film blowing process

; Bubble stability

; Rheological properties

; Mechanical properties

Abstract: Poly(lactic acid) or PLA is a biodegradable and compostable polymer derived from renewable agricultural products such as corn starch, tapioca roots, starch, and sugarcane. The applicability of PLA as packaging films is limited due to its brittleness, insufficient melt strength, and low thermal stability. The objective of this dissertation is to formulate high-performance PLA/natural rubber (NR) compounds for producing biodegradable PLA/NR blown films with high toughness and good processability. The dissertation covers the following studies 1) the effect of peroxide on the improving of bubble stability and rheological properties of PLA blown films, 2) the effect of NR and peroxide on the rheological properties, mechanical properties, morphology, and bubble stability during film blowing of PLA, 3) the degradability evaluation of biobased PLA/NR blown films, and 4) the industrial scalability of PLA/NR blown films. It was found that the rheological parameter G' at the low-frequency regime could be a good indicator for the processability of neat PLA blown films as it correlated very well with their melt strength, the highest stable blow-up ratio (BUR), and the thickness uniformity of the films, where the optimal amount of peroxide was 0.3 wt%. For the effect of NR, the addition of NR into PLA led to higher melt strength, improved processability, and remarkably higher film toughness, where the optimal NR content was 15 wt%. Moreover, it was also found that the addition of peroxide also improves the processability as well as mechanical properties of PLA/NR films, where the optimal peroxide content of 0.03 wt% could provide the highest film toughness and film clarity. It is also worth noting that the required amount of peroxide for good blown film processability of PLA/NR (0.03-0.1 wt%) was significantly lower than that of the neat PLA system (0.3 wt%). In terms of biodegradability, it was found that NR does not resist biodegradation of PLA, while the addition of peroxide to PLA/NR films induced only a slight delay in film degradation. The faster degradation of PLA film in the presence of NR indicates a good promise of NR as it not only improved the toughness but also expedited the degradation of PLA. Finally, the test run of PLA/NR compounds in an industrial-scale film blowing machine indicates that the PLA/NR compounds manufactured on an industrial scale possessed good film blowing processability as well as good mechanical properties also.

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Cattaleeya Pattamaprom

Role: advisor

Created: 2022

Modified: 2568-05-13

Issued: 2025-04-06

วิทยานิพนธ์/Thesis

application/pdf

DOI: 10.14457/TU.the.2021.1304

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Engineering

Grantor: Thammasat University

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