The Effects of Supercritical Carbon Dioxide on the Degradation and Antimicrobial Properties of Pla Biocomposite

Abstract

Biopolymer products that is biodegradable presently attracting an attention from researchers and industry. The biodegradable packaging based on polylactic acid (PLA), durian skin fibre (DSF), epoxidized palm oil (EPO) and incorporated with cinnamon essential oil (CEO) as antimicrobial agent have been developed and showed to be a promising field of research. This paper reported the effects of supercritical carbon dioxide on the degradation and antimicrobial properties of PLA biocomposite films produced via solvent casting. The biocomposites underwent supercritical carbon dioxide (SCCO2) treatment at two different conditions under 40 °C temperature and at 100 bar and 200 bar pressure. Water absorption test showed that the untreated PLA biocomposite absorbed most water as compared to treated PLA biocomposite with SCCO2 at 5.1%. This is due to the hydrophilic nature of the fibre that absorbed water molecules. Soil burial test showed that the treated PLA biocomposite possessed the highest value of weight losses after 80 days with 97.8%. Biocomposite with the presence of CEO demonstrated antimicrobial activity against both gram-positive and gram-negative bacteria. This showed that SCCO2 significantly improved the properties of PLA biocomposite films. The supercritical fluid treatment of PLA biocomposite could be an alternative for active packaging industries to ensure that the packaging product meets the requirement by consumers as well as being an eco-friendly product.
 ABSTRAK: Produk biopolimer yang biodegradasi pada masa ini menarik perhatian dari penyelidik dan industri. Pembungkusan biodegradasi berasaskan polilaktik asid (PLA), serat kulit durian (DSF), minyak kelapa sawit terepoksi (EPO) dan ditambah dengan minyak pati kayu manis (CEO) sebagai agen antimikrobial telah dibangunkan dan menjadi bidang penyelidikan. Artikel ini melaporkan kesan karbon dioksida superkritikal terhadap sifat-sifat degradasi dan antimikrobik dari filem biokomposit PLA yang dihasilkan melalui pemutus pelarut. Biokomposit telah menjalani rawatan superkritikal karbon dioksida (SCCO2) pada dua keadaan yang berbeza di bawah suhu 40 °C pada 100 bar dan 200 tekanan bar. Ujian penyerapan air menunjukkan bahawa biocomposite PLA yang tidak dirawat menyerap kebanyakan air berbanding komposisi lain dengan 5.1%. Ini disebabkan sifat hidrofilik serat yang menyerap molekul air. Ujian penanaman dalam tanah menunjukkan bahawa biocomposite PLA yang dirawat mempunyai nilai kehilangan berat tertinggi setelah 80 hari dengan 97.8%. Biokomposit dengan kehadiran CEO menunjukkan aktiviti antimikrobial terhadap bakteria gram-positif dan gram-negatif. Ini menunjukkan bahawa SCCO2 meningkatkan sifat-sifat filem biocomposite PLA. Rawatan cecair superkritikal PLA biocomposite boleh menjadi alternatif bagi industri pembungkusan untuk memastikan produk pembungkusan memenuhi keperluan pengguna serta menjadi produk mesra alam.

Experimental and Simulation of Supercritical Carbon Dioxide PLA Biocomposite Foamed

“…Material. Commercial PLA 4024D was purchased from NatureWorks with a density of 1.24 g/cm 3 and glass transition temperature between range 55 o C to 58 o C. Durian skin wastes were collected from fruits stall at Batu Caves, Gombak and processed into short fiber, DSF. Reagent, namely chloroform was purchased from EAM Sdn Bhd was used to dissolve the PLA pallet.…”

“…3 (c) have shown the surface of biocomposite foam is clean and it can be seen some fibers are pulled out from the biocomposite foamed surface which indicate poor adhesion between fibers and PLA matrix and give rise to the chance on dropping it tensile strength [16]. The addition of EPO as plasticizer is to enhanced the biocomposite foamed polymer ductility, however based on tensile result the value is slightly lower that PLA/DSF, it can be happening by the reason of the agglomeration of DSF in the polymer [3]. Therefore, it can be concluded that the addition of durian skin fiber can result in strengthened the tensile strength but the agglomeration of DSF can happen and affect the mechanical properties…”

“…However, it is quite challenging to produce a low-density PLA due to its low melting strength, and slow crystallization kinetics. Therefore, to improve the behavior of PLA foaming, PLA with either organic or micro/nanofiller is used by using a supercritical carbon dioxide (SCCO2) [3,18,14].…”