The objective of this study was to investigate the impact of amylase treatment on the properties of polylactic acid (PLA) composite, using coir fiber. The coir fiber was treated with a 5% amylase solution and the modified coir/PLA composite was produced via hot pressing. The mechanical properties, water absorption and moisture absorption properties, and microstructure of the composites were analyzed. The findings revealed that the addition of amylase-treated coir fiber significantly enhanced the strength and stiffness of the composite. Specifically, the tensile strength, bending strength, and impact strength increased by 5 times, 3.6 times, and 2 times, respectively. Furthermore, the composite’s fracture mode changed from pure tensile to shear and tensile mixed fracture. The water absorption performance of the coir fiber composite increased by an average of 29.58% after amylase treatment, which improved the composite’s ability to withstand humidity. Lastly, the microstructure of the composite material was discussed. The enzyme decomposed the starch in the fiber, removing impurities and increasing the surface area, providing more sites for binding to polylactic acid and improving the interface compatibility between the two substances. The results are significant for developing new and sustainable bio-based composites.
Background:Transgenic plant suspension cultures could be used as an effective tool for the biotransformation of exogenous compounds.Objective:To investigate the biotransformation of furannoligularenone (1) by transgenic crown galls of Panax quinquefolium.Materials and Methods:Compound 1 was administered into the crown gall cultures and co-cultured for 6 days. The cultures were dried and extracted with methanol for HPLC analyses. The extract was separated on column chromatography, and biotransformation products’ structures were elucidated by the physicochemical properties and the data of NMR and MS. Moreover, three flasks were randomly chosen each day to establish time–course during the period for co-culturing.Results:Co-culturing compound 1 with crown galls yielded two compounds, 3-oxo-eremophila-1,7(11)-dien-12,8-olide (2) and 3-oxo-8-hydroxy-eremophila-1,7(11)-dien-12,8-olide (3), which were obtained by biotransformation using P. quinquefolium crown galls for the first time. Time–course investigation revealed that the mole conversion ratio reached the highest level of 45.5% and 33.9% on fourth and fifth day after substrate administration, respectively. Furthermore, a proposal biosynthesis pathway was given from compound 1 to compounds 2 and 3.Conclusion:This was the first example of compound 1 being successfully converted into compounds 2 and 3 by transgenic crown galls of P. quinquefolium.
Wood plastic composites (WPCs) were prepared by extrusion molding with eucalyptus powder, polyvinyl chloride (PVC), and silica as additives. The mechanical properties, creep behavior, thermal properties, and cross-section microstructure of the composites were analyzed by universal testing machine, thermogravimetric analyzer, and scanning electron microscope. The results show that with the increase of silica content, the tensile strength, bending strength, and impact strength of the WPCs first increased and then decreased. When the silica content was 3.0%, the tensile strength, bending strength, and impact strength of WPC reached the maximum values of 27.5 MPa, 48.8 MPa, and 4.18 KJ·m-2, respectively, which represented increases of 12.6%, 9.4%, and 20.1%, respectively, compared with those without silica. When the stress was 13.4 MPa, the strain value of 3.0% SiO2-eucalyptus/PVC wood plastic composite was 3.3 times that of 4.46 MPa and 1.7 times that of 8.92 MPa. The pyrolysis process of eucalyptus/PVC WPCs showed a similar trend with different silica content.
Eucalyptus/polyvinyl chloride (PVC) composites were prepared by extrusion molding with eucalyptus as filler, PVC as matrix, and different contents of acrylonitrile styrene acrylate copolymer (ASA). The effects of different ASA content on the mechanical properties, water absorption properties, and thermal stability of eucalyptus/PVC composites were studied. The morphology of the tensile section of the composites was observed by scanning electron microscopy (SEM). The results showed that the addition of ASA could improve the mechanical properties, heat resistance, and interfacial compatibility of eucalyptus/PVC composites. It also could reduce the water absorption of the composites. When ASA content was 10 wt%, the mechanical properties and heat resistance of eucalyptus/PVC composite were the best, and the water absorption in 24 h was the lowest.
To investigate the change of the service performance of wood-plastic composites degraded by sea water and acid rain, three types of wood-plastic composite materials were prepared with sorghum straw reinforced with high-density polyethylene (SS/HDPE), polypropylene (SS/PP), and polyvinyl chloride (SS/PVC). Under the extreme alternate degradation conditions simulated by seawater (salinity 3.5%, temperature 55 °C) and acid rain (pH 2.5, temperature 55 °C), the effects on the mechanical and wear properties and the chemical structures of the composites were determined. The exposure to the alternate sea water and acid rain deteriorated the fiber/matrix bonding quality of the composites; the mechanical and wear properties decreased accordingly. Before and after degradation, the three composites were sorted in descending order of the mechanical and wear properties as follows: SS/PVC composites > SS/PP composites > SS/HDPE composites. Sorghum straw /PVC had the best resistance to degradation and sorghum straw /HDPE composite had the least resistance. The matrix molecular chains of the SS/HDPE under the conditions of exposure were broken after 12 days.
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