| Cellulose acetate is kind of rich and continuable material from nature. Comparing to thecellulose, cellulose acetate takes on a certain properties of thermal plastic because of acetyl.However, the hydrogen bonds between macromolecular chain formed by hydroxyl in celluloseacetate, which make the gap between hot process temperature and decomposition temperature soclose that the hot processing is hard. The plasticizing modification of cellulose acetate can expandthe gap of hot process and realize the melt process, which is got great economic and socialbenefits.We chose cellulose diacetate (CDA)/[BMIM]BF4system as the research object, studied thethermal properties of cellulose diacetate/ionic liquid system, and researched the influence ofadding heat stabilizer for performance of plasticizing system. The rheological properties ofcellulose diacetate/[BMIM]BF4were studied at the same time. According to the guidance ofrheological properties, we successfully prepared of diacetate fiber, and studied the properties ofthe fiber. The details of the research are as follows:1. We chose the1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) as theplasticizer and studied the influence of the thermal performance for plasticizing system to changethe content of [BMIM]BF4. According to the result,[BMIM]BF4was a good kind of plasticizerfor CDA. With the content of [BMIM]BF4increasing to35wt%， the Tg of plasticizing systemdecreased from225oC to95oC. However, the thermal stability and crystallization of theplasticizing system declined in a certain extent. Meanwhile,[BMIM]BF4and CDA formed a newkind of micro phase structure. At the same time, two kinds of stabilizers (the phosphate ester andphenolic antioxidants) were studied the influence of thermal performance of25wt%[BMIM]BF4/CDA. The study found that0.5wt%phenols1010mixed0.5wt%triphenylphosphite stabilizer had better effect to improve the thermal performance of CDA than singlestabilizer.2. The rheological properties of [BMIM]BF4/CDA were investigated by rotary rheometer andthe zero shear viscosity was predicted by the three-parameter Carreau viscosity model from theapparent viscosity data. The [BMIM]BF4/CDA melt showed shear-thinning behaviors, the zero shear viscosity and the non-newtonian index decreased with increase of temperature. According tothe result of the viscous flow activation energy, the melt with higher CDA concentration andhigher shear rate were found to be sensitive to the temperature, the viscous flow activation energyrespectively decreased with the increase of shear rate and the content of [BMIM]BF4. However,the structural viscosity index of the melt decreased with the increase of the [BMIM]BF4contentand went up after a decline with the temperature increase, the temperature in190oCcorresponding the least structural viscosity index42.7was regarded as the appropriate meltspinning temperature. According to the dynamic rheological performance results, the[BMIM]BF4/CDA plasticizing system had taken on a certain degree of degradation under theaction of shear force, adding stabilizer could inhibit the degradation of CDA.3. We investigated the effect of0.5wt%TPPI and0.5wt%antioxidant1010as additive on25wt%[BMIM]BF4/CDA as plasticizing system and found that the higher the blendingtemperature was, the more easiness to blend [BMIM]BF4and CDA. Meanwhile, the hightemperature would promote the thermal degeneration. We acquired diacetate fiber by the meltspinning method. According to the result, the cross section of fiber took on fracture crack andcompact internal structure. With the increase of the draw ratio from0to4, the fracture strength offiber increased from1.064cN/dtex to1.613cN/dtex, the elongation at break decresased from11.2%to4.8%, and the crystallinity increased from31.23%to37.65%. |
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