investigation of the adhesion properties of direct 3d printing of polymers and nanocomposites on textiles effect of fdm printing process parameters

Investigation of the adhesion properties of direct 3D printing of polymers and nanocomposites on textiles: Effect of FDM printing process parameters Razieh Hashemi Sanatgar a,b,c,d , Chr

Title: Investigation of the adhesion properties of direct 3D

printing of polymers and nanocomposites on textiles: Effect of

FDM printing process parameters

Authors: Razieh Hashemi Sanatgar, Christine Campagne,

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Investigation of the adhesion properties of direct 3D printing of polymers and nanocomposites on textiles: Effect of FDM printing process parameters

Razieh Hashemi Sanatgar a,b,c,d , Christine Campagne b,c , Vincent Nierstrasz a

a Textile Materials Technology, Department of Textile Technology, Faculty of Textiles, Engineering and

Business, University of Borås, SE-501 90, Borås, Sweden

b ENSAIT, GEMTEX, F-59100, Roubaix, France

c Université Lille Nord de France, F-59000, Lille, France

d Soochow University, College of Textile and Clothing Engineering, Suzhou, Jiangsu, 215006, China

Graphical abstract

Highlights

 Applying 3D printing as a novel printing process for deposition of polymers on fabrics

 Possible use of proposed method for developing innovative smart textiles by

integrating functional polymers with textiles without compromising on quality and flexibility of the fabric

 Significant effect of different 3D printing processing parameters on the adhesion of polymers to fabrics

 High adhesion force of deposited PLA and PLA nanocomposites on PLA fabrics

Abstract

In this paper, 3D printing as a novel printing process was considered for deposition of

polymers on synthetic fabrics to introduce more flexible, resource-efficient and cost effective textile functionalization processes than conventional printing process like screen and inkjet printing The aim is to develop an integrated or tailored production process for smart and functional textiles which avoid unnecessary use of water, energy, chemicals and minimize the waste to improve ecological footprint and productivity Adhesion of polymer and

nanocomposite layers which were 3D printed directly onto the textile fabrics using fused deposition modelling (FDM) technique was investigated Different variables which may affect the adhesion properties including 3D printing process parameters, fabric type and filler type incorporated in polymer were considered A rectangular shape according to the peeling

standard was designed as 3D computer-aided design (CAD) to find out the effect of the

different variables The polymers were printed in different series of experimental design: nylon on polyamide 66 (PA66) fabrics, polylactic acid (PLA) on PA66 fabric, PLA on PLA fabric, and finally nanosize carbon black/PLA (CB/PLA) and multi-wall carbon

nanotubes/PLA (CNT/PLA) nanocomposites on PLA fabrics The adhesion forces were quantified using the innovative sample preparing method combining with the peeling standard method Results showed that different variables of 3D printing process like extruder

temperature, platform temperature and printing speed can have significant effect on adhesion force of polymers to fabrics while direct 3D printing A model was proposed specifically for deposition of a commercial 3D printer Nylon filament on PA66 fabrics In the following, among the printed polymers, PLA and its composites had high adhesion force to PLA fabrics

proposed designs are mostly conductive silver tracks with different protective layers on textiles [2–8] which increase durability and conductivity of the silver This method has some advantages like use of low-cost patterning process at room temperature, high volume batch fabrication and applicability on any irregular textile surface [1] Although in comparison with traditional subtractive microfabrication processes, screen printing does not need extra

photolithographic and chemical etching processes but it involves curing step [9]

Compared to the screen printing technology, inkjet printing which is a conventional direct write deposition tool has the advantage of high precision of ink droplet, thin layer deposition capability, short run length as well as tailored/integrated production process This technology has already been used for graphene and graphene-based [10], silver-containing [11] and CNT inks [12] In addition, inkjet-printed elements such as conductors (antennas), dielectrics (capacitors) and sensors can be developed for wearable electronics applications [13]

Although with this method, it is possible to print onto the fabric but multiple printing is

needed to produce a desired functionality with a thin inkjet printed layer on the rough fabric which increase manufacturing time and cost [14] Additionally, inkjet printed layers on fabric are resilience to stretching and bending, besides, the major part of fabrics cannot resist curing temperatures above 150°C [15] A thin based coating or screen printing can be used to make

an interface layer to reduce the surface roughness of the fabrics for inkjet printing Chauraya

et al applied a screen printed interface layer to facilitate the printing of a continues

conductive surface of antennas for wearable applications [15,16]

However, there still exist many problems with these new technologies, though they provide conceivably low-cost alternatives to traditional technologies For example inkjet printers are expensive, screen printing has some pollution and waste during the process and the needed warehouse for screens as well as downtime of screen printing should be considered which increase manufacturing cost and time In addition, repairing the imperfect products produced

by these methods is not easy [17] Therefore, the manufacturing techniques still need to be improved

Introduction of 3D printing technology is proposed in this research to manufacture and

improve these systems more easily and for integrated or tailored manufacturing processes 3D printing is a term to define a technology applied for the rapid prototyping or rapid

manufacturing of 3D objects directly from digital computer aided design (CAD) files [18] The main differences between several 3D printing processes are in the way of layer deposition and used materials Some methods melt or soften the material to produce the layers like fused deposition modelling (FDM), some compact and form a solid mass of powdered material by

laser such as selective laser sintering (SLS), while others cure liquid materials using

technologies such as stereolithography based on photo-solidification, a process by which light causes chains of molecules to link together forming polymers Photo-solidification reactions are mostly chain-growth polymerizations which are initiated by the absorption of visible or ultraviolet light Since polymerization only occurs in regions which have been exposed to light, unreacted monomer can be removed from unexposed regions

The most prolific technology used in low-cost 3D printers is FDM The method uses a plastic filament which is pushed the material through a heated extrusion nozzle melting The method begins with software which processes an STL (stereolithography) or CAD (computer-aided design) file, mathematically slicing and orienting the model for the building process

FDM printing can be an alternative technology to other technologies including screen

printing, gravure, flexography, inkjet printing, etc to functionalize and modify different types

of textile substrates [19] It can be applied to develop functional or smart textiles based on the deposition of functional polymers or blends of functional compounds and polymers on textile fabrics [20] The deposited patterns follow the model without utilizing masks or subsequent etching processes It has the advantage of being able to process high-viscosity materials and print multiple layers to achieve e.g high-electrical conductivity

For effective deposition of polymers onto fabrics, there are different areas which have to be considered: a) the binding and adhesion phenomena of polymer onto fabrics, b) drape ability

of the printed fabric for free movement and c) ability to deform and recover when they are

subjected to daily wear forces [21,22] and d) washability Brinks et al [20] performed

deposition of polylactic acid (PLA) on PET bundles with pressure on the melt immediately after applying the melt to have some penetration and bonding between molten PLA and the

PET bundle Pei [21] recently investigated the adhesion of a series of functional and

decorative parts printed directly onto fabrics using an entry-level FDM machine For example

he has printed orthopedic braces onto textile where the flex and breathability of the textile will provide comfort, and the rigid structures of the polymer will provide support He found that PLA has good adhesion with high quality of print and good flexural strength Sabantina [23] also examined the combination of different textile mesh structures with PLA printed matrices due to their mechanical properties They recognized that the connection between printed material and textile threads is sufficient for garment and technical textiles

Polymer deposition depends strongly on the combination of textile and polymer and needs specific processes This area requires research into not only new, existing materials as well, polymer-textile adhesion and deposition/extrusion technology The technology can have

potential benefits such as more flexible and cost-effective production of high end products Minimization of textile waste combined with reduced consumption of energy, water and chemicals can increase the productivity and improve the ecological footprint of this method Possible uses of this technology includes smart bandages, virtual reality gloves, wearables with sensor and heat properties, safety equipment for the defense industry, unique sportswear that manages body temperature, medical equipment, automotive, aviation and aerospace accessories, and more But, contrary to all other technologies mentioned above 3D printing is not yet in industrial scale

This research focuses on how to optimize adhesion of deposited polymers and

nanocomposites on textile fabrics using FDM technique in order to produce a fabric with a certain pattern The 3D printer filaments and fabrics were chosen from sustainable materials like PLA and polyamides (PAs), thereby enabling production of smart textiles with reduced ecological footprint PLA has the benefit of being biodegradable Its monomer, lactic acid, is derived from renewable plant sources, such as starch and sugar It is processed into polymers primarily by company NatureWorks LLC [24,25] Pure PLA can be degraded into carbon dioxide, water and methane over a period of several months to two years under specific environmental conditions which is a distinct advantage compared to other petroleum plastics that need much longer periods [26] On the other hand, easy degradation of fibers can go hand-in-hand with a shorter lifespan, so advanced industrial polymerization technologies have been developed to obtain high molecular weight pure PLA, which leads to a potential for structural materials with enough lifetime to maintain mechanical properties without rapid hydrolysis [26] PAs are also less easily harmed by sources of degradation responsible for reducing life expectancy include heat, light, and chemicals used in cleaning or maintaining fabrics which defeating one of the major benefits of PAs [27]

Conductive polymer nanocomposites (CPCs) are insulating polymer matrices with conductive fillers - like carbon black, carbon nanotubes and metallic particles In the present work, the adhesion properties of two types of CPC including multi-wall carbon nanotubes/PLA

(CNT/PLA) and a nanosize carbon black/PLA (CB/PLA) are reported Distinct advantages of high aspect ratio fillers based on carbon allotropes like carbon nanotubes in comparision with more traditional fillers like carbon black originate from their sheer size [28] Since carbon black is still a desirable filler in polymers which is generally UV absorbent, heat and chemical resistant, has a low density and low thermal expansion, and acts as an antiabrasive [29], a nanosize carbon black with high aspect ratio is favarable A nanosize or high-structured CB is

made by fusion of the primary particles into an extended three dimensinal structure which the final dimension and density depends on the preparation method [30] Moreover, the

conductivity of CB allows it to be applied in radiation shielding and static dissipative

applications [31]

The effect of 3D printing process parameters such as extruder temperature, construction platform temperature and printing speed on the adhesion of mentioned polymers and

nanocomposites to fabric has been investigated with the aid of statistical design

2 Materials and methods

The 3D printer used was a two-head WANHAO Duplicator 4/4x purchased from Creative Tools AB (Halmstad, Sweden) The maximum printing size was 22.5x14.5x15 cm (length, width and height respectively) with a nozzle diameter of 0.4mm Fabrics were placed

longitudinal in warp direction

Natural white Nylon (Taulman 3D-618 Nylon, a copolymer of Polyamide 6 6,6) and orange PLA (ECO-PLA) printing filaments were also purchased from Creative Tools AB with the diameter of 1.75 mm and used as received Conductive filaments were formulated using two different fillers including a nanosize carbon black filler (Ketjenblack® EC-600JD) supplied

by AKZO NOBEL (Amersfoort, The Netherlands) and multi-wall carbon nanotubes

(MWNTs) supplied by Nanocyl (Belgium) under the reference Nanocyl®-7000 in a matrix of

a semi-crystalline thermoplastic polylactide (PLA) under the reference NatureWorks®-6201

D (Mn = 58300 g/mol; D-Isomer = 1.3%)

CAD designs were drawn and visualized in Rhinoceros software (rectangular shape with 200

mm length, 25mm width and 0.1 mm thickness) and transferred to 3D printable format using the Simplify3D software supplied by Creative Tools AB

Three different weave structures of PLA fabric (plain, twill and panama) prepared in Swedish School of Textiles and two PA66 fabrics with different number of threads per centimeter in warp and weft with different yarn count (type (1) 50×30 / 78×180 dtex, type (2) 39×27 / 180

×180 dtex) purchased from FOV fabrics AB (Borås, Sweden) were applied

2.1 Conductive filament preparation

In first step, fillers (MWCNs and CB separately) were incorporated into PLA with a weight percentage of 10% and dispersed using a Thermo Haake co-rotating, intermeshing twin-screw

extruder (L/D=25) To facilitate the dispersion of nanofillers in a polymer, the applied shear stress to the molten polymer was optimized, because of the residence time within the barrel However, the screw rotational speed was fixed at 100 rpm The applied extruder subtends five heating zones in which the temperature was independently fixed at 160, 175, 175, 170 and 160° C In second step, the pelletized masterbatch (dried at 60°C for 12 hours) was diluted with PLA pellets to obtain concentration of 0.5-5 wt.% of MWCNs and 1-7% of CB in PLA

To cool down the produced filaments more efficiently, a cooling bath (YVROUD, France) with closed circulation of water in room temperature was applied The produced

monofilaments (rods) with 2 wt.% of MWCNs and 5% of CB with almost equal conductivity

of 0.04 S/cm were introduced to 3D printer

2.2 Statistical design of experiments

To investigate the adhesion force of deposited polymers on fabrics by 3D printing, different series of experimental design was done There are three aspects of the process that were analyzed by a designed experiment [32]: (a) treatment factors or inputs to the process In this case, the controllable factors were 3D printing process parameters like extruder temperature, platform temperature and printing speed Fabric type and filler type could also be considered

as factors of the process (b) levels or settings of each factor Examples included the

temprature and speed settings of 3D printer and particular type of filler and fabric chosen for evaluation (c) response or output of the experiment Adhesion force which was measurable

by tensile tester and potentially influenced by the factors and their levels was the output of the experiment The factors and levels considered for 3D printing onto fabrics are shown in Table

1 Treatment factors were labeled F1, F2, F3, F4, F5, F6 and levels were labled 1,2, Since each experiment (Nylon on PA, PLA on PA, PLA on PLA and nanocomposites (CB/PLA and CNT/PLA) on PLA) involved more than one treatment factor, every adhesion force

measurement was on some combination of levels of the various treatment factors (Table 2) For example, if there were three treatment factors (extruder temperature, platform temperature and printig speed), whenever a measurement was taken at a certain extruder temprature, it must necessarily be taken at some platform temprature and printig speed and vice versa Suppose there were three levels of extruder temprature coded 1,2,3 and two levels of platform temprature coded 1,2 Then there were six combinations of levels coded 11, 12, , 32, where the first digit of each pair refers to the level of extruder temprature and the second digit to the level of platform temprature

The combinations of the levels were called treatments combinations and an experiment

involving two or more treatment factors was called a factorial experiment We will use the term treatment to mean a level of a treatment factor in a single factor experiment, or to mean a treatment combination in a factorial experiment [32] Adhesion force which was the output of the experiment is shown in Table 2 for each treatment Each treatment was done with three replications

2.3 Adhesion test

Adhesion tests were done according to standard test method SS-EN ISO 11339:2010 using a Zwick/Z010 tensile tester The separation rate was 100 mm/min The steps which applied for preparation and test the samples are shown in Fig 1 Firstly a double sided tape was used for installing fabric on construction platform Then, a tape was placed on one side of the sample

to avoid deposition of polymer on fabric while printing The positioned tape in one side was separated from the fabric after 3D printing to position the samples in test frame of tensile tester for peeling test

3 Results and discussion

Fig 2 represents the adhesion force of deposited Nylon and PLA on PA fabric via 3D

printing The treatment combination and adhesion force for each sample coded from 1 to 26 can be found in detail in Table 2 Apparently, different treatment combinations in 3D printing process can affect the adhesion force of deposited polymers to fabrics and can make different results

3.1 Effect of 3D printing process parameters on adhesion force of Nylon onto PA66 fabric

Experiment 1 was done for adhesion of Nylon on PA66 with three different factors and levels

of extruder temperature (235, 250 and 260 °C), platform temperature (23, 50°C) and printing speed (18, 50 and 83 mm/min) which is in total 18 treatment combinations with three

replications The detailed treatment combinations for samples 1 to 18 and the results of related adhesion force can be found in Table 2 Minitab software was used to do regression analysis, specify the model, interpret the adhesion results and determine how well the model fits

As it shown in Fig 3a, adhesion force versus extruder temperature has linear regression model and P-value is less than 0.05 which means there is significant linear effect of the factor

extruder temperature on adhesion When the extruder temperature of Nylon is close to melting point of the PA66 fabric (268.6°C), diffusion of polymers in interfaces has happened which can make higher adhesion forces [33]

Deposition of polymers directly on fabrics can be considered as a thermal welding method in which joining of the polymer as an adhesive and fabric as an adherent take place during the printing process Different theories have been applied to explain polymer-to-polymer

adhesion [34] According to adsorption theory of McLaren the bonding formation is divided into two steps In first step micro Brownian motion causes the migration of large polymer molecules from adhesive to the surface of adherent, subsequently polar groups of the adhesive macromolecules approach the polar groups of adherent Applying pressure and lowering viscosity while heating can facilitate this step Sorption process is the second step which starts when the distance between molecules of adhesive and adherent become less than 5Å and intermolecular forces begin to have an effect This theory cannot explain the high adhesion between non-polar polymers and the low adhesion of too high polar polymer to very polar adherent

Diffusion is more reasonable theory which explains the adhesion of polymers to each other by the diffusion of chainlike molecules which leads to formation of a strong bond between

adhesive and adherent (Fig 4) Polymer diffusion has major effect on properties of the layers

of polymers across the interface and is the function of temperature, composition,

compatibility, molecular weight, orientation and molecular structure of polymers [35]

Diffusion improves the adhesion between the two layers of the polymer and makes the

interface stable

In fact, the diffusion theory can easily explain the increase of adhesion force by the rise of extruder temperature for deposited 3D printed polymers on fabric Extruder temperature increase causes rise of thermal motion of macromolecules of polymer or their segments, and

as a consequence diffusive penetration into the fabric increases Hence, the higher increase in the adhesion with increasing extruder temperature (consequently contact temperature) would

be explained from a purely kinetic viewpoint by the greater intensity of micro-Brownian motion of their chains and by the fact that the increase of flexibility of molecular chains and the destruction of intermolecular links take place with increasing temperature more rapidly [34]

Furthermore, deposited polymer (a copolymer of PA 6 6,6) and applied fabric (PA66) are both polyamides which Van der Waals dispersion forces are involved in the bonding

mechanisms Depositing polymer with higher extruder temperature soften the fabric to make a stronger interface by making good contact Increasing the extruder temperature to the melting point of the fabric enhance the joint interface stability by improving good contact and Van der Waals forces It is worth mentioning that although PAs include polar amide groups which can hydrogen bond with each other but used co-polymer PA 6 6,6 for extruding which offer the most favorable combination of price, properties, and processability is designed for high adhesion of 3D printed layers together which means the cohesive forces are high

So extruder and platform temperatures can have an important role in interface stability Since the platform temperature (23 and 50°C) was chosen not higher than the glass transition

temperature of PA66 fabric (Tg=55°C), there is no significant linear effect of platform

temperature on adhesion force (Fig 3b) Proceeding from the above discussion about the nature of adhesion, it is obvious that the value of adhesion at the interface of polymer-

polymer is dependent upon the phase state of the polymers [34] Fig 3b shows that platform temperatures not higher than glass transition can cause any difference in adhesion force In fact, at glassy point of polymer when there is no mobility of the molecule chains, diffusion and consequently adhesion is nothing The middle segments and macromolecule ends start to have thermal motion in the rubberlike region In the end in a flow state, all of macromolecules participate in the diffusion Thus, the phase state of polymer of the fabric which is determined

by the platform temperature of 3D printer can play a pivotal role in adhesion when it is higher than glass transition temperature of the polymer

According to Fig 3c, the quadratic regression coefficient is significantly different from 0 So there is significant quadratic effect of printing speed on adhesion force Printing speed in middle ranges (50 mm/min) causes the highest adhesion results

In connection with the influence of thickness layer on adhesion strength and in order to find out why printing speed cause quadratic effect on adhesion force, an analysis was done on effect of printing speed on thickness of 3D printed layers Thickness of the 3D printed layers versus printing speed has linear regression model and P-value is less than 0.05 and as it is shown in Fig 5 the thickness of the layers decrease by increasing print speed

It has been shown that adhesion force is dependent on the thickness of the adhesive layer for composite interfaces [36] As the thickness of the adhesive layer is reduced, interfacial

bonding strength increases because stress is able to dissipate through the interface easier

Although highest printing speed causes the lowest layer thickness, a decrease is observed in adhesion strength (Fig 3c) Adhesion is the tendency of different surfaces to join to each other and cohesion is relevant to the tendency of similar surfaces to adhere to one another (Fig 6) Since the penetration of the macromolecules of polymers into the fabric is slow at high printing speed, adhesive forces are less than cohesive forces and subsequently adhesion strength decreases

In the following, according to different considered models in ANOVA test and related values, the best model which fits the effect of processing parameters on adhesion force of Nylon deposited onto the PA66 fabric is shown in equation 1:

P-𝑦 = 𝛽1+ 𝛽1𝑥1+ 𝛽2𝑥2+ 𝛽3𝑥22Which

parameters is shown in Fig 7 which clearly can represent the linear effect of extruder

temperature, no effect of platform temperature and quadratic effect of printing speed on adhesion force Interaction of the parameters is not effective in this experiment

3.2 PLA deposited on PA fabric

Deposition of PLA on PA was done in two steps according to Table 2: a single factor

experiment (No 2) with extruder temperature as a variable factor (190, 210, 230°C) and then

a factorial experiment (No 3) with platform temperature (23, 50, 70°C) and fabric type (1,2) variables Minitab analysis of the results showed that there is significant linear effect of the factor extruder temperature on adhesion and the highest temperature applied for extruding PLA (230°C) on PA cause the highest adhesion force (12 N/100mm) (Fig 8a) which is in agreement with previous results for Nylon on PA When the platform temperature increases to 70°C which is higher than the glass transition temperature of PA66 50°C, it has significant

linear effect on adhesion as we discussed above (Fig 8b) Fabric type also shows significant linear effect (Fig 8c) PA Fabric type 2 with higher yarn count in warp per centimeter (warp

39 × weft 27 / 180 ×180 dtex) in compare with fabric type 1 (warp 50× weft 30 / 78×180 dtex) shows higher adhesion properties The closeness of yarns increases fabric covering properties and decrease fabric surface roughness [37] and decreasing surface roughness significantly increases the pull-off force [38] Therefore, surface structure of the fabric also

affects the adhesion force

3.3 PLA deposited on plain weave PLA fabric

Samples number 27 to 44 in Table 2 are related to different treatments of experiment number

4 which the applied factors and levels and the adhesion results also are presented in detail When the deposited polymer is being debonded from fabric, there are three possible modes of failure including adhesive failure with debonding of deposited polymer from fabric, cohesive failure or breaking the deposited polymer itself and fabric tear or failure itself While peeling test for PLA deposited on PLA fabrics, two of mentioned modes happened: (1) fabric tear or failure and (2) breaking the 3D printed polymer layer (cohesive failure) (Fig 9) which shows high peeling strength and proves high adhesion of PLA deposited on PLA

PLA is an aliphatic biopolyester which has vicinal and regularly distributed polar ester groups [39] The high adhesion between deposited PLA on PLA also can be described by high

efficiency diffusion of extruded PLA filament into PLA fabric and their low interfacial

tension due to the similar chemical nature of both and interpolymer polar interactions (Van der Waals dipole-dipole interactions) across phase boundaries

In the following, as it shown in Fig 10, 3D printed polymer layer failure during peeling test has happened in samples 29, 33, 34, 38, 42 and 43 According to Table 2, it is obvious that low extruder temperature with high printing speed of 3D printing has been applied in samples

29 and 38 In this case, feeding of polymer could not be done properly to deposit layers uniformly Applying high extruder temperature with low printing speeds also cause failure of deposited layers during the peeling test in samples 33, 34, 42 and 43 Breakage of the

deposited layers can be used to denote the brittleness which means a lack of ductility or stretchability and poor flexibility [40] Brittleness of the samples prepared in low 3D printing speeds like 18 mm/min with high processing temperatures like 230°C can be attributed to formation of more polar interchain interactions when PLA remains for more time span in high temperature Therefore, polar groups can affect the physicochemical interactions between

polymer chains and reduce more the possibility of chain shear throughout physical

deformation This phenomenon can explain the high brittleness of mentioned samples In such samples deposited layer break strength is lower than the adhesion force of the deposited polymer on fabric In other samples according to Fig 10, fabric was torn during the peeling test which means that the tearing strength of the fabric was lower than adhesion force of PLA deposited on fabric

3.4 PLA nanocomposites deposited on PLA fabric

There are a number of reasons for increasing interest in PLA as a matrix in nanocomposites Firstly, PLA is one of the most advanced biopolymers in terms of its commercialization Secondly, it has high mechanical properties and can be melt processed with standard

processing equipment At the end biocompatibility is an important factor that is being taken into consideration In this part of the research, an effort has been done to find out the adhesion behavior of 3D printed PLA nanocomposites deposited on PLA fabrics (Fig 11)

For the experiment (No 5) the considered factors were extruder temperature (240, 260°C), platform temperature (23, 50°C), PLA fabric type (Panama (1), Twill (2)) and filler type (2% CNT (1), 5% CB (2)) which the treatment combination and adhesion results for samples 46 to

60 are shown in detail in Table 2 The chosen weaves were panama 2/2 and twill 2/1 In panama weave 2/2, groups of two warp and two weft threads are interlaced so they form a simple criss-cross pattern like plain weave The reason we weaved the panama instead of plain was that panama weave structure is stronger than plain weave with the same yarn for doing successful peeling test On the other hand, when the effect of weave type is taken into consideration, generally it can be said that twill fabrics are smoother than plain weaves Increasing yarn inter-sections in weave unit provides to get the yarns closer to each other in contact points and this may cause decrease in roughness values [41] Decreasing surface roughness significantly increases the pull-off force

Like PLA deposited on PLA fabric, while peeling test of deposited PLA nanocomposites on PLA fabrics, separated from treatment combination selection, two modes of failure happened including 3D printed layer break (cohesive failure) and fabric tear or failure which proves again, as discussed above, high adhesion force of PLA nanocomposites deposited on PLA Incorporation of CNTs and CB make PLA more polar ANOVA test showed that deposited layers including 5% CB in compare with 2% CNT layers have lower break strength which