Structure–property relationships of thermally bonded polypropylene nonwovens

Abstract

SynopsisThe effect of fiber structure and morphology on the resultant mechanical and low load deformation properties of thermally bonded nonwoven polypropylene fabrics has been studied. Commercially available staple polypropylene fibers varying in linear density and draw ratio (Herculon and Marvess staple fibers) were used in this study. The orientation of these fibers was characterized by birefrigence measurements. Differential scanning calorimetry measurements were made to determine the heat of fusion and melting point of fibers. Experiments confirm that tensile strength and stiffness of the fabrics correlate with this fiber structure. Under the same bonding conditions fabrics made from fibers with low draw ratios show higher tensile strength and stiffness than do fibers with high draw ratios. The mechanical properties of fabrics were found to be greatly affected by the thermal bonding temperature. The tenacity and flexural rigidity of fabrics made from poorly oriented fibers show higher values than those made from highly oriented fibers. The shrinkage of the fabrics was observed to increase with increasing bonding temperature in both machine and cross machine directions. The changes in fabric thickness due to the thermal bonding are considerably lower for poorly oriented fibers.

Morphology and Structure of Constituent Fibres in Thermally Bonded Nonwovens

“…The birefringence has been proved to be a sensitive and reliable fingerprint of polymer structure. [11,44] Birefringence of a polymer fibre stems from two basic features in its construction: (i) the chemical composition of the constituent molecules and (ii) the structural arrangement of the molecules within the fibre. [45] The chemical composition of fibre is partly responsible for the birefringence level of the fibre.…”

“…It is therefore very likely that the thermal bonding process resulted in changes in the morphology and structure of the PP/PET bicomponent fibre. The morphology and structure of polymers are very important for their many properties, including mechanical and optical properties, [9,11] and hence affect the properties of the corresponding fabrics consisting of these polymer fibres. The knowledge of morphology and structure of the PP/PET bi-component fibres before and after the thermal bonding process is important for establishing suitable windows of the process parameters to optimize the quality of the nonwoven products.…”

Micromechanisms of deformation and fracture of polypropylene nonwoven fabrics

“…In the case of nonwovens made up of polyolefin fibers, most of the results in the open literature on the mechanical behavior come from market-oriented manufacturers, which emphasize the material performance rather than the micromechanisms of deformation and fracture. Investigations into the relationship between the microstructure and the macroscopic properties were limited to assessing the influence of critical processing parameters (fiber orientation, bonding strength, density) on the macroscopic mechanical behavior (Wei et al, 1985;Bhat et al, 2004;Kim, 2004;Mattu et al, 2002;Hou et al, 2009;Kim and Pourdeyhimi, 2001). Nevertheless, from a fundamental viewpoint, it is important to experimentally establish the actual sequence of deformation and failure processes which control the behavior of this class of material.…”

Design of pipe diameter of polyester‐ramie nonwoven lining material for pipeline rehabilitation

“…Polyester‐ramie nonwovens are coated with impermeable film to form polyester‐rice nonwoven lining materials, which causes thermal shrinkage due to high temperature of the film covering, resulting in the size reduction of polyester‐ramie nonwoven . By comparing the size of polyester‐ramie nonwovens before and after lamination, the thermal shrinkage rate of polyester‐ramie nonwovens during lamination can be obtained as follows: where Y 2 is the thermal shrinkage rate of polyester‐ramie nonwoven with film covering, %; H is the size of polyester‐ramie nonwovens before lamination, mm; and H 1 is the size of lining material after lamination, mm.…”