دوست عزیز این پدیده بیشتر از اینکه به قطبیت حلاله بستگی داشته با شه به قدرت حلالیت حلال وتوانایی حل کردن آن بستگی دارد به طور خلاصه:
ابتدا بایید رزین اصلی چسب رو مشخص کنید و بر حسب پارامتر حلالیت رزین حلالی رو که پارامتر حلالیتش به رزینتون نزدیکه رو انتخاب کنید به طور مثال اگه فرض کنیم که رزین اصلیتون PVC که پارامتر حلالیتش
9.5 – 9.7 cal/cm 3 بایید یه حلالی پیدا کنید با حلالیت نزدیک به اون مثلاTHF با حلالیت 9.52 نه یه حلالی مثل تولون با حلالیت 8.91در مورد ترکیبی از حلالها هم به همین صورت عمل میکنیم برای اطلاعات بیشتر من اصل متن رو برات میزارم امیدوارم مفید واقع بشه
9.2.1 Solubility Parameter
Solvents used to cement plastics should be chosen with approximately the
same solubility parameter ( d ) as the plastic to be bonded. The solubility
parameter is the square root cohesive energy density (CED) of the liquid
solvent or polymer. It is defi ned as follows:
d ( Δ E / V ) 1/2 (measured in Hildebrand ’ s)
where Δ E is the energy of vaporization, V is the molar volume, and Δ E / V
is the CED or internal pressure.
A non-polar molecule, such as methane, evaporates readily and is a gas at
ordinary temperatures. It has a low CED, hence a low d ( ∼ 6). By contrast,
a highly polar, associated (hydrogen-bonded) molecule of the same size,
such as water, requires high heat input to evaporate it, and consequently
has a very high d of 23.4. Literature sources provide data for d ’ s of a number
of plastics and resins. [ 3 , 4 ] A great deal of the data is shown in Tables 9.1
and 9.2. The solubility parameters help explain why polystyrene ( d = 9.1)
9: Solvent Cementing of Plastics 211
Table 9.1 Hildebrand Solubility Parameters for Solvents
Solvent Standard (cal/cm 3 ) 1/2 SI Unit (MPa) 1/2
n -Pentane (7.0) 14.4
n -Hexane 7.24 14.9
Freon ® TF 7.25
n -Heptane (7.4) 15.3
Diethyl ether 7.62 15.4
1,1,1-Trichloroethane 8.57 15.8
n -Dodecane 16.0
White spirit 16.1
Turpentine 16.6
Cyclohexane 8.18 16.8
Amyl acetate (8.5) 17.1
Carbon tetrachloride 8.65 18.0
Xylene 8.85 18.2
Ethyl acetate 9.10 18.2
Toluene 8.91 18.3
Tetrahydrofuran 9.52 18.5
Benzene 9.15 18.7
Chloroform 9.21 18.7
Trichloroethylene 9.28 18.7
Cellosolve ® acetate 9.60 19.1
Methyl ethyl ketone 9.27 19.3
Acetone 9.77 19.7
Diacetone alcohol 10.18 20.0
Ethylene dichloride 9.76 20.2
Methylene chloride 9.93 20.2
Butyl Cellosolve ® 10.24 20.2
Pyridine 10.61 21.7
Cellosolve ® 11.88 21.9
Morpholine 10.52 22.1
Dimethylformamide 12.14 24.7
n -Propyl alcohol 11.97 24.9
Ethyl alcohol 12.92 26.2
Dimethyl sulfoxide 12.93 26.4
n -Butyl alcohol 11.30 28.7
Methyl alcohol 14.28 29.7
Propylene glycol 14.80 30.7
Ethylene glycol 16.30 34.9
Glycerol 21.10 36.2
Water 23.5 48.0
Standard Hildebrand values from Hansen. [ 13 ] SI Hildebrand values from Hansen. [ 14 ] Values
in parenthesis from Crowley et al. [ 15 ]
212 Adhesives Technology Handbook
is soluble in butane ( d = 9.3), but not in acetone ( d = 10.0), while cellulose
acetate ( d = 10.9) dissolves in ethyl acetate ( d = 9.1), but not in butyl acetate
( d = 8.5). The concept of d also explains why a plastic would
sometimes dissolve in a mixture of two liquids of which neither by itself
is a solvent for the plastic. The classic example is the solubility of nitrocellulose
( d = 11.0) in ethyl alcohol ( d = 12.7, poor solvent) and diethyl
ether ( d = 7.4).
9.2.2 Factors Affecting Adhesive and Solvent Bonding
9.2.2.1 Solubility
Solvent bonding is most effective with polymers having low intermolecular
forces. Amorphous polymers or polymers with low crystallinity are more
soluble in most solvents. Lower molecular weight polymers and polymer
molecules with less cross-linking and more branching structures are more
easily dissolved in solvents. Elevated temperatures increase the solubility
of all polymers. Polymers dissolve most easily in solvents of the same
polarity; polar polymers generally dissolve in polar solvents, and non-polar
Table 9.2 Solubility Parameters for Polymers [ 16 ]
Polymer Solubility Parameter (cal/cm 3 ) 1/2
Polytetrafl uoroethylene 6.2
Polydimethyl siloxane 7.3– 7.6
Butyl rubber 7.7
Polyethylene 7.9– 8.1
Polyurethane 10.0
Polystyrene 9.1
Neoprene 8.2 – 9.4
Polyvinyl acetate 9.4
Polymethyl methacrylate 9.3
Polyvinyl chloride 9.5 – 9.7
Epoxy 9.7 – 10.9
Polyethylene terephthalate 10.7
Phenolic resin 11.5
Polyvinylidene chloride 12.2
Nylon 6,6 13.6
Polybutadiene 8.4
Phenol-formaldehyde 11.5