Chapter 5Adhesives and coatings
Chapter 5 Adhesives and coatings
ContentsIntroductionFHistory General terms Basic properties Basic chemistryTheories of adhesion Type of adhesivesAdhesive resinsApplication
Contents ◼ Introduction ◼ History ◼ General terms ◼ Basic properties ◼ Basic chemistry ◼ Theories of adhesion ◼ Type of adhesives ◼ Adhesive resins ◼ Application
5.lAdhesives5iIntroductiontoadhesion&adhesivesNatural gluesfrom plants &animals (a) Animal glues were mostly based onmammalian collagen, which is the mainprotein of skin, bone and sinew. (b) The plant kingdom provided starchesand dextrins from corn, wheat, potatoesand rice
5.1 Adhesives 5.1.1 Introduction to adhesion & adhesives ◼ Natural glues —— from plants & animals ◼ (a) Animal glues were mostly based on mammalian collagen, which is the main protein of skin, bone and sinew. ◼ (b) The plant kingdom provided starches and dextrins from corn, wheat, potatoes and rice
Synthetic adhesivesused in all types ofmanufacture- (a) Shoes(b) Aircraft(c) Automobile & railway- (d) Human beings
◼ Synthetic adhesives —— used in all types of manufacture ◼ (a) Shoes ◼ (b) Aircraft ◼ (c) Automobile & railway ◼ (d) Human beings
Disadvantages & advantages of adhesivesDisadvantages:They are generally weakened by water and itsavapor.Their service temperature ranges are less than(b)for metal fastenersAdvantages:
◼ Disadvantages & advantages of adhesives ◼ Disadvantages: (a) They are generally weakened by water and its vapor. (b) Their service temperature ranges are less than for metal fasteners ◼ Advantages:
5.1.2History of adhesivesThe first evidence of something used as an adhesiveIdatesbackto4000B.C. The period of time between 1500-1000 B.C. gavefurther proof that glue had become a method ofassembly. The first references in literature concerning glueand the art of glue appear about the year 200 B.C.The next period of activity is from 1-500 A.D. whenthe Romans and Greeks developed the art ofveneering and marquetry.Adhesives were used in the building of furniturefr0m 1500 to 1700 A.D
5.1.2 History of adhesives ◼ The first evidence of something used as an adhesive dates back to 4000 B.C. ◼ The period of time between 1500-1000 B.C. gave further proof that glue had become a method of assembly. ◼ The first references in literature concerning glue and the art of glue appear about the year 200 B.C. ◼ The next period of activity is from 1-500 A.D. when the Romans and Greeks developed the art of veneering and marquetry. ◼ Adhesives were used in the building of furniture from 1500 to 1700 A.D
The first commercial glue factory was started inHolland to manufacture animal glue from hides inlabout 1700 A.D. The first glue patent was issued in Britain for a fishglue in about 1750 A.D. The industrial revolution caused an explosion intechnical breakthroughs, most of the technology ofadhesives has been developed during the last 100years.Adhesives touch our lives every day
◼ The first commercial glue factory was started in Holland to manufacture animal glue from hides in about 1700 A.D. ◼ The first glue patent was issued in Britain for a fish glue in about 1750 A.D. ◼ The industrial revolution caused an explosion in technical breakthroughs, most of the technology of adhesives has been developed during the last 100 years. ◼ Adhesives touch our lives every day
5.ll.3GeneraltermsAdhesion Adhesion is the process by whichtwo surfaces are held together by interfacialforces (surface attraction) or mechanicalinterlocking Adhesive An adhesive is a substance which iscapable of holding materials together in auseful fashion by means of surface attractionSurface attraction results from placing a thinlayer of adhesive between two objects
5.1.3 General terms ◼ Adhesion Adhesion is the process by which two surfaces are held together by interfacial forces (surface attraction) or mechanical interlocking. ◼ Adhesive An adhesive is a substance which is capable of holding materials together in a useful fashion by means of surface attraction. Surface attraction results from placing a thin layer of adhesive between two objects
Cohesion ‘Cohesion' is the force prevailing betweenthe molecules within an adhesive which keeps thematerial together. These forces include:intermolecularforces of attraction (Van der Waals forces)interlocking of the polymer molecules among themselves.Substrate-1AdhesivemoleculesRSubstrate2AdhesionCohesion
◼ Cohesion ‘Cohesion’ is the force prevailing between the molecules within an adhesive which keeps the material together. These forces include: ◼ intermolecular forces of attraction (Van der Waals forces) ◼ interlocking of the polymer molecules among themselves
Bond line The bond line is the space or gap between twoisubstrates which contains the adhesive.Substrate A substrate is a material which is held by anadhesive. Substrate is a generic term for the objects which arebeing bonded.Surface The surface of an object is that face of the objectwhich is coated with an adhesive. Surfaces are usually notwhat they seem.BondLineSubstrate
◼ Bond line The bond line is the space or gap between two substrates which contains the adhesive. ◼ Substrate A substrate is a material which is held by an adhesive. Substrate is a generic term for the objects which are being bonded. ◼ Surface The surface of an object is that face of the object which is coated with an adhesive. Surfaces are usually not what they seem