Tengzhou Xu

Sound insulation of multi-layer glass-fiber felts: Role of morphology

Glass-fiber felts have emerged as a popular material for noise reduction. This paper investigates the effect of various morphologies (micro-layer, macro-layer and air-layer) of glass-fiber felts on sound insulation. The sound transmission loss is measured by a Brüel & Kjár (B&K) impedance tube. The results show that the sound insulation of glass-fiber felts can be improved by increasing the number of macro-layers. The comparison between the macro- and micro-layer of glass-fiber felts on sound insulation is systematically carried out. Notably, the sound transmission loss of glass-fiber felts with similar areal density and thickness favors macro-layer structures over micro-layer structures. A simple model is established to explain this phenomenon. In addition, the sound transmission loss exhibits period fluctuations due to the presence of the air-layer between glass-fiber felts, which can be theoretically explained by the resonance effect. It is found that sound transmission loss can be improved by increasing the number of air-layers.

Development of the Biomaterials Technology for the Infection Resistance

Infections caused by microbial proliferation are one of the common issues and serious threats to the medical care, and they usually result in disease spread. Therefore, it is a significant issue for developing the antiinfective biomaterials to control this problem, according to the specific clinical application. Meanwhile, all their properties, the best anti-infective performance, the safe biocompatibility and the appropriate tissue interactions must be conformed to each other. At present, technologies are developing novel biomaterials and surfaces endowed with anti-infective properties, relying either on bactericidal or anti-biofilm activities. This review focuses on thoroughly summarizing numerous kinds of antibacterial biomaterials, including the antibacterial matrix biomaterials, antibacterial coatings and films, nanostructured materials and antibacterial fibers. Among these strategies, the utilization of bio-glass base and graphene base antibacterial matrix, and their effects on the antibiosis mechanism were emphatically discussed. Simultaneously, the effects and mechanisms of nano-coated metallic ions are also mentioned. Overall, there is a wealth of technical solutions to contrast the establishment of an implant infection. The lack of well-structured prospective multicenter clinical trials hinders the achievement of conclusive data on the efficacy and comparative performance of antibacterial biomaterials.

Sound insulation of glass fiber felt composite structure via the flame blowing process

Glass fiber felt has emerged as a popular material for noise reduction. In this paper, glass fiber felt is produced by flame blowing process. Fiber distribution, microstructure, permeation rate and sound transmission loss (STL) are explored. The results show that, the internal and cross-sectional structures of glass fiber felt are disordered and micro-layer, respectively. There is a directly proportional relationship between fiber diameter and permeation rate. For composite structure, if the face sheet of glass fiber felt with high reflection coefficient, STL of composite structure can be improved. It is also found that STL can be improved by increasing the number of air-layers. However, the influence of the position changing of air-layer can be ignored for STL.

Correlation between the Thermo-physical Properties and Core Material Structure of Vacuum Insulation Panel: Role of Fiber Types

Vacuum insulation panel (VIP), which is composed of an evacuated core material encapsulated in an envelope and supplemented with a desiccant, is a high performance thermal insulation material. In this paper, thermos-physical properties of chopped fiber, centrifugal-spinneret-blow (CSB) fiber, flame-spinneret-blow (FSB) fiber and hybrid (CSB: FSB=1:1) fiber as fillers of vacuum insulation panel are explored. The results show that the increase of pore size can improve thermal insulation property; fibers distribute in 2-D structure, which can reduce the heat conduction, leads to reduce the thermal conductivity. VIP with chopped fiber has the best thermal insulation, and thermal conductivity is 1.4 mW/m.K. Due to difference of core materials, thermal insulation characteristics of VIP can be divided into three distinct regions based on the internal pressure range, i.e., (I) ≥12000 Pa region, (II) 80-12000 Pa region, (III) ≤ 80 Pa region. It also finds that service life of VIP can be improved by the reducing the pore size of core materials. VIP with different core materials shows different degradation and the degradation rate of VIP with FSB core material is minimum.