1. MET FACULTY OF ARCHITECTURE, MORADABAD
SESSION 2010-11
PRESENTATION ON ADHESIVES
BY
VISHVENDU PANDEY

2. ADHESIVES
AN ADHESIVE IS A SUBSTANCE WHICH IS USED TO JOIN TWO OR MORE
PARTS SO AS TO FORM A SINGLE UNIT. THE APPLICATION OF ADHESIVE
HAS THE FOLLOWING ADVANTAGES OVER THE CONVECTIONAL
METHODS OF BOLTING, RIVETING AND WELDING :
 A WIDE VARIETY OF COMBINATIONS IN JOINING IS POSSIBLE.
 IT CAN BE USED FOR BONDING THE SURFACES OF GLASS, METAL,
PLASTICS AND WOOD.
 IT CREATES A MASSIVE EFFECT.
 IT IS POSSIBLE TO PREVENT CORROSION BETWEEN DIFFERENT
METALS JOINED BY ADHESIVE.
 IT PRODUCE ADEQUATE STRENGTH.
 THE PERMEABLE JOINT CAN BE MADE IMPERMEABLE FOR WATER
AND GAS BY THE APPLICATION OF ADHESIVES.
 THE PROCESS OF APPLYING ADHESIVE IS EASY, ECONOMICAL AND
SPEEDY.

3. DISADVANTAGES:
 IT IS NOT POSSIBLE TO ADOPT ANY ADHESIVE FOR ALL
SUBSTANCES. DEPENDING UPON THE PROPERTIES OF
SUBSTANCES TO BE JOINED, SUITABLE ADHESIVE HAS TO BE
SELECTED.
 THE ADHESIVE SUBSTANCE DOES NOT BECOME STRONG
IMMEDIATELY AFTER ITS APPLICATION. IT REQUIRES SOME TIME
TO ATTAIN THE DESIRED STRENGTH.
 THE ADHESIVE SUBSTANCE GENERALLY DOES NOT REMAIN
STABLE AT HIGH TEMPERATURE
FOLLOWING FACTORS DETERMINE THE QUALITY OF AN
ADHESIVE :
 ITS DEGREE OR INTENSITY OF STICKING.
 ITS DURABILITY.
 ITS RESISTANCE TO HEAT.
 THE STRENGTH OF BOND DEVELOPED AFTER DRYING OR
SETTING.
 THE REQUIRED TO DEVELOP THE REQUIRED BOND ETC.

4. PROPERTIES
ADHESIVES SHOULD HAVE HIGH TENSILE STRENGTH. THE IMPORTANT
PHYSICAL PROPERTIES OF ADHESIVES ARE COHESIVE STRENGTH,
ADHERENCE, FLUIDITY AND WET ABILITY OF THE SUBSTRATE.
 COHESIVE STRENGTH : ADHESIVE SHOULD HAVE MORE COHESIVE
STRENGTH THAN EITHER OF THE SURFACES BEING HELD TOGETHER.
USUALLY THE ADHESIVE BECOMES MORE BRITTLE AS ITS COHESIVE
STRENGTH IS INCREASED.
 ADHERENCE : FOR AN ADHESIVE TO HOLD TWO SURFACES
TOGETHER THE FORMER SHOULD FORM A STRONG BOND AT EACH OF
THE INTERFACES BETWEEN THE SURFACE AND THE ADHESIVE, AND
THE ADHESIVE MUST HAVE STRONG COHESIVE STRENGTH. SINCE
ADHESIVE FAILURE OCCURS IN THE WEAKEST BOND, FAILURE CAN
OCCUR AT EITHER INTERFACE, AS ALSO FOR COHESIVE FAILURE.
FAILURE MAY ALSO OCCUR INSIDE THE ADHESIVE ITSELF. IN
PRACTICE THE BOND FAILURE AT THE INTERFACE IS RARE.
REGARDLESS OF THE QUALITY OF THE ADHESIVE CLEAN SURFACES
ARE NECESSARY TO GET THE BEST RESULT.

5. FLUIDITY : WHEN THE LIQUIDS ARE STIRRED, THEY BECOME
TEMPORARILY MORE FLUID BECAUSE OF ALIGNMENT OF THEIR TINY
CRYSTALS. THE FLUIDS THICKENS AS SOON AS STIRRING IS
STOPPED. THIS PROPERTY, CALLED THIXOTROPY OF ADHESIVE AND
PAINTS HELPS TO PREVENT A SAG OR RUN WHEN THESE COATINGS
ARE APPLIED ON VERTICAL SURFACES. IF THE VISCOSITY OF A LIQUID
INCREASES WITH INCREASE IN TEMPERATURE, AN ADHESIVE SHOULD
BE APPLIED WHILE HOT.
 WETTABILITY: ADHESIVE MUST WET THE SURFACE THOROUGHLY
AS IT SPREADS. IT MUST BE ABLE TO FLOW INTO THE SURFACE
CREVICES DISPLACING DIRT, MOISTURE AND TRAPPED AIR. FOR THIS
PURPOSE THE SURFACE TENSION OF ADHESIVE CAN BE LOWERED BY
ADDING A SURFACTANT WETTING AGENT.

6. ADHESIVES
ORGANIC
ANIMAL
PROTIEN
GLUES
BLOOD
ALBUMIN
GLUES
CASEIN
ADHESIVES
STARCH
ADHESIVES
SYNTHETIC
PHENOLIC
RESINS
RESORCINOL
RESINS
UREA
RESINS
MELAMINE
RESINS

7. ORGANIC ADHESIVES
 ANIMAL PROTEIN GLUES : THESE GLUES ARE OBTAINED BY
BOILING THE WASTE PIECES OF SKINS, BONES, TRIMMINGS ETC OF
ANIMALS WITH HOT WATER. ANIMAL GLUES DEVELOP STRONG AND
TOUGH JOINTS AND ARE EASILY APPLIED, BUT THEY ARE AFFECTED
BY DAMP AND MOIST CONDITIONS. ANIMAL GLUES ARE AVAILABLE
IN THE FORM OF FLAKES, PEARLS, CAKES, CUBES, GRANULES AND
IN THE FORM OF JELLY. THIS IS USED IN THE MANUFACTURE OF
PLYWOOD, LAMINATED TIMBERS ETC
 BLOOD ALBUMIN GLUES : THIS TYPE OF GLUE IS MADE BY DRYING
RAW BLOOD. THIS GLUE IS OF BETTER QUALITY AND IS AFFECTED
LITTLE BY DAMP AND MOIST CONDITIONS. THIS TYPE IS USED FOR
MAKING FURNITURE.
 CASEIN ADHESIVES : THESE ARE PREPARED FORM CASEIN
PRECIPITATED FROM SKIMMED MILK. IT HAS BEEN SPECIFIED THAT
THESE ADHESIVES SHOULD FULFILL THE FOLLOWING FINENESS
REQUIREMENTS.

8. FOR WET MIX GLUE----SHOULD PASS THROUGH I.S. SIEVE 60
WHEN SHAKEN FOR 10 MINUTES.
FOR DRY MIX GLUE----SHOULD PASS THROUGH I.S. SIEVE 25.
THESE GLUES POSSESS HIGH RESISTANCE TO MOISTURE WHEN
USED FOR JOINING PURPOSES. HOWEVER, THEY ARE NOT
RESISTANT TO MOULDS AND BACTERIA.
STARCH ADHESIVES : THESE GLUES ARE MADE FROM
VEGETABLE STARCH. THEY POSSESS GOOD STRENGTH ON
DRYING BUT ARE NOT MOISTURE RESISTANT .
SYNTHETIC ADHESIVES OR GLUES
SYNTHETIC GLUES ARE BASED ON SYNTHETIC RESINS. BROADLY
SPEAKING, THEY ARE OF TWO TYPES :
THERMO-SETTING GLUES AND
THERMO-PLASTIC GLUES.
THESE GLUES HAVE REVOLUTIONIZED THE METHOD OF GLUING
FOR PLYWOOD AND OTHER WOOD WORKS. THESE GLUES ARE
APPLIED IN THE LIQUID AND DRY FORM.
THERMO-SETTING GLUES ARE PERMANENT, ONCE THEY ARE
SET. WHERE AS THERMO-PLASTIC GLUES CAN BE MADE PLASTIC
AGAIN BY REHEATING.

9. ADHESIVES ARE GENERALLY CLASSIFIED AS:
 THERMOPLASTIC ADHESIVES
 THERMOSETTING ADHESIVES
THERMOPLASTIC ADHESIVES:
THERMOPLASTIC ADHESIVES ARE FUSIBLE, SOLUBLE, AND POOR
HEAT AND CREEP RESISTANT. THEY ARE NORMALLY USED FOR
LOW/MEDIUM LOAD ASSEMBLIES UNDER RESONABLE SERVICE
CONDITIONS. THEY HAVE GOOD RESISTANCE TO OILS BUT POOR
RESISTANCE TO WATER.
THERMOPLASTIC ADHESIVES INCLUDE
POLYVINYL ACETATE, POLY VIMYL ALCOHOL, POLYACRYLA

10. ALL THESE GLUES FROM SYNTHETIC RESINS ARE STRONG,
WATERPROOF AND THE SETTING TIME CAN BE REGULATED BY
VARYING THE KIND AND AMOUNT OF THE HARDENER. THEY ARE
RESISTANT TO FUNGAL ATTACK AND POSSES NON-STAINING
QUALITIES.
PHENOLIC RESINS : THE GLUES OF THESE RESINS ARE AVAILABLE
IN FILM, POWDER AND LIQUID FORMS. THEY REQUIRE HEAT AND
PRESSURE TO FORM A PERMANENT STRONG BOND. THEY ARE USED
IN THE MANUFACTURE OF RESINS BONDED PLYWOOD.
RESORCINOL RESINS : GLUES OF THESE RESINS ARE DARK
VISCOUS LIQUIDS. THEY BECOME HARD IN SHORT TIME AT LOW
TEMPERATURES. THEY ARE RESISTANT TO HEAT, MOISTURE, FUNGI
AND BACTERIA.
UREA FORMALDEHYDE RESINS: GLUES OF THESE RESINS ARE
AVAILABLE IN THE FORM OF SYRUPS AND POWDERS. THEY ARE
EXTENSIVELY USED IN JOINERY WORK TO FORM WATER-RESISTANT
GLUE JOINTS.

11.  MELAMINE RESINS: GLUES OF THESE RESINS REQUIRE HEAT AND
PRESSURE FOR SETTING. THEY ARE USED IN THE MANUFACTURE
OF PLYWOOD.
 RUBBER-BASED SOLVENT CEMENTS: THESE ARE THE ADHESIVES
MADE BY COMBINING ONE OR MORE RUBBERS OR ELASTOMERS
IN A SOLVENT, RUBBER–BASED ADHESIVES ARE USED IN A WIDE
VARIETY OF APPLICATIONS, SUCH AS CONTACT ADHESIVES FOR
PLASTIC LAMINATES LIKE COUNTER TOPS, CABINETS, DESKS, AND
TABLES
 EPOXIES: THESE ARE THE ADHESIVE SYSTEM MADE BY A
COMPLEX CHEMICAL REACTION. VARIOUS RESINS ARE MADE
SYTHETICALLY BY REACTING TWO OR MORE CHEMICALS. EPOXY
ADHESIVE CAN BOND A VARIETY OF SUBSTRATES WITH HIGH
STRENGTH, THEY HAVE BEEN USED TO REPLACE SOME
TRADITIONAL METALWORKING METHODS OF JOINING LIKE NUTS
AND BOLTS, RIVETS, WELDINGS ETC.

12. THERMOSETTING ADHESIVES ARE ESSENTIALLY INFUSIBLE ,
INSOLUBLE, AND SHOW GOOD CREEP RESISTANCE. THEY ARE
USED FOR HIGH LOAD ASSEMBLIES AND SEVERE SERVICE
CONDITIONS SUCH AS HEAT, COLD, RADIATION, ETC.
THERMOSET ADHESIVES ARE GENERALLY MORE
EXPENSIVE TO PURCHASE AND TO USE,THAN THE OTHER
ADHESIVE TYPES. THEY ARE THE ADHESIVES MOST USED FOR
STRUCTURAL,LOAD BEARING APPLICATIONS. SOME OF THE
TOUGHENED VARIANTS PROVIDE EXCEPTIONAL PROPERTIES
DIRECTLY COMPARABLE WITH WELDED AND RIVETED
ALTERNATIVES.