Polymers & Processes I

Polyolefins are typically used to produce nonwovens by various processes for different applications. Polypropylene is one polymer of the polyolefinic family which dominates the market. In recent years, there has been a growing interest in the use of other polymers. This interest was stimulated by the development of bicomponent fibers.  One common strategy in the production of bicomponent fibers relies on the combination two polymers with different melting points. An example of a bicomponent fiber is the combination of PP/PE.  Another polymer which has the potential of providing a number of advantages is Polybutene-1 (PB-1). It is an isotactic polyolefinic polymer derived from the polymerization of butene-1 monomer to produce homopolymer grades, or in the presence of ethylene co-monomer to produce random copolymer grades. PB-1 has the same chemical resistance than polypropylene. However unlike PP, PB-1 has excellent creep resistance, low heat of fusion, lower melting point than PP, and exhibits a shear thinning behavior. When converted into melt-spun fibers which were produced and tested under similar conditions, PB-1 was found to yield higher moduli and tenacities than PP. When used as carrier for additives to improve the hydrophilic character of nonwovens made from PP, PB-1 was found to reduce the amount of the additive needed.
In bicomponent fibers consisting of PB-1/PP, the nonwoven fabric was found to exhibit soft handle, better compression recovery, and thermal bonding. This presentation will discuss the properties of polybutene-1 made with an entirely new technology by Basell, and contrast them with those of polyethylene and propylene. In addition, some examples of PB-1/PP mechanical properties and electron photomicrographs will be presented. It will be shown that the potential for use of polybutene-1 in conjunction with polypropylene will be ideally positioned to encompass applications for medical, hygiene, and industrial.

In terms of mechanical characteristics, nonwoven composites can neither be described as a completely linear elastica with large stress and small strain, nor be treated as a highly nonlinear flexible material like textile fabric with small stress and large strain. Research on mechanical properties of nonwoven composites is needed. This paper discusses a set of testing methods for evaluating basic mechanical properties of nonwoven composites related to extension, shear, compression, bending, and twist. With availability of these testing approaches plus an assumption that nonwoven composites are considered as two-dimensional continuous and homogeneous sheeting materials with in-plane isotropy and symmetry, complex deformations of nonwoven composites in two dimensions and three dimensions can be simplified and studied. Some testing results from biobased nonwoven composites, woven and knitted fabric composites, and pure polymer composites are exhibited and illustrated. Because the testing methods are all based on a desktop tensile tester only, they can be afforded and executed by small laboratories.

This paper will be a random walk through the various non-woven technologies that are currently supporting both the consumer and industrial wipers “explosion”. It will not only cover the evolution of the category to its present state, but also identify untapped opportunities for the future growth of non-woven materials and the wipe market segment.

Of all the disposable categories currently in the market today, no other product category allows for the use and creativity of so many varied non-woven technologies. As the wipe category started primarily with paper type products, it soon gave way to the evolution of air-lay, carded, meltblown, SMS and spunlace fabrics.

Not only does the category allow for the use of the above mentioned conventional technologies, but as niche type wipe products are being developed significant technical and material innovations have been used to modify the basic technologies providing a very large playground for creative material and product developers to revel in. This paper will discuss some of the inherent advantages and disadvantages of the various non-woven technologies for the several key wipe applications.

Even though significant creativity has been demonstrated in recent years, great opportunities for very large volume markets are still waiting to be tapped. This paper will discuss one of these major opportunities and present the challenge to the industry at large.

The authors have been producing fibers from a variety of polymeric materials. Sometimes we would like to have properties peculiar to more than one polymer. We have been experimenting with fibers that are combinations of more than one polymer extruded from a single solvent.

When polymers are mixed in the melt, most often they maintain separate phases. Frequently, however, mixtures of polymers in a single solvent appear to form rather uniform fibers, perhaps indicating that there is only one solution phase. We have produced fibers from some of these mixed polymer solutions and have evaluated the fiber properties. These are reported in this presentation.

Many premature wear problems that create costly downtime facing our manufacturing plants today, including those in the Nonwovens industry, could be significantly reduced through the use of cemented tungsten carbide as a die, wear parts and tooling material. To achieve profitability in the increasingly competitive global market our manufacturing plants must operate with minimal downtime. Cemented tungsten carbide is a popular choice of material for knife blades and anvils used in the converting industry and other wear parts used in manufacturing throughout the Nonwovens industry because of its wear resistance, corrosion resistance, high compressive strength and anti-galling properties. When the proper grade of cemented tungsten carbide is selected it will provide exceptional performance.

The purpose of this paper is to provide background information on the material and to describe a process used in selecting the grade of cemented tungsten carbide that has the properties that will deliver optimum performance for specific applications within the Nonwovens industry.

The amount and uniformity of electrostatic charge developed on nonwoven forming belts can influence both operability and product uniformity.  A three point multi probe field meter was adapted to measure electrostatic potential at three points across a moving forming belt and used to assess static development as a function of speed, tension, and forming wire type.  Machine behavior was related to stationary static decay behavior.