CN106519173A - Method for preparing shape memory polyurethane from hyperbranched modified sisal microcrystals - Google Patents

Abstract

The invention discloses a method for preparing shape-memory polyurethane by using hyperbranched modified sisal microcrystals. Prepare sisal microcrystals, react with 3,5-diaminobenzoic acid to prepare hyperbranched modified sisal microcrystals, put polycaprolactone diol into a round bottom flask, and heat to 80°C under nitrogen atmosphere Stir magnetically until it melts, then add N,N-dimethylformamide and dibutyltin dilaurate, heat to 105°C and keep it for 15 minutes to remove water, then cool down to 80°C, add hexamethylene diisocyanate, at 80°C The mixture was reacted for 3-5 hours to prepare a mixed solution containing isocyanate-terminated polyurethane prepolymer, and then added the prepared hyperbranched modified sisal microcrystals and 4,4'-biquinone, and stirred and reacted in a nitrogen atmosphere. Then pour it into a preheated mold and heat and solidify for 6-8 hours to obtain a shape-memory polyurethane containing hyperbranched modified sisal microcrystals. The method of the invention is simple to operate, and the prepared shape-memory polyurethane material has excellent mechanical, thermal and shape-memory properties.

Description

A method for preparing shape memory polyurethane by using hyperbranched modified sisal microcrystals

technical field

The invention belongs to the technical field of intelligent polymer materials, and in particular relates to a method for preparing shape-memory polyurethane by using hyperbranched modified sisal microcrystals.

Background technique

Shape memory materials have important application value in the fields of biomedicine, structural parts and textiles, and have become a research hotspot and focus in academia and industry in recent years. In particular, shape memory polymer (Shape Memory Polymer, referred to as SMP) material has the advantages of easy processing, easy molding, light weight, etc., and has very huge potential application value. Since the 1980s, researchers from all over the world have increased their research on SMP. The investment and research of SMP have led to the rapid development of SMP research and become an important functional material at present.

As one of the earliest materials to be used in the research and development of SMP, Shape Memory Polyurethane (SMPU) has received extensive attention since it was successfully developed by Japan's Mitsubishi Heavy Industries in the 1980s. Polyurethane is a polymer prepared from polyisocyanate, polyether polyol or polyester polyol, small molecule polyol, polyamine, etc. as chain extenders and other raw materials. In this polymer, the chain rigidity of the isocyanate group and the chain extender is represented as a hard segment, and the hydrogen bonds between the hard segments and other chain winding effects can play a role in physical crosslinking in the SMP, while the polyester or polyether binary Alcohol is a soft segment, which can act as a molecular switch. Therefore, the structural design and ratio adjustment of soft and hard segments are the key to the preparation of high-performance SMPU.

Polycaprolactone (PCL for short) is a semi-crystalline polyester polymer obtained by ring-opening polymerization of ε-caprolactone, and is often used in the preparation of SMPU. Since PCL has end group reactivity, PCL with different structures such as star and branch can be prepared by selecting different initiators, so as to prepare SMPU with different structures, which makes PCL occupy an important place in the research of SMP materials. However, the poor mechanical properties of PCL limit the application of SMP.

Sisal is a common perennial plant of the genus Agave. It mainly grows in a few countries such as Brazil, Kenya, and China. It is mainly distributed in Guangxi, Guangdong, and Hainan in China. The global annual output is as high as 4.5 million tons. Sisal leaves are rich in crude fibers, the cellulose content can reach 50% to 74%, and the fiber diameter is about 150 to 200 μm. Each fiber is composed of several hollow thin tubes. The surface of the fiber is scaly and uneven. , It is not easy to peel off after being combined with the resin matrix, and the sisal fiber is very suitable for use as a resin-based reinforcing material. Compared with other cellulose microcrystals, sisal fiber microcrystals have the advantages of tough texture, high strength, high modulus, friction resistance, acid and alkali resistance and low temperature resistance, and have irreplaceable advantages of other fibers in many special fields. It is an ideal polymer-based reinforcement material.

Cellulose microcrystalline is a renewable and degradable natural polymer microcrystalline material, which has the characteristics of large specific surface area, compressibility, water absorption, good reaction performance and functional effect, and is widely used in food and beverage Daily chemical, medical and health and light chemical industry and other fields. At the same time, cellulose microcrystals also have the advantages of high modulus, low density, good heat resistance, and good compatibility with polymer matrix, which can be used to improve the mechanical and thermal properties of polymers.

The present invention prepares hyperbranched modified sisal microcrystals through molecular design, and then introduces hyperbranched modified sisal microcrystals into the "PCL+HDI+BP" system to prepare SMPU with good comprehensive performance. This idea has not been reported in the literature so far.

Contents of the invention

The purpose of the present invention is to provide a method for preparing shape-memory polyurethane by using hyperbranched modified sisal microcrystals.

The specific steps are:

(1) The sisal fibrils are cut to a length of 5±0.1 cm, washed with water to remove impurities, and dried at 80° C. to obtain dry sisal fibrils for use.

(2) Weigh 10g of dried sisal fibrils prepared in step (1) into a 200mL reaction kettle, then add 100mL of hydrochloric acid solution with a pH value of 3±0.1, react at 165°C for 40~45min, and then wash with water until the filtrate Colorless, the obtained sisal fibrils are squeezed dry and added to a 200mL reaction kettle, then add _4gNaOH , _{4gNa2SO4 ·} 10H2O and 100mL water to mix and dissolve, react at 170°C for 2h, filter with suction, and wash until the filtrate If the color remains unchanged, dry sisal must be used for later use.

(3) Add the dry sisal hemp that step (2) makes into a 500mL three-necked flask, then add 3.35g of sodium chlorite, 325mL of water and 2.5mL of acetic acid with a mass percentage concentration of 36 to 38%, and heat to 75 to 38%. React at 80°C for 2 hours, wash and filter with high-purity water, and then dry at 75°C to constant weight to obtain sisal microcrystals.

(4) Take 0.5 g of sisal microcrystals prepared in step (3), 2.5 ml of KH550, 30 ml of absolute ethanol and 2.5 ml of distilled water and add them together to a 50 ml three-necked flask, and react in a water bath at 60°C for 3 hours to obtain the product Filter and dry, then disperse into N-methylpyrrolidone, then add 0.5g 3,5-diaminobenzoic acid, 5ml pyridine and 0.2g triphenylphosphine, react in a water bath at 100°C for 3h, the resulting reaction solution After cooling to room temperature, pour it into a LiCl methanol solution with a concentration of 0.1% by mass to precipitate, filter and separate, and wash the filtrate with N,N-dimethylacetamide and methanol alternately for 3 times to remove unreacted monomers and unreacted branched polymer, and the final obtained product was vacuum-dried at 90°C to constant weight to obtain hyperbranched modified sisal microcrystals.

(5) Put 2.0 g of polycaprolactone diol with a weight-average molecular weight of 1000 into a round-bottomed flask, heat to 80°C under a nitrogen atmosphere and magnetically stir until it melts, then add 20ml of N,N-dimethyl formamide (DMF) and 0.1 ml dibutyltin dilaurate (DBTDL), heat the mixture to 105 ° C for 15 min to remove water, then cool down to 80 ° C, add 0.67 ml hexamethylene diisocyanate (HDI), at 80 ° C The reaction was carried out for 3~5 hours to prepare a mixed liquid containing isocyanate-terminated polyurethane prepolymer.

(6) 0.015g of hyperbranched modified sisal microcrystals and 0.3g of 4,4'-biphenyldiol prepared in step (4) were added to the isocyanate-terminated polyurethane prepolymer prepared in step (5). In the mixed solution, stir and react at 80°C for 12 hours in a nitrogen atmosphere, then pour them into a preheated mold at 50-80°C, heat and cure at 70-90°C for 5-7 hours, and the hyperbranched Shape memory polyurethane with modified sisal microcrystals.

The method of the invention is simple to operate, and the prepared shape-memory polyurethane material has excellent mechanical, thermal and shape-memory properties. Its main performance indicators are as follows: the highest elongation at break reaches 1100%; the highest tensile strength reaches 29.64Mpa; the 5% thermal weight loss temperature is ≥280°C; the shape recovery rate is 94%~100%.

detailed description

Example:

(1) The sisal fibrils are cut to a length of 5 cm, washed with water to remove impurities, and dried at 80° C. to obtain dry sisal fibrils for use.

(2) Weigh 10g of dried sisal fibrils prepared in step (1) and add them to a 200mL reactor, then add 100mL of hydrochloric acid solution with a pH value of 3, react at 165°C for 42min, then wash with water until the filtrate is colorless, and the obtained Squeeze the sisal fibrils to dry the water and put them into a 200mL reactor, then add _4gNaOH , _{4gNa2SO4 ·} 10H2O and 100mL water to mix and dissolve, react at 170°C for 2h, filter with suction, wash until the color of the filtrate does not change, The sisal must be dried and set aside.

(3) Add the dried sisal obtained in step (2) into a 500mL three-necked flask, then add 3.35g of sodium chlorite, 325mL of water and 2.5mL of acetic acid with a concentration of 37% by mass, and heat to 78°C for reaction After 2 hours, wash and filter with high-purity water, and then dry at 75°C to constant weight to obtain sisal microcrystals.

(4) Take 0.5 g of sisal microcrystals prepared in step (3), 2.5 ml of KH550, 30 ml of absolute ethanol and 2.5 ml of distilled water and add them together to a 50 ml three-necked flask, and react in a water bath at 60°C for 3 hours to obtain the product Filter and dry, then disperse into N-methylpyrrolidone, then add 0.5g 3,5-diaminobenzoic acid, 5ml pyridine and 0.2g triphenylphosphine, react in a water bath at 100°C for 3h, the resulting reaction solution After cooling to room temperature, pour it into a LiCl methanol solution with a concentration of 0.1% by mass to precipitate, filter and separate, and wash the filtrate with N,N-dimethylacetamide and methanol alternately for 3 times to remove unreacted monomers and unreacted branched polymer, and the final obtained product was vacuum-dried at 90°C to constant weight to obtain hyperbranched modified sisal microcrystals.

(5) Put 2.0 g of polycaprolactone diol with a weight-average molecular weight of 1000 into a round-bottomed flask, heat to 80°C under a nitrogen atmosphere and magnetically stir until it melts, then add 20ml of N,N-dimethyl formamide (DMF) and 0.1 ml dibutyltin dilaurate (DBTDL), heat the mixture to 105 ° C for 15 min to remove water, then cool down to 80 ° C, add 0.67 ml hexamethylene diisocyanate (HDI), at 80 ° C The reaction was carried out for 3~5 hours to prepare a mixed liquid containing isocyanate-terminated polyurethane prepolymer.

(6) 0.015g of hyperbranched modified sisal microcrystals and 0.3g of 4,4'-biphenyldiol prepared in step (4) were added to the isocyanate-terminated polyurethane prepolymer prepared in step (5). In the mixed solution, stir and react at 80°C for 12h in a nitrogen atmosphere, then pour them into a preheated mold at 60°C, heat and solidify at 80°C for 6h, and then obtain a hyperbranched modified sisal microcrystal shape memory polyurethane.

The shape-memory polyurethane prepared in this example was tested, and its elongation at break was 1100%, its tensile strength was 29.64MPa; its shape recovery rate was 97.67%; its 5% thermal weight loss temperature was 282°C, and its overall performance was excellent .

Claims (1)

1. a kind of method for preparing shape memory polyurethane using hyperbranched modified Folium Agaves Sisalanae crystallite, it is characterised in that concrete steps For：

(1) Folium Agaves Sisalanae fibril is cut into the length of long 5 ± 0.1cm, and then washing goes the removal of impurity, 80 DEG C of drying to be obtained and be dried Folium Agaves Sisalanae original Fibre, it is stand-by；

(2) weigh that 10g steps (1) are obtained to be dried Folium Agaves Sisalanae fibril and be added in 200mL reactors, adding 100mL pH value is 3 ± 0.1 hydrochloric acid solution, reacts 40 ~ 45min at 165 DEG C, and it is colourless to be then washed to filtrate, gained Folium Agaves Sisalanae fibril extruding stem It is added to after moisture in 200mL reactors, adds 4gNaOH, 4gNa₂SO₄·10H₂O and 100mL water mixed dissolutions, in 170 2h is reacted at DEG C, sucking filtration washs constant to filtrate color, obtains dry Folium Agaves Sisalanae, standby；

(3) dry Folium Agaves Sisalanae obtained in step (2) is added in 500mL there-necked flasks, adds 3.35g sodium chlorite, 325mL water Be 36 ~ 38% acetic acid with 2.5mL mass percent concentrations, be heated to 2h being reacted at 75 ~ 80 DEG C, using high-purity water washing sucking filtration, Then dry to constant weight at 75 DEG C, Folium Agaves Sisalanae crystallite is obtained；

(4) Folium Agaves Sisalanae crystallite, 2.5ml KH550,30ml dehydrated alcohol and 2.5ml distilled water obtained in 0.5g steps (3) are taken together Being added in 50ml there-necked flasks, 3h being reacted under the conditions of 60 DEG C of water-bath, products therefrom filtering drying is subsequently dispersed N- first In base ketopyrrolidine, 0.5g 3 is added, 5- diaminobenzoic acids, 5ml pyridines and 0.2g triphenylphosphines, in 100 DEG C of water-bath Under the conditions of react 3h, gained reactant liquor is poured into after being cooled to room temperature in the LiCl methanol solutions that mass percent concentration is 0.1% and is sunk Form sediment, be separated by filtration, much filtrate N,N-dimethylacetamide and methanol are alternately rinsed 3 times, remove unreacted monomer and do not connect and prop up Polymer, last products therefrom vacuum drying at 90 DEG C, to constant weight, are obtained hyperbranched modified Folium Agaves Sisalanae crystallite；

(5) polycaprolactone diols that 2.0g weight average molecular weight is 1000 is put in round-bottomed flask, is heated under nitrogen atmosphere 80 DEG C and magnetic agitation are subsequently adding 20ml DMFs and 0.1 ml dibutyl tin laurates until melt, 105 DEG C of insulation 15min eliminating waters are heated the mixture to, then is cooled to 80 DEG C, add 0.67ml hexamethylene diisocyanates, in 3 ~ 5h is reacted at 80 DEG C, the mixed liquor containing isocyanate terminated base polyurethane prepolymer for use as is obtained；

(6) hyperbranched modified Folium Agaves Sisalanae crystallite and 4,4 '-'-biphenyl diphenols of 0.3g obtained in 0.015g steps (4) are added to into step (5) in the obtained mixed liquor containing isocyanate terminated base polyurethane prepolymer for use as, in blanket of nitrogen at 80 DEG C stirring reaction 12h, Then pour into together in mould preheated at 50 ~ 80 DEG C, be heating and curing at 70 ~ 90 DEG C 5 ~ 7h, that is, be obtained containing hyperbranched The shape memory polyurethane of modified Folium Agaves Sisalanae crystallite.