Michał Chrzanowski

Influence of the calender temperature on the crystallization behaviors of polylactide spun-bonded non-woven fabrics:

In this paper the influence of calender temperature on the crystallization behavior of polylactide (PLA) non-woven fabrics during their manufacturing by the spun-bonding technique is described. Non-woven samples were studied by wide-angle X-ray diffraction, differential scanning calorimetry and birefringence. In addition, physical–mechanical properties of the non-woven fabrics were determined. The results are discussed in terms of structural changes of PLA and meso-phase content during the calendering process in the temperature range 70–130℃. The rebuilding of the supermolecular structure of the investigated samples of PLA fabrics under the influence of increasing calender temperature is observed in terms of the disorder-to-order phase transition (ά to α form) during heating around 110℃, and increased degree of crystallinity up to 100℃. The presented structural rebuild of PLA explains observed changes of physical–mechanical properties of the non-woven fabrics obtained at different calendering temperatures. During calendering above 100℃, thermal degradation of PLA occurs at the point of contact between the non-woven fabrics and the calender rollers.

Application of melt-blown technology in the manufacturing of a solvent vapor-sensitive, non-woven fabric composed of poly(lactic acid) loaded with multi-walled carbon nanotubes

We evaluated a solvent vapor-sensitive, non-woven fabric made from a biodegradable, poly(lactic acid) (PLA) polymer loaded with multi-walled carbon nanotubes. The sensory properties of the fabric were obtained by optimizing the process parameters for manufacturing the melt-blown, non-woven fabric composed of 98% PLA 4060D (Nature Works) and 2% multi-walled carbon nanotubes (Nanocyl®). The diffusion of polar and non-polar solvent molecules influenced the electron flow between the separated carbon nanotubes in percolation paths built into the PLA, resulting in an increase of the resistance of the melt-blown, non-woven fabrics. The statistically significant differences between the mean values of electrical resistance before and after the influence of the tested solvent vapors were achieved for the non-woven fabrics manufactured at high air velocity and low extruder screw speed, taking the values of 30 m3/h and 20 rpm, respectively. The results obtained for the non-woven fabric manufactured in the optimal conditions show that methanol vapor response has the lowest amplitude of 15%, whereas for benzene, acetone and toluene sensitivity reaches values of 60%, 40%, and 35%, respectively. The values of the relative resistance amplitude correspond with Flory–Huggins interaction parameters κPLA\benzene < κPLA\acetone < κPLA\toluene < κPLA\methanol.

Effect of processing variables on the thermal and physical properties of poly(L-lactide) spun bond fabrics

In this paper, the influence of the take-up velocity (Vt–u) of fibers on the molecular ordering and ά – α form transition of polylactide (PLA) non-woven fabrics during their manufacturing by spun-bonding is described. Non-woven samples were studied by wide-angle X-ray diffraction, differential scanning calorimetry and Fourier transform infrared spectroscopy. In addition, the physical and mechanical properties of the non-woven fabrics were determined. The results are discussed in terms of the structural changes of the PLA and the meso-phase content during the spun-bonded non-woven fabric forming process. This technological process includes preliminary molecular ordering of the PLA fibers in a downstream spinning block and crystallization on a calender system at a temperature higher than the glass transition. The molecular ordering of the investigated PLA fabric samples under different technological conditions was observed as follows: creation of the meso-phase and a disorder-to-order phase transition (ά to α form) during heating to approximately 110℃ and an increase in the degree of crystallinity for take-up velocities higher than 1400 m/min. The structural changes of the PLA explain the observed changes in the physical and mechanical properties of the non-woven fabrics obtained under different technological conditions.

Investigation of the Influence of PLA Molecular Structure on the Crystalline Forms (α’ and α) and Mechanical Properties of Wet Spinning Fibres

In this paper, the influence of the molecular structure of polylactide (PLA)—characterised by its molar mass and content of d-lactide isomer—on the molecular ordering and α’–α form transition during fibre manufacturing by the wet spinning method is described. Fibres were studied by wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). Additionally, the physical and mechanical properties of the fibres were determined. This study also examines the preliminary molecular ordering and crystallisation of PLA fibres at various draw ratios. The performed experiments clearly show the dependence of the molecular ordering of PLA on the molar mass and d-lactide content during the wet spinning process. The fibres manufactured from PLA with the lowest content of d-lactide and the lowest molar mass were characterised by a higher tendency for crystallisation and a higher possibility to undergo the disorder-to-order phase transition (α’ to α form). The structural changes in PLA explain the observed changes in the physical and mechanical properties of the obtained fibres.

Study on Sensing Properties of Electro-spun PEO/MWNT Non-woven Fabric

This paper presents a study on the sensing properties of a conductive polymer composite (CPC) that is processed by an electrospinning technique. The CPC is obtained by mixing multi-walled carbon nanotubes (MWNT) with a poly (ethylene oxide) (PEO) matrix. Sensors made of this composite are characterised by measuring their electrical properties as a function of external stimuli. In particular, their responses to vapours of toluene, methanol and dioxan are investigated. As studied, the PEO/MWNT material shows high and stable sensitivity over three testing cycles for the selected vapours. An increase in electrical resistance is observed under the influence of chemical substances. This paper supports the concept that penetration of molecules of selected chemical substances leads to the partial disorder of contact between neighboured nanotubes located in the polymer matrix. The electro-spun non-woven fabric with a low amount of MWNT (3 wt.%) in the PEO matrix seems to be a good textile product for application a...

Application of the melt-blown technique in the production of shape-memory nonwoven fabrics from a blend of poly(L-lactide) and atactic poly[(R,S)-3-hydroxy butyrate]:

Shape-memory materials have recently gained significant attention from scientists and industries around the world. Their useful properties and ability to change their shape when triggered by different stimuli have encouraged researchers to develop this area of science. The examinations conducted herein concern a nonwoven material with thermally induced shape-memory properties, produced by the melt-blown technique. The subject of the research was a nonwoven fabric made from biodegradable poly(L-lactide) (PLLA) blended with atactic polyhydroxybutyrate (a-PHB). The main aim of the presented research was to determine the technological parameters of the melt-blown process and investigate the shape fixing and recovery mechanisms in the obtained material. Thermal, mechanical, and structural analyses were conducted to describe the properties of the smart fabric. The results obtained for the nonwoven fabric produced under specific conditions and selected process parameters showed that it possesses a controllable, thermally induced shape-memory effect. Shape-memory textiles have great potential for diverse applications, in particular in medical science.

Influence of the homehold composting conditions on the structural changes of polylactide spun-bonded nonwovens during degradation

In this study, the influence of homehold composting conditions on the molecular and supramolecular structure of polylactide (PLA) in the form of spun-bonded nonwovens was investigated. Nonwoven samples were studied using size-exclusion chromatography coupled with multiangle laser light scattering detection, wide-angle X-ray diffraction, differential scanning calorimetry and Fourier transform infrared spectroscopy. In addition, the physical and mechanical properties of the nonwovens before and after composting were determined. The results show the varying degree of influence of the prepared compost mixtures of soil with common horticultural additives, such as chalk, commercially available agents, cow manure and chicken litter, on the molecular and supramolecular structure of PLA and its degradation rate. The obtained experiment explained which popular homehold agent had the strongest affect on the PLA nonwoven dedicated for agriculture use in the first period of season composting (first 6 months).

Research on a Nonwoven Fabric Made from Multi-Block Biodegradable Copolymer Based on l-Lactide, Glycolide, and Trimethylene Carbonate with Shape Memory

The presented paper concerns scientific research on processing a poly(lactide-co-glycolide-co-trimethylene carbonate) copolymer (PLLAGLTMC) with thermally induced shape memory and a transition temperature around human body temperature. The material in the literature called terpolymer was used to produce smart, nonwoven fabric with the melt blowing technique. Bioresorbable and biocompatible terpolymers with shape memory have been investigated for its medical applications, such as cardiovascular stents. There are several research studies on shape memory in polymers, but this phenomenon has not been widely studied in textile products made from shape memory polymers (SMPs). The current research aims to explore the characteristics of the PLLAGLTMC nonwoven fabric in detail and the mechanism of its shape memory behavior. In this study, the nonwoven fabric was subjected to thermo-mechanical, morphological, and shape memory analysis. The thermo-mechanical and structural properties were investigated by means of differential scanning calorimetry, dynamic mechanical analysis, scanning electron microscopic examination, and mercury porosimetry measurements. Eventually, the gathered results confirmed that the nonwoven fabric possessed characteristics that classified it as a smart material with potential applications in medicine.

RESEARCH CONCERNING FABRICATION OF FIBROUS OSTEOCONDUCTIVE PLGA/HAP NANOCOMPOSITE MATERIAL USING THE METHOD OF ELECTROSPINNING FROM POLYMER SOLUTION

Abstract The aim of the work was to obtain nano fibrous structures from biodegradable polymer with the addition of hydroxyapatite using electrospinning technique. Research was conducted with two types of solvent: dichloromethane and 50:50 mixture of dimethyl sulfoxide and dichloromethane. As a polymer a copolymer of L-lactide and glycolide (PLGA), commercial product with trade name Resomer®LG 824, was used. The preliminary electrospinning tests enabled to match optimal polymer solution concentration of tested samples. Rheological properties of all tested polymer solutions has been determined. Influence of electrospinning conditions and the type of solvent on macroscopic structure has been investigated.

Analysis of the Tension Course of Polyester Monofilaments Characterized by a Variable Cross-Section Field

Analysis of the literature indicates that there is no method to forecast the course of the stress-strain curve of monofilaments characterized by variable cross-section fields. Knowledge of the tension course is crucial for predicting the durability of monofilaments often used in technical applications. Therefore, it was decided to conduct a study to show that it is feasible to describe the course of tensioning irregular polyester monofilaments on the basis of a modified rheological link model and the theory of the monofilament internal irregularity effect on elongation. A comparison of both the theoretical and experimental curves indicates that the proposed rheological model allowed us to calculate the theoretical curve, and to reliably anticipate the behaviour of irregular monofilaments during tension. In all the tested cases, the coefficient of curvilinear correlation exceeded 0.95, and it was higher than 0.99 for the majority of the analysed curves.