Recycling of Poly Lactic Acid Reinforced with Calcium Carbonate by Multiple Processing

The upward trend of the bioplastics and biocomposites usage among consumers could have great consequence for the recycled plastics industry in the next few decades. As a result,industries’ attentions have been directed towards Poly Lactic Acid (PLA) which combines the advantages of renewable and biodegradable resources at the same time. Since PLA is more environmentally friendly compared to traditional petroleum-based commodity polymers, it has benefited from an upturned trend of interest in different markets, like the packaging, textile, and automotive industries. However, it is not applicable in many fields due to its inherent brittleness; even though it is very beneficial as the result of high strength and high modulus. Due to the low production cost of Nano calcium carbonate (nano-CaCO3) (NCC) which is useful to improve the toughness of PLA, it has reached a wide market in such industries as plastics, paints, and inks. By adding Nano calcium carbonate to polymer, thermal,crystallization, mechanical, biodegradability and melt rheological properties will be improved. The mechanical recycling of neat PLA has previously studied as well as some research on blend PLA/NCC by Sabzi et al. However, the purpose of this project is to investigate the characterization of PLA blend with Chalk (CaCo3) and Plasticizer by focusing on thermaland mechanical properties. The filler, which is 30% calcium carbonate, and 5% plasticizer compound with PLA in a two screws extruder. Plasticizer is added to composite to make it softer and it is consider constant in all samples. Multiple extrusions and compress molding are methods which can help in studying the recyclability of polymeric materials containing bioplastic and its derivatives and in figuring out the stability or service life respectively. In addition, these methods make it possible to determine the impacts of thermal and thermo mechanical degradation. Bio composite was recycled up to 6 times by using extruder equipment and crushing. The mechanical and thermal properties were characterized after each cycle by TGA, DSC,DMTA, FTIR, tensile machine and flexural test. The study represents that by introducing 30% calcium carbonate to PLA, it can be recycled up to 6 times without meeting any significant change in the mechanical and thermal properties.</p

Mechanical Recycling of Polylactic Acid Reinforced with Calcium Carbonate

Biopolymers are becoming increasingly popular and may help reduce oil dependency. As a result, industries’ attentions have been directed towards polylactic acid (PLA) which combines the advantages of being renewable and biodegradable resources at the same time. The upward trend of the bioplastics and biocomposites usage among consumers could have great consequence for the recycled plastics industry in the next few decades. While the mechanical recycling of many of the traditional, petro-based polymers have been studied in detail, bio-based polymers still need to be better characterized. The mechanical recycling of neat PLA has previously studied and tests show that it is possible to process PLA several times without significant loss of mechanical properties. However, commercial plastics are often used with some kind of filler. Due to the low production cost of chalk (mainly consisting of CaCO3) it is often added to commercial polymers. PLA can be filled with chalk and other fillers in order to improve the toughness and lowering the cost. The purpose of this project was to investigate the mechanical recycling of PLA compounded with chalk. PLA was compounded with 30 wt-% chalk and 5 wt-% plasticizer using a twin screw extruder. The mechanical recycling was simulated by multiple extrusion. Samples for mechanical testing were prepared by compress molding. The prepared compound was recycled up to 6 times by multiple extrusion. The mechanical and thermal properties were characterized after each cycle by TGA, DSC, DMTA, FTIR and tensile tests.</p

Repeated mechanical recycling of polylactic acid filled with chalk

Polylactic acid (PLA) was compounded with 30 wt% chalk and 5 wt% of a biobased plasticiser on a twin screw extruder. Mechanical recycling of the obtained compound was studied by multiple extrusions up to six cycles. The degradation was monitored by mechanical and thermal tests. Tensile and flexural tests did not reveal any major degradation after six cycles of processing. Characterising the material with differential scanning calorimetry (DSC) did not detect any significant change of the thermal properties. The material was also characterised by FTIR and, again, no significant change was detected. The material was finally characterised by melt flow index and by proton nuclear magnetic resonance (1H-NMR). Both tests revealed that some degradation had occurred. The 1H-NMR clearly showed that the chain length had been reduced. Also, the MFI test showed that degradation had occurred. However, the study reveals that PLA filled with chalk can be recycled by repeated extrusion for up to 6 cycles, without severe degradation. This should be of relevance when considering the end-of-life treatment of polymer products made from PLA.</p

The role of adrenoceptors in the electrophysiological effects of hydroalcoholic extract of Citrus bigaradia in experimental model of atrial fibrilation of isolated atrioventricular node of rabbits

(Received 3 Nov, 2008; Accepted 4 Mar 2009)AbstractBackground and purpose: Preliminary studies have been established to examine the cardiotonic effect of Citrus bigaradia extract, by implenenting various mechanisms. The functional protective role of this plant against supraventricular tachyarrhythmia remains to be determined.The present study is designed to assess the role of hydroalcoholic extract of Citrus bigaradia by modifing the electrophysiological properties of atrioventricular node, during simulated experimental atrial fibrillation in rabbits and also, to determine the role of adrenoceptores regarding effects of Citrus bigaradia on the AV node.Materials and methods: In this present study, Newsland male rabbits(1.5-2 kg) was used. Programmed stimulation protocols (Recovery, Wenckbach, Atrial fibrilation and Zone of concealment) were applied in two groups (N=23) to assess electrophysiological properties of isolated rabbit AV node. In the first group (N=10), different concentrations of hydroalcoholic extract of Citrus bigaradia were added to thyrods to detect nodal concealed conduction. In the second group (N=13), the effects of extracts (54-108 mg/L) were analysied in the presence of β-adereceptor blocker(Nadolol 2 µm). AF protocol was simulated by high-rate atrial pacing with random coupling intervals (range 75-125 ms). All data have been shown as Mean±SE.Results: Citrus bigaradia, had biphasic concentration-effect pattern, such as in low and intermediate concentrations (0.8-3.2 mg/L), shortened nodal functional refractory period and Wenckebach. We observed a non-significant decrease in the average H-H intervals and numbers of concealed beats in all concentrations of Citrus bigaradia. Zone of concealment was shortened by this plant. Nadolol (2 µm) prevented the whole effects of Citrus bigaradia on the nodal conduction time, refractoriness and concealed conduction.Conclusion: The above results indicate the potential pro-arrhythmic effects of Citrus bigaradia in worsing supraventricular tachyarrhythmia. The effects of plant to decrease the AV-nodal refractory period and concealment zone may be considered the major mechanism of this plant.At least some parts of effects of Citrus is mediated through β-adrenoceptores.J Mazand Univ Med Sci 2009; 19(68): 1-10 (Persian

Fungal biomass and ethanol from lignocelluloses using Rhizopus pellets under simultaneous saccharification, filtration, and fermentation (SSFF)

The economic viability of the 2nd generation bioethanol production process cannot rely on a single product but on a biorefinery built around it. In this work, ethanol and fungal biomass (animal feed) were produced from acid-pretreated wheat straw slurry under an innovative simultaneous saccharification, fermentation, and filtration (SSFF) strategy. A membrane unit separated the solids from the liquid and the latter was converted to biomass or to both biomassand ethanol in the fermentation reactor containing Rhizopus sp. pellets. Biomass yields of up to 0.34 g/g based on the consumed monomeric sugars and acetic acid were achieved. A surplus of glucose in the feed resulted in ethanol production and reduced the biomass yield, whereas limiting glucose concentrations resulted in higher consumption of xylose and acetic acid. The specific growth rate, in the range of 0.013-0.015/h, did not appear to be influenced by the composition of the carbon source. Under anaerobic conditions, an ethanol yield of 0.40 g/g was obtained. The present strategy benefits fromthe easier separation of the biomass from the medium and the fungus ability to assimilate carbon residuals in comparison with when yeast is used. More specifically, it allows in-situ separation of insoluble solids leading to the production of pure fungal biomass as a value-added product. (C) 2016 BRTeam. All rights reserved