WO2004110132A2

WO2004110132A2 - Water vapor permeable hydrophilic membranes and devices made there-from and process for using the devices

Info

Publication number: WO2004110132A2
Application number: PCT/US2004/019079
Authority: WO
Inventors: Charles W. Cahill; Ann W. Kaplan; Olaf Norbert Kirchner; Christopher P. Mcardle; Ranganathan Soundararajan; Kenneth E. Stevens
Original assignee: E.I. Dupont De Nemours And Company
Priority date: 2003-06-12
Filing date: 2004-06-10
Publication date: 2004-12-23
Also published as: WO2004110132A3

Abstract

A water delivery device used, for example, for controlling moisture in a plant growing medium or for a water purification device; the device comprises a water vapor permeable non porous hydrophilic membrane of a polymer blend of one or more thermoplastic polyether-ester polymer(s) and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m2/24 hrs measured according to ASTM F-1249 -90 on a film 3 mils (76.2 microns) thick using air at 30°C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend; whereby an aqueous liquid comprising water is placed in contact with the membrane and water passes through the membrane by pervaporation to, for example, a plant growing medium thereby controlling the moisture in the medium or water can be collected and used as purified water.

Description

TITLE

Water Vapor Permeable Hydrophilic Membranes and Devices Made

There-from and Process for Using the Devices.

Background of the Invention

1. Field of the Invention

This invention is directed to water vapor permeable hydrophilic membranes and devices made there-from for water delivery and in particular irrigation devices for plants utilizing such membranes.

2. Description of the Prior Art

Irrigation devices and processes for using these devices that utilize membranes of thermoplastic polyether ester copolymers are described US Patent 6,484,439 and US Patent 6,453,610. Flat tubular irrigation devices and corrugated irrigation devices have been formed from thermoplastic polyether-ester copolymers but have been found to be inadequate since the devices have a tendency to kink and collapse particularly when buried under ground. When polyether esters are hydrated with water, they swell and expand to form a breathable structure that allows for the pervaporation of water but when irrigation devices expand when completely hydrated with water, the dimensional stability of the device is reduced and kinks form in the device that significantly restrict the flow of water. Typically, these irrigation devices are buried under several inches of soil. The devices, when partially constrained under the soil expand in a longitudinal direction when hydrated with water, thereby producing a longitudinal wave pattern in the device. Due to the partial constraint and weight of the soil, the crest of the wave that has formed will fold over on itself, for example, like a wave breaking in the surf, and form a fold, or a kink in the device in the transverse direction thus preventing flow of water through channels in the device. These folds are termed "Z folds" since they resemble the letter "Z" when viewed from the short axis side of the device. This has been in particular a problem with corrugated irrigation devices. There is a need to form a structure, particularly a corrugated structure, that has reduced linear expansion when swollen by hydration with water to prevent kinking and collapsing and allow for the flow of water through the structure, but the desirable properties of the polymer that provide for the pervaporation of water must be retained to form a viable water delivery device, for example, an irrigation device for the irrigation of plants.

Summary of the Invention The present invention is directed to a water delivery device used, for example, for controlling moisture in a plant growing medium or for a water purification device; the device comprises a water vapor permeable non porous hydrophilic membrane of a polymer blend of one or more thermoplastic polyether-ester polymer(s) and a liquid crystalline thermotropic polyester; wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mil (76.2 micron) thick using air at 3O⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend; whereby an aqueous liquid comprising water is placed in contact with the membrane and water passes through the membrane by pervaporation to, for example, a plant growing medium thereby controlling the moisture in the medium or water can be collected and used as purified water.

In particular, the present invention is directed to irrigation devices, for example, of a corrugated hydrophilic water vapor permeable non porous polymeric sheet structure having a top polymeric membrane layer and a bottom polymeric membrane layer and polymeric structures, which may be vertical or at some angle, such as 45 degrees from the vertical, positioned between the top and bottom membrane layers to form a corrugated structure that has at least two channels and whereby an aqueous liquid is passed through the channels and by pervaporation provides water to a plant growing medium; similarly, an irrigation device can be used wherein the channels in the device are tubular instead of the device having a corrugated structure.

The present invention is also directed to a process for providing water to a plant growth medium, a process for augmenting the humidity in an air space of an enclosed chamber and a method for hydrating dehydrated matter by using the novel water vapor permeable non porous non porous membrane, and the novel water vapor permeable membrane itself.

Brief Description of the Drawings

Fig. 1 shows a perspective view of a tubular water vapor permeable device.

Fig. 2 shows a cross sectional view of an irrigation device having a corrugated polymeric sheet structure. Fig. 3 shows a perspective view of a roll of the irrigation device having a corrugated polymeric sheet structure.

Detailed Description of the Invention

The membrane used to form the devices of the present invention is a water vapor permeable non-porous hydrophilic membrane that absorbs water and allows water to pass through only by pervaporation. If there is a vapor pressure gradient across the hydrophilic membrane, water is absorbed into the membrane and the absorbed water diffuses through the thickness of the membrane and is emitted from its opposite face. These nonporous hydrophilic membranes have sufficiently high water vapor transmission rates (VWTR) as defined below, so that water that has passed through these membranes can be used, for example, in forming a water delivery device that can be used, for example, to directly irrigate plants. Such membranes can comprise one or more layers made from materials including but not limited to the same or different hydrophilic polymers. As long as the water vapor permeation rate of the membrane in total is sufficiently high, water can be provided at a rate consistent with its use in a given practical application. The non- porous nature of the membranes serves to exclude any particulate impurities in an aqueous liquid containing water and impurities from passing through such a membrane, where the impurities may include suspended solids, salts, microbes, such as bacteria and viruses and also prevents penetration by the growing roots of plants that are being irrigated by the device.

The rate at which water pervaporates through the water vapor permeable hydrophilic non-porous membrane made from the hydrophilic polymer depends, among other factors, upon the moisture content on the non-water side. Therefore, irrigation systems formed from such membranes that are part of this present invention are self-regulating and may be "passive" in nature, providing, for example, more water to plants under dry conditions and less under humid conditions.

The standard test for measuring the water vapor transmission rate (WVTR) of a given membrane is ASTM F 1290-90 using a Modulated Infrared sensor and is measured using a membrane 3 mils (76.2 microns) in thickness using air at 30⁰C and 100% relative humidity at a velocity of 3 m/s and calculated as g/m²/24 hrs.

Typically useful water vapor permeable non porous hydrophilic membranes formed from the polymer blend useful in this invention have a VWTR of more than 400 g/m²/24 hrs., preferably, 400 up to 10,000 g/m²/24hrs and more preferably 2,000- 4,000 g/m²/24 hrs.

The test used to determine the linear expansion of a polymer blend used to form the water vapor permeable non porous hydrophilic membrane is to fully hydrate a 10 foot (3 m) long sheet, 6 inches (15.24 cm) wide, and 3 mil (76.2 micron) thick by submerging the sheet in water for 30 minutes and then re-measuring the sheet after it has been hydrated. The difference in length is calculated as percent linear expansion. Typically useful water vapor permeable non porous hydrophilic membranes have a linear expansion of less than 7 % and preferably, 0.5 - 6.0%.

"Hydrophilic polymers" means polymers that absorb water when in contact with liquid water at room temperature according to the International Standards Organization specification ISO 62 (equivalent to the American Society for Testing and Materials specification ASTM D 570).

Polymers suitable for preparing the water vapor permeable non-porous hydrophilic membranes for use in the present invention are a blend of one or more polyether-ester polymers and a liquid crystalline thermotropic polyester polymer. The blend of polymers comprises 85- 99.5% by weight, based on the weight of the polymer blend, of a polyether-ester polymer or mixture of such polymers and 0.5-15% by weight of the liquid crystalline thermotropic polyester polymer. Preferably, a blend of 95-99 % by weight of the polyether-ester and 1-5% by weight of the liquid crystalline thermotropic aromatic polyester is used. Useful polyether-ester polymers and liquid crystalline thermotropic aromatic polyester are available from E. I. du Pont de Nemours and Company, Wilmington, Delaware, under the trade names Hytrel® and Zenite®, respectively.

In the place of or in a mixture with the polyether ester, the following polymers can be used: a polyether-block-polyamide or a mixture of two or more polyether-block-polyamides, such as polymers available from the Elf-Atochem Company of Paris, France under the trade name of PEBAX; or a polyether urethane or a mixture of polyether urethanes; or homopolymers or copolymers of polyvinyl alcohol or a mixture of homopolymers or copolymers of polyvinyl alcohol.

A particularly preferred polyether-ester polymer having the desired water vapor transmission used in this invention or a mixture of two or more polyether-esters have a multiplicity of recurring long-chain ester

units and short-chain ester units joined head-to-tail through ester linkages, where the long-chain ester units are represented by the formula:

and short-chain ester units are represented by the formula:

wherein: a) G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly(alkylene oxide)glycol having a number average molecular weight of about 400-4000; b) R is a divalent radical remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight less than 300; c) D is a divalent radical remaining after removal of hydroxyl groups from a diol having a molecular weight less than about 250; optionally, d) the polyether-ester contains 0-68 weight percent based on the total weight of the polyether-ester, ethylene oxide groups incorporated in the long-chain ester units of the polyether-ester; and e) the polyether-ester contains about 25-80 weight percent short-chain ester units. These preferred polyether-esters and methods of making them are known in the art, such as are disclosed in U.S. Patent 4,725,481 for a polyether-ester having a WVTR of at least 3500 g/m² /24 hr, or U.S.

Patent 4,769,273 having a WVTR of 400-2500 g/ m²/24hr. Both patents are hereby incorporated by reference. Typically useful liquid crystalline thermotropic polyester have a melting point that is compatible with the polyether ester polymer and is not higher than the processing temperature used for the polyether ester polymer. Typically useful polyesters are shown in 3,991 ,013, 3,991 ,014 4,011,199, 4,048,148, 4,075,262, 4,083,829, 4,118,372, 4,122,070, 4,130,545, 4,153,779, 4,159,365, 4,161,470, 4,169,933, 4,184,996, 4,189,549, 4,219,461, 4,232,143, 4,232,144, 4,245,082, 4,256,624, 4,269,965, 4,272,625, 4,370,466, 4,383,105, 4,447,592, 4,522,974, 4,617,369, 4,664,972, 4,684,712, 4,727,129, 4,727,131 , 4,728,714, 4,749,769, 4,762,907, 4,778,927, 4,816,555, 4,849,499, 4,851,496, 4,851 ,497, 4,857,626, 4,864,013, 4,868,278, 4,882,410, 4,923,947, 4,999,416, 5,015,721, 5,015,722, 5,025,082, 5,086,158, 5,102,935, 5,110,896, and 5,143,956, and European Patent Application 356,226. One particularly useful polyester is liquid crystalline aromatic polyester is a polymerized blend of 20-60 % by weight polyethylene terephthalate and 40-80% by weight of para-hydroxybenzoic acid and preferably 30-50% by weight polyethylene terephthalate and 50% - 70% by weight para-hydroxybenzoic acid and more preferably 40% by weight polyethylene terephthalate and 60% by weight of para-hydroxybenzoic acid.

The polymer blend of the polyester- ether polymer and the liquid crystalline thermotropic polyester has a Melt Flow Index in the range of 0.1 - 10 and preferably 0.3-1.0. The Melt Flow Index is determined according to ASTM D 1238.

The polymer blend usually contains carbon black to reduce degradation from sunlight. Generally, the polymer blend contains 0.5-10% by weight carbon, based on the weight of the polymer blend, and preferably contains 3-7% by weight carbon black and most preferably 5% by weight carbon black.

The polymer blend can be compounded with antioxidant stabilizers, ultraviolet stabilizers, hydrolysis stabilizers, dyes or pigments, fillers, anti-microbial reagents and the like as are used in the extrusion fabrication of articles and structures. One structure of a water delivery device that can be used as an irrigation device is shown in Fig 1. An extruded flat sheet structure (1) is illustrated having multiple tubular channels (3) each being connected to another by a flat segment of the sheet (2). The aqueous liquid passed through the channels of the structure may be relatively pure water or an aqueous liquid containing water and contaminates, such as suspended materials, salts, for example, from sea water and variety of other impurities. The aqueous liquid passes through the channels and by pervaporation provides moisture in the form of pure water to the surrounding area, which can be a plant growth medium, such as soil.

Fig. 2 shows a structure of the corrugated irrigation device This cross sectional view shows a top polymeric membrane layer (4) and a bottom polymeric membrane layer (5) and vertical polymeric membrane walls (6) forming channels resulting in a corrugated structure. There are at least two channels in the structure through which water flows.

Generally, 5-500 channels are provided depending on the width of the structure, the size of the channels and the amount of water to be passed through the irrigation device. Typically, the top and bottom layers are 0.05 to 0.50 mm in thickness and the channel walls are about 0.05 to 0.50 mm in thickness and the overall thickness of the device is about 0.50 to 50 mm.

For practical utilization of the devices shown in Fig. 2 and 3, continuous sheet are formed and cut into the desired length, such as 10 m, 25 m, 50 m or more. Practical upper limits depend on the distance between the upper and lower membranes and the size of the area wherein the device is to be installed. A roll of the device, as shown in Fig. 3, can be made since they are easily transported without damage and can easily be laid out on the ground adjacent to plants that are to be irrigated. The devices of Fig. 2 and 3 are attached to a water source using techniques well known to those skilled in the art and usually buried under several inches of soil.

Typically useful irrigation devices have an output of water of least 10 to 50 liters/day/30m. One useful irrigation device has about 32 corrugated channels, is about 4mm wide, 4 mm high and has total width of about 165mm and delivers water for irrigation at about 20-40 and preferably, about 30 liters/day/30m. A variety of devices with channels of different sizes and shapes and various lengths can be made depending on the intended end use and the types of plants that are to be irrigated. The hydrophilic polymer blend can be manufactured into the watering device of the invention by any of a number of commercial processes to form corrugated structures, structures containing multiple tubes or a variety of other structures. Typically melt extrusion of the polymer blend is used on a commercial extrusion line that forms these structures. This entails heating the polymer blend to a temperature above the melting point, extruding it through a flat die configured to form the desired structure, such as a corrugated structure or a tubular structure. The structures of this invention may include one or more layers of support materials. Useful support materials include woven, non- woven or bonded papers, fabrics and screens permeable to water vapor, including those constructed from fibers of organic and inorganic polymers stable to moisture, such as polyethylene, polypropylene, fiberglass and the like. The support material both increases strength and protects the device. The support material may be disposed on one side of the top or bottom polymeric membrane or both sides or may be sandwiched between two or more layers. Typically the support material can be positioned on the exterior surfaces of a device to best protect the device from physical damage and/or degradation by light. In use, a typical irrigation device of this invention is positioned near plants, usually buried under the soil and connectors are attached to the ends of the device to allow for the flow of water through the irrigation device. The amount of water permeating through the device and into the surrounding soil is dependent on the moisture of the soil. Dry soil causes a larger differential across the irrigation device and more water permeates into the surrounding soil. As pointed out above, an aqueous liquid containing water and a wide variety of impurities can be used and only the water permeates through the device into the soil.

The novel water vapor permeable non-porous hydrophilic membranes of this invention have a variety of other uses. The membrane can be used a water purification device wherein an aqueous liquid containing impurities, such as sea water or waste water, is contacted with one side of the membrane and pure water is collected from the other side of the membrane due to pervaporation of the water while the impurities remain in the aqueous liquid.

The membrane can be used as a humidity augmenting device that provides moisture to an air space that is enclosed by the membrane which would be particularly beneficial to sprouting seeds and growing plants in an enclosed environment.

The membrane can be used in a process for increasing the moisture content of dehydrated matter, such as foods or drugs. The dehydrated matter is place in a container wherein at least a portion of the container is the membrane. Water by pervaporation is passed into the container thereby rehydrating the matter contained therein.

All of the ranges previously disclosed herein include all of the intermediate numerical points between the upper and lower limits of the range. The following examples illustrate the invention and all parts and percentages are on a weight basis unless otherwise indicated.

Testing Procedures used in the Examples

WVTR (Water Vapor Transmission Rate) is determined according to ASTM F 1249-90 using a Modulated Infrared Sensor on a film 3 mils (76.2 microns) thick using air at 30°C and 100% relative humidity at a velocity of 3 m/s. and reported as g/m²/24 hrs.

Melt Flow Index determined according to ASTM D 1238. % Linear Expansion of a polymer blend used to form the water vapor permeable non porous hydrophilic membrane is measured by fully hydrating a 10 foot (3 m) long sheet, 6 inches (15.24 cm) wide and 3 mils (76.2 micron) thick of the polymer blend by submerging the sheet in water for 30 minutes and re-measuring the sheet after it has been hydrated. The difference in length is calculated as % Linear Expansion. EXAMPLES Example 1

A mixture of the following ingredients was charged into a 5 inch single screw extruder to form a polymer blend: Hytrel® 8206 thermoplastic polyether-ester polymer, 5% by weight, based on the total weight of resin charged into the extruder, of Hytrel® 40 CB (carbon black) for protection against UV light, 1% by weight, based on the total weight of the resin, of Erucamide, a slip additive, 2.5% by weight, based on the weight of the resin, of a LCP polymer (liquid crystalline polyester).

Hytrel® 8532 and Hytrel® 40 CB are both polyether ester polymers manufactured by E.I. duPont de Nemours and Company, Wilmington, Delaware,

The LCP polymer is a 40/60 blend of polymerized polyethylene terephthalate/para-hydroxybenzoic acid.

The resulting polymer blend has a Melt Index of 0.4.

A non porous membrane of the above polymer blend has a WVTR of 3400 g/m²/24 hr determined as described above and a % Linear Expansion determined as described above of 4.17%. The above polymer blend was extruded at 200-240 ⁰C at a rate of

90 kg/hour to form a corrugated sheet structure (as shown in Fig.2) 1.4 - 1.45 m in width, having top and bottom layers 0.10-0.13 mm in thickness and the corrugated structure has a nominal profile height of 4 mm. The sheet of the corrugated structure (165 linear m) is wound onto a master roll. The sheet is subsequently slit using conventional slitting equipment into rolls that are 17 cm in width and 159 linear m in length and has a nominal 32 channels. The water delivery rate of the corrugated sheet structure is about 70 liters/day/30m. Example 2

Two polymer blends A and B were prepared as above. Polymer blend A contained 95% by weight of Hytrel®8532 and 5% by weight of Hytrel®40 CB. Polymer blend B contained 93.6% by weight of

Hytrel®8532 and 5% by weight of Hytrel®40 CB and 1.4% by weight of LCP polymer described in Example 1.

Hytrel®8532 and Hytrel®40 CB are polyether ester polymers manufactured by E.I. duPont de Nemours and Company, Wilmington, Delaware.

The resulting polymer blends A and B have a Melt Flow Index of about 0.4.

A non porous membrane of the above polymer blend A has a VWTR of 2572 g/m²/24 hr determined as described above and a % Linear Expansion determined as described above of 7.55%.

A non porous membrane of the above polymer blend B has a VWTR of 2345 g/m²/24 hr determined as described above and a % Linear Expansion determined as described above of 3.82%.

Two corrugated sheet structures A and B were formed as in Example 1 using corresponding polymer blends A and B.

A field was cultivated with a Johnson Cultivator and 12 beds 78 m in length on 1.5 m centers were constructed. In each bed corrugated sheet structure A and corrugated sheet structure B were placed 0.4 meters off of the bed center line, at a shallow burial depth of 13 cm. The moisture of the soil at the time of installation was 15%. Each of the structures was connected to a lay flat header that supplied water to each of the corrugated structures A and B at 1.05 kg/cm². Water pressure was applied and observations taken after 2 hours. The water pressure was reduced to 0.15 - 0.21 kg/cm² overnight and water flow data was measured at the end of the device after 16 hours and at a water pressure of 1.05 kg/cm². The results are shown below After 2 hours:

Corrugated structure A exhibited kinking and Z folding of the vertical polymeric membrane walls of the channels and little or no water flow («3.1 l/min). Corrugated structure B (invention) exhibited minimal distortion, no kinking of Z folding of the vertical polymeric membrane walls of the channels and an excellent water flow (>5.0 l/min).

After 16 hours: Corrugated structure A - same condition as above and water flow <0.1-1.2 l/min.

Corrugated structure B - same condition as above and water flow of 6.0-17.0 l/min..

The above data shows that corrugated structure B (invention) containing LCP polymer when formed into an irrigation device, did not collapse under use conditions and provided an acceptable flow of water in comparison to corrugated structure A that did not contain LCP polymer and basically did not form an acceptable irrigation device since the structure kinked and collapsed and did not allow for the adequate flow of water through the device.

Example 3

Four tubular flat sheet structures C, D, E and F were extruded by using conventional extrusion equipment and extrusion dies. Each structure was a flat sheet having 16 circular tubes linked together, each tube having a diameter of 2 mm and each structure was 10 feet (3 m) in length. Structures C and D were 3 mils (76.2 microns) thick and structures E and F were 6 mils (152.4 microns) thick. Fig. 1 illustrates the structure. The polymer blend used to form structures D and F was Hytrel® 8206 and 10.0% by weight, based on the total weight of the resin, of the LCP polymer, both described in Example 1. The polymer used to form structures C and E did not contain LCP polymer. Each of the structures C-F were connected to a water source and filled with water and the length of each was measured after 24 hours. The results are shown below:

Lenqth after 24 hrs. % Elonqation

Structure C (3 mil) 133.5 in. 11.25

Structure D (3 mil) (Invention) 122.5 in 1.88

Structure E (6 mil) 130.25in 6.88

Structure F (6 mil) (Invention) 122.75 in 2.29

The above data shows that Structures D and F representing the invention have a surprising and unexpected reduction in % elongation when the structure is completely hydrated with water in comparison to Structures C and E that did not contain LCP polymer.

The water out-put over 32, 48, 72 and 144 hours was measured and a three day average of water out put was measured for each of the Structures C-F and the results are shown below.

Time 32 hrs .48hrs72hrs. 144hrs. 3 day Ave.

Structure C (3 mil) 320 133 170 360 120

Structure D (3 mil) (Invention) 250 95 110 300 100 Structure E (6 mil) 310 125 140 350 116

Structure F (6 mil) (Invention) 350 120 160 400 133

The above data shows that within the limits of measurement of this test, all of the Structures C-F have substantially the same water out-put and that the addition of LCP polymer did not significantly reduce the water out-put.

Claims

1. A water delivery device for controlling moisture in a plant growing medium which comprises a water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F- 1249-90 on a film 3 mils (76.2 microns) thick using air at 3O⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend; whereby an aqueous liquid comprising water is placed in contact with the membrane and water passes through the membrane by pervaporation to the plant growing medium thereby controlling the moisture in the medium.

2. The water delivery device of claim 1 wherein the polymer blend comprises 85 to 99.5 % by weight of the thermoplastic polyether- ester and 0.5 to 15 % by weight of the liquid crystalline thermotropic polyester, the weight percentages are based on the weight of the polymer blend.

3. The water delivery device of claim 2 wherein the polymer blend has a melt flow index of at least 0.1 and a water vapor transmission rate of 400 to 10,000 g/m²/24 hr.

4. The water delivery device of claim 3 wherein the polymer blend contains 0.5 to 10 % by weight, based on the weight of the polymer blend, of carbon black pigment.

5. The water delivery device of claim 3 wherein the polyether- ester polymer comprises at least one polyether-ester having a multiplicity of recurring long-chain ester units and short-chain ester units joined head- to-tail through ester linkages, where the long-chain ester units are represented by the formula:

and short-chain ester units are represented by the formula:

wherein:

a) G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly(alkylene oxide)glycol having a number average molecular weight of about 400-4000;

b) R is a divalent radical remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight less than 300;

c) D is a divalent radical remaining after removal of hydroxyl groups from a diol having a molecular weight less than about 250; optionally

d) the polyether-ester contains 0-68 weight percent based on the total weight of the polyether-ester, ethylene oxide groups incorporated in the long-chain ester units of the polyether-ester; and

e) the polyether-ester contains about 25-80 weight percent short-chain ester units and wherein the liquid crystalline thermotropic polyester comprises an aromatic polyester.

6. The water delivery device of claim 5 wherein the liquid crystalline thermotropic polyester comprises a polymerized blend of polyethylene terephthalate and para-hydroxy benzoic acid.

7. The water delivery device of claim 6 wherein the polymer blend has a melt flow index of 0.3 - 1.0, a water vapor transmission rate of 2,000 to 4,000 g/m²/24 hr and a linear expansion of 0.5-6.0%.

8. An irrigation device comprising a corrugated polymeric sheet structure having a top hydrophilic water vapor permeable non porous polymeric membrane layer and a bottom hydrophilic water vapor permeable polymeric membrane layer and polymeric structures positioned between the top and bottom membrane layers to form a corrugated structure that has at least two channels therein and whereby an aqueous liquid comprising water is passed through the channels and by pervaporation provides water to a plant growing medium; wherein the water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249 90 on a film 3 mils (76.2 microns) thick using air at 3O⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.

9. The irrigation device of claim 8 wherein the polymer blend comprises 85 to 99.5 % by weight of the thermoplastic polyether-ester and 0.5 to 15 % by weight of the liquid crystalline thermotropic polyester, the weight percentages are based on the weight of the polymer blend.

10. The irrigation device of claim 9 wherein the polymer blend has a melt flow index of at least 0.1 and a water vapor transmission rate of

400 to 10,000 g/m²/24 hr.

11. The irrigation device of claim 10 wherein the polymer blend contains 0.5 to 10 % by weight, based on the weight of the polymer blend, of carbon black pigment.

12. The irrigation device of claim 10 wherein the polyether- ester polymer comprises at least one polyether-ester having a multiplicity of recurring long-chain ester units and short-chain ester units joined head- to-tail through ester linkages, where the long-chain ester units are represented by the formula:

and short-chain ester units are represented by the formula:

wherein:

13. The irrigation device of claim 12 wherein the liquid crystalline thermotropic polyester comprises a polymerized blend of polyethylene terephthalate and para-hydroxy benzoic acid.

14. The irrigation device of claim 13 wherein the polymer blend has a melt flow index of 0.3 - 0.5, a water vapor transmission rate of 2,000 to 4,000 g/m²/24 hr and a linear expansion of 0.5-6.0%.

15. The irrigation device of claim 8 wherein the top layer and the a bottom layer having a thickness of 0.05 - 0.50 mm, having 5-500 channels and having a total thickness of 0.50 - 50 mm and wherein the walls of the channels have a thickness of 0.50 -0.50 mm.

16. An irrigation device for providing water to a plant growth medium comprising a polymeric sheet structure of a hydrophilic water vapor permeable non porous polymeric membrane defining at least two tubular channels therein and wherein the channel are connected to each other by a flat section of the polymeric membrane whereby an aqueous liquid is passed through the channels and by pervaporation provides water to a plant growing medium; wherein the water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mils (76.2 microns) thick using air at 30^cC and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.

17. A process for providing water to a plant growing medium by passing an aqueous liquid through the water delivery irrigation device of claim 1.

18. A process for providing water to a plant growing medium by passing an aqueous liquid through the irrigation device of claim 8.

19. A process for providing water to a plant growing medium by passing an aqueous liquid through the irrigation device of claim 16.

20. A water purification device wherein an aqueous liquid comprising water and impurities is passed over water vapor permeable non porous hydrophilic membrane that retains impurities and water by pervaporation is passed through the membrane and collected; wherein the water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mils (76.2 microns) thick using air at 30⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.

21. A humidity augmenting device for providing moisture to an airspace of an enclosed chamber, wherein the device comprises a water vapor permeable hydrophilic membrane having in contact therewith an aqueous liquid comprising water; whereby the vapor permeable non porous hydrophilic membrane allows water by pervaporation to pass through the membrane and into the airspace of the enclosed chamber; wherein the water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mils (76.2 microns) thick using air at 30⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.

22. Process for the purification of an aqueous liquid containing water and impurities which comprises passing the aqueous liquid over a water vapor permeable non porous hydrophilic membrane whereby the membrane retains impurities and water by pervaporation is passed through the membrane and collected; wherein the water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mils (76.2 microns) thick using air at 30⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.

23. A process for augmenting the humidity in an air space of an enclosed chamber which comprises contacting an aqueous liquid comprising water with a water vapor permeable non porous hydrophilic membrane; whereby the vapor permeable hydrophilic membrane allows water by pervaporation to pass through the membrane and into the airspace of the enclosed chamber; wherein the water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline themnotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mils (76.2 microns) thick using air at 3O⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.

24. A process for increasing the moisture content in dehydrated matter which comprises the steps of contacting an aqueous liquid comprising water with a water vapor permeable non porous hydrophilic membrane that forms at least a portion of a sealed container containing dehydrated matter; whereby the vapor permeable hydrophilic membrane allows water by pervaporation to pass through the membrane and the container thereby providing moisture to the dehydrated matter; wherein the water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mils (76.2 microns) thick using air at 3O⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.

25. A water vapor permeable non porous hydrophilic membrane comprising a polymer blend of one or more thermoplastic polyether-ester polymer and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mils (76.2 microns) thick using air at 3O⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.

26. A water vapor permeable non porous hydrophilic membrane comprising a polymer blend wherein one polymer is selected from the group consisting of polyether-blocked polyamides, a mixture of two or more polyether-blocked amides, polyether urethanes or a mixture of polyether urethanes, homopolymers of polyvinyl alcohol, copolymers of polyvinyl alcohol, and mixtures of homopolymers and copolymers of polyvinyl alcohol and a liquid crystalline thermotropic polyester; and wherein the membrane has a water vapor transmission rate of at least 400 g/m²/24 hrs measured according to ASTM F-1249-90 on a film 3 mils (76.2 microns) thick using air at 3O⁰C and 100% relative humidity at a velocity of 3 m/s and the polymer blend has a linear expansion of less than 7% measured on a fully hydrated film of the polymer blend.