| The problem of"white pollution"has become increasingly serious recent years,and countries have introduced relevant policies to limit the use of disposable non degradable plastic products.The emergence of biodegradable polymer materials has become an effective solution to solve the environmental pollution caused by plastic wastes.As a member of biodegradable polymer materials,poly(terephthalic acid adipate/butylene glycol ester)(PBAT)is a copolymer composed of aliphatic BA segments and aromatic BT segments,so it has good mechanical properties,processing properties and degradability,becoming a strong competitor to replace traditional plastics.However,there are few comprehensive and in-depth studies on the structure and properties of PBAT,and the application of PBAT in biodegradable fibers needs to be improved.In this paper,the structure and properties of three brands of PBAT were analyzed and characterized.PBAT fibers were successfully prepared by melt spinning.The effects of process conditions on fiber properties were investigated.The degradation behavior of PBAT fibers and films was studied by using three degradation methods,and PBAT was reinforced with cellulose nanofibers(CNF).The main contents of the paper are as follows:1.The sequence structures of three kinds of PBAT were studied by ~1H NMR and IR,and the thermal properties,molecular weight and molecular weight distribution of PBAT were characterized.It was found that the three grades of PBAT were random copolymers,and the content of aliphatic group in PBAT was higher than that of aromatic group.The thermal stability of the three PBATs was good,and the glass transition temperature increased slightly with the increase of aromatic content.2.PBAT fiber was successfully prepared by melt spinning.It was found that PBAT still had good spinnability at the spinning speed of 2500 m/min.When the ratio of aliphatic aromatic content is close to 1:1,the breaking strength of the obtained PBAT fiber can reach 2.32 c N/dtex after drawing,but the elastic recovery rate of PBAT fiber is low,and the elastic recovery rate is only 44.81%when the elongation is 80%at a time.The effects of drafting ratio and temperature on fiber properties were investigated.It was found that the breaking strength,initial modulus,sound velocity orientation and crystallinity of the fiber increased with the increase of drafting ratio,while the breaking elongation and elastic recovery decreased.It was also found that when the drafting temperature was 40℃-50℃,the sound velocity orientation of the drawn wire reached the maximum value,and gradually decreased with the increase of the drafting temperature.3.The degradability of PBAT was preliminarily explored.In this paper,three degradation methods,including buried soil method,aqueous culture solution degradation method and enzymatic solution degradation method,were used to explore their degradability.The study found that the three PBATs can be degraded successfully,and the high concentration enzymatic solution has the fastest degradation rate compared with the soil burial method and the aqueous culture solution at the appropriate temperature.Because the surface area of PBAT fiber is much higher than that of PBAT film,the enzymatic degradation rate of fiber is much faster than that of PBAT film,and its degradation rate in the enzymatic solution can reach 10%in 30 days.4.To solve the problem of insufficient strength of PBAT,CNF were selected to strengthen and modify PBAT.Within the experimental range,the mechanical strength of the composite reaches the maximum when the CNF content is 7%.CNF dispersed in PBAT matrix has the function of nucleating agent,which can improve the crystallinity of the composite,but CNF has no obvious effect on the thermal stability of the composite.It was found that the degradation performance of CNF/PBAT composites was much higher than that of pure PBAT by enzymatic degradation method,and the degradation rate reached 10%in only 20 days,and the degradation rate gradually accelerated with the increase of CNF content. |
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