Thermal bonding of polypropylene nonwovens: Effect of bonding variables on the structure and properties of the fabrics

Properties of the point‐bonded nonwoven fabrics are dependent on the bonding conditions, in addition to those of the polymer/fiber. Thermally bonded carded webs were produced and characterized to investigate the role of bond area, bond size, and bonding temperature on the structure and properties of point‐bonded nonwoven fabrics. It was observed that the bond strength increases with bond area and bond size. The effects of bond area and bond size on fiber morphology were negligible. Significant morphological differences were observed in the bonded and the unbonded regions of the thermally bonded webs. To see how the staple fiber studies relate to the behavior of continuous filaments, similar sets of samples were produced and characterized by using the spunbond system. The observed trends for properties with respect to bonding conditions were similar for spunbond samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3593–3600, 2004     

Development of Structure and Properties during Spunbonding of Metallocene Catalyzed Polypropylene

Spunbonding is one of the most widely used processing techniques to convert polymers into nonwoven fabrics. metallocene-catalyzed polypropylene is becoming more and more important. A study was carried out to understand the development of structure and properties of a metallocene-catalyzed isotactic polypropylene during spunbonding. This research was conducted using the Reicofil spunbond line at the University of Tennessee, Knoxville. The filaments at three different throughput rates were studied for tensile properties and for structural features by birefringence, X-ray diffraction, and thermal measurements. The fabrics produced at different process conditions were tested for various mechanical properties. The failure mechanism of the fabrics at different bonding temperatures was studied using the scanning electron microscope. The results are compared with a conventional polypropylene processed under similar conditions. The results showed that the mPP produced fabrics with better strength and elongation at comparable processing conditions. Also, failure mechanisms were found to be different for the fabrics produced from the two polymers, which are due to differences in the produced structures.     

Complex char formation in flame‐retarded fibre‐intumescent combinations — IV. Mass loss and thermal barrier properties

Previously reported fibre/intumescent composite textile systems are leading to the development of a range of high performance thermal barrier fabrics. These systems comprise nonwoven cores of flame retardant cellulose/regenerated cellulose throughout which fibre‐interactive intumescent chemicals (melamine and phosphate based) are dispersed. When heated, both components decompose by compatible physical and chemical mechanisms leading to a complex carbonaceous ‘char‐bonded structure’. Mass loss studies of these samples indicate that decomposition takes place in three stages, an initial volatilization, char formation (both occurring during the first 3.5 min exposure period) and a char oxidative stage continuing over a much longer period. Kinetic analysis of mass loss curves gives insight into their thermal behaviour. Thermal insulative properties of these samples have been observed by embedding thermocouples within layers of fabrics and measuring their temperatures as functions of time. Using this technique, a measure of the time dependence of the thermal barrier properties has been gained at heat fluxes in the range 25–75 kW m⁻². Derived thermal resistivity values illustrate the superior barrier properties afforded by the complex chars formed. Copyright © 2000 John Wiley & Sons Ltd.     

Structure–property relationships of thermally bonded polypropylene nonwovens

The 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.     

Relationships Between Birefringence of Constituent Fibers and Properties of Thermally Bonded Nonwovens

Summary: Three‐dimensional nonwoven fabrics have been produced using a newly developed air‐laid web forming and through‐air thermal‐bonding process directly from commercial PP/polyester (sheath/core) bi‐component staple fibers. Following the previous study on the morphology and structure of constituent fibers, this paper reports the breaking force and abrasion resistance of the fabrics. Results indicate that the relationships between both the breaking strength and abrasion resistance of the samples, and the thermal‐bonding process conditions are similar to each other. The appropriate thermal‐bonding temperature and dwell time are critical for achieving fabrics with high breaking strength and abrasion resistance. Such relationships are inconsistent with those between the tensile strength of the constituent fiber reflected by the birefringence and the thermal‐bonding process conditions. The birefringence of the constituent fiber appears to decrease with increasing thermal‐bonding temperature and dwell time. These results provide evidence that both the breaking force and abrasion resistance for the thermally bonded nonwoven fabrics are governed not only by the mechanical properties of constituent fibers, but also by the bonding properties between the fibers.

Abrasion mass loss and breaking force of fabric and birefringence of constituent fiber for the thermally bonded nonwoven samples as functions of the dwell time.     

Physical characteristics and morphologies of PTT/m-iPP bi-component filaments of the island-in-sea type

The work discusses preparation, structure and selected properties of two special filaments based on poly(trimethylene terephthalate) (PTT) and metallocene isotactic polypropylene (m-iPP) bi-component filaments of the island-in-sea type. PTT microfilaments are formed by removing m-iPP from PTT (island)/m-iPP (sea) conjugated filaments. m-iPP exhaust dyeable filaments are produced from m-iPP (island)/PTT (sea) conjugated filaments. This study thoroughly investigates the physical characteristics and morphologies of PTT/m-iPP bi-component filaments of the island-in-sea type. The dye exhaustions of the fabrics made of PTT series filaments are compared. Experimental DSC results indicated that PTT and m-iPP crystallites formed an immiscible system. The tenacity of the PTT/m-iPP (and m-iPP/PTT) conjugated filaments initially declined and then increased as the proportion of m-iPP (and PTT) increased. Clearly, the 50/50 weight ratio PTT/m-iPP had the lowest tenacity. The experimental crystallinities revealed that PTT and m-iPP crystallites easily formed individual domains, indicating that PTT and m-iPP together constituted an immiscible system. On the morphology, the blends were had a dispersed phase structure. PTT and m-iPP polymers were immiscible. In this investigation, PTT microfilaments were produced and a large size from 2.3 to 2.6 μm in diameter was clearly observed. m-iPP exhaust dyeable filaments were also prepared. The dye exhaustions of various fabrics followed the order, m-iPP exhaust dyeable filaments, conventional PTT filaments, PTT microfilaments respectively.     

Effect of processing conditions on the structure and properties of polypropylene spunbond fabrics

The structure and properties of a spunbond fabric are determined by numerous process variables. The development of fiber morphology is influenced and controlled by extrusion and quenching conditions. The properties of the fabric are the result of the properties of the filaments, their arrangement in the web, and the bonding conditions. It is therefore critical to understand the relationship between the process conditions and the properties of the fabrics produced. This study was conducted to investigate the effects of some of the important process variables on the structure and properties of the filaments and ultimately on that of the fabrics. Process variables such as polymer throughput rate, cooling and suction air speed, web basis weight, and bonding temperature were investigated. Filament samples were collected before bonding and were analyzed for various properties such as crystallinity, crystallite size, birefringence, density, thermomechanical stability, and tensile properties. The fabric samples were analyzed for tensile properties, tear strength, stiffness, and crystallinity. Ruptured strips obtained from the tensile test were observed with a scanning electron microscope to understand the failure mechanism. The results were statistically analyzed to evaluate the effect of process variables on the properties and to predict the properties for different process conditions. The findings are helpful in determining the optimum processing conditions so as to achieve the desired properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2355–2364, 2005     

Thermomechanical characteristics of basalt hybrid and nonhybrid woven fabric–reinforced epoxy composites

In this study, experimental investigations are performed to check the thermal and mechanical behavior of woven Basalt/PP and Basalt/Jute fiber hybrid and nonhybrid woven fabrics and their composite laminates with epoxy. Three types of weaves are used for both hybrid and nonhybrid structures. Tensile testing of all the woven fabrics is performed. The thermal properties of the fabrics, that is, thermal resistance, diffusivity, and thermal conductivity, etc. are also studied vis‐a‐vis physiological behavior. Results are discussed in terms of fiber composition, woven geometry, and the fiber : resin ratio. Fabricated composite samples are subjected to dynamic mechanical analysis (DMA) and thermo gravimetric analysis (TGA). The thermophysiological properties are also studied in reference to yarn and fabric structure. POLYM. COMPOS., 37:2982–2994, 2016. © 2015 Society of Plastics Engineers     

Features of the structure of carbon fibres used as filler for carbon-fibre-reinforced plastics

The structure of carbon fibres and filaments in carbon fabrics used as fillers for carbon-fibre-reinforced plastics was investigated. The basic characteristics of the pore structure of the carbon fillers were determined. It was found that the carbon fibres Uglen-9R “b”, Uglen-9R “c”, and Uglen-9R have sorption properties that can negatively affect the quality of carbon-fibre-reinforced plastic articles.     

异形截面聚酯纤维显深色效果试验及其评价

主要研究了异形截面聚酯纤维织物的显深色性以及异形度对显深黑色性的影响。采用K/S值、L*值和Integ值3个指标表征织物的显深黑色效果,结果表明:异形截面聚酯纤维织物具有较好的显深黑色效果;同时,聚酯纤维截面异形度对纤维织物的显深色效果影响颇大,高截面异形度可以提高织物的显深黑色效果。定性分析了所设计的异形截面纤维的反光特性,解释了其显深色性的原因,对设计纤维的色光特性有参考价值。     

Effect of initial take-up speed on properties and structure of as-spun and drawn/heat-set poly(ethylene terephthalate) filaments

The effect of initial take-up speed on the properties and structure of both as-spun and drawn/heat-set poly(ethylene terephthalate) filaments was characterized through measurements of birefringence, percent crystallinity, tensile properties, high temperature shrinkage, loss tangent temperature dependence, DSC melting behavior, and wide-angle (WAXS) and small-angle X-ray scattering (SAXS). While a steady trend toward improved as-spun filament orientation and tensile properties occurred with increasing initial take-up speed, the reduced drawability of these more structured precursor filaments resulted in corresponding drawn/heat-set filaments that were of relatively lower overall orientation and tensile strength. The observed trends in tenacity, initial modulus, and high temperature shrinkage of the drawn/heat-set filaments appeared to be well correlated with the extent and distribution of amorphous phase rigidity as perceived through inferences made from the loss tangent temperature dependence. The WAXS patterns of the drawn/heat-set samples indicated that these filaments all possess a well-developed and highly oriented crystalline structure. Application of a simple two phase model allowed the determination of an amorphous orientation factor, which for the drawn/heat-set filaments was generally found to decrease as the draw ratio imposed in order to achieve comparable levels of elongation to break decreased. The SAXS patterns of the drawn/heat-set filaments indicated that comparable long period spacings exist in all cases and that a transition from a four-point pattern to a two-point bar-shaped pattern occurred when the precursor filament possessed some significant amount of as-spun crystallinity. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2115–2131, 1998     

Investigation of the effects of perlite additive on some comfort and acoustical properties of polyester fabrics

Natural perlite material was added for the first time into a polyester filament yarn structure. The water absorption and heat and sound insulation properties of the fabrics produced from textured and twisted polyester yarns containing 1.25% perlite additive were tested, and the results were compared with those obtained on the fabrics produced from reference polyester yarns. Although there are differences between the mechanical properties of the polyester yarns, the yarns including perlite remained within commercial usage limits. The thermal resistance values of polyester sateen fabrics obtained from perlite‐containing yarns were higher than those of the reference fabrics. The contribution of perlite led to a marked improvement, especially in the hydrophilicity and sound insulation of the polyester fabrics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43128.     

Bonding in fabric-cement systems: Effects of fabrication methods

This paper compares the effects on the bond between fabric and cement matrix of three different processing methods: casting, pultrusion and vacuum condition. The fabrics included bonded glass mesh, woven polyvinylalcohol, and warp knitted weft insertion polypropylene. Pullout tests were performed to examine the bond between fabric and cement matrix. A microstructural analysis was conducted and correlated with pullout data. Improved bonding was obtained for fabric-cement composites produced with the pultrusion process, particularly for fabrics composed of multifilament yarns that have open junction points and no sizing to seal individual yarns. This improved bonding results from the impregnation of the fabric in the cement chamber during the pultrusion process, which filled the spaces between the filaments of the multifilament yarns.     

Development of flame retardancy properties of new halogen‐free phosphorous doped SiO2 thin films on fabrics

In this study, flame retardancy properties of fabrics treated with phosphorous (P) doped and undoped SiO₂ thin films were developed by sol–gel technique. As to this aim, P‐doped and undoped SiO₂ film were coated on cotton fabric from the solutions prepared from P, Si‐based precursors, solvent, and chelating agent at low temperature in air using sol–gel technique. To determine solution characteristics, which affect thin film structure, turbidity, pH values, and rheological properties of the prepared solutions were measured using a turbidimeter, a pH meter, and a rheometer machines before coating process. The thermal, structural, and microstructural characterization of the coating were done using differential thermal analysis/thermograviometry, fourier transform infrared spectroscopy, X‐ray diffractometry, and scanning electron microscopy. In addition, tensile strength, wash fastness, flame retandancy, and lightness properties of the coated fabrics were determined. To compensate the slight loss of tensile strength of samples, which occurred at the treated fabrics with P‐doped Si‐based solutions, the cotton fabrics were coated with polyurethane films during second step. In conclusion, the flame retardant cotton fabric with durability of washing as halogen‐free without requiring after treatment with formaldehyde was fabricated using sol–gel processing for the first time. Moreover the cotton fabrics, which were treated with P‐doped Si‐based solutions and then coated with polyurethane at second step, still has got nonflammable property. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Relationships between the properties of fibers and thermally bonded nonwoven fabrics made of polypropylene

Typical polypropylene fibers for use in light nonwoven fabrics were produced in a full scale compact-spinning line. Molecular weight distribution (MWD), extrusion temperature, draw-down ratio, and draw ratio were varied. The fibers were thermally bonded (welded) into nonwoven fabrics, at different bonding temperatures, using a pilot calender line. The tensile properties of the fabrics are influenced by the MWD and the processing conditions of the fibers, and the effects of these fiber parameters increase with increasing bonding temperature. The fabric strength increases with increasing M_w/M_n, decreasing draw ratio, and increasing extrusion temperature, while in all these cases the fiber strength generally follows the opposite trend. Furthermore, the fabric strength, as well as the fiber strength, have a maximum as a function of draw-down ratio. The tensile properties of the fabrics seem to be governed by the bonding properties of the constituent fibers, not the fiber strength per se. Bond characteristics are discussed in terms of skin-core structures. Some details of the macroscopic fracture mechanisms of fabrics were revealed by scanning electron microscopy and the shape of load-elongation curves. © 1995 John Wiley & Sons, Inc.     

Preparations of microencapsulated PCMs‐coated nylon fabrics by wet and dry coating process and comparison of their properties

To analyze the thermal insulation effect in textiles, waterproof, and breathable nylon fabrics PCMs microcapsules (PCMMcs) were prepared by wet and dry coating processes. The morphology, water vapor permeability (WVP), water penetration resistance (WPR), and peel strength of the PCMMcs‐coated fabrics were characterized. At the same time, DSC was used to measure the thermal insulation properties of the PCMMcs‐treated fabrics as a means of testing the thermal storage/release capacity according to their phase change temperature. The result showed that the heat storage capacity of the PCMMcs‐treated fabrics prepared by wet coating was noticeably better than that of the PCMMcs‐untreated samples, whereas the PCMMcs treatment had an insignificant effect on the heat capacity of the fabrics prepared by the dry coating process. From the SEM analysis, it was found that the PCMMcs were physically unstable during the dry coating process, so, they could not be observed. Also, the WVP, WPR, and peel strength were found to decrease with increasing PCMMcs contents. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

The effect of acrylate on structure and properties of waterborne polyurethane porous coated fabrics

Porous‐coated fabrics used for synthetic leather were prepared by mechanical foaming method using blends of waterborne polyurethanes (WPUs) and polyacrylate (AC). The effect of AC on structure and properties of WPU/AC coated fabrics was investigated. Fourier transform infrared spectroscopy and differential scanning calorimetry results indicated that there is hydrogen bonding between WPU and AC and the compatibility of the blend system gets worse after AC/WPU ratio is higher than 30/70. Thermogravimetric analysis demonstrated that the thermal stability of porous coatings is improved with increasing AC. Scanning electron microscopy images showed that porous coatings have semi‐open cellular structure with a great number of surface pores and window pores, imparting excellent air permeability and water vapor permeability to coated fabrics. On the basis of morphology analysis, the forming process of cell structure of WPU/AC coated fabrics was proposed. Performance tests showed that the overall performance of coated fabrics is best with AC/WPU ratio ranging from 15/85 to 30/70. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45783.     

碳纤维布/玻纤布增强聚氨酯复合材料的研究

以聚氨酯为基体树脂,分别以碳纤维布、玻璃纤维布和这两种纤维布交替铺叠作为增强材料,采用真空辅助灌注成型工艺制备了4种复合材料.考察了纤维布的铺层结构对复合材料的弯曲、拉伸和冲击性能的影响.结果显示,复合材料的拉伸模量和弯曲模量随碳纤维含量增加而增加,冲击强度则降低.分别采用TGA、DMA和SEM对复合材料的热性能、界面...     

PTT抗折皱织物的开发及服用性能测试

将聚对苯二甲酸丙二酯(PTT)长丝分别与PTT长丝、聚酯(PET)长丝、棉纱以交织的方法开发了PTT抗折皱平纹织物,对产品的服用舒适性、织物风格、抗折皱效果进行了测试、分析与评价。测试结果表明:PTT抗折皱织物具有较好的弹性,在拉伸变形时的回复能力较好,同时在弯曲和剪切变形时也具有相当高的回复能力,即织物拥有较好的抗折皱功能,其各项服用性能也符合开发PTT抗折皱机织类产品的标准。     

Development of thermoregulating textile materials with microencapsulated phase change materials (PCM). II. Preparation and application of PCM microcapsules

Melamine–formaldehyde microcapsules containing eicosane were prepared by in situ polymerization. The characterization of the microcapsules, including the particle size and size distribution, morphology, thermal properties, and stability, was carried out. The prepared microcapsules were added to polyester knit fabrics by a conventional pad–dry–cure process to develop thermoregulating textile materials. The morphology, thermal properties, and laundering properties of the treated fabrics were also investigated. The microcapsules were spherical and had melamine–formaldehyde shells containing eicosane. The microcapsules were strong enough to secure capsule stability under stirring in hot water and alkaline solutions. The heat storage capacity increased as the concentration of the microcapsules increased. The thermoregulating fabrics had heat storage capacities of 0.91–4.44 J/g, which depended on the concentration of the microcapsules. The treated fabrics retained 40% of their heat storage capacity after five launderings. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2005–2010, 2005