Effect Of Microwave-freezing Treatment On Structure And Properties Of Silk Knitted Fabrics

Silk knitwear is a high-end fabric that is favored by people.Not only has the advantages of soft luster,soft hand and excellent elasticity,but also has good skin-friendly properties.It is of great significance for both manufacturers and consumers to further improve its wearability.However,the commonly chemical modification or the combination of chemical and physical modification,due to the introduction of other chemical agents,have a negative impact on the fine properties of silk itself.In this paper,silk knitted fabric was treated by microwave,freezing or microwave combined with freezing without introducing chemical reagent,and the influences of processing technology on the structure and properties of knitted fabric were studied.It can be used as a reference to improve the wearability of silk knitted fabric.Therefore,the main research work was carried out as follow:(1)The silk knitted fabric was treated by microwave technology.Under constant power supply,the effects of microwave treatment time on the structure,thermal-moisture properties,mechanical properties and anti-pilling performance of silk knitted fabrics were studied on the basis of pre-experiment.The results within the range of experiment time show that microwave treatment has no obvious effect on the main chemical structures of silk knitted fabric.After microwave treatment,the amorphous region of silk fibers transformed to sub-crystallization,and the crystallinity increased slightly.Compared with the untreated fabric,the silk knitted fabric treated by microwave becomes fluffy and has more micropores in the cross-section of the silk fiber.With the increase of treatment time,the thermal resistance of the fabric increased,and the moisture regain,moisture permeability,bursting strength,anti-pilling performance of the fabric increased firstly and then decreased.After long time microwave treatment,the thermal,moisture and mechanical properties of silk knitted fabric decreased.It is concluded that microwave treatment at 700 watts for 10 minutes can optimize the wearability of silk knitted fabric.Theprocess is suitable for the treatment of knitted fabrics used in spring,autumn and winter seasons.(2)Silk knitted fabric was treated by freezing technology.On the basis of pre-test,the effects of freezing time on the structure,thermal-wet properties,mechanical properties and anti-pilling performance of knitted fabrics at constant temperature were studied.The results show that the freezing treatment has no obvious effect on the chemical structures of silk knitted fabrics.With the increase of freezing time,the crystallinity of silk knitted fabric increased firstly and then decreased.Compared with the untreated silk knitted fabric,the frozen treated silk knitted fabric becomes fluffy and obvious micro-pores appeared in the cross-section of the fibers,and the number of micro-pores increased with the increase of the treatment time.The moisture regain of silk knitted fabric increased with the increase of treatment time.The thermal resistance of silk knitted fabric decreases first and then decreases.The moisture permeability,air permeability,bursting strength and wear resistance of the fabric increased first and then decreased.It is concluded that the wearing performance of silk knitted fabric can be optimized by freezing treatment for 12 hours under the condition of-28 degrees.The technology is suitable for the treatment of summer fabrics.(3)The influences of combined treatment on the structure,thermal and mechanical properties of silk knitted fabric were studied by means of freezing-microwave treatment and microwave-freezing treatment.The results showed that the single property was improved,but the comprehensive properties were different,such as single microwave treatment or single freezing treatment,no matter whether they were treated by microwave first or by microwave first,or by microwave before freezing.Therefore,unless a single performance is required,such as good moisture permeability,2 hours of freezing and 5~15 minutes of microwave can be used;under normal conditions,joint application is not recommended.In general,the combination of microwave and freezing is not recommended.In conclusion,both microwave and freezing treatment make silk produce micro-pores structure.The proper treatment process can improve the heat-moisture comfort and mechanical properties of the silk knitted fabric,and improve the anti-pilling performance of the silk knitted fabric.