| Melt-blown nonwoven technology,one of the fastest growing technologies for manufacturing microfiber materials in recent years,is a moulding process that combines short process times,simple operation,high production efficiency and environmental friendliness.The melt-blown nonwoven technology produces microfiber materials with a fluffy structure and soft texture,which can be widely used in the fields of health care,filtration and separation and personal protection.At a time when petroleum resources are scarce,white pollution is prevalent and carbon neutral initiatives are being implemented,the replacement of petroleum-based polymers is an inevitable trend.Currently,microfiber nonwoven materials made from bio-based polymers are gradually taking over the market and being used in various applications due to their environmental and renewable advantages,while polylactic acid(PLA)is not only biodegradable,but also biocompatible and non-irritating to the skin,which has been widely studied and paid attention to.However,the current microfiber materials made from PLA are generally poor in toughness and weak in hydrophilicity,which limits the development and industrial application of PLA microfiber materials.Based on this,this paper investigates the wettability control process of PLA/PEG@SDS blended polymers based on the analysis of the properties of PLA/PEG@SDS blended polymers with Polyethylene glycol(PEG)as the plasticizer and Sodium dodecyl sulfate(SDS)as the hydrophilic agent.The analysis focused on the influence of melt-blown process parameters on the macroscopic as well as microscopic characteristics,crystalline properties,mechanical properties,comfort properties and liquid conductivity of PLA/PEG@SDS microfiber materials.Meanwhile,PLA/PEG@SDS-CE fiber materials with a double-layer wetting gradient structure and PLA/PEG@SDS composites with a multi-stage step structure were prepared by thermal compounding.New research ideas are provided for the development and preparation of medical and hygienic fiber materials such as dressings and bandages.(1)Experimental analysis of the properties of PLA/PEG@SDS blended polymers was carried out and the DSC results showed that the temperature rise curves of PLA/PEG@SDS blended polymers showed three heat absorption peaks around 55,145 and 155°C and one exothermic peak around 105°C,respectively.With the addition of SDS,the secondary ramp-up curves of the PLA/PEG@SDS blended polymer were shifted forward,with the cold crystallization temperature falling from 116.5°C to 93.6°C(a reduction of approximately24.4%)and the melt temperature falling from 164.1°C to 150.6°C(a reduction of approximately 8.9%).The results of rheological tests and melt flow rate tests show that SDS can reduce the complex viscosity of PLA(by approx.286.48%).(2)PLA/PEG@SDS microfiber materials were prepared by melt-blown non-woven technology and the effect of the melt-blown process(SDS ratio,die head temperature and air pressure)on the structure and wettability of the material was analysed.As the SDS ratio increased from 0%to 1.2%,the number of ultra-fine fibres(d_f<5μm)in the PLA/PEG@SDS microfiber increased by 57%;the dynamic contact angle decreased gradually,and the liquid absorption and retention rates increased from 235.2%and 200.6%to 429.9%and 359.4%,respectively;the longitudinal and transverse tensile breaking strengths and the top breaking strength increased from 10.8 N and 5.4 N and 5.4%,respectively.With the increase in die head temperature from 210°C to 225°C,the percentage of superfine fibers was nearly 100%,and the liquid absorption and retention rates increased from 243%and 198%to 310%and 267%,respectively;the longitudinal and transverse tensile breaking strengths and top breaking strengths increased from 7.6 N,7.5 N and 18.2 N,respectively.With the increase in wind pressure from 36 k Pa to 45 k Pa and the decrease in pore size distribution from about 77μm to about 50μm,the liquid absorption and retention rates increased from 229.4%and 201.3%to 291.7%and 274.4%,respectively;the longitudinal and transverse tensile breaking strength and top breaking strength increased from10.1 N,5.8 N and 6.5%,respectively,The longitudinal and transverse tensile strength and top breaking strength increased from 10.1 N,5.8 N and 6.5 N to 21.1 N,9.5 N and 23.4 N respectively.(3)The PLA/PEG@SDS-CE fiber material was prepared by a thermal lamination process using PLA/PEG@SDS microfiber material and viscose spunlace nonwoven material as substrates.Based on the different wetting properties of the two substrates the samples form a wetting gradient effect in the vertical direction.When the PLA/PEG@SDS microfiber material has a surface density of 70 g/m~2 and the treated pattern is diamond-shaped,the samples achieve maximum longitudinal and transverse tensile breaking strengths and top breaking strengths of 165.4 N,45.8 N and 128.8 N respectively,a permeability of 67.3 mm/s,a soft score of 78.5,a liquid absorption and retention rate of 335%and 257%respectively,and The best liquid asymmetric transfer characteristics at this time,with a liquid unidirectional moisture transfer index of 425.1.(4)Three layers of PLA/PEG@SDS microfiber materials with different pore sizes or wettability were thermally compounded to prepare multi-step PLA/PEG@SDS composites based on the differential capillary effect or the wettability gradient effect.When the sum of the wind pressure or SDS ratio of the three layers of the sample was the largest,its longitudinal and transverse tensile breaking strengths were the largest,35.92 N,54.09 N and35.38 N,67.37 N respectively.When the difference between the wind pressure or SDS ratio of the two sides was larger,the asymmetric liquid transfer performance of the sample was better,at which time the liquid unidirectional moisture transfer index was 500.9 and 191.1respectively;if the wind pressure or If the wind pressure or SDS ratio on both sides is the same,the greater the wind pressure or SDS ratio in the middle layer,the better the liquid asymmetric transport performance of the sample,and the highest liquid unidirectional moisture transfer index is 533.2 and 230.5 respectively.In this paper,based on the preparation of tough and hydrophilic enhanced PLA/PEG@SDS microfiber materials,composites with a two-layer wetting gradient structure and a multi-stage step structure were prepared by thermal lamination methods.It provides a new idea for the development of fiber materials for medical and health care,and also provides useful exploration and practice for the industrial application of bio-based microfiber nonwovens. |
PDF Full Text Request