The high-damping property of polyurethane elastomers and the low density of the hollow glass microspheres (HGM) were used to prepare the sound insulation materials in the present work. The transmission loss (TL) was measured to evaluate the HGM content on the sound insulation properties. The experimental results showed that the addition of HGM improved the hardness and compression modulus of the HGM-filled polyurethane composites, and the loss factor (tan δ) of polyurethane composites were greater than 0.9. The average transmission loss (ATL, from 63 to 6300 Hz) reached 37.32 dB when the content of HGM was 10 wt%. The ATL of the HGM-filled polyurethane composites with 15 wt% HGM in the damping control region and the mass control region were 31.94 and 46.78 dB, respectively. The synergistic effect of the microphase separation, the interfacial effect and the rigidity of polyurethane composites resulted in the improvement on sound insulation property. The polyurethane composite has a great potential application for the field of sound insulation materials.
[a] 1IntroductionMany countries are facings erious ecological and toxicological problems resultingf rom the release of complex effluents and toxics ubstances to the water environment [1]. More and more attentionw as paid to the development of technologies to detect the toxicity of wastewater.C onventional techniques offer high precision but have disadvantages of the high cost of specialized equipment, the need for trained personnel, and non-on-site analysis.H ence research efforts in recenty ears have been directed to develop simple,r apid, on site and inexpensive environmental monitoring test methods.T raditionala quatic acute toxicity tests use the aquatic organism such as fish, rats and invertebrates as the detecting subject. It is time-consuming and expensive,r equiring lengthy exposure times and abundanceo fo rganismsc ausing moral controversy. Therefore MICREDOX,ar apid biosensor-based assay, has been attracted attentions recently and recognized as an early warnings ystem for environmental risk assessment [2].I tw as originallyp ut forward by Lincoln Technology to detect the biochemical oxygen demand (BOD) of wastewater and then was developed by Tizzard as ar apid mediated microbial-based assay [3].T here are intracellular redox reactionsd uring microbic normal respiration and whens ome toxicants exist, the respiration will be inhibited. Them ediated microbial assay brings in the mediators or synthetic co-substrate to replace the natural co-substrate oxygen during cellular catabolic redoxp rocesses.T he accumulation of the reduced mediators becomes ar eadily quantifiable index of cellular catabolism [4].E lectro-analytical techniques are adopted to measure the quantity of reduced mediator, indicating the microbial respiration activity.T he characteristic of the method is that high concentrations of microorganisms and mediator facilitatet he fast reaction.Conventional research on FM-TOX( ferricyanide-mediated respiration for toxicity measurement) method is to measure broad properties including toxicity,m utagenicity or BOD based on single bacteria such as Escherichia coli (E.coli),c yanobacteria and algal [5,6].Fore xample, B.subtilis,E .coli and P. Putida were incorporated to monitor BOD for rapid toxicity screening [7]. Pasco et al. also used FM-TOXt os tudyt he inhibitory properties of variousc hlorinated phenol compounds on E. coli and Klebsiellao xytoca (K.oxytoca) [8].A nother progress made in FM-TOX method was the use of ultramicroelectrode array(UMEA) to amplify the signal from the totall imiting currents so that to distinguish little change of toxicity.I nt hat paper, E. coli was taken as am odel microorganism [9].S ingle bacteria can be sensitive to certain toxicant, while the real water system is complex and diverse.I ti sd ifficult to use single bacteria for the aquatic comprehensive toxicity evaluation [ 10]. Considering the universality of practical application, am ore complicated organism system is in great demand. Activated sludge contains ac onsortium of ab iological organisms [11].M any...
The monomer N,N 0 -[(4,5-dihydroxy-1,2-phenylene)bis(methylene)]bisacrylamide (OHABA) was successfully synthesized by the Friedel-Crafts reaction. Using precipitation polymerization, POHABA microspheres were easily obtained in a size-controlled manner. The microsphere diameters were controlled by the dosage of initiator (2,2 0 -azobisisobutyronitrile, AIBN). The minimum and maximum microsphere size are 0.83 AE 0.07 mm and 1.98 AE 0.13 mm, respectively. Antimicrobial activity test resultsshowed that both OHABA and POHABA microspheres had a broad-spectrum inhibitory effect on both Gram-positive and Gram-negative bacteria, but POHABA performed better than the OHABA monomer.The inhibition rate of larger (1.98 mm in diameter) and smaller (1.00 mm in diameter) POHABA microspheres at the concentration of 0.238 mg mL À1 were 74.3% and 37.0% for soil microorganisms after a 48 hour reaction, respectively.
Polymeric materials are used for vibration protection owing to their high-energy dissipation or adsorption. In this study, polyurethane elastomers (PUEs) were prepared using six kinds of chain extender and three types of cross-linking agent. The relationships between their structures and vibration isolation performances were investigated in detail using an independent building vibration isolation sensor. The results showed that elastomers with fewer main chain carbon atoms exhibited better vibration isolation performance. With increasing number of side groups of the chain extender, both the damping and vibration isolation properties were improved. For different cross-linkers, a more irregular structure of the cross-linkers resulted in the better vibration isolation performance of the PUEs.
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