Hydrophobic polyurethane is usually used to fill voids and stabilize soil because of its low viscosity, high expansion rate, and ability to set up under wet conditions without diluting. When injected into loose soil or voids, it expands to form a rigid foam that displaces any water present.
Full Answer
Why to use polyurethane foam?
The invention is a hydrophobic polyurethane foam prepared from a conventional PO/EO polyether polyol, a graft polyol and a hydrophobicity inducing surfactant. The foam is …
Is great stuff polyurethane foam?
SikaFix® HH+ is a hydrophobic polyurethane foam grout that, when used with accelerator, is designed to stop water infiltration and fill voids outside a structure or joint and cracks in concrete structures. It may also be used in applications with high pressure flowing water. Read more + Easy to apply, one component with accelerator
Does polyurethane foam absorb water?
The invention is a hydrophobic polyurethane foam prepared from a conventional PO/EO polyether polyol, a graft polyol and a hydrophobicity inducing surfactant. The foam is …
What are the medical uses of polyurethane foam?
JP-S5450099-A chemical patent summary.
Is polyurethane foam hydrophilic?
The hydrophilic polyurethane foam is prepared by the materials in parts by weight: 50-75 parts of hydrophilic polyether A, 25-50 parts of polyether polyol B, 36.5-42 parts of TDI (toluene diisocynate), 0.5-1.5 parts of diethanol amine, 0.12-0.3 part of polyurethane catalyst A-33, 0.5-1.5 parts of silicon oil and 3 ...
What is hydrophobic foam?
Hydrophilic foams are the ideal flexible foam solution for applications in which moisture absorbency, breathability and softness are vital properties.
Why is polyurethane hydrophobic?
Hydrophobic polyurethanes naturally repel water (similar to the way oil would repel water and stay separate if you were trying to mix them in a glass). These products push water out of the area in question as they expand. Hydrophobics are used with catalysts which allow you to adjust the set time.
What is hydrophilic resin?
Hydrophilic (hydro meaning 'water', philic meaning 'has an affinity for') resins seek out water in a crack. They chase the water and absorb into the tight micro-cracks and pores of the concrete. Hydrophobic (hydro - water, phobic - fearing) resins repel water in a crack.
Is urethane hydrophobic?
In polyurethanes containing PDMS, polar interactions are very weak. Phase separation is significantly lower. These coatings are definitely hydrophobic materials.
What type of plastic is polyurethane?
Polyurethane is a polymer joined by urethane links. These links are formed by reacting a di- or poly-isocyanate with a polyol. Polyurethane is unique in that it is not manufactured like many other plastics. Most polymers, such as polyethylene, are produced in the form of a powder and then molded into a desired form.
Is polyurethane water soluble?
In general, the polyurethanes are hydrophobic in nature and insoluble in water. Therefore, in order to disperse them in water, they must be modified by, for example, incorporating ionic groups and/or non-ionic hydrophilic segments into the polymer structure.
Why do hydrophobic molecules repel water?
Water does not tend to wet hydrophobic surfaces; rather, the droplets stay beaded up with high values of contact angle. Hydrophobic molecules called hydrophobes repel bodies of water and, owing to the fact that hydrophobes are non-polar, they attract other neutral molecules and non-polar solvents.
What is the charge of polyurethane?
Symbols in the table— Polyurethane (top) tends to charge positive; teflon (bottom) charges negative. The charge affinity listings show relative charging. Two materials with almost equal charge affinity tend not to charge each other much even if rubbed together.
Is epoxy hydrophobic or hydrophilic?
hydrophilicEpoxy polymers are generally hydrophilic due to the presence of polar epoxy groups.
What is hydrophobic grout?
Simply translated as a “water fearing” material, hydrophobic grouts have little to no affinity for water. These grouts need very little, if any, water to react and cure.
Is concrete a Hydroscopic?
Typical concrete is quite hydrophilic. This comes from its intricate system of tiny capillaries, which suck water through the microcrack network within a concrete slab.
What are the advantages of hydrophobic reagents?
Advantages. Easy to apply, one component with accelerator. Hydrophobic, only a small amount of water is needed for reaction. Expands up to 30 times the liquid volume. Non-flammable. Contains no volatile solvents. 100% solids. Non-Toxic formulation.
What is Sikafix HH+?
SikaFix® HH+ is a hydrophobic polyurethane foam grout that, when used with accelerator, is designed to stop water infiltration and fill voids outside a structure or joint and cracks in concrete structures. It may also be used in applications with high pressure flowing water.
Can you use Sikafix grout with a sikafix accelerator?
The grout should never be used with more than 5 % SikaFix Accelerator. Excess acceleration will cause vigorous expansion that is prone to shrinkage. Pour the desired amount of SikaFix HH+ into a clean pail. Measure the appropriate amount of SikaFix Accelerator and pour it into the SikaFix® HH+ and mix adequately.
What is hydrophobic foam?
Hydrophobic urethane foam reacts on contact with water in a concrete crack to expand and foam. A closed cell foam is created that stops water leaks through a basement wall crack. The final product is flexible and will not shrink in volume.
What temperature should concrete be?
Concrete should be above 40 F. Can be used to stop leaks in dry or wet cracks. Surface of the concrete must be dry for use. Hydra Stop 300 forms a closed cell flexible foam to stop water penetration. The expansion is up to 30x the initial volume.
What is hydrophobic polyurethane used for?
Use of Hydrophobic and Hydrophilic Polyurethanes for Crack Injection. Polyurethane foams used in concrete repair to prevent water penetration through concrete cracks are said to be either hydrophobic or hydrophilic in behavior.
What is hydrophilic foaming?
A hydrophilic system acts like a sponge and will absorb as much water as is available in its surroundings during the foaming process. It reacts with the amount of water needed for reaction and subsequently contains the excess water within its structure, as would a sponge.
What happens when water is again present in a concrete crack?
When water is again present, the foam can absorb the water and return to its original size, as would a sponge (at least theoretically). A typical hydrophilic system is very flexible and has good adhesion to concrete, and thus bonds well to the sides of a concrete crack.
What is hydrophobic system?
A hydrophobic system has time to not only permeate the crack but to fill any void behind the crack. A void is a separation of the foundation wall and the back-fill which can allow collection of water behind the crack and cause it to leak.
What is the best way to repair a leaking basement?
Both types can be used to stop water in concrete crack repair, but hydrophobic systems are best suited for permanent repair of most leaking basement cracks unless there are structural issues (where epoxies coupled with carbon fiber staples are the best choice). A hydrophobic system will absorb and mix with only as much water as is needed ...
How much water does a hydrophobic system absorb?
A typical hydrophobic system will expand up to 30 times its initial volume.
Can hydrophobic concrete be used for crack repair?
Today, there are hydrophobic formulations available which are flexible and stable, and are suitable for concrete crack repair. They bond well to concrete, do not shrink even in the absence of water, and can expand enough to fill voids economically.
Highlights
The hydrophobic and oleophilic Al 2 O 3 /PUF foam sponge was prepared.
Abstract
In current work, hydrophobic and oleophilic polyurethane (Al 2 O 3 /PUF) foam sponge was prepared by foaming technology. The material was characterized by XRD, TEM, BET, SEM and water contact angles (CA). The Al 2 O 3 /PUF was applied to removal of oil or organic solvent from oil/water system. Water contact angle of Al 2 O 3 /PUF could exceed 140°.
Introduction
Crude oil spills, the petrochemical and metallurgical industries, pharmaceutical factories and toxic organic solvents have caused serious environmental pollution on a global scale [1]. It is extremely urgent and important to develop effective and inexpensive materials that can remove oils or organic solvents from water [2], [3].
Experimental
Polyether polyol (NJ-330, M = 3000 g/mol) was obtained from Ningwu Chemical Co., in Jurong, Jiangsu, China. Isophorone diisocyanate (IPDI, purity ≥ 99.5% and -NCO content ≥ 37.5%) was supplied by Rongrong Chemical Co., in Shanghai, China.
Results and discussion
XRD patterns of hollow Al 2 O 3 spheres at 600 °C for 2 h (a) and 180 °C for 3 h (b) are shown in Fig. 1 ．As can be seen from Fig. 1 (a), all the diffraction peaks of 66.9°, 45.9°, 39.5°, 37.3° and 32.7° are in good accordance with those of the (440), (400), (222), (311) and (220) planes of the Al 2 O 3 crystal orthorhombic (JCPDS card no.
Conclusion
In current work, the hollow Al 2 O 3 spheres were prepared by one-pot hydrothermal method. Then the hydrophobic Al 2 O 3 was obtained using hollow Al 2 O 3 spheres modified with γ-methacryloxypropyltrimethoxysilane (KH-570).
What is the difference between hydrophobic and hydrophilic?
But, to a contractor, these terms can mean a world of a difference. Hydro means water while phobic means “to fear” and philic means “to love”.
Does AP seal 500 absorb water?
Some hydrophilic materials will keep absorbing water (10-15 times their original volume). Others (such as our AP Seal 500) only absorb as much water as is necessary for their reaction and then they reject the rest. Yes, hydrophilic gels will shrink like crazy in the absence of water, but the AP Seal 500 won't.
Is Alchemy Spetec hydrophobic or hydrophilic?
Alchemy-Spetec offers both hydrophobic and hydrophilic polyurethanes, so it is important to be aware of the differences between the two types.
Do hydrophilic polyurethanes need a catalyst?
This characteristic allows for a very strong chemical and mechanical bond, as water helps pull the material into the pores of the concrete. These products do not require a catalyst.
Which resin is stronger, hydrophobic or hydrophilic?
Hydrophilic resins can achieve a strong bond to the wet concrete which can be superior to hydrophobic resins, which rely more on high injection pressures to penetrate into fine pores and rely more on a compression seal created by the reactive expansion.
What is hydrophilic grout?
Hydrophilic polymer injection gel grouts achieve a mechanical bond in rough areas of the concrete as they absorb deep into the pores and micro cracks of the concrete. Hydrophilic resins can achieve a strong bond to the wet concrete which can be superior to hydrophobic resins, which rely more on high injection pressures to penetrate into fine pores and rely more on a compression seal created by the reactive expansion.
Does water need to be in the substrate to form gel?
The presence of sufficient water in the substrate is necessary for the product to form a gel. It may be advisable to introduce water prior to injection. In areas of very little water content and little counter pressure the product may expand to a foam.
How effective is hydrophobic resin?
There is no doubt that hydrophobic resins can be very effective at stopping water leaks. They will expand and fill up a wet crack as well as most hydrophilic resins . The failure will usually occur a few months after the job is finished. If it happens during the warranty period, the contractor will have to return to the job and fix it again. All of the profit made on the job goes out the window. The only one who benefits is the hydrophobic material supplier.
Why is polyurethane used in soil stabilization?
Polyurethanes are usually used to fill voids and stabilize soil because of their low viscosity, high expansion rates, and ability to set up under wet conditions without diluting. Hydrophobic resins repel water. When injected into loose soil or voids, they expand and displace any water that is present. The rigid hydrophobic soil stabilization materials that are on the market expand up to 1 ,000% in the soil and form a strong, impermeable mass.
How much water does hydrophilic soil stabilization absorb?
The rigid hydrophobic soil stabilization materials that are on the market expand up to 1 ,000% in the soil and form a strong, impermeable mass. Hydrophilic resins absorb water. The hydrophilic soil stabilization materials that are on the market absorb as much water as they come into contact with during initial cure.
What resins seek out water?
Hydrophilic resins seek out water in a crack. Learn why that matters when sealing hairline cracks. Hydrophilic (hydro meaning 'water', philic meaning 'has an affinity for') resins seek out water in a crack. They chase the water and absorb into the tight micro-cracks and pores of the concrete.
How long does it take for polyurethane to cure?
The initial cure is the time when the polyurethane resin foams up. The final cure may take up to 24 hours. It is during this time that hydrophilic resins bite into the pores and micro cracks of the concrete.
What happens when the water table drops?
When water tables drop, the moisture in the hydrophilic stabilization products evaporates and the products shrink. Manufacturers claim that when the water table returns to original levels, the material will re-absorb the water and regain their original size.
How long does it take to set Prime Flex 910?
The set time can be adjusted from 1 hour and 40 minutes for slow penetration down to 1 minute and 50 seconds for cutting off underground streams.