Papers by Keyword: Poly(lactic acid) (PLA)

Abstract: The aim of this research was to modify Poly (lactic acid) (PLA) and Natural Rubber (NR) using maleic anhydride (MA). The preparation was carried out using internal mixer by free radical melt grafting reaction to produce PLA-g-MA and NR-g-MA as a compatibilizer. The effects of concentrations of MA (3-12 phr) were studied in details. The samples structure of copolymers were then characterized using ¹H nuclear magnetic resonance (¹H-NMR) and Fourier transforms infrared spectrometer (FTIR). Quantities of grafted MA (% grafting) were characterized by titration analysis and when increasing the monomer used, the quantities of the grafted MA on PLA and NR molecules also increased. The optimum grafting degree for PLA-g-MA and NR-g-MA was at 9 phr of MA with value of 1.63% and 5.02%, respectively.

Abstract: Derived from renewable resources, Poly (lactic) acid (PLA) exhibits good mechanical properties comparable with conventional polyolefins. However, major obstacle in PLA which may limit its application is due to brittleness. Thus, PLA requires toughening to overcome the weakness. In this study, PLA was blended with different ratio of natural rubber (0 to 20 wt.%) through melt blending in a twin screw extruder. The results of tensile strength and Young’s modulus of PLA/NR blends were decreased. In order to enhance the blend performance, PLA grafted maleic anhydride (PLA-g-MA) was used as compatibilizer. The preparation of PLA-g-MA was carried out using internal mixer by free radical melt grafting reaction followed by Fourier Transform Infrared Spectroscopy (FTIR) analysis to confirm the grafting reaction. To investigate the compatibilization effect on the mechanical properties of PLA/NR blends, PLA-g-MA was added to the blends at various compositions (1 – 10 phr). Mechanical properties increased markedly compared to the virgin PLA/NR blends and FTIR result confirmed grafting reaction occurred between MA and PLA.

Abstract: The objective of the study is to improve the mechanical properties of Polylactic acid (PLA)/Ethylene Vinyl Acetate (EVA) blend. The blend was prepared via twin screw extruder and compression molding with different composition. The effect of different blend ratio on the mechanical properties was investigated by Tensile and Flexural test. The mechanical properties of PLA shown an improvement compared to the pure PLA with the incorporation of EVA. The flexural modulus increased with the increased of EVA content, while the tensile and flexural strength also increased when EVA increased. The optimum tensile and flexural strength was at 90PLA/10EVA of blends ratio.

Abstract: In this study, concept of green geosynthetics was introduced in terms of biodegradability. Development of green geosynthetics, its background and technical concerns were discussed through some research results of PLA(polylactic acid) specimens. Test method for biodegradability of PLA(polylactic acid) as a green geosynthetics were considered and suggested based on composting method. Finally, the rest result shows that the concept of biodegradability for green geosynthetics is available in the environmental application. PLA 4032D/PBAT(80/20) blend shows improvement of environmental performance as a green geosynthetics application than PLA 4032D only used.

Abstract: An own-designed pressure vessel with glass windows has been employed to perform an in-situ characterization of the temporal evolution of the crystallization process of an amorphous polylactic acid (PLA) under different controlled CO₂ pressures and temperatures. It has been proven that crystallinity can be related to optical parameters such as transmissivity, obtaining information about the whole process by optical measurements. The method has the advantage of measuring in-situ over bulk samples with a non-destructive tool. The obtained results have shown some unexpected trends that have been explained taking into account the complex phenomena occurring during the crystallization process of PLA in the presence of CO₂ at high pressure.

Abstract: Bio-based biodegradable Poly (lactic acid) (PLA) suffers limitations such as brittleness and slow crystallization. This study aims to resolve the brittle nature of PLA by blending with Poly (butylene succinate) (PBS), a more ductile biodegradable polymer with superior toughness and flexural properties. In this research, a series of PLA/PBS blends was prepared at the blend ratios of 100/0, 80/20, 60/40, 40/60, 20/80 and 0/100. FTIR showed that there was no change in the functional groups of the PLA/PBS blends. Thermal stability assessed by TGA revealed that PBS degraded at higher temperature than that of PLA; the decomposition temperature (T_d) at 10% weight loss of PLA and PBS were 330.8 and 356.4°C respectively. The T_d of all the blends increased gradually with the addition of PBS. The flexural properties in terms of the flexural strength and the flexural modulus of the blends reduced significantly with PBS content. The PLA/PBS specimens with greater PBS content were softened and flexed more easily, thereby requiring a much lower flexural strength. The flexural modulus of the 80/20 and 60/40 blends dropped from 3.5 GPa for neat PLA to 3.2 GPa and 2.1 GPa while the flexural strength also declined from 105.3 MPa to 90.9 MPa and 69.1 MPa respectively. The toughness of all the blends was greater than that of neat PLA; in particular the 60/40 blend exhibited superior impact strength of 48.7 J/m compared with 30.9 J/m of the neat PLA. The microscopic images of all the blends showed two distinct phases; the 60/40 blend consisted of well dispersed small particles of the tough PBS, resulting in greater absorption of energy upon impact.

Abstract: This research work was carried out on the production of rice bran/poly (lactic acid) (PLA) composites. The composition during the batch molding process included rice bran, PLA, glycerol, and magnesium stearate (mold released agent). Afterwards, the composition was molded by bio-compression at temperature of 170°C for 5 min, and a pressure range of 50-100 kg/cm³. The result showed that the composition of rice bran, PLA, and glycerol could be used in the formation of food packaging. Also the mechanical properties, such as compressive strength and hardness, were investigated. It could be concluded that the most appropriate formulation of rice bran packaging was 5 phr PLA and 3 phr glycerol and 2 phr magnesium stearate. Moreover, FTIR results indicated the non-toxic nature of this method of food packaging.

Abstract: In order to improve the mechanical properties of poly (lactic acid) (PLA), cotton fiber/PLA composites were prepared by melting compounding and injection molding. The effects of cotton fiber content and coupling agent on mechanical properties, crystalline behavior and interface morphology of the composites were studied by universal testing machine, DSC and SEM, respectively. The results showed that the crystallinity of the composites increased gradually with the increase of cotton fiber content, whereas the mechanical properties of the composites increased firstly and then decreased with further addition of cotter fiber. The composite with 20wt% cotton fiber had an optimal mechanical performance. In addition, with the incorporation of 1wt% coupling agent, the interfacial adhesion between cotton fiber and PLA improved obviously, and the mechanical properties of the composites increased accordingly. Compared with the neat PLA, the tensile strength, flexural strength, flexural modulus and impact strength of the resultant composites were increased by 66.0%, 27.4%, 45.8% and 60.4%, respectively.

Abstract: This study focuses on the influence of surface treatment and fibre sizes on mechanical behavior, physical properties and morphology of rice husk fibre (RHF) reinforced polylactic-acid (PLA). Modified RHF was prepared by using 6w.t.% sodium hydroxide (NaOH) and distilled water. PLA composite reinforced with 25w.t.% volume fractions of modified RHF was mixed using the internal mixer and fabricated by the mini injection moulding. Tensile and flexural strength results showed that the PLA composite with 100, 200 and 500μm particles sizes of water treated fibre are much higher than those of alkaline treated. DSC measurement was performed and indicated that the T_g, T_m and ΔH_m of PLA reduced after reinforcement with water treated and alkaline treated fibres. TGA results showed that the treatment reduced the thermal stability of the PLA. FESEM micrographs for flexural fractured surfaces of composites showed micro crack and pores due to brittle fracture of the PLA matrix adjacent to the fibre as a result of the brittle nature of the PLA resin.

Abstract: Polylactic acid (PLA) is a synthetic polymer that has biocompatibility and biodegradation. This study aims to examine the influence of manufacturing parameters on the physical properties of tubular PLA/Spandex/Gelatin composite braids. PLA fibers and spandex are combined, braided and then immersed in gelatin solution to form tubular PLA/Spandex/Gelatin composite braids. The tensile strength, bursting strength, and porosity of the resulting braids are tested, and the experiment results show that a greater twist per inch (T.P.I.) causes a higher tensile strength and bursting strength, but does not change the porosity distinctively.