胶原/异丙醇共混溶液的稳态流变及其触变行为

采用流变仪考察了异丙醇对胶原溶液稳态剪切、屈服应力和触变性质的影响。实验表明,在低剪切速率下,异丙醇的浓度对体系的粘度影响较大,在高剪切速率下各体系粘度则对异丙醇浓度不敏感。幂律方程和Carreau方程能很好地拟合胶原/异丙醇共混溶液的流动曲线,通过粘度系数K、非牛顿指数n和零剪切粘度η0等准确地描述共混溶液的流变性质。通过屈服应力测试发现,异丙醇的加入降低了体系的屈服应力,改善了胶原的流动性质,但同时也使体系不稳定程度增加。另外含有1mol/L异丙醇的共混溶液触变面积小于纯胶原溶液,受剪切破坏的结构能较快速恢复,而含有2和3mol/L异丙醇浓度的共混溶液触变面积大于纯胶原溶液,受剪切而破坏的结构恢复慢,溶液不稳定性增加。     

天然胶原的稳态流变性能和数学模拟

用旋转流变仪研究胶原溶液的稳态流变性能,讨论了浓度和温度的变化对胶原溶液流动曲线的影响。实验数据显示胶原溶液的剪切粘度随着剪切速率的增大而降低,表明胶原溶液具有明显的假塑性。同一剪切速率下,温度升高,胶原溶液的剪切粘度降低;浓度增大,剪切粘度增大。用幂律方程、Carreau方程和Cross方程对胶原溶液的流动曲线进行数学拟合,结果表明幂律方程,Carreau方程和Cross方程都能准确地描述胶原的流动曲线,其中幂律方程的粘度指数K和非牛顿指数n的变化能准确反映胶原假塑性的变化;Carreau方程和Cross方程的参数比幂律方程多,其拟合得到的曲线和实验数据吻合得更好。但在本实验条件下,Carreau方程和Cross方程预测的零剪切粘度η0和无穷剪切粘度η∞不准确。     

聚丙烯腈/二甲基亚砜溶液的流变学性质

用HAAKE公司RSl50L型流变仪研究了PAN／DMSO溶液的流变学性质．讨论了温度、溶液浓度及PAN的分子量对流动曲线的影响。结果表明,在较低的剪切速率下,随温度的升高、浓度的降低及分子量的减小,流动曲线下移,并且开始向非牛顿区转变的临界切变速率增大．在较高剪切速率下,初始粘度低的溶液的粘度最高．在一定的浓度和剪切速率下溶液的粘度随温度的变化符合Arrhenius方程式．溶液在非牛顿区存在粘度突变现象．     

胶原溶液流变性能的研究

以纯化猪皮为原料提取胶原,配制不同浓度胶原溶液研究其流变性能,采用幂律方程拟合流动曲线,拟合程度非常高,以黏流活化能分析了黏度对温度的依赖性。讨论了胶原溶液浓度、剪切速率、温度对其黏度的影响。结果表明,该胶原溶液具有假塑性流体特征,浓度越高,非牛顿指数n越小,假塑性越强,黏度随剪切速率增大而下降的程度越明显。相同剪切速率下,温度升高,各浓度胶原溶液黏度下降。浓度越高,黏流活化能越大,对温度越敏感。     

丝素蛋白/聚乳酸共混溶液的流变性能

以六氟异丙醇(HFIP)为丝素/聚乳酸(SF/PLA)的溶剂,得到了不同质量比的SF/PLA共混溶液。采用锥板流变仪研究了共混溶液的流变性能,探讨了共混溶液的非牛顿指数、流动曲线及表观粘流活化能。研究结果表明,在本实验条件下,共混溶液为非牛顿流体;低剪切速率时,SF/PLA共混液是剪切增稠流体;高剪切速率时,SF/PLA共混溶液是剪切变稀流体,添加PLA组分使共混液的黏度下降;各种比例SF/PLA共混溶液的黏度受温度影响不大。     

全同聚1-丁烯/低密度聚乙烯共混体系的流变性能

采用双毛细管流变仪研究了全同聚1-丁烯/低密度聚乙烯(iPB/LDPE)共混体系的流变性能。结果表明,随着iPB用量的增加,共混熔体的剪切黏度呈先下降后上升的趋势;iPB/LDPE共混熔体在剪切速率为100 s-1~1000 s-1时,为假塑性流体,且随着iPB含量增加和温度升高,其非牛顿性增大;共混体系的表观黏度随剪切速率和剪切应力的增大、温度的升高而减小;粘流活化能随剪切速率的增大呈逐渐减小的趋势。     

聚乙烯醇缩丁醛/聚乙二醇体系的流变性能

采用美国TA公司的AR2000型应力控制流变仪研究了聚乙烯醇缩丁醛/聚乙二醇(PVB/PEG)体系的流变学性能,研究了温度、PVB质量分数与PEG分子量对PVB/PEG体系的流动曲线和非牛顿指数等流变特性的影响。结果表明PVB/PEG体系存在剪切变稀行为,为假塑性流体;温度升高,表观黏度减小,非牛顿指数增大;PVB质量分数增加,表观黏度增加,非牛顿指数减小;PEG分子量增加,表观黏度增加,非牛顿指数变化很小。在一定的浓度和剪切速率下体系的黏度随温度的变化符合Arrhenius方程式,粘流活化能随剪切速率的增加而减小。     

聚对苯二甲酸乙二醇酯-聚酰胺嵌段共聚物/聚酰胺6共混物的流变性能

通过熔融共混挤出的方法,制备了不同共聚比例的聚对苯二甲酸乙二醇酯-聚酰胺嵌段共聚物(PET-PA)与聚酰胺6(PA6)的共混物,采用毛细管流变仪对PET-PA/PA6共混物的流变性能进行了研究。结果表明,PET-PA/PA6共混物熔体为剪切变稀的非牛顿流体。随温度升高,PET-PA/PA6共混物熔体的表观黏度下降,非牛顿指数增大,表观黏度对剪切速率的敏感性减小,因此升高温度能改善共混物熔体的流动性能。随PET-PA中PA共聚比例的增加,PET-PA/PA6共混物的黏度减小,非牛顿指数增大,这为开发酸性染料可染聚酯纤维提供了参考。     

PA1010／CSM／EPR共混物的流变性能（Ⅰ）

用ＸＬＹ－Ⅱ毛细管流变仪研究了ＰＡ１０１０／ＣＳＭ／ＥＰＲ共混物的流变性能。结果表明，共混物的非牛顿指数ｎ＜１，且ｎ随ＥＰＲ用量的增加而减小，即非牛顿性增强；共混物熔体服从假塑性流体的流动规律，表观粘度随剪切速率和剪切应力的增大而降低；温度升高，表观粘度降低。     

壳聚糖/环糊精复合体系水溶液性质和流变行为

通过溶液共混法制备了壳聚糖/环糊精(CS/CD)复合溶液,并通过流变测试和透射电镜研究了其流变特性及相关影响因素.研究结果表明,CS溶液发生临界剪切变稀的临界剪切速率γc受到浓度影响,浓度越高,γc则越小.β-CD与CS通过氢键形成的CS/CD复合结构对强剪切十分敏感.相比纯CS溶液,CD浓度为0.5％的CS/CD复合...     

Morphology and antibacterial properties of plasticized chitosan/metallocene polyethylene blends

In this work, plasticized chitosan-based materials were produced through a molten process. A thermo-mechanical treatment was used to achieve chitosan plasticization in the presence of water, acetic acid, and glycerol. Water and glycerol acted as plasticizers, while acetic acid was used as a solvent and plasticizer for chitosan. The influence of acetic acid total content, chitosan/acetic acid solution ratio, and chitosan/glycerol ratio were examined in this study. The various plasticized compounds were blended with a metallocene polyethylene (mPE) and the morphology, rheological, and antibacterial properties of this novel blend system were examined. It was found that an increase in acetic acid content allowed better chitosan dissolution, while a higher glycerol concentration resulted in improved dispersion of the plasticized chitosan phase in the mPE. Following thermo-mechanical treatment, blends presented good antibacterial properties with a reduction of the number of bacteria (non-pathogenic Escherichia coli) by 2 log(CFU/mL) for the chitosan-containing systems with respect to neat mPE. Mechanical properties of the mPE/plasticized chitosan blends were improved by compatibilization with ethylene vinyl acetate, while antibacterial properties were not affected.     

PC/HBPS共混物的流变性能

通过熔融共混法制备了PC/HBPS共混物,研究了其流变特性。结果表明,此共混物属于假塑性流体,随着HBPS含量的增加,非牛顿指数增加;随着剪切速率的增加,表观黏度下降,但下降趋势较缓慢;随着温度的增加,表观黏度下降,但下降趋势很快;共混物的粘流活化能都比纯PC的粘流活化能高;随着HBPS含量的增加,表观黏度下降。     

Physical properties of edible films based on cassava starch as affected by the plasticizer concentration

The aim of this work was to investigate the effect of glycerol contents on physical properties of cassava starch films. The films were prepared from film‐forming solutions (FFS) with 2g cassava starch/100g water and 0, 15, 30 and 45g glycerol/100g starch, and were analysed to determine its mechanical properties by tensile tests, the glass‐transition temperature (Tg) by differential scanning calorimetry (DSC) and the crystallinity by X‐ray diffraction (XRD). The infrared spectra of the films were also recorded. The resistance values of the films decreased, while those of the elasticity increased with an increase in glycerol concentration due to the plasticizer effect of glycerol, which was also observed in DSC curves. The Tg of the films prepared decreased with the glycerol content. However, for samples with 30 and 45g glycerol/100g starch, two Tg curves were observed, probably due to a phase separation phenomenon. According to the XRD diffractograms, the films with 0 and 15gglycerol/100g starch presented an amorphous character, but some tendency to show crystalline peaks were observed for films with 30 and 45g glycerol/100g starch. The results obtained with Fourier transform infrared (FTIR) corroborated these observations. Copyright © 2007 John Wiley & Sons, Ltd.     

THERMAL TRANSITIONS AND MORPHOLOGICAL BEHAVIOR OF POLYETHER ETHER KETONE AND LIQUID CRYSTALLINE POLYMER BLENDS

Polyether ether ketone (PEEK) and thermotropic liquid crystalline polymer (TLCP) based on hydroxy benzoic acid and hydroxy naphthoic acid (HBA/HNA) were prepared on a single-screw extruder with rotor speed 45 rpm at 350°C. Thermal analysis data, especially the glass transition temperature (T_g), indicated that the blends were incompatible in the entire range of concentration. Melting temperature (T_m) of the blends was found to be close to melting temperature of pure PEEK. Thermogravimetric analysis data show the poor thermal stability of the blends compared to the parent material. The percent weight loss increased with increasing LCP concentration. Analysis with a scanning electron microscope clearly indicated that a distinctive fibrous morphology was developed in the extruded samples at the low concentration of LCP, but the adhesion of the fiber to the PEEK matrix was poor, with circular voids around the LCP phase at higher concentration.     

利用粘度法和二维红外相关光谱法研究胶原/羟丙甲基纤维素共混物的相互作用

采用粘度法和二维红外相关光谱法对胶原/羟丙甲基纤维素共混体系的相容性及相互作用进行了研究。粘度法测定结果表明,羟丙甲基纤维素含量<30%时共混体系相容,超过50%则不相容。二维红外相关光谱法的分析结果表明,当羟丙甲基纤维素含量<30%时,归属于羟丙甲基纤维素的C—O(H)伸缩振动峰1061cm-1与归属于胶原酰胺带的CO对称伸缩振动峰1660cm-1、N—H摇摆振动峰1553cm-1和N—H面内变形振动峰1238cm-1之间存在同步负交叉峰,表明胶原和羟丙甲基纤维素之间存在氢键作用;而当羟丙甲基纤维素含量>30%时,同步图中负交叉峰强度减小的同时同步峰1061cm-1的强度明显变大,表明此时羟丙甲基纤维素与胶原之间的氢键作用变弱,羟丙甲基纤维素更倾向于在自身分子之间形成氢键。     

动态硫化 EPDM／PP 共混物的动态力学性能

探讨了硫化剂用量、橡塑比对ＥＰＤＭ／ＰＰ共混物动态力学性能的影响。实验表明,在相同温度下,随着硫化剂用量增加,共混物的动态模量及ＥＰＤＭ的玻璃化温度（Ｔｇ）升高;随着树脂含量的增加,共混物的动态模量增大,ＥＰＤＭ的玻璃化温度降低。     

环氧树脂改性双环戊二烯型氰酸酯树脂固化反应性

采用凝胶试验、 FTIR和DSC等手段研究了环氧E-51与双环戊二烯型氰酸酯(DCPDCE)共聚体系的固化反应性以及阶梯固化过程中—OCN基、 三嗪环、 唑啉、 噁唑啉酮的变化情况。结果表明, 环氧树脂既能够催化氰酸酯本身三聚成环反应, 又对氰酸酯三聚成环反应有稀释作用。当环氧树脂含量(环氧占混合物总量的质量百分比)大于5wt％时, 催化效果增加不明显, 稀释作用加强; 当环氧树脂含量约为25wt%时, 以上两种作用效果基本平衡, 改性体系的固化反应活性和纯DCPDCE相当。阶梯固化时, 低温阶段(160~180℃)主要发生生成三嗪环和唑啉的反应, 高温阶段(200~220℃)主要发生三嗪环和唑啉向噁唑啉酮的转化反应。另外, —OCN基的低温转化率随着环氧树脂含量的增大而提高, 固化树脂的最终结构组成和环氧树脂的含量有关。      

High molecular weight plasticizers in thermoplastic starch/polyethylene blends

In this study thermoplastic starch (TPS) was prepared with four different molecular weight polyol plasticizers: glycerol, sorbitol, diglycerol and polyglycerol. Diglycerol-TPS (DTPS) and polyglycerol-TPS (PTPS) show significantly lower moisture uptake and a higher temperature stability when compared to conventional glycerol-TPS (GTPS). TPS formulations were blended with HDPE at a concentration of 20 TPS/80 HDPE wt% and a range of interfacial modifier contents via a one-step extrusion process. The emulsification curves of the blends, which track the volume and number average diameter of the dispersed TPS domains with per cent interfacial modifier, show significantly different profiles and a non-correspondence between the d _n and d _v values at the critical concentration for interfacial saturation. The addition of small amounts of interfacial modifier to the blends prepared with diglycerol and polyglycerol results in TPS dispersed phases of wide polydispersity with droplets in the order of 200–300 nm coexisting with droplets of 5–7 µm. This wide polydispersity of TPS phase size can give insight into the mechanism of droplet formation in these systems with interfacial modifier and is indicative of an erosion-type mechanism, where small portions of the TPS droplet break off at the outer part of the droplet. Blends prepared with GTPS and sorbitol-TPS do not display this behaviour and show a more classic correspondence of d _n and d _v at the critical concentration. Dynamic mechanical analysis shows miscible behaviour for DTPS and PTPS and partially miscible behaviour for GTPS. This phenomenon was attributed to the presence of ether bonds in the chemical structure of diglycerol and polyglycerol. The increased chain flexibility and lower cohesive energy forces of diglycerol and polyglycerol lead to a more homogeneous TPS phase and consequently an erosion-type compatibilization at the interface. The mechanical properties of blends prepared with polyglycerol and diglycerol show a similar overall behaviour to glycerol.     

HTPB/增塑剂共混物的介观动力学模拟

高分子粘接剂与小分子增塑剂癸二酸二辛酯(DOS)的相分离会严重影响端羟基聚丁二烯(HTPB)固体推进剂的使用性能.文中应用分子动力学(MD)和介现动力学(MesoDyn)模拟方法研究了不同增塑剂含量和温度对HTPB/DOS共混物的相容性和介现形貌的影响.结果表明,在室温时当增塑剂DOS的含量为6%时,HIPB和DOS的...     

土豆塑料的制备与研究

本课题通过采用甘油和柠檬酸三乙酯复合增塑剂对土豆淀粉进行了塑化,并制备了添加了增强剂Joncryl的聚乳酸和土豆淀粉的共混物。结果表明,增强剂能很好的提高土豆淀粉和聚乳酸的相容性。聚乳酸含量的增加以及添加增强剂能够有效地提高产品的力学性能和耐水性能。