复合增塑剂种类对玉米淀粉塑化性能的影响

采用甘油、甲酰胺和尿素按不同比例混合,作为复合增塑剂对玉米淀粉进行塑化处理,通过单螺杆挤出机挤出制备热塑性淀粉(TPS),研究了复合增塑剂种类对淀粉塑化性能的影响。利用DSC和SEM对塑化效果进行了表征,并对TPS的热稳定性、机械性能和吸水率进行了测试。结果表明,复合增塑剂采用甘油/甲酰胺/尿素三者混合时,对淀粉的塑化效果最好,制备的TPS热稳定性和机械性能都较好,吸水率较低。     

淀粉粒度效应对热塑性微细化淀粉熔体流变学行为影响

应用丙三醇/聚乙烯醇复合增塑剂分别塑化不同粒度微细化淀粉,对热塑化过程以及塑化产物的流变行为进行分析测定,结果表明,随着微细化淀粉的粒度降低,比表面积增加,与复合增塑剂反应接触位点增多,复合增塑剂与淀粉间的相互渗透作用增强,塑化效果得到改善,塑化产物熔体的流动性提高,因此适当降低淀粉粒度可以提高塑化效果,改善热塑性淀粉的机械加工性能.     

增容剂对热塑性淀粉/聚丙烯复合材料的力学及流变加工性能的影响

先通过甘油对淀粉进行塑化制备热塑性淀粉(TPS),然后以马来酸酐接枝聚丙烯(MA-g-PP)作为增容剂将聚丙烯(PP)与TPS共混,制成TPS/PP复合材料。通过电子拉力机、热重法、转矩流变仪、挤出毛细管流变仪以及熔融指数仪,研究了不同含量的MAg-PP对TPS/PP性能的影响。结果表明,MA-g-PP的添加可有效提高材料的力学和加工性能,综合生产成本和增容效果考虑,当MA-g-PP的添加量为PP/TPS总量的4%(质量分数)时,材料具有较高的力学性能和较佳的加工性能。     

增容剂对PP/TPS共混材料性能的影响

以甘油为塑化剂,制备了热塑性淀粉(TPS);利用自制的甘油基阴离子表面活性剂:(2-十六烷基羧酸酯)丙二羧酸钠(C)为增容剂,制备了PP/TPS/C共混材料,并对其力学性能、熔点、结晶温度、热稳定性、流变性能等进行了分析。结果表明,在100份的PP/TPS(70∶30)共混材料中加入2份C时,其力学性能和流变性能最好。拉伸强度由21.3MPa降至17.8MPa,断裂伸长率由9.3%升高至19.7%,提高了115%;流动性变好,表观粘度明显降低。由于增容剂是甘油基阴离子表面活性剂,其与增塑剂甘油、淀粉以及PP都能产生一定的相互作用,从而影响了共混材料的性能。     

聚乙烯抗菌片材的制备及其迁移性能研究

目的 研制可降解新型复合材料,以缓解传统石油基材料带来的环境污染。方法 以高密度聚乙烯(HDPE)为基材,热塑性淀粉(TPS)为改性剂和添加剂,采用熔融共混法制备TPS质量分数为0,10%,20%,30%和40%的复合片材。结果 通过分析比较TPS含量对TPS/HDPE片材物理性能的影响发现,TPS的加入降低了材料的韧性和塑性,增加了材料的刚性;当TPS质量分数达到40%时,与HDPE相比,拉伸强度下降了52.3%,断裂伸长率减少了90%以上,弯曲强度和弯曲模量分别提高了100.2%和70.5%。红外光谱分析显示在1200 cm^?1处出现了新峰。DSC分析表明材料的熔融温度由136.1 ℃降低为132.7 ℃。当TPS质量分数为40%时,复合材料的疏水性最好。结论 加入一定量的TPS可以改善HDPE的刚性和疏水性,为制备高性能淀粉基食品接触材料提供了一定的理论依据。     

甘油增塑热塑性淀粉的流变相变性质

流变性质和相变性质是指导热塑性淀粉(TPS)生产加工的重要参数。文中利用转矩流变仪(密炼机)和差示扫描量热法(DSC)研究甘油增塑淀粉时TPS流变相变性质的变化。结果表明,甘油增塑时,对淀粉流变性能的影响与水不同;由于转子扭矩的变化主要由TPS相变产生,而甘油的润滑效应不利于淀粉塑化,因此TPS的塑化程度随着甘油含量的增多先减小后增大;升高转子转速会加大剪切力,加剧相变;同样初始温度越高,相变越容易发生,且温度对相变程度的影响显著于转速。     

聚己内酯改性聚乳酸/淀粉共混材料的性能研究

将热塑性淀粉(TPS)与聚己内酯(PCI)、聚乳酸(PLA)共混后,采用溶剂挥发法制备出完全生物降解的聚己内酯改性聚乳酸/淀粉共混材料.测试了材料的力学性能、共混形态、疏水性能和降解性能等.结果表明:甘油和水能够很好增塑淀粉,当淀粉:甘油:水为4:1.2:10时,拉伸强度最高达44.84MPa,断裂伸长率达93%,共混材料具有较好的力学性能;FT-IR和SEM显示聚己内酯的加入提高了共混材料的相客性;随着淀粉含量的增加,吸水率增大;土埋70天后,共混材料最高降解率达42.41%.     

基于双转子连续混炼挤出机的聚乳酸/淀粉共混物的制备及性能

以淀粉和聚乳酸(PLA)为原料、甘油为增塑剂,采用双转子连续混炼挤出机通过熔融共混法制备了PLA/淀粉共混物,研究不同转子转速和甘油含量下,共混物的微观结构、流变性能、结晶性能和力学性能,得到剪切作用及增塑剂含量对共混物两相相容性的影响。对共混物的扫描电镜照片、红外光谱图以及动态频率扫描曲线进行分析。结果表明,适当提高转子转速及甘油含量有利于提高淀粉的塑化程度,改善淀粉与PLA之间的相容性。差示扫描量热分析曲线表明,共混物的结晶度随着甘油含量的提高而降低。当甘油质量分数为20%、转速为300 r/min时,淀粉分散相与PLA基体的相容性最好,共混物具有良好的力学性能,拉伸强度达到25.1 MPa、弯曲强度达到33.1 MPa。     

拉伸挤出加工聚对苯二甲酸-己二酸-丁二醇酯/热塑性淀粉共混物的结构与性能

采用偏心转子挤出机制备了聚对苯二甲酸-己二酸-丁二醇酯(PBAT)/热塑性淀粉(TPS)共混物。通过与双螺杆挤出方式进行对比,研究了拉伸挤出对PBAT/TPS共混物形态结构、结晶结构、流变特性和力学性能的影响。结果表明,拉伸挤出加工促进了淀粉的塑化及在PBAT基体中的分散,强化了PBAT与TPS之间的界面相互作用。与双螺杆挤出共混物相比,拉伸挤出加工PBAT/TPS共混物的拉伸强度、断裂伸长率和冲击强度分别提高了19%,9%和28%。当TPS含量为40%时,拉伸挤出共混物拉伸强度仅比PBAT降低了29%,但其断裂伸长率与PBAT相当,冲击强度比PBAT提高了75%。偏心转子挤出机为制造低成本、高性能生物降解高分子材料提供了有效工具。     

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。     

Processing and thermal,mechanical and morphological characterization of post-consumer polyolefins/thermoplastic starch blends

Mixtures of high density polyethylene (HDPE) and polypropylene (PP), both post-consumer polymers were blended with thermoplastic starch (TPS). Corn starch plastification was carried out by extrusion with glycerin addition. The behaviour of TPS produced was investigated in the processing and thermal, mechanical and morphology characterization of post-consumer HDPE/PP blends (100/0, 75/25, and 0/100 wt.%) in different proportions of TPS (30%, 40% and 50% wt.%) by melting flow index (MFI), tensile property measurements, and scanning electron microscopy (SEM), respectively. The addition of TPS reduced the MFI of PP and increased of HDPE and HDPE/PP blends. TPS also decreased the tensile strength and elongation at break, and increased the rigidity of the materials. SEM showed separation of phase between the poliolefins and TPS.     

Effects of glycerol and sorbitol on optical,mechanical, and gas barrier properties of potato peel‐based films

Potato peel is a by‐product of potato‐based food production and seen as a zero‐ or negative‐value waste of which millions of tons are produced every year. Previous studies showed that potato peel is a potential material for film development when plasticized with 10% to 50% glycerol (w/w potato peel). To further investigate potato peel as a film‐forming material, potato peel‐based films containing the plasticizer sorbitol were prepared and investigated on their physicochemical properties in addition to films containing glycerol. Due to sufficient producibility and handling of casted films in preliminary trials, potato peel‐based films containing 50%, 60%, or 70% glycerol (w/w potato peel) and films containing 90%, 100%, or 110% sorbitol (w/w potato peel) were prepared in this study. Generally, with increasing plasticizer concentration, water vapor and oxygen permeability of the films increased. Films containing glycerol showed higher water vapor and oxygen permeabilities than films containing sorbitol. Young's modulus, tensile strength, and elongation at break decreased with increasing sorbitol concentration, whereas no significant effect of plasticizer content on elongation at break was shown in films containing glycerol. Due to crystallization of films containing sorbitol as a plasticizer, potato peel‐based films containing 50% glycerol (w/w) were identified as the most promising films, characterized by a water vapor transmission rate of 268 g 100 μm m^?2 d^?1 and an oxygen permeability of 4 cm³ 100 μm m^?2 d^?1 bar^?1. Therefore, potato peel‐based cast films in this study showed comparable tensile properties with those of potato starch‐based films, comparable water vapor barrier with those of whey protein‐based films, and comparable oxygen barrier with those of polyamide films.     

Environmentally friendly polymer hybrids Part I Mechanical, thermal, and barrier properties of thermoplastic starch/clay nanocomposites

As an attempt to develop environmentally friendly polymer hybrids, biodegradable thermoplastic starch (TPS)/clay nanocomposites were prepared through melt intercalation method. Natural montrorillonite (Na⁺ MMT; Cloisite Na⁺) and one organically modified MMT with methyl tallow bis-2-hydroxyethyl ammonium cations located in the silicate gallery (Cloisite 30B) were chosen in the nanocomposite preparation. TPS was prepared from natural potato starch by gelatinizing and plasticizing it with water and glycerol. The dispersion of the silicate layers in the TPS hybrids was characterized by using wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). It was observed that the TPS/Cloisite Na⁺ nanocomposites showed higher tensile strength and thermal stability, better barrier properties to water vapor than the TPS/Cloisite 30B nanocomposites as well as the pristine TPS, due to the formation of the intercalated nanostructure. The effect of clay contents on the tensile, dynamic mechanical, and thermal properties as well as the barrier properties of the nanocomposites were investigated.     

增塑剂对马铃薯淀粉基复合膜物理机械性能的影响

以马铃薯淀粉、普鲁兰多糖、明胶为成膜物质,氯化钙为交联剂,甘油、山梨醇、聚乙二醇为增塑剂,采用流延法制备了马铃薯淀粉基复合膜,研究了3种增塑剂对复合膜物理机械性能的影响。结果表明:复合膜的抗拉强度和弹性模量均随增塑剂含量的增加而显著减小,断裂伸长率随甘油和山梨醇含量的增加而显著增加,聚乙二醇对其影响不显著;复合膜的水蒸气透过率和水溶性均随增塑剂含量的增加而增加;聚乙二醇能够显著降低复合膜的透光率。     

Manufacture and research of TPS/PE biocomposites properties

In this paper the process of native starch preparing for modification by extrusion and manufacture of biocomposites is presented. The first aim of this study was to determine the mixing and granulating condition of native starch to obtain granulated native starch. For mixing and granulation of native starch Intensive Mixer manufactured by Maschinenfabrik Gustav Eirich was used. Mixing and granulation in a single process is a new method of preparation of powders for other processing. The main task of granulation is the elimination of dust emissions and the increase in density of powders. Granules are easy for dosage and more handy for transport and storage than powders, which is important from a technological point of view.The second aim of this study was to manufacture TPS/PE biocomposites. At first thermal modification of waxy maize starch was carried out with the use of a co-rotating twin screw extruder. During extrusion native starches have been deprived of their crystallinity and the obtained starch (TPS) has fully amorphous structure. XRD analysis revealed that semi crystalline phase of native starch after extrusion disappeared. During extrusion crystal structure of native starch is transformed into amorphous structure of thermoplastic starch (TPS), which was confirmed by XRD analysis.Reactive extrusion of obtained thermoplastic starch and high density polyethylene (HDPE) in the presence of polyethylene-grafted maleic anhydride (PE-g-MA) was done. To modify properties of TPS/PE blend polycaprolactone (PCL) was added in amount of 5 and 10 wt.%. The mass flow rate, static mechanical properties, thermal properties and morphology of obtained biocomposites were examined. The results show that the increased amount of TPS caused an increase in tensile strength and modulus of elasticity of prepared biocomposites. Addition of PCL to TPS/PE blends decreased tensile strength and modulus of elasticity. Moreover, higher amount of TPS and PCL in TPS/PE blends caused decrease of the elongation at break. On the other hand, using of PE-g-MA in TPS/PE blends cause increasing phase compatibility, which was confirmed by mechanical properties and morphology measurements.Biocomposites filled with higher TPS content (45 and 60 wt.%) possess lower resistance to hydrolytic degradation, which cause decrease of mechanical properties.It was found that higher amount of TPS in TPS/PE blends have small effect on mass flow rate and thermal properties estimated by differential scanning calorimetry (i.e. melting temperature, degree of crystallinity, melting enthalpy). This phenomenon have significant influence on processing of obtained biocomposites.     

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.     

聚乳酸/热塑性淀粉/POE-g-GMA共混材料的制备和性能

采用甲基丙烯酸缩水甘油酯（GMA）接枝（乙烯/辛烯）共聚物（GPOE）作为增韧剂,利用Haake转矩流变仪熔融制备了聚乳酸（PLA）/热塑性淀粉（TPS）/GPOE共混材料。通过拉伸、冲击、动态热力学、差示扫描量热、扫描电镜等方法对共混材料进行研究：PLA共混材料伸长率可达到400%左右,冲击性能有大幅提高;TPS中甘...     

The effect of partially stabilized zirconia on the biological properties of HA/HDPE composites in vitro

The effect of partially stabilized zirconia (PSZ) on the biological properties of the hyroxyapatite - high density polyethylene (HA/HDPE) composites was studied by investigating the simultaneous effect of hydroxyapatite and PSZ volume fractions on the in vitro response of human osteoblast cells. The biocompatibility of composite samples with different volume fraction of HA and PSZ powders was assessed by proliferation, alkaline phosphatase (ALP) and cell attachment assays on the osteoblast cell line (G-292) in different time periods. The effect of composites on the behavior of G-292 cells was compared with those of HDPE and TPS (Tissue Culture Poly Styrene as negative control) samples. Results showed a higher proliferation rate of G-292 cells in the presence of composite samples as compared to the HDPE sample after 7 and 14 days of incubation period. ALP production rate in all composite samples was higher than HDPE and TPS samples. The number of adhered cells on the composite samples was higher than the number adhered on the HDPE and TPS samples after the above mentioned incubation periods. These findings indicates that the addition of PSZ does not have any adverse affect on the biocompatibility of HA/HDPE composites. In fact in some experiments PSZ added HA/HDPE composites performed better in proliferation, differentiation and attachment of osteoblastic cells.     

Starch films from a novel (Pachyrhizus ahipa) and conventional sources: Development and characterization

Biodegradable films from ahipa, cassava and corn native starches were developed by casting method and their physicochemical, mechanical and barrier properties were analyzed taking into account the different starch botanical sources. Filmogenic suspensions were prepared; their rheological behaviors were studied and all of them exhibited film-forming ability. However, mechanical assays demonstrated that unplasticized films were too rigid, limiting their technological applications. Thus, 1.5% w/w of glycerol as plasticizer was added to filmogenic suspensions and film flexibility and extensibility were improved, this effect was more significant for ahipa and cassava starch films. Furthermore, thickness, moisture content and water solubility of the developed films were increased when plasticizer was incorporated. Glycerol addition reduced film water vapor permeability and the lowest reduction corresponded to cassava starch films due to the high viscosity of its filmogenic suspensions. Plasticized starch films resulted to be UV radiation barriers; ahipa starch films had the lowest light absorption capacity and higher transparency than cassava and corn starch films. Dynamic-mechanical analysis indicated that plasticized films were partially miscible systems exhibiting two relaxations, one attributed to the starch-rich phase and the other to the glycerol-rich one. Likewise, it could be demonstrated that glycerol exerted a major plasticizing effect on ahipa starch matrixes.