WO2014132266A2

WO2014132266A2 - Acrylonitrile polymer composite using modified starch and a method of preparation thereof

Info

Publication number: WO2014132266A2
Application number: PCT/IN2014/000110
Authority: WO
Inventors: Anasuya Sahoo; Preeti Lodha; Karuppasamy PARASURAMAN; Bandu Madhukar KALE
Original assignee: Aditya Birla Science And Technology Company Limited
Priority date: 2013-02-26
Filing date: 2014-02-21
Publication date: 2014-09-04
Also published as: WO2014132266A3; WO2014132266A8

Abstract

An acrylonitrile polymer composite suitable for fibers is disclosed. The acrylonitrile polymer composite is formed by modifying an acrylonitrile polymer with a modified starch, wherein the modified starch has a degree of substitution of at least 1.5 obtained by modifying a starch with a starch modifier with a formula R-X wherein R is six to ten membered ring of carbon. A method of making an acrylonitrile polymer composite is also disclosed.

Description

ACRYLONITRILE POLYMER COMPOSITE USING MODIFIED STARCH AND A METHOD OF PREPARATION THEREOF

The present disclosure provides an acrylonitrile polymer composite suitable for fibers. The present disclosure also provides a method of making an acrylonitrile polymer composite.

BACKGROUND

Acrylic polymer is defined as a polymer containing at least 85% of acrylonitrile monomer in the backbone. A polymer with < 85% acrylonitrile is defined as modacrylic. Typical properties of acrylonitrile polymer (acrylic and modacrylic polymer) based fibers include resistance to moths, oils, and chemicals.

Acrylonitrile polymer based fibers are lightweight, soft, and warm, with a woollike feel. It dyes very well and has excellent colorfastness. Acrylonitrile polymer based fibers are commonly used in non-woven and wovens including sweaters, hand-knitting yarns, rugs, awnings, boat covers etc.

Acrylonitrile polymer based fibers are stretched at elevated temperature to obtain the desired denier. Further, the thermal processing temperature requirement of the acrylonitrile polymer based fibers is high hence the process is energy intensive. Additionally, the acrylonitrile polymer based fibers have poor wrinkle recovery as compared to wool and are non-biodegradable.

Further, a commercial technology for manufacturing acrylonitrile polymer and casting various forms out of this polymer uses aqueous sodium thiocyanate as a solvent. The process is energy intensive as it requires sub zero temperature for precipitation and high temperature for stretching, but is eco-friendly and safe process for manufacturing acrylic fibers for indoor and outdoor textile, non-woven and plastic applications. The thermal processing temperature(s) requirement and the properties of the acrylonitrile polymer based fibers are strong function of the glass transition temperature. Several efforts have been reported to control the glass transition temperature of acrylic polymer by use of co-monomers during polymerization. The change in co- monomer however, also alters the fiber properties significantly as the basic molecule is changed. Therefore there is a need for an alternate approach to reducing the glass transition temperature of acrylic polymer based products.

Starch is one of the most abundant available carbohydrate polymers obtained from natural renewable resources. Starch includes amylose and amylopectin. Starch has been considered as one source for the industrial plastics because of its known biodegradability and low cost. A number of studies have been carried out on thermoplastic starch and starch / synthetic polymer blends. However, most of these starch products are hydrophilic, and the hydrophilic nature is responsible for the gelling of the starch in water medium or aqueous sodium thiocyanate solvent. One of the most commonly available starch derivatives, cellulose acetate is thermoplastic in nature and hence can be processed at high temperature. It is however based on cellulose and is stable in water, but shows high swelling behavior in aqueous sodium thiocyanate solution. Several other modified cellulose based products are also used as viscosity modifier in cement and food industry, but these products either show gelling behavior in aqueous sodium thiocyanate solution or are water soluble making it difficult to process and to retain them during product processing and washing with water.

Accordingly, there is a need of an acrylonitrile polymer composite having desired properties preferably for fiber, fabric, non-wovens and polymeric moulds. Additionally, there is need to develop a method of making an acrylonitrile polymer composite.

SUMMARY

An acrylonitrile polymer composite suitable for fibers is disclosed. The acrylonitrile polymer composite is formed by modifying an acrylonitrile polymer with a modified starch, wherein the modified starch has a degree of substitution of at least 1.5 obtained by modifying a starch with a starch modifier with a formula R-X wherein R is six to ten membered ring of carbon. An article formed of an acrylonitrile polymer composite is also disclosed. A method of making an acrylonitrile polymer composite is disclosed. The method of making an acrylonitrile polymer composite comprising modifying starch with a starch modifier having a formula R-X wherein R is six to ten membered ring of carbon to obtain a modified starch and mixing an acrylonitrile polymer with the modified starch in an aqueous sodium thiocyanate solution to obtain a polymer dope. The method further comprises precipitating an acrylonitrile polymer composite by adding the polymer dope to an aqueous sodium thiocyanate solution; separating and washing the acrylonitrile polymer composite before passing it through a heated water bath to remove the sodium thiocyanate (NaSCN).

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1 illustrates a DSC curve of acrylonitrile polymer. The sample is analyzed on a differential scanning calorimetry, DSC-Q200 by TA Instruments. The glass transition temperature was calculated as per ASTM method D7426 - 08.

DETAILED DESCRIPTION

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the disclosed process, and such further applications of the principles of the invention therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.

Reference throughout this specification to "one embodiment" "an embodiment" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase "in one embodiment", "in an embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. The term "fiber" means a substance which is capable of being spun into a yarn or made into a fabric by bonding or by interlacing in a variety of methods including weaving, knitting, braiding, felting, twisting, or webbing, and which is the basic structural element of textile products. The fiber is also capable of being used in preparing films, sheets and moulds.

The term "starch" means a polysachharide (carbohydrate polymer) which comprises of anhydroglucose units chained together by glycosidic bonds.

The term "glass transition temperature" or "Tg" refers to the temperature at which a polymeric material transitions from a glassy state to a rubbery state. The glassy state is typically associated with a material that is, for example, brittle, stiff, rigid, or a combination thereof. In contrast, the rubbery state is typically associated with a material that is, for example, flexible and elastomeric. The glass transition temperature can be determined using a method such as Differential Scanning Calorimetry (DSC) or Dynamic Mechanical Analysis (DMA). Tg of acrylonitrile polymer is generally considered to be 100°C.

The term "degree of substitution" refers to the (average) number of substituent groups attached per base unit (in the case of condensation polymers) or per monomeric unit (in the case of addition polymers).

The present disclosure provides a method of making an acrylonitrile polymer composite and an acrylonitrile polymer composite thereof. Particularly, a method of making an acrylonitrile polymer composite suitable for fibers is disclosed. More particularly, a method of making an acrylonitrile polymer composite comprising modifying starch with a starch modifier having a formula R-X wherein R is six to ten membered ring of carbon to obtain a modified starch and mixing an acrylonitrile polymer with the modified starch in an aqueous sodium thiocyanate solution to obtain a polymer dope. The method further comprises precipitating a acrylonitrile polymer composite by adding the polymer dope to an aqueous sodium thiocyanate solution; separating and washing the acrylonitrile polymer composite before passing it through a heated water bath to remove the sodium thiocyanate (NaSCN). In accordance with an embodiment, starch is modified by reacting starch with the starch modifier in presence of a base, preferably aqueous solution of sodium hydroxide and the excess base is neutralised with an acid, preferably hydrochloric acid. Thus obtained solution is filtered to obtain a white solid mass which is subsequently dried to obtain the modified starch. By way of specific example, starch is modified in accordance with the chemical reaction illustrated below:

NaOH / H₂0 Modified starch

In accordance with an embodiment, the starch modifier has a formula R-X wherein R is selected from cyclic, substituted, non-substituted, aromatic, non-aromatic, hetero- aromatic or combination thereof and X is a leaving group. By way of example X is a halide selected from chlorine, iodine or bromine. Use of Fluorine is not recommended. By way of specific example, R-X is:

R^1"7 = H, CI, Br, F, CH₃, N0₂, OR⁸ (optionally being substituted by one or more), R^s = C1-C4 (linear or branched), R⁸≠ H,

X = CI or Br or I

In accordance with an embodiment, the anhydroglucose unit in the starch and the starch modifier are in a molar ratio of at least 1 :1.5 in the modified starch. In accordance with an embodiment, the anhydroglucose unit in the starch and the starch modifier are in a molar ratio in the range of 1 : 1.5 to 1 : 15 in the modified starch. By way of example, 1.5 to 15 moles of the starch modifier is used per mole of anhydroglucose unit in the starch to obtain the modified starch. By way of specific example, 189 gm to 1899 gm of benzyl chloride (molecular weight of 126.58) is used per mole of anhydroglucose unit in the modified starch i.e 1.16 gm to 1 1.72 gm of benzyl chloride per gram of the starch is used.

In accordance with an embodiment, the modified starch has a degree of substitution (DS) of at least 1.5.

In accordance with an embodiment, the acrylonitrile polymer comprises of at least 50% acrylonitrile monomelic units. Other monomelic units are selected from methacrylate, vinyl acetate, methacrylic acid, acrylic acid, ethyl vinyl ether, vinyl bromide, vinyl chloride, vinylidene chloride, vinyl sulfonic acid, itaconic acid, methylmethacrylate, and sulfonated monomers such as sodium styrene sulfonate, sodium methallyl sulfonate, sodium sulfophenyl methallyl ether or combination thereof.

In accordance with an embodiment, mixing of acrylonitrile polymer with the modified starch in aqueous sodium thiocyanate solution may be carried out in a single or two step process to achieve desired percentage loading (w/w of acrylonitrile polymer) of the modified starch in the acrylonitrile polymer composite. By way of specific example, a starch solution containing modified starch is prepared in aqueous sodium thiocyanate solution and mixing the same with a solution of acrylonitrile polymer prepared in aqueous thiocyanate solution to obtain a polymer dope.

In accordance with an embodiment, the aqueous sodium thiocyanate solution used for preparing the polymer dope has a concentration in the range of 30-50% (w/w). By way of specific example, 38% (w/w) of aqueous sodium thiocyanate solution is used for preparing the polymer dope.

In accordance with an embodiment,, the polymer dope has at least 0.5% by weight of the modified starch to the acrylonitrile polymer. It is preferred that the polymer dope has at least 0.5% to 25% by weight of the modified starch to the acrylonitrile polymer.

In accordance with an embodiment, precipitation of acrylonitrile polymer composite is carried out by adding the polymer dope to the aqueous sodium thiocyanate solution having concentration in the range of 2% to 14% (w/w) and temperature in the range of -5°C to 10°C. By way of example, precipitation of acrylonitrile polymer composite is carried out by adding the polymer dope to a 14 % (w/w) aqueous sodium thiocyanate solution having temperature of -2.3°C.

The precipitated acrylonitrile polymer composite is washed. The washing is preferably done in water, may be carried out once or more. By way of example, washing of the acrylonitrile polymer composite is carried out in water having temperature in the range of 0 °C to 50°C. It is preferred that washing of the acrylonitrile polymer composite is carried out at approximate temperature of 50 °C. Alternatively, the washing may be done in multiple steps. By way. of specific example, washing is carried out by first contacting the acrylonitrile polymer composite with water at 0°C for a residence time of 1 -5 minutes, then contacting with a water bath at 30°C for 5-15 minutes followed by washing with water having temperature of 50°C.

In accordance with an embodiment, after washing, the acrylonitrile polymer composite is passed through a heated water bath. The heated water bath is used to remove sodium thiocyanate from the acrylonitrile polymer composite. By way of specifie example, the heated water bath has a temperature in the range of 75-99°C, preferably 95°©|

The present disclosure also provides an acrylonitrile polymer composite suitable for fibers. Particularly, the present invention provides an acrylonitrile polymer composite prepared by method disclosed herein.

In accordance with an embodiment, the acrylonitrile polymer composite has a reduced glass transition temperature as compared to acrylonitrile polymer. The acrylonitrile polymer composite requires lower thermal processing temperature as compared to acrylonitrile polymer. By way of specific example, the acrylonitrile polymer composite shows reduction of glass transition temperature by 3-35° C.

In accordance with an embodiment, the acrylonitrile polymer composite is suitable for use as, but not limited to, fibers, films, sheets and plastic moulds. By way of specific example, the acrylonitrile polymer composite used as fibers for preparing textile fabrics show reduction in thermal processing temperature such as dyeing temperature and hot stretching temperature. By way of specific example, the dyeing temperature and the hot stretching temperature have been reduced by 3-35 ⁰ C. Furthermore, the acrylonitrile polymer composite used as fibers for preparing textile fabrics show improved wrinkle recovery as compared to conventional acrylonitrile polymer.

In accordance with an embodiment, the modification of the acrylonitrile polymer with the modified starch and the modification of the starch by. the starch modifier is carried out in an aqueous sodium thiocyanate solution.

In accordance with an embodiment, the acrylonitrile polymer composite is biodegradable in nature.

The following example(s) of method of making an acrylonitrile polymer composite and an acrylonitrile polymer composite thereof are exemplary and should not be understood to be in any way limiting.

Example 1:

Starch Modification:

A mixture of maize starch (10 gm dried in oven at 50 °C for 12 h) and acetic anhydride (40 g); is added to 50% aqueous sodium hydroxide solution (3.4 gm). The weight ratio of maize starch to acetic anhydride is 1 :4, which amounts to 6.35 moles of acetic anhydride per anhydroglucose unit in starch. The temperature of the reaction was increased to 123 °C in 15 minutes and the reaction mixture was stirred at the same temperature for 4 h before quenching with excess cold water to obtain white acetylated product. The white acetylated product was filtered through Buckner funnel and washed with distilled water till the filtrate pH is neutral. The product was dried at 50 °C for 8 h in an oven (17 g). The starch acetate (Starch-O- Ac) showed a degree of substitution of 1.3 and showed gelling tendency in aqueous NaSCN. Hence further dope preparation and film preparation is not done. Example 2:

Starch Modification:

To a suspension of maize starch (10 g) in Tetrahydrofuran: water (50 mL: 75 mL) was added methyl ethyl ketone (MEK; 123 mL) and stirred at 8 °C. A solution of freshly prepared acrolylchloride (20 g) in MEK (130 mL) and toluene (25 mL) was added drop by drop for 20 minutes. Thus, 3.56 moles of acrylol chloride is used per anhydroglucose unit in starch. The reaction mixture was stirred at 0-5 °C for 45 minutes and kept for phase separation. The organic layer is removed and the thick and pasty aqueous layer is evaporated under vacuum. The residue is washed with acetone and dried in an oven at 100°C for 2 h. The starch acrolyl (Starch-O- Acrolyl) showed a degree of substitution of 1.29 and showed gelling tendency in aqueous NaSCN. Hence further dope preparation and film preparation was not done.

Example 3:

Starch Modification:

To a suspension of maize starch (10 g) in a saturated solution of iso-propanol in sodium sulphate (40 mL) aqueous sodium hydroxide solution (0.8 g) is added. N- Butyl bromide (40 g) is added, to the mixture obtained in previous step, drop by drop over 20 minutes at 45-50 °C and stirring is continued for 58 h. Thus, 4.72 moles of n-butyl bromide is used per anhydroglucose unit in starch. The reaction mixture was cooled to room temperature and acetic acid (pH = 5) is added. The thick viscous solid was filtered and washed with 80% (50 mL) then 100% (50 mL) alcohol, finally with 85% acetone (50 mL) and dried in air and over for 1 h at 100 °C. The butylated starch (Starch-O-But) showed a degree of substitution of 0.87 and showed gelling tendency in aqueous NaSCN. Hence further dope preparation and film preparation is not done. Example 4:

Starch Modification:

The maize starch is dried at 50 °C for 12 hours to remove the moisture. 10 g of the dried starch is dispersed in 25 mL of water saturated with sodium sulfate. Then 0.4 g of 20% aqueous sodium hydroxide solution is added to the above mixture. The reaction mixture is heated to 65 °C and benzyl chloride is added in the weight ratio of 1 :2.5 (starch: benzyl chloride). Thus, 3.19 moles of benzyl chloride is used per anhydroglucose unit in starch. The benzyl chloride is added over 15 minutes and reaction is carried out for 1 hour at 65 °C. Then 12.5 g of 20% aqueous sodium hydroxide solution is added and stirred for 6 hours at a temperature of 65 °C to obtain slurry. The slurry was neutralized with dil. HCl (50% solution) to obtain white solid mass. The white solid mass is filtered using Buckner funnel and washed with distilled water. The white solid is dried in an oven at 50 °C for 12 hours to obtain modified starch. The modified starch or benzylated starch (Starch- O-Benzyl) showed a degree of substitution of 0.49 and showed gelling tendency in aqueous NaSCN. Hence further dope preparation and film preparation is not done.

Example 5:

Starch Modification:

The maize starch is dried at 50 °C for 12 hours to remove the moisture. 10 g of the dried starch is dispersed in 25 mL of water saturated with sodium sulfate. Then 0.4 g of 20% aqueous sodium hydroxide solution is added to the above mixture. The reaction mixture is heated to 65 °C and benzyl chloride is added in the weight ratio of 1 :4 (starch: benzyl chloride). Thus, 5.12 moles of benzyl chloride is used per anhydroglucose unit in starch. The benzyl chloride is added over 15 minutes and reaction is carried out for 1 hour at 65 °C. Then 12.5 g of 20% aqueous sodium hydroxide solution is added and stirred for 24 hours at a temperature of 65 °C to obtain slurry. The slurry was neutralized with dil. HCl (50% solution) to obtain white solid mass. The white solid mass is filtered using Buckner funnel and washed with distilled water. The white solid is dried in an oven at 50 °C for 12 hours to obtain modified starch. The modified starch or benzylated starch (Starch- O-Benzyl) showed a degree of substitution of 1.76 and no gelling tendency in aqueous NaSCN.

Acrylonitrile Polymer Solution:

An acrylonitrile polymer (consisting of 91.1% acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) was dissolved in an aqueous solution of sodium thiocyanate (38% w/w) to prepare a spinning solution having a viscosity of 3000-5000 centipoises at 30°C.

Polymer Dope preparation:

The above modified starch (15% w/w of sodium thiocyanate solution) is dispersed in 38% aqueous sodium thiocyanate solution (85% w/w). The solution obtained in previous step is homogenized using a high pressure homogenizer at 200 bar pressure for 1 pass to reduce the particle size. Then the required quantity of the above solution containing modified starch (1% loading on the weight of the polymer) is added to the acrylonitrile polymer solution at constant stirring at 30°C to obtain polymer dope, which is maintained at a temperature in the range of 30°C -50°C.

Preparation of Acrylonitrile Polymer Composite

The polymer dope obtained from the previous steps maintained at 50°C is precipitated by contacting with an aqueous sodium thiocyanate solution (14% w/w) maintained at -2.3°C with a residence time of 2 to 60 seconds to obtain acrylonitrile polymer composite. The precipitated thus obtained of acrylonitrile polymer composite is contacted with water at 0°C for a residence time of 1 to 5 min and at 30°C in water bath from 5 to 15 min. and water washed at a temperature of 50°C. Further the acrylonitrile polymer composite is contacted with water bath at a temperature of 95°C for 2 seconds to remove residual sodium thiocyanate from the acrylonitrile polymer. Then the film was analysed for thermal property using Differential Scanning Colorimetry. It showed a Tg of 95.3 °C. Example 6:

Starch Modification:

The maize starch is dried at 50 °C for 12 hours to remove the moisture. 10 g of the dried starch is dispersed in 25 mL of water saturated with sodium sulfate. Then 0.4 g of 20% aqueous sodium hydroxide solution is added to the above mixture. The reaction mixture was heated to 65 °C and benzyl chloride is added in the weight ratio of 1 :4 (starch: benzyl chloride). Thus, 5.12 moles of benzyl chloride is used per anhydroglucose unit in starch. The benzyl chloride is added over 15 minutes and reaction is carried out for 1 hour at 65 °C. Then 12.5 g of 20% aqueous sodium hydroxide solution is added and stirred for 24 hours at a temperature of 65 °C to obtain slurry. The slurry is neutralized with dil. HC1 (50% solution) to obtain white solid mass. The white solid mass is filtered using Buckner funnel and washed with distilled water. The white solid is dried in an oven at 50 °C for 12 hours to obtain modified starch. The modified starch or benzylated starch (Starch- O-Benzyl) showed a degree of substitution of 1.76 and no gelling tendency in aqueous NaSCN

Acrylonitrile Polymer Solution:

An acrylonitrile polymer (consisting of 91.1 % acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) was dissolved in an aqueous solution of sodium thiocyanate (38% w/w) to prepare a spinning solution having a viscosity of 3000-5000 centipoises at 30°C.

Polymer Dope preparation:

The above modified starch (15% w/w of sodium thiocyanate solution) is dispersed in 38% aqueous sodium thiocyanate solution (85%). The solution obtained in previous step is homogenized using a high pressure homogenizer at 200 bar pressure for 1 pass to reduce the particle size. Then the required quantity of the above solution containing modified starch (based on 5 % loading on the weight of the polymer) is added to the acrylonitrile polymer solution at constant stirring at 30°C to obtain polymer dope, which is maintained at a temperature in the range of 30°C -50°C. Preparation of Acrylonitrile Polymer Composite

This polymer dope solution maintained at 50°C was precipitated by contacting with an aqueous 14% sodium thiocyanate solution maintained at -2.3 °C with a residence time of 2 to 60 seconds. The precipitated thus obtained of acrylonitrile polymer composite is contacted with water at 0°C for a residence time of 1 to 5 min; at 30°C in water bath from 5 to 15 min and water washed at a temperature of 50°C. Further the acrylonitrile polymer composite is contacted with water bath at a temperature of 95°C for 2 seconds to remove residual sodium thiocyanate from the acrylonitrile polymer. Then the film was analysed for thermal property using Differential Scanning Colorimetry. It showed a Tg of 84.1 °C.

Example 7:

Starch Modification:

The maize starch is dried at 50 °C for 12 hours to remove the moisture. 10 g of the dried starch is dispersed in 25 mL of water saturated with sodium sulfate. Then 0.4 g of 20% aqueous sodium hydroxide solution is added to the above mixture. The reaction mixture was heated to 65 °C and benzyl chloride is added in the weight ratio of 1 :4 (starch: benzyl chloride). Thus, 5.12 moles of benzyl chloride is used per anhydroglucose unit in starch. The benzyl chloride is added over 15 minutes and reaction was carried out for 1 hour at 65 °C. Then 12.5 g of 20% aqueous sodium hydroxide solution is added and stirred for 24 hours at a temperature of 65 °C to obtain slurry. The slurry is neutralized with dil. HC1 (50% solution) to obtain white solid mass. The white solid mass is filtered using Buckner funnel and washed with distilled water. The white solid is dried in an oven at 50 °C for 12 hours to obtain modified starch. The modified starch or benzylated starch (Starch- O-Benzyl) showed a degree of substitution of 1.76 and no gelling tendency in aqueous NaSCN.

Acrylonitrile Polymer Solution:

An acrylonitrile polymer (consisting of 91.1% acrylonitrile, 8.5% methyl acrylate and 0.4% sodium methacryl sulfonate) was dissolved in an aqueous solution of sodium thibcyanate (38% w/w) to prepare a spinning solution having a viscosity of 3000-5000 centipoises at 30°C.

Polymer Dope preparation

The above modified starch (15% w/w of sodium thiocyanate solution) is dispersed in 38% aqueous sodium thiocyanate solution (85%). The solution obtained in previous step is homogenized using a high pressure homogenizer at 200 bar pressure for 1 pass to reduce the particle size. Then the required quantity of the above solution containing modified starch (based on 10 % loading on the weight of the polymer) is added to the acrylonitrile polymer solution at constant stirring at 30°C to obtain polymer dope, which is maintained at a temperature in the range of 30°C -50°C.

Preparation of Acrylonitrile Polymer Composite

This polymer dope solution maintained at 50°C was precipitated by contacting with an aqueous 14% sodium thiocyanate solution maintained at -2.3°C with a residence time of 2 to 60 seconds. The precipitated thus obtained of acrylonitrile polymer composite is contacted with water at 0°C for a residence time of 1 to 5 min; at 30°C in water bath from 5 to 15 min and water washed at a temperature of 50°C. Further the acrylonitrile polymer composite is contacted with water bath at a temperature of 95°C for 2 seconds to remove residual sodium thiocyanate from the acrylonitrile polymer. Then the film was analysed for thermal property using Differential Scanning Colorimetry. It showed a Tg of 79.1°C.

Example 8:

Starch Modification:

The maize starch is dried at 50 °C for 12 hours to remove the moisture. 10 g of the dried starch is dispersed in 25 mL of water saturated with sodium sulfate. Then 0.4 g of 20% aqueous sodium hydroxide solution is added to the above mixture. The reaction mixture was heated to 65 °C and benzyl chloride is added in the weight ratio of 1 :4 (starch: benzyl chloride). Thus, 5.12 moles of benzyl chloride is used per anhydroglucose unit in starch. The benzyl chloride is added over 15 minutes and reaction is carried out for 1 hour at 65 °C. Then 12.5 g of 20% aqueous sodium hydroxide solution is added and stirred for 20 hours at a temperature of 65 °C to obtain slurry. The slurry is neutralized with dil. HC1 (50% solution) to obtain white solid mass. The white solid mass is filtered using Buckner funnel and washed with distilled water. The white solid is dried in an oven at 50 °C for 12 hours to obtain modified starch. The modified starch or benzylated starch (Starch- O-Benzyl) showed a degree of substitution of 1.57 and no gelling tendency in aqueous NaSCN

Acrylonitrile Polymer Solution:

Polymer Dope preparation

The above modified starch (15% w/w of sodium thiocyanate solution) is dispersed in 38%o aqueous sodium thiocyanate solution (85%>). The solution obtained in previous ste is homogenized using a high pressure homogenizer at 200 bar pressure for 1 pass to reduce the particle size. Then the required quantity of the above solution containing modified starch (based on 10 % loading on the weight of the polymer) is added to the acrylonitrile polymer solution at constant stirring at 30°C to obtain polymer dope, which is maintained at a temperature in the range of 30°C -50°C.

Preparation of Acrylonitrile Polymer Composite

This polymer dope solution maintained at 50°C was precipitated by contacting with an aqueous 14% sodium thiocyanate solution maintained at -2.3 °C with a residence time of 2 to 60 seconds. The precipitated thus obtained of acrylonitrile polymer composite is contacted with water at 0°C for a residence time of 1 to 5 min; at 30°C in water bath from 5 to 15 min and water washed at a temperature of 50°C. Further the acrylonitrile polymer composite is contacted with water bath at a temperature of 95°C for 2 seconds to remove residual sodium thiocyanate from the acrylonitrile polymer. . Then the film was analysed for thermal property using Differential Scanning Colorimetry. It showed a Tg of 83.3 °C.

Example 9:

Starch Modification:

The maize starch is dried at 50 °C for 12 hours to remove the moisture. 10 g of the dried starch is dispersed in 25 mL of water saturated with sodium sulfate. Then 0.4 g of 20% aqueous sodium hydroxide solution is added to the above mixture. The reaction mixture is heated to 65 °C and benzyl chloride is added in the weight ratio of 1 :2.5 (starch: benzyl chloride). Thus, 3. 19 moles of benzyl chloride is used per anhydroglucose unit in starch. The benzyl chloride is added over 15 minutes and reaction is carried out for 1 hour at 65 °C. Then 12.5 g of 20% aqueous sodium hydroxide solution is added and stirred for 24 hours at a temperature of 65 °C. The slurry was neutralized with dil. HC1 (50% solution) to obtain white solid mass. The white solid mass is filtered using Buckner funnel and washed with distilled water. The white solid is dried in an oven at 50 °C for 12 hours to obtain modified starch. The modified starch or benzylated starch (Starch-O-Benzyl) showed a degree of substitution of 1.53 and showed no gelling tendency in aqueous NaSCN.

Acrylonitrile Polymer Solution:

An acrylonitrile polymer (consisting of 91.1%o acrylonitrile, 8.5% methyl acrylate and 0.4%) sodium methacryl sulfonate) was dissolved in an aqueous solution of sodium thiocyanate (38% w/w) to prepare a spinning solution having a viscosity of 3000-5000 centipoises at 30°C.

Polymer Dope preparation

The above modified starch (15%> w/w of sodium thiocyanate solution) is dispersed in 38% aqueous sodium thiocyanate solution (85%). The solution obtained in previous step is homogenized using a high pressure homogenizer at 200 bar pressure for 1 pass to reduce the particle size. Then the required quantity of the above solution containing modified starch (based on 10 % loading on the weight of the polymer) is added to the acrylonitrile polymer solution at constant stirring at 30°C to obtain polymer dope,, which is maintained at a temperature in the range of 30°C -50°C.

Preparation of Acrylonitrile Polymer Composite

This polymer dope solution maintained at 50°C was precipitated by contacting with an aqueous 14% sodium thiocyanate solution maintained at -2.3°C with a residence time of 2 to 60 seconds. The precipitated thus obtained of acrylonitrile polymer composite is contacted with water at 0°C for a residence time of 1 to 5 min; at 30°C in water bath from 5 to 15 min and water washed at a temperature of 50°C. Further the acrylonitrile polymer composite is contacted with water bath at a temperature of 95°C for 2 seconds to remove residual sodium thiocyanate from the acrylonitrile polymer. Then the film was analysed for thermal property using Differential Scanning Colorimetry. It showed a Tg of 83.1 °C.

ExamplelO:

Starch Modification:

The maize starch is dried at 50 °C for 12 hours to remove the moisture. 10 g of the dried starch is dispersed in 25 mL of water saturated with sodium sulfate. Then 0.4 g of 20% aqueous sodium hydroxide solution is added to the above mixture. The reaction mixture was heated to 65 °C and 4-fluorobenzyl chloride was added in the weight ratio of 1 :4 (starch: 4-fluoroebenzyl chloride). Thus, 4.37 moles of 4- fluorobenzyl chloride is used per anhydro glucose unit in starch. The 4- fluoroebenzyl chloride is added over 15 minutes and reaction was carried out for 1 hour at 65 °C. Then 12.5 g of 20% aqueous sodium hydroxide solution is added and stirred for 24 hours at a temperature of 65 °C to obtain slurry. The slurry is neutralized with dil. HC1 (50% solution) to obtain white solid mass. The white solid mass is filtered using Buckner funnel and washed with distilled water. The white solid is dried in an oven at 50 °C for 12 hours to obtain modified starch. The modified starch or fluoro benzylated starch (Starch-O-4-fluoro-benzyl) showed a degree of substitution of 2 and showed no gelling tendency in aqueous NaSCN. Acrylonitrile Polymer Solution:

Polymer Dope preparation

Preparation of Acrylonitrile Polymer Composite

This polymer dope solution maintained at 50°C was precipitated by contacting with an aqueous 14% sodium thiocyanate solution maintained at -2.3°C with a residence time of 2 to 60 seconds. The precipitated thus obtained of acrylonitrile polymer composite is contacted with water at 0°C for a residence time of 1 to 5 min; at 30°C in water bath from 5 to 15 min and water washed at a temperature of 50°C. Further the acrylonitrile polymer composite is contacted with water bath at a temperature of 95°C for 2 seconds to remove residual sodium thiocyanate from the acrylonitrile polymer. Then the film was analysed for thermal property using Differential Scanning Colorimetry. It showed a Tg of 75.3 °C.

Example 11:

Various types of the modified starch are prepared in accordance with the disclosure and their respective properties are enlisted below: S.N Modified DS Swelling Dispersible Dispersible Dosage Tg of Tg of Starch in Water in NaSCN in control acrylonit acrylonitr (acrylo rile ile nitrile polymer polymer polyme composit r) e

Target No Yes Yes 15% 100.1 < 100

1 Starch 0 Yes Dissolves Gelling NF 100.1 NF

Starch- 1.3 Yes Yes Gelling NF 100.1 NF O-Ac

3 Starch- 1.29 Yes No Gelling NF 100.1 NF

0-

Acrolyl

Starch- <1 Yes No ^■ Gelling NF 100.1 NF O-But

Starch- 0.49 Yes No Gelling NF 100.1 NF O-Benzyl

Starch- 1.76 No Yes Yes 1 100.1 95.3 O-Benzyl

Starch- 1.76 No Yes Yes 5 100.1 84.1 O-Benzyl

Starch- 1.76 No Yes Yes 10 100.1 79.1 O-Benzyl

Starch- 1.76 No Yes Yes 20 100.1 75.0 O-Benzyl

Starch- 1.57 No Yes Yes 10 100.1 82.3 O-Benzyl

10 Starch- 1.53 No Yes Yes 10 100.1 83.1 O-Benzyl

11 Starch- 2 No Yes Yes 10 100.1 75.3 0-4- fluoro- benzyl SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW

An acrylonitrile polymer composite suitable for fibers formed by modifying an acrylonitrile polymer with a modified starch, wherein the modified starch has a degree of substitution of at least 1.5 obtained by modifying a starch with a starch modifier with a formula R-X wherein R is six to ten membered ring of carbon.

Such acrylonitrile polymer composite(s), wherein the modified starch is at least 0.5 % by weight of the acrylonitrile polymer.

Such acrylonitrile polymer composite(s), wherein the starch has anhydroglucose units and the molar ratio of anhydroglucose unit in the starch and the starch modifier is at least 1 : 1.5 in the modified starch.

Such acrylonitrile polymer composite(s), wherein the modification of the acrylonitrile polymer with the modified starch and the modification of the starch by the starch modifier is carried out in an aqueous sodium thiocyanate solution.

FURTHER SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW

A method of making an acrylonitrile polymer composite comprising modifying starch with a starch modifier having a formula R-X wherein R is six to ten membered ring of carbon to obtain a modified starch, mixing an acrylonitrile polymer with the modified starch in an aqueous sodium thiocyanate solution to obtain a polymer dope, precipitating an acrylonitrile polymer composite by adding the polymer dope to an aqueous sodium thiocyanate solution, and separating and washing the acrylonitrile polymer composite before passing it through a heated water bath to remove the sodium thiocyanate.

Such method (s). wherein the polymer dope has at least 0.5 percent by weight of modified starch to the acrylonitrile polymer.

Such method (s). wherein concentration of aqueous sodium thiocyanate solution for making the polymer dope is in a range of 30-50% (w/w).

Such method (s). wherein the modified starch has a degree of substitution of at least 1.5. Such method (s). wherein the degree of substitution of at least 1.5 is obtained by a molar ratio of at least 1 :0.5 of anhydroglucose unit in the starch and the starch modifier.

FURTHER SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW

An article formed of an acrylonitrile polymer composite wherein the acrylonitrile polymer composite is formed by modifying an acrylonitrile polymer with a modified starch, wherein the modified starch has a degree of substitution of at least 1.5 obtained by modifying a starch with a starch modifier with a formula R-X wherein R is six to ten membered ring of carbon.

Such article (s), wherein the article is a sheet, particles, moulded products, films, non-wovens or fabric.

INDUSTRIAL APPLICATION

The method of making an acrylonitrile polymer composite as disclosed above is easy to perform and energy efficient. The acrylonitrile polymer composite disclosed herein is suitable for fibers used in the preparation of textile fabrics, non-wovens, films and polymeric moulds. The acrylonitrile polymer composite has a reduced glass transition temperature and require reduced thermal processing temperature as compared to acrylonitrile polymer. The acrylonitrile polymer composite is biodegradable and the textile fabrics based on such acrylonitrile polymer composite possess improved wrinkle recovery. These properties are advantageous in several industrial as well as household applications. The acrylonitrile polymer composite disclosed herein may be used for indoor and outdoor textile, non-woven and plastic applications.

Claims

WE CLAIM:

1. An acrylonitrile polymer composite suitable for fibers formed by modifying an acrylonitrile polymer with a modified starch, wherein the modified starch has a degree of substitution of at least 1.5 obtained by modifying a starch with a starch modifier with a formula R-X wherein R is six to ten membered ring of carbon.

2. An acrylonitrile polymer composite as claimed in claim 1 , wherein the modified starch is at least 0.5 % by weight of the acrylonitrile polymer.

3. An acrylonitrile polymer composite as claimed in claim 1 , wherein the starch has anhydroglucose units and the molar ratio of anhydroglucose unit in the starch and the starch modifier is at least 1 : 1.5 in the modified starch.

4. An acrylonitrile polymer composite as claimed in claim 1, wherein the modification of the acrylonitrile polymer with the modified starch and the modification of the starch by the starch modifier is carried out in an aqueous sodium thiocyanate solution.

5. A method of making an acrylonitrile polymer composite comprising:

modifying starch with a starch modifier having a formula R-X wherein R is six to ten membered ring of carbon to obtain a modified starch;

mixing an acrylonitrile polymer with the modified starch in an aqueous sodium thiocyanate solution to obtain a polymer dope;

precipitating an acrylonitrile polymer composite by adding the polymer dope to an aqueous sodium thiocyanate solution; and

separating and washing the acrylonitrile polymer composite before passing it through a heated water bath to remove the sodium thiocyanate.

6. A method of making an acrylonitrile polymer composite as claimed in claim 5, wherein the polymer dope has at least 0.5 percent by weight of modified starch to the acrylonitrile polymer.

7. A method of making an acrylonitrile polymer composite as claimed in claim 5, wherein concentration of aqueous sodium thiocyanate solution for making the polymer dope is in a range of 30-50% (w/w).

8. A method of making an acrylonitrile polymer composite as claimed in claim 5, wherein the modified starch has a degree of substitution of at least 1.5.

9. A method of making an acrylonitrile polymer composite as claimed in claim 8, wherein the degree of substitution of at least 1.5 is obtained by a molar ratio of at least 1 : 1.5 of anhydroglucose unit in the starch and the starch modifier.

10. An article formed of an acrylonitrile polymer composite wherein the acrylonitrile polymer composite is formed by modifying an acrylonitrile polymer with a modified starch, wherein the modified starch has a degree of substitution of at least 1.5 obtained by modifying a starch with a starch modifier with a formula R-X wherein R is six to ten membered ring of carbon.

1 1. An article formed of an acrylonitrile polymer composite as claimed in claim 10, wherein the article is a sheet, particles, moulded products, films, non-wovens or fabric.