This thesis aims at characterizing tridimensional (3D) printed polymers onto PET textile materials via fused deposition modeling (FDM) that uses both non-conductive and conductive polymers, optimizing their mechanical and electrical properties through statistical modeling and enhancing them with pre and post-treatments and the development of polymer blends. This research work supports the development of technical textiles through 3D printing that may have functionalities. The FDM process was considered in this thesis for its strong potential in terms of flexibility, resource-efficiency, cost-effectiveness tailored production and ecology compared to the existing conventional textile finishing processes, for instance, the digital and screen printings. The main challenge of this technology is to warranty optimized electrical and mechanical (bending, flexibility, tensile, abrasion, etc.) properties of the 3D printed polymer onto textiles for the materials to be used in textile industry. Therefore, the development of novel 3D printed polymers onto PET materials with improved properties is necessary.First of all, 3D printed non-conductive Polylactic Acid (PLA) and PLA filled with 2.5wt% Carbon-Black filled onto PET fabrics were purchased and manufactured through melt extrusion process respectively, to characterize their mechanical properties including adhesion, tensile, deformation, wash ability and abrasion. Then, the relationship between the textile structural characteristics and thermal properties and build platform temperature and these properties through statistical modeling was determined. Subsequently, different textile pre-treatments that include atmospheric plasma, grafting of acrylic acid and application of adhesives were suggested to enhance the adhesion properties of the 3D printed PLA onto PET fabrics. Lastly, novel biophasic blends using Low-Density Polyethylene (LDPE) / Propylene- Based Elastomer (PBE) filled with multi-walled carbon nanotubes (CNT) and high-structured carbon black (KB) were developed and manufactured to improve the flexibility, the stress and strain at rupture and the electrical properties of the 3D printed PLA onto PET fabric. The morphology, thermal and rheological properties of each blends are also accessed in order to understand the material behavior and enhanced mechanical and electrical properties.The findings demonstrated that the textile structure defined by its weft density and pattern and weft and warp yarn compositions has a significant impact on the adhesion, deformation, abrasion, tensile properties of 3D printed PLA onto PET fabrics. Compromises have to be found as porous and rough textiles with low thermal properties showed better wash-ability, adhesion and tensile properties and worse deformation and abrasion resistance. Statistical models between the textile properties and the 3D printed PLA onto PET materials and the properties were successfully developed and used to optimize them. The application of adhesives on treated PET with grafted acrylic acid did significantly improve the adhesion resistance and LDPE/PBE blends filled with CNT and KB that have co-continuous LDPE and PBE phases as well as CNT and KB selectively located at the interface and in the LDPE phase revealed enhanced deformation and tensile and electrical properties.

Denna avhandling syftar till att karakterisera tredimensionella (3D) tryckta polymerer på textilamaterial av polyester (PET) via fused deposition modeling (FDM) som använder både icke-ledande ochledande polymerer, optimerar deras mekaniska och elektriska egenskaper genom statistisk modelleringsamt förbättrar dem med för- och efterbehandlingar och utvecklingen av polymerblandningar. Dettaforskningsarbete stöder utvecklingen av tekniska textilier genom 3D-utskrift som kan ha funktioner. FDMprocessenvaldes i denna avhandling för sin stora potential i flexibilitet avseende process, resurseffektivitet,kostnadseffektiv skräddarsydd produktion och ekologi jämfört med befintliga konventionellatextilbearbetningsprocesser, till exempel digital- och skärmtryck. Den huvudsakliga utmaningen med dennateknik är att garantera optimerade elektriska och mekaniska egenskaper (böjning, flexibilitet, drag, nötning,etc.) för 3D-tryckta polymerer på textilier för material att användas i textilindustrin. Därför är utvecklingenav nya 3D-tryckta polymerer på PET-material med förbättrade egenskaper nödvändig.Först och främst köptes icke-ledande polylaktid (PLA) och PLA fylld med 2,5 viktprocent kimröktillverkades genom smältextrudering och 3D-trycktes på PET-tyger, för att karakterisera deras mekaniskaegenskaper inklusive vidhäftning, draghållfasthet, deformation, tvättbarhet och nötningstålighet. Därefterbestämdes förhållandet mellan textilens strukturella och termiska egenskaper och plattformstemperatur ochdessa egenskaper bestämdes genom statistisk modellering. Därefter testades olika textila förbehandlingarså som atmosfärisk plasma, ympning av akrylsyra och applicering av lim för att förbättravidhäftningsegenskaperna hos 3D-tryckt PLA på PET-tyger. Slutligen utvecklades och tillverkades nyabiofasiska blandningar med lågdensitetspolyeten (LDPE) / propylenbaserad elastomer (PBE) fyllda medflerväggade kolnanorör (CNT) och högstrukturerad kimrök (KB) för att förbättra flexibiliteten, spänningoch belastning vid bristning och de elektriska egenskaperna hos 3D-tryckt PLA på PET-tyg. Morfologin,samt de termiska och reologiska egenskaperna hos varje blandning analyserades också för att förståmaterialegenskaper och förbättrade mekaniska och elektriska egenskaper.Resultaten visade att textilstrukturen så som den är definierad av dess väfttäthet och konstruktion ochväft- och varpgarnskompositioner har en signifikant inverkan på vidhäftning, deformation, nötning ochdragegenskaper hos 3D-tryckt PLA på PET-tyger. Kompromisser måste göras eftersom porösa och grovatextilier med låga termiska egenskaper visade bättre tvättförmåga, vidhäftning och dragegenskaper ochsämre deformation och nötningsbeständighet. Statistiska modeller mellan textilegenskaperna, 3D-trycktPLA på PET-material och egenskaperna har framgångsrikt utvecklats och använts för optimering.Applicering av lim på behandlad PET med ympad akrylsyra förbättrade signifikant vidhäftningsresistensenoch LDPE/PBE-blandningar fyllda med CNT och KB som har ko-kontinuerliga LDPE- och PBE-faser samtCNT och KB selektivt belägna vid gränssnittet och i LDPE-fasen gav förbättrad deformation, drag- ochelektriska egenskaper.

Cette thèse vise à caractériser des polymères imprimés tridimensionnellement (3D) sur des matériaux textiles PET via une méthode de dépôt de polymère fondu connu sur le nom de Fused Deposition Modeling (FDM) utilisant à la fois des polymères non conducteurs et conducteurs. Les propriétés mécaniques et électriques ont été optimisées par le biais de modèles statistiques et améliorées grâce à des pré et post-traitements ou le développement de mélanges de polymères. Ce travail de recherche apporte de nouveaux résultats sur le développement de textiles techniques par l'impression 3D de polymères fonctionnels. Le procédé FDM a été considéré dans cette thèse pour son fort potentiel en termes de flexibilité, d'efficacité des ressources, de production sur mesure et d'écologie par rapport aux procédés de finition textile conventionnels existants, par exemple, les impressions numériques et sérigraphiques. Le principal enjeu de cette technologie est de garantir des propriétés électriques et mécaniques optimisées (flexion, flexibilité, traction, abrasion, etc.) du polymère imprimé en 3D sur les textiles afin d’être utilisé dans l'industrie textile. Par conséquent, le développement de nouveaux polymères imprimés en 3D sur des matériaux PET avec des propriétés améliorées est nécessaire. Dans un premier temps, de l’'acide polylactique (PLA) non conducteur et du PLA contenant 2.5% de noir de carbone ont été imprimé en 3D sur des tissus en PET. Les polymères conducteurs ont été fabriqués par le procédé d'extrusion à voie fondu. Les propriétés mécaniques, notamment d’adhésion, de traction, de déformation, de résistance au lavage et d’abrasion ont été déterminées. Ensuite, la relation entre les caractéristiques structurelles et thermiques du textile et la température du plateau de l’imprimante 3D et ces propriétés par le biais de modèles statistiques a été déterminée. De plus, différents pré-traitements sur textiles incluant le plasma atmosphérique, le greffage d'acide acrylique et l'application d'adhésifs ont été suggérés pour améliorer les propriétés d’adhésion du PLA imprimé en 3D sur les tissus en PET. Enfin, de nouveaux mélanges biphasiques utilisant du polyéthylène basse densité (LDPE) et un élastomère à base de propylène (PBE) contenant de nanotubes de carbone à parois multiples (CNT) et de noir de carbone à haute structure (KB) ont été développés et fabriqués pour améliorer la flexibilité, le la contrainte et la déformation à la rupture et les propriétés électriques du PLA imprimé en 3D sur le tissu PET. La morphologie, les propriétés thermiques et rhéologiques de chaque mélange sont également déterminées afin de comprendre le comportement du matériau et l’amélioration de ses propriétés mécaniques et électriques. Les résultats ont démontré que la structure textile définie par sa densité en trame, son motif et la composition des fils de trame et de chaîne a un impact significatif sur l'adhésion, la déformation, l'abrasion et les propriétés de traction du PLA imprimé en 3D sur les tissus en PET. Des compromis doivent être trouvés car les textiles poreux, rugueux possédant de faible conductivité thermique ont montré de meilleures propriétés de lavage, d’adhésion et de traction et une moins bonne résistance à la déformation et à l'abrasion. Des modèles statistiques entre les propriétés textiles et le PLA imprimé en 3D sur des matériaux PET et les propriétés ont été développés avec succès et utilisés pour les optimiser. L'application d'adhésifs sur des tissus en PET traité avec de l'acide acrylique greffé a considérablement amélioré la résistance d'adhésion. Par ailleurs, les mélanges LDPE / PBE de phases co-continues et contenant du CNT et de KB localisés à l'interface ou dans la phase LDPE a révélé améliorer considérablement la déformation et les propriétés de traction et électriques des imprimés 3D sur textiles.

本论文旨在通过熔融沉积成型（FDM）将导电和非导电高分子材料通过3D打印到纺织品上。通过数据建模分析来优化纺织品的机械性能和导电性能，并通过纺织品的前处理和后处理来增强性能，以开发功能性高分子共聚物。本研究有助于3D打印功能性技术纺织品的研发。本研究采用的熔融沉积成型过程跟传统的纺织品整理过程如数码或筛网印花相比，具有较高的加工灵活性，原料使用的高效性以及成本低廉的优势。熔融沉积成型3D打印技术的关键在于确保加工后的纺织具有最优的电学和力学性能（弯曲、柔韧、拉伸、耐摩擦等）。因此，对熔融沉积成型3D打印技术应用于纺织品的研究具有十分重要的意义。

本课题首先通过熔融加工制备了含有2.5wt%炭黑的PLA复合材料并将其运用于PET织物上，并对该织物和3D打印非导电PLA材料进行机械性能包括粘附性、拉伸性、变形性、可洗性和摩擦性进行表征。运用数据建模分析了纺织品结构特征和热学性能以及加工平台温度的关系。然后通过不同的纺织品前处理过程如大气压等离子体、丙烯酸接枝和粘合剂应用以增强3D打印的PLA与PET织物的粘合性。最后，使用填充有多壁碳纳米管（CNT）和高结构炭黑（KB）的低密度聚乙烯（LDPE）/丙烯基弹性体（PBE）制备新型二相共混物，以提高PLA 3D打印PET织物的柔韧性、断裂应力应变以及电学性能。同时，对复合物的表面结构、热学性能和流变性能进行表征以了解材料机械和电学特性。

试验表明，织物的结构如纬密，样式以及经纬纱线的成分对3D打印PLA在PET织物上的粘附性、变形性、摩擦性和拉伸性能有明显影响。多孔和具有较低热学性能的粗糙的纺织品具有较好的可洗性、粘附性和拉伸性，变形性和耐磨性较差。通过数据建模分析对PLA 3D打印PET织物的性能进行分析和优化。将丙烯酸作为粘合剂运用于PET织物上时可以明显的提高粘合性。LDPE/PBE与CNT和KB的复合物具有共连续的LDPE和PBE相，且CNT和KB有选择性的分布于界面和LDPE相中的，从而提高了耐变形性和力学以及电学性能。

3D printing utilized as a direct deposition of conductive polymeric materials onto textilesreveals to be an attractive technique in the development of functional textiles. However, the conductivefillers—filled thermoplastic polymers commonly used in the development of functional textiles through3D printing technology and most specifically through Fused DepositionModeling (FDM) process—arenot appropriate for textile applications as they are excessively brittle and fragile at room temperature.Indeed, a large amount of fillers is incorporated into the polymers to attain the percolation thresholdincreasing their viscosity and stiffness. For this reason, this study focuses on enhancing the flexibility,stress and strain at rupture and electrical conductivity of 3D-printed conductive polymer onto textiles bydeveloping various immiscible polymer blends. A phase is composed of a conductive polymer composite(CPC)made of a carbon nanotubes (CNT) and highly structured carbon black (KB)- filled low-densitypolyethylene (LDPE) and another one of propylene-based elastomer (PBE) blends. Two requirements areessential to create flexible and highly conductive monofilaments for 3D-printed polymers onto textilematerials applications. First, the co-continuity of both the thermoplastic and the elastomer phases and thelocation of the conductive fillers in the thermoplastic phase or at the interface of the two immisciblepolymers are necessary to preserve the flexibility of the elastomer while decreasing the global amountof charges in the blends. In the present work based on theoretical models, when using a two-stepmelt process, the KB and CNT particles are found to be both preferentially located at the LDPE/PBEinterface. Moreover, in the case of the two-step extrusion, SEM characterization showed that the KBparticles were located in the LDPE while the CNT were mainly at the LDPE/PBE interface and TEManalysis demonstrated that KB and CNT nanoparticles were in LDPE and at the interface. For one-stepextrusion, it was found that both KB and CNT are in the PBE and LDPE phases. These selectivelocations play a key role in extending the co-continuity of the LDPE and PBE phases over a much largercomposition range. Therefore, the melt flow index and the electrical conductivity of monofilament,the deformation under compression, the strain and stress and the electrical conductivity of the 3D-printedconducting polymer composite onto textiles were significantly improved with KB and CNT-filledLDPE/PBE blends compared to KB and CNT-filled LDPE separately. The two-step extrusion processed60%(LDPE16.7% KB + 4.2% CNT)/40 PBE blends presented the best properties and almost similar to theones of the textile materials and henceforth, could be a better material for functional textile developmentthrough 3D printing onto textiles.

Wear resistance of conductive Poly Lactic Acid monofilament 3D printed onto textiles, through Fused Deposition Modeling (FDM) process and their electrical conductivity after abrasion are important to consider in the development of smart textiles with preserved mechanical and electrical properties. The study aims at investigating the weight loss after abrasion and end point of such materials, understanding the influence of the textile properties and 3D printing process parameters and studying the impact of the abrasion process on the electrical conductivity property of the 3D printed conductive polymers onto textiles. The effects of the 3D printing process and the printing parameters on the structural properties of textiles, such as the thickness of the conductive Poly Lactic Acid (PLA) 3D printed onto polyethylene terephthalate (PET) textile and the average pore sizes of its surface are also investigated. Findings demonstrate that the textile properties, such as the pattern and the process settings, for instance, the printing bed temperature, impact significantly the abrasion resistance of 3D printed conductive Poly Lactic Acid (PLA) onto PET woven textiles. Due to the higher capacity of the surface structure and stronger fiber-to-fiber cohesion, the 3D printed conductive polymer deposited onto textiles through Fused Deposition Modeling process have a higher abrasion resistance and lower weight loss after abrasion compared to the original fabrics. After printing the mean pore size, localized at the surface of the 3D-printed PLA onto PET textiles, is five to eight times smaller than the one of the pores localized at the surface of the PET fabrics prior to 3D printing. Finally, the abrasion process did considerably impact the electrical conductivity of 3D printed conductive PLA onto PET fabric.

Adhesion of conductive poly-lactic acid filament (PLA) 3D printed onto polyethylene terephthalate (PET) fabrics is a one of the fundamental properties to guarantee their use in smart textiles field. The conductive PLA layer is made of carbon black (CB) incorporated into PLA polymer prior to extrusion process. It is commonly known that due to the low surface tensions of polymeric materials, 3D printed conductive PLA onto PET textiles possess poor adhesion. Therefore, an improvement of this property, even already approached by some researchers (1–6), is still highly required. In this research work, a pre and post-treatments were applied to significantly improve the adhesion strength at the interface polymeric layer/textile compared to former techniques used in other researches such as plasma treatment; coating of glue stick, washing and ironing processes. The pre-treatment consists in grafting acetic acid by UV curing onto both PET fabric and PLA filament through digital printing and deep coating respectively and then applying a solution pressure sensitive adhesive (PSA) on the fabric via digital printing. After 3D printing process on textiles, heat and pressure were applied on the materials using a heat press to chemically bond the PLA layer to the PET fabric. The findings are very promising as they demonstrate the possibility of significantly improving the adhesion of thermoplastic polymer 3D printed on textiles for smart textiles applications. Compared to other alternative solutions, these findings can potentially be implemented, in the future, by using 3D printing technology for pre-treatment and printing processes followed by thermo-compression technique for complete chemical bonding.

Purpose

This paper aims to evaluate and simulate the impact of the build platform temperature of the three-dimensional (3D) printer, the structure and heat transfer of textiles on the adhesion and durability after washing properties of 3D printed polymer onto textile materials using thin layers of conductive and non-conductive extruded poly lactic acid monofilaments (PLA) deposited on polyethylene terephthalate (PET) woven fabrics through fused deposition modeling (FDM) process.

Design/methodology/approach

Prior to FDM process, thermal conductivity, surface roughness and mean pore size of PET woven fabrics were assessed using the “hot disk,” the profilometer and the capillary flow porometry methods, respectively. After the FDM process, the adhesion and durability after the washing process properties of the materials were determined and optimized based on reliable statistical models connecting those properties to the textile substrate properties such as surface roughness, mean pore size and thermal conductivity.

Findings

The main findings point out that higher roughness coefficient and mean pore size and lower thermal conductivity of polyester woven textile materials improve the adhesion properties and the build platform presents a quadratic effect. Additionally, the adhesion strength decreases by half after the washing process and rougher and more porous textile structures demonstrate better durability. These results are explained by the surface topography of textile materials that define the anchorage areas between the printed layer and the textiles.

Originality/value

This study is for great importance in the development of smart textiles using FDM process as it presents unique and reliable models used to optimize adhesion resistance of 3D printed PLA primary layer onto PET textiles.

Although direct deposition of polymeric materials onto textiles through 3D printing is a great technique used more and more to develop smart textiles, one of the main challenges is to demonstrate equal or better mechanical resistance, durability and comfort than those of the textile substrates before deposition process. This article focuses on studying the impact of the textile properties and printing platform temperature on the tensile and deformations of non-conductive and conductive poly lactic acid (PLA) filaments deposited onto polyethylene terephthalate (PET) textiles through 3D printing process and optimizing them using theoretical and statistical models. The results demonstrate that the deposition process affects the tensile properties of the printed textile in comparison with the ones of the textiles. The stress and strain at rupture of the first 3D printed PLA layer deposited onto PET textile material reveal to be a combination of those of the printed layer and the PET fabric due to the lower flexibility and diffusion of the polymeric printed track through the textile fabric leading to a weak adhesion at the polymer/textile interface. Besides, printing platform temperature and textile properties influence the tensile and deformation properties of the 3D printed PLA on PET textile significantly. Both, the washing process and the incorporation of conductive fillers into the PLA do not affect the tensile properties of the extruded polymeric materials. The elastic, total and permanent deformations of the 3D-printed PLA on PET fabrics are lower than the ones of the fabric before polymer deposition which demonstrates a better dimensional stability, higher stiffness and lower flexibility of these materials.

In this study, conductive tracks are integrated onto textiles through Fused Deposition Modelling (FDM) process and the correlation between the FDM process parameters, the textile properties (the porosity and the structure for instance) and the electrical resistance of the composites is investigated. Many researchers have studied the electrical conductivity of polymers composites using incorporation of conductive fillers such as carbon black or carbon nanotube–polymer composites and the effect of the 3D printing process parameters, such as extruder temperature, on the electrical properties [1–7]. However, in this paper, in addition to study and understand the electrical properties of these conductive materials deposited onto textiles, they are maximized to guarantee the use of the textile composites in smart textiles field.Findings are very promising and important in the development of functionalized textiles as they demonstrate the feasibility of enhancing the electrical conductivity of textile composite materials through theoretical models based on the experimental data.

FDM technology used for printing functionalized layers on textiles brought new challenges such as the understanding and the improvement of the adhesion performance of the thermoplastic filaments on synthetic textile materials. In addition to the impact of printing parameters, the correlation between the heat transfer and structure of the textile material and the adhesion performance after varying printer platform temperature was an important parameter considered in this paper. A factorial design, using material density, direction, and structure and platform temperature as factors, was followed. 3D-printed materials made of PLA filaments deposited on polyester woven and knit materials were manufactured on a dual-head printer and their adhesion was measured according to DIN EN ISO 13937-2 and ISO 11339 and the heat transfer of the fabrics according to ASTM D4966-98, ISO 6330 and ISO 22007-2. The findings showed that the heat transfer and structure of textile materials affect the adhesion properties of the 3D-printed material.