Binder in cable harness

(1)

Binder in cable harness

Beatrice Rugland Timgren

2015 Master Thesis KTH Macromolecular Materials

SE-100 44 STOCKHOLM

(2)

Sammanfattning

Det här projektet har utförts på Scania och är en förstudie till en standardbeskrivning där olika bindemedel i ledningsnät studerats för att kunna användas i olika miljöer i lastbilen så som hytt chassi och drivlina. Olika krav som temperatur, kemikaliebeständighet och fuktresistans ställs för de olika miljöerna. Bindemedlet ska hålla kablarna på plast i en skyddsslang och samtidigt fungera som tätning.

De limtyper som har studerats i den här rapporten är ett epoxilim, ett epoxy-cyanoacrylate hybrid lim, ett smältlim av polyamid och två siliconlim. De har limmats på några av de platser som används i lastbilen och sedan utsatts för dragtester, kemikalietester, åldring- och klimattest.

Inget av de testade limmerna klarade alla testerna men den limgrupp som klarade testen bäst var de av silicon.

Examensarbete MMK 2015 KF205X

Bindemedel i ledningsnät

Beatrice Rugland Timgren

Godkänt

2015-

Examinator

Ulrika Edlund

Handledare

Ulrika Edlund

Uppdragsgivare

Scania CV AB

Kontaktperson

Peter Li

(3)

Master of Science Thesis MMK 2015 KF205X

Binder in cable harness

Beatrice Rugland Timgren

Approved

2015-

Examiner

Dr. Ulrika Edlund

Supervisor

Dr. Ulrika Edlund

Commissioner

Scania CV AB

Contact person

Peter Li

Abstract

This project has been performed at Scania and it is a pre-study for a standard description of binders in cables harness in different environments in the truck. The different environmental zones are the cab, chassis and power train. Different zones in the truck have different requirements such as temperature, chemicals and moister resistance. The function of the binder is to glue cables into a protective hose of plastic and also act as a seal.

The different types of adhesives that have been study in this report is epoxy adhesive, epoxy- hybrid cyanoacrylate adhesive, hot melt by polyamide and two types of silicon glue. They have been glued to some of the different plastics that the cables are made of in the truck and then they have been exposed to tensile tests, chemical tests, aging and climate tests.

None of the tested adhesives passed all the tests, but silicon glue passed most of the tests.

(4)

(5)

Acknowledgments

This thesis has been interesting and fun subject and I would like to thank Scania and all its employees at RECE for the possibility to do my Master thesis at their department. I would also like to thank the employees at the UTM department for the assistance in my experimental work during the thesis.

I would especially like to thank my supervisor at RECE, Peter Li and the group manager at RECE, Paula Härelind who has assisted me during my thesis.

Finally I would like to thank my family for their support through this process.

Beatrice Timgren Stockholm, April 2015

(6)

Denotation

Symbols Description

E Elasticity Modulus (Pa)

r Radii (m)

t thickness (m)

D Shear modulus (pa)

X Mean value

σ Standard deviation

Abbreviations

PVC poly(vinyl chloride)

PUR Polyurethane

PA6 Polyamide 6

ETEF poly(ethene-co-tetrafluoroethene) PFC Perfluorinated compound

CAS Numerical identification (Chemical Abstracts Service)

PP polypropylene

PE Polyethylene

TPU thermoplastic polyurethane

(7)

List of Figures

Figure 1: The epoxy reaction with biphenyl A [15] ... 5

Figure 2: The cross linking reaction. [15] ... 6

Figure 3: Gluing for tensile tests first one is a normal tensile test, second one is a peel tensile test and the last one is shear tensile test. ... 9

Figure 4: A typical shear tensile test ... 9

Figure 5: A typical curve from a shear tensile test ... 10

Figure 6: Glue used in trucks ... 12

Figure 7: Hot melted adhesive on polyolefin. The lower part is the reference. ... 13

Figure 8: Hot melted adhesive on untreated PVC protecting hose made by PA6. ... 13

Figure 9: Loctite 4090 on sanded PVC, the left cable is a reference. ... 14

Figure 10: Loctite 9466 on sanded PUR. The left one is a reference. ... 14

Figure 11: SI 5980 on PUR and the protecting hose is made of PAER. The left one is a reference. ... 15

Figure 12: PUR cable glued with Loctite 4090 after 39 h in brake fluid. ... 15

Figure 13: 3M hotmelt adhesive 3779 separate from all the cables. ... 16

Figure 14: the upper one have small white edges. ... 16

Figure 15: AS 1622 on PVC cables. ... 17

Figure 16: PVC cables with AS 1622 adhesive for 39 h in diesel fuel. The lower one is reference. ... 18

Figure 17: AS 1622 on PVC the upper one is a reference. ... 18

Figure 18: PVC cable with hot melted adhesive for 39 h in ATF. The middle one is the reference. ... 19

Figure 19: PVC cable with Loctite 4090 for 39 h in ATF. The upper one is the reference. ... 19

Figure 20: PVC cable with hot melted adhesive for 39 h in ethanol. The second from top is the reference... 20

Figure 21: Polyolefin cable with Loctite 4090 for 39 h in ethanol. The upper one is the reference. ... 21

Figure 22: PUR cable with Loctite 4090 for 39 h in ethanol. The lower one is the reference. ... 21

Figure 23: PVC cables with Loctite 9466 for 39 h in ethanol. ... 22

Figure 24: PUR cables with Loctite 9466 after 570 h aging in 120 °C. The upper one is the reference. ... 24

Figure 25: Polyolefin cable with Loctite 4090 after 570 h. The upper one is the reference. ... 24

Figure 26: Polyolefin with hot melted adhesive after aging in 150 °C at 570 h. The lowest one is the reference. ... 25

Figure 27: treated PVC cables with si 5980 adhesive... 27

Figure 28: AS 1622 on treated PVC cables. ... 27

Figure 29: Loctite 9466 on treated PVC cables. ... 28

Figure 30: Loctite 4090 on treated PVC. ... 28

Figure 31 PVC cable with hot melted adhesive ... 29

Figure 32: Treated polyolefin cable with hot melted adhesive after aging test in 150˚ C in 570 h and treated cables with hot melt adhesive. ... 30

Figure 33: 3M hot melted adhesive on treated polyolefin ... 31

Figure 34: Loctite 4090 on treated PUR. ... 33

Figure 35: Loctite 4090 on treated PUR. ... 33

Figure 36: The first one is what happen with the samples. ... 37

Figure 37: Describe how the sample could be glued to avoid bending... 37

Figure 38: Hot melted adhesive on sanded PVC. Both tested was glued together after tests. ... 45

Figure 39: Hot melted adhesive on PUR from climate chamber. ... 45

Figure 40: Loctite 4090 on sanded PUR the left cable is a reference. ... 45

Figure 41: Loctite 4090 on PUR and a protecting hose made of PAER. Left is a reference. ... 46

Figure 42: Loctite 4090 on sanded polyolefin. ... 46

Figure 43: Loctite 9466 on PUR and protecting hose made of PAER. The left is a reference. ... 46

Figure 44: Loctite 9466 on sanded PVC. The left one is a reference. ... 47

Figure 45: AS 1622 on polyolefin. The left one is a reference. ... 47

Figure 46: AS 1622 on PUR. The left one is a reference... 47

Figure 47: AS 1622 on sanded PVC. The left one is a reference. ... 48

Figure 48: AS 1622 on sanded PUR and the protecting hose is made of PAER. The left one is a reference. ... 48

Figure 49: SI 5980 on polyolefin and PUR on the two right. The left is a reference glued on PVC. ... 48

Figure 50: PVC cable with hot melted adhesive after 39 h with brake fluid at rum temperature. ... 49

Figure 51: PUR cable glued with Loctite 4090 after 39 h in barke fluid. the lower is a reference. ... 49

Figure 52: PUR cables with hot melted adhesive after 39 h in brake fluid. The lower cables is a reference. ... 50

Figure 53: PVC cable with si 5980. ... 50

Figure 54: Polyolefin cable with AS 1622. ... 51

Figure 55: PVC cable with Loctite 9466. The upper one is a reference. ... 51

Figure 56: PVC cable with Loctite 9466 adhesive after 39 h in white spirit solvent. The upper one is the reference. ... 51

Figure 57: PVC cable with hot melted adhesive for 39 h in white spirit solvent. The upper one is the reference. ... 52

Figure 58: PVC cable with Loctite si 5980 for 39 h in white spirit solvent. ... 52

Figure 59: PUR cable with hot melted adhesive for 39 h in IRM 902. ... 52

Figure 60: Polyolefin cable with Loctite 4090 adhesive for 39 h in IRM 902. ... 53

Figure 61: PVC cable with Loctite 9466 adhesive for 39 h in IRM 902. ... 53

(8)

Figure 62: PVC cable with Loctite 4090 adhesive for 39 h in IRM 902. ... 53

Figure 63: PVC cable with AS 1622 adhesive for 39 h in IRM 902. ... 53

Figure 64: PVC cable with Loctite si 5980 adhesive for 39 h in IRM 902. ... 54

Figure 65: PUR cable with Loctite 4090 for 39 h in diesel fuel. ... 54

Figure 66: Both PVC cables for 39 h in diesel fuel. The upper adhesive is Loctite 4090 and the lower one is Loctite 9466. ... 54

Figure 67: PUR cables with hot melt adhesive for 39 h in diesel fuel. The lower one is reference. ... 55

Figure 68: PUR cables with AS 1622 adhesive for 39 h in diesel fuel. The lower one is reference. ... 55

Figure 69: PVC cables with AS 1622 adhesive for 39 h in diesel fuel. ... 56

Figure 70: Polyolefin cable with Loctite 4090 for 39 h in ATF. The lower one is a reference. ... 56

Figure 71: PUR cable with Loctite 9466 for 39 h in ATF. The lower one is a reference. ... 57

Figure 72: Polyolefin cable with hot melted adhesive for 39 h in urea. The upper one is the reference. ... 57

Figure 73: PUR cable with AS1622 adhesive for 39 h in urea. The upper one is the reference. ... 58

Figure 74: PUR cable with Loctite 4090 adhesive for 39 h in urea. ... 58

Figure 75: PVC cable with Loctite si 5980 adhesive for 39 h in urea. The upper one is the reference. ... 58

Figure 76: Cable with Loctite 9466 adhesive for 39 h in urea. ... 59

Figure 77: Polyolefin Loctite 4090. ... 60

Figure 78: Polyolefin hot melt. ... 60

Figure 79: Polyolefin si 5980. ... 61

Figure 80: PUR AS 1622... 61

Figure 81: PUR Loctite 4090. ... 62

Figure 83: PUR Loctite si 5980. ... 63

Figure 84: PUR hot melt. ... 63

Figure 85: PVC AS 1622... 64

Figure 86: PVC Loctite 4090. ... 64

Figure 87: PVC Loctite 4090. ... 65

Figure 88: PVC Loctite si 5980. ... 65

Figure 89: PA6 AS 1622. ... 66

Figure 90: PA6 3M melt. ... 66

Figure 91: PA6 Loctite 4090. ... 67

Figure 92: PA6 Loctite 9466. ... 67

Figure 93: PA6 Loctite si 5980. ... 68

Figure 94: PAER Loctite si 5980. ... 68

Figure 95: PUR OSLIPAD CA. ... 69

Figure 96: Untreated PUR Loctite 9466. ... 69

Figure 97: Untreated PUR Loctite 9466. ... 70

Figure 98: PUR untreated hot melt. ... 70

Figure 99: Untreated PVC Loctite 4090. ... 71

Figure 100: Untreated PVC Loctite 9466. ... 71

Figure 101: Untreated PVC hot melt ... 72

Figure 103: Untreated PVC Loctite si 5980. ... 73

Figure 104: Climate Loctite 4090 on PUR. ... 73

Figure 105: PUR Climate Loctite si 5980. ... 74

Figure 106: PUR Climate hot melt. ... 74

Figure 107: PVC Climate Loctite 9466. ... 75

Figure 108: PVC Climate hot melt. ... 75

Figure 109: PVC Climate Loctite 4090. ... 76

Figure 110: Aging Test for Loctite 9466 on PUR. ... 76

Figure 111: Loctite 4090 after aging test. ... 77

Figure 112: Polyolefin hot melt adhesive after aging test. ... 77

List of Tables

Table 1 : Chemical test results... 23

Table 2 : Aging test results ... 26

Table 3 : Tensile tests of untreated cables ... 29

Table 4 : Summary of aging tests. ... 32

Table 5: Summary of climate tests. ... 34

Table 6: Std. and average values for tensile tests. ... 34

(9)

1 INTRODUCTION

1.1 Purpose

The goal of this project is too create a pre study to a standard describing binder in cable harness. The best suited binder for each location is depending on the different environmental requirements for the zones in the truck such as engine, chassis and the cab. The first part of this project is to make a clear picture of all of the requirements in the different zones, followed by a study of all types of glue which are used today.

The study will provide different types of glue that meet the requirements on paper, lab tests in the different zones as well as that different test methods are followed to ensure that the binders meets the desired requirements. The result will be a pre-study to a future Scania glue standard.

1.2 Background

In the early 19th century the adhesive most commonly used was made of bones and other parts from animals [1]. Today many different types of adhesives are used. The most common adhesives are cyanoacrylate, epoxy glue, hot melt adhesive, methacrylate and urethane adhesive.

There are several plastic materials that are difficult to glue, especially if they don’t have any functional group. Low porosity and nonpolar surface are some characteristics of materials which inhibits the adhesive performance of glues. Some adhesives contain solvents that even can destroy some plastic materials [2].

In this study temperature and moisture resistance in the glues are especially important. In chassis and engine compartment it is also important that the chemical and solvent resistance meets the requirements of their respective environments and that the harness should also be able to handle the stress of the test methods. Since all glues increase their flexibility in higher temperatures and increases its hardiness in low temperatures it is important to find adhesives which fit the correct requirements for the desired temperature interval.

The adhesive needs to have good lap shear strength, the lap shear is the attachment force that is applied in parallel to the bonding line.

Sometimes it can be necessary to pre-treat the surface before the adhesive is applied and that can include cleaning and/or grinding for the glue to get better attachment to the surface [3]. A primer can be used to reduce oil, water and plasticizer that have migrated out from the plastic material [4].

Not all types of adhesive needs a primer, this mainly depends on which substrates that shall be attached together. The way the glues are applied on the surface and application technique can differ allot, some adhesives are easy to apply without any preparation or mixing. Two-part additive are really common. They consist of a resin and a hardener which cure when they are mixed together. The mixing method can differ between different types of adhesives, some of them requires a type of dispense equipment to achieve the best result. One part adhesive often cures by contact with the humidity in the air, cure after heating or by UV.

The cure time is the time when the glue have achieved the full strength and this time can vary between different types of glue. It is not always necessary to wait the whole cure time before the

(12)

2 next step in the operation. The fixture time or setting time is the time when the glue have cured so much that the strength is high enough to proceed to the next step of the process. [3]

1.3 Requirements

The glue should ideally meet and pass the same tests as the cable needs to do. Scandia’s test document for cables (TB1914) has been studied to get a hint of what the glue needs to handle.

The cable need to be resistant to Diesel fuel, Biodiesel fuel (FAME), Ethanol fuel, Engine oil (oil IRM 902), Hydraulic oil, Coolant additive (undiluted antifreeze additive), Brake fluid (oil DOT 4), Windscreen washer fluid, White spirit solvent (~17 % aromatic content), Urea, Car/engine wash chemicals, Alkaline washing chemicals and Battery acid. It is more important in the engine and chassis that the resistance requirements are higher because they have higher probability to be exposed by those chemicals.

There are three different zones in the truck where the glue should be placed and they have different requirements and the glue needs to handle different chemical and physical environment depending on where in the truck they are placed. In the cab the main types of cables are single core cables and they have a square area of 0.75 – 6 mm². The main type of material that the glue need to stick on is PVC, and but also some PA6 and perhaps some PFC. The area in the cab is a humid environment and it is important that the glue is water resistant and can handle high humidity for a long time. The environmental test needs to handle hot water of 82°C and NaCl.

The cab is a low vibration area and the glue doesn’t need to be of a vibration resistant adhesive type. In this study the temperature requirements that the glue needs to handle in the cab ranges from -40 to 105 °C.

The cables in the chassis are manly multicore cables, shrinking tubing and protection hose. The multicore cables consist mainly of PVC, TPU, PE, polyolefin material, ETFE, and silicon.

ETEF is a copolymer based on fluorocarbon [5]. It means that the demands on the glue are higher than for the glue in the cab because more materials have to be taken into account. The temperature requirement in this area is between -40 °C to 125 °C. Some of the most important environmental requirements the cables must handle are humidity (80 to 100 %), NaCl, water and UV.

Engine consists mainly of the same cables and the same material as chassis. It is exposed to the same chemicals but need to handle higher temperature than chassis need to do. In this study the temperature range in the engine is between -40 °C to 150 °C. It is also a high vibration area which must be taken into account. [6]

1.4 Delimitations

In the first part of the project, all the glue was selected after their chemical and physical properties and no account was taken to the price. The price could be an important factor later in this project when recommendations on further studies to the final standard are presented.

The thickness, depth of the glue, how many cables that the protective hose need to hold and how high force they need to handle is not known.

(13)

3 All chemicals that the cables are exposed by in TB 1914 are not tested. All chemicals were not available and the chemicals that involved risk of birth defects were avoided. The cables that are glued are primarily meant to be used in chassis, engines and cabs environments.

In this project it is only possible to test glue that already exists in Europe. The process to import glues and chemicals from other places outside Europe is a long process and probably too long to make it possible to test them for this project. All glue that is not already registered in “Chester”

(that is Scania’s register for chemicals including glue) need to be approved by Scania before they are allowed to be ordered.

1.5 Method

An investigation of the requirements for the different zones in the truck is performed, that includes the material, temperature and chemicals resistance. That requirement is obtained by information from the supervisor at Scania and by looking in the database for different cables.

Some of the materials are a mix of different materials and it was necessary to contact the supplier to find out exactly what this material was made of.

The most common types of glue on the market are studied in order to find out what there characteristics and limitations are. Then the different types of adhesives were selected to meet the requirements for the different zones in the truck. The different types of fabricates were studied to find the ones that seemed to meet the requirements according to their respective datasheet for the different zones. All of the different fabricates of glue were put in a excel document and all of the glues was studied by going through the safety sheet, the technical data sheet and match all the chemicals CAS number to Scania standard 4158 and 4159 (Scania’s black and grey list over chemicals). If some of the chemicals in the glue occurred in these lists, the glue was discarded.

The next step involved contacting the respective adhesive manufacturers for all studied glues that meet the requirements and was not present in the black and grey list to obtain more information about them if deemed necessary. The glues in the excel file is excluded one by one when more information about the different glues was collected. In the end it was only a few left that seemed to meet the different requirements. The suppliers were contacted to order a small amount of glue in order to test the material at lab in Scania.

To be able to buy and use the glue here at Scania it was necessary to write an application form for each glue. Different departments on Scania need to accept all the glues that should be tested.

The application form required including all fact about the hazard classification and investigation if it is necessary with medical check-up due to some of the glue is classified as thermoset. It is also necessary to make documentation about the safety in the lab area before the lab can start.

All possible risks in the lab and how to handle them should be included in a document and also what kind of safety equipment that is available in the lab. Some of the cables that did not already exist on Scania took too long time to order therefore those were not possible to test. One of these materials was ETEF which were unfortunately since that plastic is hard to glue and would be interesting to test.

(14)

4

2 THEORY

2.1 Materials and pre-treated methods

The main materials that require testing are mainly PVC, ETFE, polyolefin, acrylic rubber, polyamide, silicon rubber and thermoplastic polyurethane.

The adhesive properties depend on the intermolecular forces in the plastic. Many of these plastics are really difficult to glue partly because the force between the plastic and the glue becomes stronger if the plastic contains any polar groups. That’s why PVC is easy to glue compared to other plastics because of the polar Cl groups in the polymer chain. ETFE and Polyolefin like PE, PP and are other examples of more difficult plastics to glue. They often need to be pre-treated. It can be a chemical, mechanical or physical method [4].

Mechanical method includes grinding or blasting, the physical methods often include plasma, Flame or corona discharge treatments [7].

Plasma is created by low pressure at about 0.2 mbar and with a high frequency alternating current. The gas discharged, ionization, radicals and UV are created in the process. A chemical reaction occurs between the polymer and the radicals, resulting in an oxidized top layer and the number of polar groups increases. This method takes around 5 minutes and requires a special aperture. Flame treatment doesn’t require such advanced equipment. The surface is treated by a flame and a surplus of oxygen. The surface reacts with the oxygen and becomes cleaner and easier to glue.

Corona discharge is an electrical method, the surface is reacting with the oxygen in the air and the surface becomes cleaner. The chemical method is often some type of primer, it is common to use metallic sodium to increase the surface tension and the adhesive will stick better to the material. Many of the more difficult plastics to glue are often called fat plastics because the chemistry is similar to fat but in solid form. [8]. [9]

2.2 Cyanoacrylate

Cyanoacrylate is often recommended for gluing plastic materials together, with a primer it is often possible to glue plastics which have difficulties with attachment. It is also possible to glue many polyolefin and it has high shear strength. [7]

It is a solvent free adhesive based on cyanoacrylate monomers in presence of a weak base and water. The viscosity can vary from thin liquids to gel types. It is a thermoplastic adhesive and cures very fast on many different materials. It cures in room temperature by ionic polymerizing on the surface and forms a rigid thermoplastic. Cyanoacrylate adhesive exist in many different forms to meet the many different application requirements, for example most cyanoacrylates cannot handle high temperatures but some heat resistant types can handle temperatures up 120

0C. It is also common to blend it with a rubber material to get more impact resistance and higher peel strength adhesive.

Cyanoacrylates normally reach full strength after 24 h but the fix time i.e. the time it takes for the glue to hardened is just a couple of minutes. Light curing cyanoacrylate has been more

(15)

5 common and has a very rapid cure time, it prevents blooming and cracks. It is possible to use a primer or some accelerator technique to accelerate the cure time and to prevent cracking and blooming. Blooming when referred to as frosting is when a white haze is creating around the bond line. [10]. The bond strength can be increased by 20 times if a primer is used.

Methyl and ethyl cyanoacrylates are the most common glue and the cure mechanism is an anion polymerization in the present of a weak base and is stabilized by a weak acid. When it comes in contact to hydroxide ions in the water the weak acid is neutralized and the polymerization is started. [10] The optimal conditions are when the relative humidity is 40 to 60 %. Higher humidity leads to lower strength but accelerates the cure time. Normally a primer is used to neutralize the acidic surface because it can prevent that the cure process occur. [11]

Some of the disadvantages that can limit the use in the trucks are the solubility in polar solvent.

That means that the strength is decreasing in high humidity or by water. The low temperature resistance limit the areas where the glue can be used in the truck. The bond strength seems to decrease if the temperature changes many times hence it is not optimal to use outdoors and for mechanical use. [12]

2.3 Epoxy adhesive polymers

Epoxy is a group of polymers, the epoxy group can be placed anywhere in the polymer chain but the most common place is in the end. [13] It is a two-component adhesive and it is possible to cure it in room temperature. Epoxy adhesive is a thermoset adhesive and cured when a covalent bond is created between the hardener and the epoxy resin see Figure 1. The resin consists of either diepoxide or poly epoxide and the hardener usually consist of polyamines, mercaptans and phenolic resins. The hardener and the core resin can be toxic hence it is important to be careful.

The epoxy group is not presented in the polymer only in the monomer group. More functional group means more cross linked polymer. The reaction is exothermic and release heat.

The epoxy can be mixed together with a amid group and an reaction of one of the NH group is possible and the OH group makes it possible get hydrogen bond to a polar surface see Figure 2 on next page. [14].

Catalysis can be used to increase the reaction time, even heat can be used to accelerate the reaction rate and it results in a more stiff material. They are often brittle and rigid.

Figure 1: The epoxy reaction with biphenyl A [15]

(16)

6 Figure 2: The cross linking reaction. [15]

It is really important to let them react stoichiometrically. The cure time can be from h up to several days. [16]. Cured epoxy can normally handles high temperature but epoxy glue can differ very much from each other. There are many different types of chemicals that can react with epoxy ends group and that gives the possibility to a wide variation of glue and it can be designed to match a special function. The properties can be varied by using fillers for example ceramic filler can be used to improve impact resistance. [10] Epoxy can be water resistant and can cure under water. [12] They have good adhesive properties because of the polar group [13] . Some of the problem with using epoxy is that it is a very hard glue and the elongation is low and the T_g(Glass Transition Temperature) on cured material is often between 60-70°C. T_g resides within the operating temperature. That means that the glues properties are changed dynamically within the operating temperature. The material becomes softer when the temperature exceeds Tg thus the properties are more unpredictably. [17]

2.4 Methyl methacrylate

They are very flexible in cure time, viscosity and can be made to have high elongation, more than 200%. It will still have good adhesive properties and they can handle high temperatures over 200 °C for a limited time. They cure by polymerization and crosslinking by free radical reaction. The initiated radical created is reacting with the double bond in the monomer. [18]

It is a two components adhesive. But it is not sensitive to big variations in the mixing ratio, it can vary a lot. The cure time can hence be varied more by changing the mixing ratio. It bounds to many materials like metal, wood, glass and many plastic materials. It has low polar and aromatic solvent resistance but is resistant to chemicals including water and resistance to petroleum based lubricants, diesel and gasoline. The high temperature resistant is limited by the T_g of MMA but the heat resistance can be improved by decreasing the amount of elastomers and increase the density of cross linking and that can be made by using multi-functional monomers. [3]

(17)

7 They cure quickly in room temperature and form a strong thermoplastic material which have good shear and peel impact resistance. It easily bonds too many different types of materials including many types of plastics even if the surface is unclean. They are often used to glue different types of material and cure fast. They are commonly used in the transport sector, cars, airplanes, trucks and electrical motors. One of the reasons is that they can easily be placed in a fast production line. One of the drawbacks with methyl methacrylate is that it has a high odour and is flammable. [19] They generate heat during curing and waste material should not be placed in a plastic container because they can melt. [20]

They have good properties and can potentially be used in the truck but they are flammable and the glue needs to kept away from fire and sparks before and during the curing process. [19]

2.5 Hot melt adhesive

It is a one part thermoplastic adhesive and solid solvent free adhesive that cures in room temperature after heating. It is applied on the material at high temperature often over 195 °C.

The most common hot melt material is EVA (ethylene vinyl acetate) based hot melt adhesive. It can be used for many different materials including many plastic materials but it is also common to use it on textile, ceramic and wood. EVA has the lowest temperature resistance of all the hot melt adhesive [21]

Ethylene acrylate based adhesive is good to use on hard to glue plastic. Polyamide based hot melt adhesive can be used in a wider temperature range and can handle temperatures up to 150

°C and the chemical resistance is also higher than for EVA. Polyester based adhesive have properties similar to ethylene acrylate but the water resistance is higher. Polyolefin adhesive have really god attachment to material like polyolefin plastic that otherwise is hard to glue.

One new technique in hot melt adhesive is reactive Polyurethane adhesive. When it cools down PUR react with the water in the air and is creating a cross linked thermoset. It can take some days to create a good cross linked material. That means that it cannot be melted again and can handle higher temperatures. Hot melt adhesive have high adhesive to many different types of plastics up to 150 °C but can absorb moisture. Polyolefin adhesives are especially good to use on polyolefin materials. [10]

Many of the hot melt adhesive can be used in contact to battery acid and oil because of the chemically resistance and it shows adhesion to both polar and non-polar materials. [10]

2.6 Urethane adhesive

Urethane adhesive is elastic after curing and has an elongation value around 200%. The cure time can differ from just a few minutes to many hours. Two part urethane adhesive is not depending on the depth of curing because it cures by a reaction between polyol and isocyanate and forms a thermoplastic material with good impact strength and good abrasion resistance [12].

To achieve high bond strength on some substrate it may need a primer. Polyurethane adhesive have poor temperature resistance but good water and moister resistance [22], all urethanes have the urethane bond in the main chain which is formed by oligomers by step wise polymerization.

The reaction can go backwards and isocyanate is formed and they are really reactive in high temperatures, hence polyurethanes are not the best choice in areas with very high temperatures.

Because of the good abrasion resistance, impact strength, elongation, water and chemical

(18)

8 resistant it is a good choice to have on the zones of the truck where temperature resistance doesn’t need to be so high,. Many of them can handle temperatures over 100 °C but most of them are below 100 °C. [23]

2.7 Light curing acrylic adhesive

It is a solvent free one part adhesive and cures fast when it is exposed to light and forms a thermoset. It bonds too many different types of substrates including many plastics. It cures very rapidly, the cure time is depending on the light but it’s somewhere between 2 to 60 minutes.

Light curing acrylic adhesive consist of a blend of both monomers, oligomers and polymers and all of them consist of an acrylate where a photo initiator is added. When the bond line is exposed to light radicals it released and a free radical polymerization starts. To avoid oxygen that can destroy the photo initiator and create a sticky surface because of the uncompleted curing. The polymerization will occur in inert gas or increase the light by matching light to the absorbance spectra in the material. The light curing acrylic adhesive has good environmental resistance. This adhesive is a good adhesive to most materials because it’s polar nature and have good adhesive to PVC plastic. One of the problems with light curing adhesive is that a light source is needed and the light needs to reach the bond line. If the light is too intense ozone can be created and ventilation is needed. It needs to be protected from oxygen to cure ideally. It has good chemical and solvent resistance. [10]

2.8 Silicon adhesive

This is a one part system and forms soft elastomeric thermoset. It can be used for many different types of materials. Silicon adhesive have low cohesive strength and are therefore limited as construction adhesives. The most common silicon adhesive cure in reaction to the moisture in the air and the cure time is dependent on the relative humidity. UV and heat cured silicon adhesive are also common. After the cure time the adhesive strength can continue for many weeks take because the reactive groups on the material and silicon react slower than the cross linked process. [10]

Some of the benefit with silicon adhesive is that they have a very low Tg and are soft and flexible even after curing. They are chemical and water resistant and can handle big temperature differences, some can handle a temperature from -65 up to 315 °C.

There is big differences between different kind of silicon glue, all of them have their own benefits where some of them is a one component and some are two components that needs to mix together to cure but they can cure in thicker section. Silicon have been used to seal cables for a long time [24]

After curing the most common colours are transparent, black or metallic colours [25]

Silicon glue is easy to modify and to make new copolymers that give the glue new properties.

Different types of moister curing silicon exist and some of them are acetoxy, alkoxy and oxime curing silicones, they are defined by the product that curing with a reaction with water and give a product. For examples, alkoxy silicon glue produce during curing alcohols like methanol or ethanol. Alcohol is none corrosive and is therefore good to use in electrical applications.

Oxime cure silicon produces methyl ethyl ketoxime and that is bad due to health effect and its flammable behaviour.

(19)

9 All silicon is made by the silicon that bond to oxygen and form siloxanes bond which gives them the high temperature resistance. [10]

2.9 Tensile tests

In order to describe the different tensile tests following pictures and formula will give a short introduction to this mater.

Figure 3: Gluing for tensile tests first one is a normal tensile test, second one is a peel tensile test and the last one is shear tensile test.

The shear stress is defined by equation (1) 𝜏 = ^𝐹

𝐴 (1) Where F is the force and A is the exposed area. The shear modulus is defined as equation 2:

𝐺 = ^𝜏

𝛾 (2)

Where γ is the elongation and τ is the shear stress.

Figure 4: A typical shear tensile test

(20)

10 Figure 5: A typical curve from a shear tensile test

Figure 5 is a typical sheer stress graph. The first part is a linear part and it is a temporary deformation of the glue. After the yield point a permanent deformation occurs until the ultimate strange is reach and then the material is broken. Therefore the G (share modulus) is calculated before the yield point. [26].

Ƭ^Max

G = Ƭ/Ƴ ; Ƴ= Strain; Ƭ = Force/Aria Yield strength

(21)

11

3 IMPLEMENTATION

3.1 Experimental part

Adhesives used in this study are:

Loctite SI 5980 ( -55 – 250 °C ) Loctite 4966 (-55 – 120 °C) Loctite 4090 (-40 - 150 °C)

AS 1622 Glimo Technolgy (-50 – 275 °C) 3M hot melt adhesive 3779 ( -40 - 149 °C)

3.1.1 Temperature and age testing

Polyolefin material is the only one that can handle temperatures up to 150 °C and all glues that shall handle temperatures up to 150 °C are therefore only glued together on polyolefin material (cables). Those are tested in an owen with the maximal temperature that they should handle in the truck. In an ideal case they should be tested for 1000hr but because of the long process to obtain the glue they will only be tested for 570 h. This test must be done to see how the maximum used temperature affects the glue after a certain time.

It is not possible to use accelerating aging test by using higher temperature because the cables and glue cannot take that high temperature. If it was possible it should be a good way to see what happens after 1000 h in a shorter time. It is possible for silicon adhesive to accelerate age testing by elevating the temperature but the cables only handles 150 °C. To calculate the time that the elevated temperature corresponds to the Arrhenius equation can be used if the activation energy can be found for the glue.

3.1.2 Climate tests

For this test case it’s a good idea to glue the cables in the way that they should be used in the truck according to Figure 6 (on next page) and even glue them together to be able to do tensile tests. The first gluing process is done in order to make it easier for visual test. That means that it should be possible to check for the glue also on the inside of the cable. Therefore the cables used for tensile tests are glued according to Figure 3 (on page 9). And is made in according to Figure 4. The moister and low temperature resistance is tested in a climate cabinet in cycles according to Scania document TB1914.

Two samples from each glue and material is placed in the climate chamber. The temperature varied between -40 up to 90 °C and the relative humidity must be between 80 to 100%. This must be done in cycles of 8 h and should preferably be done in 40 cycles but due to booking problems it was done for 35 cycles.

(22)

12 Figure 6: Glue used in trucks

3.1.3 Chemical resistance

The glue need to handle most of the chemicals that the cables will be exposed to. That include Diesel fuel, Ethanol fuel, Engine oil (oil IRM 902), Hydraulic oil (ATF), Brake fluid (oil DOT 4), white spirit solvent (~17 % aromatic content) and Urea.

All tests are done in room temperature for 39 h. All are cleaned with paper material and let dry for 45 minutes. A visible inspection was made to find if any cracks or deformation of the glue was found.

3.1.4 Mechanical test

The most common mechanical test method for glue is ordinary tensile test, shear tensile test and peel tensile test , in this case shear tensile force is the main force that the glue will be exposed to.

It is good to do both shear tensile test and normal tensile test and compare the results between them. Due to limited time this study only included shear tensile test. This test was done after the glue have been cured in the maximal cure time, and after ageing and climate tests.

In order to see how close the samples is to each other and if it is a big distribution between them, different types of methods can be used but the most common one is to calculate the standard derivation see equation (3) [27]. In the tests if three samples or more was obtained the average and standard deviation has been calculated. Small deviations between the individual samples and using more samples give more reliable results. If it is a miss allocation of the variable the standard derivation gives a misleading result. In this case many of the tests have too few samples to make a normal distribution.



^X ^X



 



n^

(3)

X is the strength. X is the average of all strength and n is the number of samples. The coefficient of variation can be calculated by dividing the standard derivation by the average and multiply by 100, see equation (4).

.C V *100 X

  (4)

(23)

13

4 RESULTS

4.1 Climate tests

4.1.1 Hot melted adhesive

The hot melt glue did even separate from some of the cables like PUR, polyolefin and from the untreated PVC cables, see Figure 7.

Figure 7: Hot melted adhesive on polyolefin. The lower part is the reference.

The test samples below were separated. Some differences in colour could be seen. That can be seen in the Figure 8 below. The cable was not glued after aging test. The left one on the figure is a reference

Figure 8: Hot melted adhesive on untreated PVC protecting hose made by PA6.

(24)

14

4.1.2 Loctite 4090 adhesive

Figure 9: Loctite 4090 on sanded PVC, the left cable is a reference.

The adhesive turns yellow on all cables this can be seen in Figure 9, see Appendix1 for more pictures.

4.1.3 Loctite 9466 adhesive

Figure 10: Loctite 9466 on sanded PUR. The left one is a reference.

The adhesive change colour after climate test and became whiter see Figure 10.

4.1.4 AS 1622 adhesive

There were no changes after climate tests on this adhesive. See Appendix1 for pictures.

(25)

15

4.1.5 Loctite si 5980 adhesive

Figure 11: SI 5980 on PUR and the protecting hose is made of PAER. The left one is a reference.

As can be seen in the Figure 11 the adhesive did turn more matte after climate test. For more information see Appendix1

4.2 Chemical testing 4.2.1 Brake fluid

3M 3779 hot melt adhesive broke away from the PVC cables after 39 h in brake fluid at room temperature. The glue was still hard and has not change colour after the test. See all the pictures in Appendix1.

Loctite 4090 become a little bit whiter after 39 h in brake fluid and become softer, flexible and easy to bend, see Figure 12.

Figure 12: PUR cable glued with Loctite 4090 after 39 h in brake fluid.

(26)

16 3M 3779 hot melt adhesive hold PUR together better than PVC and polyolefin but when trying to clean the cables from brake fluid with a viper even PUR cables fell apart see Figure 13.

Figure 13: 3M hotmelt adhesive 3779 separate from all the cables.

4.2.2 With spirit solvent

Loctite 4090 on polyolefin material did not have any visible changes after 39 h in white spirit solvent. On PUR this adhesive did have some white stuff around the adhesive after the 39 h in white spirit solvent. It looks like it has started to come loose on some parts but not entirely se Figure 14.

Figure 14: the upper one have small white edges.

(27)

17 The hot melted adhesive did stick together on sanded PUR and PVC but the hot melted adhesive become more flexible and softer after the 39 h in white spirit solvent.

AS1622 detached from cables and just fall of from PUR, polyolefin and PVC material when taking them up from the chemicals see Figure 15.

Figure 15: AS 1622 on PVC cables.

No changes on Loctite si 5980. For more pictures see Appendix1.

4.2.3 IRM 902

The hot melted adhesive on PUR, polyolefin and PVC come loose after 39 h in IRM 902.

Loctite 4090, Loctite si 5980, AS 1622 and Loctite 9466 on polyolefin, PUR and PVC did not show any visible changes after 39 h in IRM902 se Appendix1

4.2.4 Diesel fuel

There were no visible changes for Polyolefin, PUR and PVC with Loctite 4090, Loctite 9466 and Loctite si 5980 after 39 h in diesel fuel.

3M Hot melt adhesive 3779 detached from the cables. See Appendix1.

(28)

18 Figure 16: PVC cables with AS 1622 adhesive for 39 h in diesel fuel. The lower one is reference.

The AS 1622 adhesive on PVC did get blurred on the adhesive edges but did still stick together see Figure 16. But if the cables were treated this was not seen. This did not appear on polyolefin and PUR. All except one of the PUR cables did get apart. The hot melted adhesive has become more flexible after 39 h in diesel fuel.

4.2.5 ATF

There were no visible changes on Loctite 9466 and Loctite si 5980 but some changes could be seen on hot melted adhesive, Loctite 4090 and AS 1622. See Figure 17 and Figure 18 below.

Figure 17: AS 1622 on PVC the upper one is a reference.

(29)

19 Figure 18: PVC cable with hot melted adhesive for 39 h in ATF. The middle one is the reference.

The hot melted adhesive did come loose when touched. The adhesive has become darker after 39 h in ATF.

Figure 19: PVC cable with Loctite 4090 for 39 h in ATF. The upper one is the reference.

The Loctite 4090 did come loose after 39 h in ATF. More pictures in Appendix1.

(30)

20

4.2.6 Ethanol

Figure 20: PVC cable with hot melted adhesive for 39 h in ethanol. The second from top is the reference.

The hot melted adhesive has come loose from the treated cable after 39 h in ethanol. The adhesive looks more blurred and brittle.

(31)

21 Figure 21: Polyolefin cable with Loctite 4090 for 39 h in ethanol. The upper one is the reference.

The Loctite 4090 did change colour and more brittle after 39 h in ethanol. It was easy to break loose the polyolefin cables form the glue, see Figure 21.

Figure 22: PUR cable with Loctite 4090 for 39 h in ethanol. The lower one is the reference.

The Loctite 4090 did change colour and become more brittle after 39 h in ethanol. It was easy to break loose the PUR cables form the glue.

(32)

22 Figure 23: PVC cables with Loctite 9466 for 39 h in ethanol.

The Loctite 9466 has changed colour after 39 h in ethanol but become harder and no changes in keeping the PVC cables together when touching the cables. No tensile tests have been performed on the samples. The lighter part of the glue was not in the ethanol fluid.

4.2.7 Urea

There were no visible changes on the adhesive after 39 h in Urea. For pictures see Appendix1.

(33)

23

4.2.8 Summary of the chemical test

Table 1 describes the results from the chemical test. The green square implies no difference, yellow means that at least one of tree cables still hold together or possible to see a different in colour and consistent and red means that all of the tree cables was separates or gave a distinct colour difference.

Table 1 : Chemical test results

Loctite 4090 Loctite 9466 3M Hot melt Loctite si 5980 AS 1622

Diesel fuel

No difference No difference Separated from all cable glue more flexible

No difference Separated on

edges on

untreated PVC Ethanol Less

transparent easy to crack

Turned light brown

Cracked after a few hours before drying flexible

No difference No difference

Engine oil (IRM 902)

No difference No difference Separated from

PUR and

polyolefin cables

Hydraulic oil (ATF)

Separated from PVC

No difference Separated from polyolefin and become darker

No difference Separated from PVC

Brake fluid

Less

transparent.

Separated from all cables

No difference Separated from all cables. Turned very flexible.

White spirit solvent

White stuff around edges of adhesive

No difference Adhesive more flexible easy to separate

No difference Separated from

PVC and

polyolefin.

Separates easy from PUR

Urea No difference No difference No difference No difference No difference Gasoline Separated

from one of

three PVC

cables

White stuff around edges of adhesive

No difference No difference Separated from all cables

(34)

24

4.3 Aging tests

After aging test both 3M hot melt 3779 and Loctite 4090 became black, see Figure 25 and Figure 26. While silicon glue don't show any difference either in colour or in tensile tests. Loctite 9466 was in aging tests for 570 h and 120˚ C but it changed colour see Figure 24.

4.3.1 Loctite 9466

Figure 24: PUR cables with Loctite 9466 after 570 h aging in 120 °C. The upper one is the reference.

4.3.2 Loctite 4090

Figure 25: Polyolefin cable with Loctite 4090 after 570 h. The upper one is the reference.

(35)

25

4.3.3 Hot melted adhesive

Figure 26: Polyolefin with hot melted adhesive after aging in 150 °C at 570 h. The lowest one is the reference.

(36)

26

4.3.4 Summary of the aging test

Table 2 : Aging test results

4.4 Tensile tests 4.4.1 Treated cables

Tensile test was made on treated and untreated cables and after climate and aging test. Loctite si 5980 and Acc AS 1622 on treated PVC. Loctite si 5980 did show some increase in strength, small differences compered to Acc As 1622. The G shear modulus which is the stiffness is almost

almost the same around 0.1 see Figure 27 and Figure 28.

(37)

27 Figure 27: treated PVC cables with si 5980 adhesive.

Figure 28: AS 1622 on treated PVC cables.

Loctite 4090 and Loctite 9466 have both high strength but Loctite 9466 might have better strength on PVC and polyolefin. The distribution on PUR is very large and not possible to see any significant difference between them. There is a big distribution on the slope on the tensile tests and it is not possible to see any significant different between different glues on PUR, see Figure 29 and Figure 30.

On PA6 is it possible to see that shear modulus G is higher for Loctite 9466. Loctite 4090 do have higher strength on polyolefin then on PVC and PUR cables, see appendix2.

-1 0 1 2 3 4 5 6 7 8 9

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Strain (mm) Force/Area (N/mm2)

PVC Loctite si 5980

PVC1sSI PVC2sSI PVC3sSI PVC4sSI PVC5sSI PVC6sSI PVC7sSI

-0.50 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16

PVC AS 1622

PVC1sAS PVC2sAS PVC3sAS PVC4sAS PVC5sAS PVC6sAS PVC7sAS

(38)

28 Figure 29: Loctite 9466 on treated PVC cables.

Figure 30: Loctite 4090 on treated PVC.

Binding strength is better on Loctite 9466 and Loctite 4090 on PVC than for Hot Melt Adhesive 3779.

-2 0 2 4 6 8 10 12 14 16 18

0 0.5 1 1.5 2 2.5 3 3.5 4

PVC Loctite 9466

PVC1sEpoxy PVC3sEpoxy PVC4sEpoxy PVC5sEpoxy PVC7sEpoxy PVC10sEpoxy

-2 0 2 4 6 8 10 12 14 16

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

PVC Loctite 4090

PVC1sCA PVC2sCA PVC3sCA PVC4sCA PVC5sCA PVC6sCA PVC7sCA

(39)

29 Figure 31 PVC cable with hot melted adhesive

4.4.2 Summary on untreated cables

Table 3 describes differences between tensile tests off the untreated and treated cables. Green means no difference, yellow means too few samples but there is some noticeable differences, red shows clear differences in the tensile tests. See Appendix 2 for the tensile tests.

Table 3 : Tensile tests of untreated cables

-2 0 2 4 6 8 10 12 14

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

PVC hot melt

PVC1sSmalt PVC2sSmalt PVC3sSmalt PVC4sSmalt PVC5sSmalt PVC6sSmalt PVC7sSmalt PVC8sSmalt PVC9sSmalt PVC10sSmalt

PVC PUR POLYOLEFIN

Loctite 4090 Problem to stick to cable

Strength slightly lower but more tests needed to give better result

Less strength

Loctite 9466 Problem to stick to cable

Strength about the same but less variation in strength.

Not tested due to low temperature on adhesive

3M Hot Melt No difference Not possible to give result due to too few samples

Not possible to give result due to too few samples

Loctite Si 5980 Show no

difference on few cables

Strength slightly lower but more tests needed to give better result

Not possible to give result due to too few samples

ACC AS 1622 Not possible to glue

Did stick but very low strength Did stick but too low strength to do tests

(40)

30

4.4.3 Aging test

There was not any clear difference between the strange before and after the aging test on Loctite 4090 and Loctite si 5980 and AS 1622, see Appendix 2.

Because of the big variation on PUR tests it is not easy to see any significant difference in the tensile tests after and before aging. The results are normalized by measuring the area of the glue lines and dividing force by the measurements. It is still difficult to see any significant difference on the tensile tests.

The only thing that can be stated after comparing the tensile tests before and after aging tests on hot melt adhesive is that the aging seems to have very little impact on the strength and the stiffness have increased.

On 3M Hot melt adhesive was it possible to see a small decrease in both strength and stiffness after aging tests, it was even possible to see a small differences in the G modulus.

Figure 32: Treated polyolefin cable with hot melted adhesive after aging test in 150˚ C in 570 h and treated cables with hot melt adhesive.

-2 0 2 4 6 8 10 12

0 1 2 3 4 5 6

Strain (mm) Force/Area (N/mm2 )

Polyolefin hot melted adhesive after aging

RX1oldsmalt RX2oldsmalt RX3oldsmalt

(41)

31 Figure 33: 3M hot melted adhesive on treated polyolefin

-1 0 1 2 3 4 5 6 7

0 0.5 1 1.5 2 2.5 3

Polyolefin hot melt

EX1sSmalt EX2sSmalt EX3sSmalt EX4sSmalt EX5sSmalt EX6sSmalt

(42)

32

4.4.4 Summary aging test

Table 4 shows a summary of the aging tests. Red means differences from the cables that has not been in the climate cabinets. Green is no difference and yellow means that it seems like it is a difference but more tests must be performed.

Table 4 : Summary of aging tests.

Glue Colour change Tensile change

Loctite 4090 Turns black No Some indications show

some improvements but more samples are needed to be sure of the result

Loctite 9466 Turns brown No difference in strength but

the shear modulus (G) seems to be higher which means higher stiffness

3M Hot melted Turns black Shear modulus (G) seems to

be higher which means higer stiffness. The strength might be little bit higher after aging.

Needs more samples to be sure of the result

Loctite si 5980 No No test

AS 1622 No No test

4.4.5 Climate test

It was only Loctite 4090 that showed any difference in the tensile test but there is too few samples in order to make any clear conclusion.

(43)

33 Figure 34: Loctite 4090 on treated PUR.

Figure 35: Loctite 4090 on treated PUR.

-1 0 1 2 3 4 5 6 7 8 9

0 0.5 1 1.5

Climate Loctite 4090 on PUR

PUR1KCA PUR2KCA

-2 0 2 4 6 8 10 12 14 16

0 0.5 1 1.5 2 2.5 3

PUR Loctite 4090

PUR1sCA PUR2sCA PUR5sCA PUR6sCA PUR9sCA PUR10sCA PUR11sCA

Binder in cable harness