No abstract

Recent research on all aspects of thermally point bonded nonwovens has led to considerable improvements in the understanding of material requirements for these nonwovens, the changes that occur during bonding and the resultant deterioration of the mechanical properties of the nonwoven materials. This paper addresses how one may use a bicomponent fiber technology to overcome the shortcomings of the thermal bonding and obtain high strength spunbond fabrics. In particular, we present the utility of islands-in-the-sea (I/S) bicomponent fibers for optimizing the strength of thermally bonded fabrics. To examine the role of various bonding temperatures on the fabric performance, preconsolidated webs were formed and subsequently, thermally bonded. Thus, any influence introduced by potential variations in the structure was minimized. Point-bonded bicomponent samples made up of nylon-6 (N6) as the islands and low density polyethylene (PE) as the sea showed great promise with respect to their mechanical properties, suggesting that the use of bicomponent fibers can be beneficial for strength optimization of thermally bonded spunbond nonwovens.

This paper deals in general with fabrics consisting of bicomponent fibers that are fractured/fibrillated and bonded using mechanical and/or thermal means to form micro-denier fibers. Bicomponent filaments produced by the spunbonding process, where two polymers are co-extruded to form a fiber are used to demonstrate the feasibility of fracturing bicomponents. This process of nonwoven fabric manufacture combined with the fiber-fracturing process is discussed. These fabrics are processed using commercially accepted practices. Differences in the physical properties due to the different polymer ratios and cross-sections produced are discussed. In particular, this paper deals with the production of modified 'Islands-in-the-Sea' filament cross-sections that enhance the fracturing of such filaments to produce micro-fiber webs that have considerably higher surface area compared to their conventional counterparts. Point-bond calendered bicomponent samples were also tested for their mechanical properties with different island counts and polymer compositions. The optimal bonding techniques for the fabrics were identified. The role of the Islandsin-the-Sea fiber cross-section was demonstrated for optimizing the fabric strength and enhancement of surface area.

In many cases, treatment of wastewaters requires a combination of processes that very often includes biological treatment. Wet oxidation (WO) in combination with biotreatment has been successfully used for the treatment of refractory wastes. Therefore, information about the biodegradability of wastewater solutes and particulates after wet oxidation is very important. The present work proposes a model that can describe the oxidation process via organic concentration characteristics such as chemical oxygen demand (COD), biochemical oxygen demand (BOD), and immediately available BOD (IA BOD) and so can allow the prediction of biodegradability (i.e., BOD/COD ratio). The reaction mechanism includes the destruction of nonbiodegradable substances bytwo pathways: oxidation to carbon dioxide and water and oxidation to larger biodegradable compounds with their further degradation to smaller ones measured via IA BOD. The destruction of small biodegradable compounds to end products is also included in the model. The experiments were performed at different temperatures (170-200 degrees C) and partial oxygen pressures (0.5-1.5 MPa) in a batch stainless steel high-pressure autoclave. The model of concentrated thermomechanical pulp circulation water was selected for the experiments. The proposed model correlates with the experimental data well and it is compared with other WO models in the literature.

No abstract