| With the development of synthetic latex,the requirements of the national sustainable development strategy and the improvement of people’s environmental protection concept,the market demand for latex products has been greatly improved,especially the outbreak of the new crown epidemic,which has led to a sharp increase in the consumption of disposable latex examination gloves.The price of carboxylated nitrile latex（XNBRL）as a raw material has also risen accordingly,and the consumption of a large number of latex rubber products has put forward requirements for post-processing,environmental protection and degradability of waste products.Carboxylated nitrile latex（XNBRL）is widely used in medical,chemical,meteorological observation and daily life due to its excellent properties such as oil resistance,solvent resistance and no protein allergic reaction.However,carboxylated nitrile rubber is a non-self-reinforcing polar rubber.Compared with natural rubber latex（NRL）,XNBRL has low wet gel strength,poor mechanical stability,and low mechanical properties of the film.Softness and wearing comfort need to be improved.Carrying out functional research on latex and related products and taking into account environmental protection performance will help improve the performance of latex products and reduce costs.It is of great significance to further expand the application scope of the latex industry and create a good environment in line with the concept of green and sustainable development.In this paper,the effect of corn starch on the properties of XNBRL film was firstly studied.Two kinds of physical miniaturization methods were used to prepare starch dispersions.Through the analysis of the test results,it was confirmed that the starch dispersions in the subsequent experiments all adopted the gelatinization method with better stability of the dispersions,small particle size and concentrated distribution of starch particles.The preparation method was carried out,and the effect of different gelatinization conditions on the particle size of starch dispersion was continued to be studied,so as to determine the best preparation condition of the dispersion:gelatinize 4%starch/water mixture at 90°C for 45min,After cooling to room temperature,ultrasonic treatment was performed for 25 min.Afterwards,the starch dispersion was added to XNBRL to investigate the effect of the number of starch parts on the properties of the film.The results showed that the effect was the best when the amount of starch added was 5 parts.Then,the amount of starch was fixed at 10 parts,and different parts of polyethylene glycol（PEG）were added as a modifier when preparing the starch dispersion.It was found that adding PEG can improve the dispersion uniformity of starch particles in the film,and improve the strength of the film,an appropriate amount of PEG can reduce the water absorption of the film,and an excessive amount will cause a sharp increase in water absorption.The optimal amount of PEG is 2 parts.At the same time,the effect of starch on the degradation performance and solvent resistance of the composite film was studied.The results showed that the addition of starch can give the film a certain strength,and with the increase of the starch content in the film,its thermal oxygen,natural and buried organisms degradation performance was gradually improved,and the addition of appropriate amount of starch also significantly reduced the water absorption of the film,and the solvent resistance of the film was improved.Based on the reinforcement of XNBRL by starch and polyethylene glycol,the effect of properly adjusting the vulcanization system ratio of sulfur（S）/zinc oxide（Zn O）/accelerator diethylzinc dithiocarbamate（EZ）and accelerator dibutylzinc dithiocarbamate（BZ）on the properties and crosslinking degree of carboxylated nitrile latex film was studied.The results show that when the ratio of S:accelerator:Zn O vulcanization system is 1:0.66:2,the comprehensive performance of the film is the best.Increasing the amount of sulfur vulcanization system is beneficial to the thermal degradation performance of the film,while increasing the amount of zinc oxide is beneficial to the natural degradation performance of the film.The reinforcement effect of acrylamide grafted modified starch on XNBRL film was further studied.Potassium persulfate（KPS）is used as the initiator of the reaction to carry out graft copolymerization of acrylamide（AM）monomer on the starch（St）molecular chain,and the initial product is purified to obtain the graft copolymer（St-PAM）The total reflection infrared spectrum（ATR）of the graft copolymer at 1641cm-1（the characteristic absorption peak of starch）1664,1610 and 1427cm-1（the characteristic absorption peak of polyacrylamide）indicated that the amide groups were introduced into the starch chain.The gelatinization properties of grafted starch are significantly improved,the temperature required for gelatinization is lowered,the retrogradation of amylose is weakened,and the cold water solubility and dispersibility of starch are improved.The modified starch was added to XNBRL to prepare the composite material film.The research results showed that the reinforcement of starch after acrylamide graft modification was significantly improved,and the comprehensive performance of the film was the best when the amount of St-PAM was 4 phr.Finally,the effects of microcrystalline cellulose（MCC）and hydroxypropyl methylcellulose（HPMC）on the properties of XNBRL composite film were studied.First,by comparing the dissolution system and method of microcrystalline cellulose,it is determined to use alkali/urea（Urea）/thiourea to freeze at-10°C for 20 hours,then thaw at room temperature,and dilute and stir with deionized water dropwise in an ice-salt bath.Different parts of MCC dispersions were added to XNBRL to prepare composite films and perform performance tests.The research results showed that the effect was the best when the amount of MCC was 0.5 parts,and the films were uniform and transparent,with thinner thickness and higher strength.The addition of MCC can also improve the degradation and solvent resistance of the film.The experiment determined that the preparation method of HPMC dispersion was to stir rapidly in a70°C water bath for 30 minutes,then cool to room temperature and then slowly stir for10 hours,and finally a transparent hydroxypropyl methylcellulose dispersion was prepared.The HPMC dispersion was studied separately.The effects of the concentration and dosage of HPMC dispersion on the properties of XNBRL composite film were studied respectively.The research results show that the overall performance of the HPMC/XNBRL composite film is better when the dispersion concentration is 2%and the amount of HPMC is 1 part.The addition of HPMC will improve the thermal oxygen degradation and natural degradation properties of the composite film,and with the increase of HPMC addition amount and degradation time,the degradation performance of the film is more obvious,but the addition of HPMC will reduce the water absorption and solvent resistance of the composite adhesive film. |
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