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%.     

增塑剂对聚乳酸/热塑淀粉复合膜性能的影响

目的改善聚乳酸(PLA)/热塑淀粉(TPS)共混复合膜的使用性能。方法探究乙酰柠檬酸三丁酯(ATBC)和环氧大豆油(ESO)2类增塑剂对复合膜力学性能、透湿性、透光性、微观结构及热力学性能的影响。结果增塑剂的添加可显著改变复合膜力学性能,当ATBC添加量(质量分数)从10%升至20%时,复合膜断裂伸长率增加38倍,而抗拉强度仅为前者的36%。单一ATBC或ESO的添加对复合膜透湿性及透光性影响基本一致,且优于复合增塑剂效果。增塑剂对复合膜体系能够起到一定增容效果,但会造成热分解起始温度下降。对于单一增塑剂,ATBC的增塑效果更为优良;ATBC和ESO复合增塑剂虽具有一定协同作用,但由于二者相容性较差,在总添加量相同的情况下,其对复合膜的增塑作用相较于单一ATBC未展现出明显优势。结论 ATBC添加量为20%的复合膜拥有最佳综合性能。     

三种添加物对聚乳酸复合膜性能影响

目的 研究聚乳酸复合膜的降解性能,加快聚乳酸材料降解速率。方法 选取淀粉、羧甲基纤维素钠（CMC）、聚乙二醇（PEG）等3种材料,与聚乳酸混合制备4种不同的复合膜。测定复合膜的透光率、力学性能、热性能等指标,使用红外光谱仪对复合膜的基团组成进行表征,使用磷酸盐缓冲液浸泡,测试其降解性能。结果 红外光谱结果显示PLA膜与PLA复合膜的吸收峰没有明显的差别,这证明改性材料与聚乳酸没有发生化学反应。复合膜的DSC曲线显示,添加改性剂后,熔融温度变化不大,无明显影响。降解性能方面,按PLA与复合物的质量比9∶1,8∶2,7∶3,6∶4,5∶5制备多种复合膜,其中质量比9∶1,7∶3,5∶5的PLA/淀粉复合膜在第70天降解率分别为24.11%,24.8%,35.6%;PLA/CMC复合膜的3种质量比降解率为27.64%,30.37%,45.2%。按照PLA与PEG质量比为99∶1,98∶2,97∶3,96∶4,95∶5制备了PLA/PEG复合膜,其中质量比为99∶1,97∶3,95∶5的PLA/PEG复合膜在第70天的降解率分别为25.45%,38.83%,45.83%。PLA/淀粉/PEG复合膜是在PLA/淀粉复合膜的基础上添加PEG制备的,复合膜成分与PEG的质量比为99∶1,98∶2,97∶3,96∶4,95∶5,其中99∶1,97∶3,95∶5这3种复合膜的降解率为40.52%,49.54%,55.67%。各种复合膜的降解率均远优于PLA膜2.5%的降解率。结论 复合材料的添加改变了聚乳酸薄膜的透光性能,增强了薄膜的拉伸强度和断裂伸长率。改性材料的添加能够在不影响聚乳酸本身结构的情况下,显著增强聚乳酸的降解率。     

聚乳酸/茶多酚抗氧化膜的制备及其性能研究

以聚乳酸（PLA）为基材,茶多酚（TP）为抗氧化剂,通过流延法制备了具抗氧化活性的可降解PLA/TP共混膜,并研究了茶多酚添加量对共混膜包装性能及抗氧化性能的影响。研究结果表明：茶多酚与聚乳酸基质间发生了相互作用,茶多酚在聚乳酸基质中具有较好的分散性。天然抗氧化物茶多酚的添加使共混膜的拉伸强度、断裂伸长率以及透光率降低,但显著提高了共混膜的热封强度、透湿系数、透氧系数、溶解度和自由基清除率。当茶多酚的质量分数为0.9%时,共混膜的热封强度为3.31 N/(15 mm),透湿系数和透氧系数分别是纯PLA膜的1.68倍和6倍,透光率为88.1%,自由基清除率为89.18%,是一种具有应用潜力的环境友好型食品活性包装材料。     

改性淀粉/聚乳酸共混物的制备

采用接枝共聚-共混法,制备了乳酸接枝淀粉/聚乳酸复合材料.实验表明,淀粉和乳酸进行接枝反应的最佳温度为90℃,最佳反应时间为3h,在此条件下所得接枝共聚物的接枝率最高为31.62%.共混物的形貌分析和性能研究表明,相对于未经改性的淀粉/聚乳酸复合材料,改性淀粉/聚乳酸复合材料的相容性和机械性能得到明显改善.     

聚乳酸改性丝素膜的性能研究

用不同分子量的聚乳酸共混改性丝素,研究结果表明,与纯的丝素膜相比,共混合膜的力学性能明显提高,透汽性也有所提高,但透湿性略有下降;聚乳酸的分子量对共混膜的力学性能、透湿性均有一定的影响,但对共混膜的透汽性影响不大.FTIR和XRD表征结果表明聚乳酸的加入丝素分子β构像的含量明显增多;用Vigot 函数以1265和1235cm-1为中心在1200～1300cm-1之间对红外光谱进行了分峰,用I1265/1235cm-1来表征混合膜中β构像丝素分子的含量,结果表明比例为5/100的聚乳酸/丝素共混膜中,丝素分子β构像含量最多,为0.64.     

扩链剂对聚乳酸/改性淀粉共混物性能的影响

首先制备了马来酸酐(MA)功能化的热塑性淀粉(MTPS),对其结构进行了表征。以环氧扩链剂(REC)为增容剂,采用熔融共混法制备了聚乳酸(PLA)/MTPS/REC共混材料,研究了环氧扩链剂对共混材料性能的影响。结果表明:REC上的环氧基团能与MTPS和PLA上的羧基和羟基反应,提高了淀粉和PLA的相容性,促进了淀粉在PLA基体中的分散,使淀粉颗粒尺寸减小至0.5μm以下。同时,REC对PLA产生扩链作用,共混材料的力学性能得到明显改善,尤其是断裂伸长率可达280%。此外,PLA的结晶能力下降,耐溶剂性能提高。     

热塑性乙酰化淀粉/聚乳酸的性能及形态

采用熔融共混的方法制备了热塑性乙酰化淀粉(TPAS)/聚乳酸(PLA)复合材料, 研究了TPAS/PLA复合材料力学性能、 热性能和形态结构。TPAS以乙酰化改性淀粉为基体, 甘油为增塑剂。实验结果表明: 随着TPAS含量的增加, TPAS/PLA复合材料韧性明显提高, 当TPAS加入量为40%(质量分数)时, 断裂伸长率提高4倍多, 同时TPAS的加入对复合材料的热稳定性影响不大。DSC、 DMTA和SEM分析结果表明, PLA与TPAS是不相容的。     

乙酰柠檬酸三正丁酯增塑改性淀粉/聚乳酸共混材料的结构与性能

以乙酰柠檬酸三正丁酯(ATBC)作为增塑剂,采用熔融共混法制备了淀粉/聚乳酸(PLA)共混材料。采用红外吸收光谱、扫描电镜、X射线衍射、热重分析及力学性能测试方法研究了ATBC对淀粉/PLA共混材料结构和性能的影响。结果表明,ATBC能与PLA和淀粉分子发生强相互作用,破坏淀粉/PLA共混物中原有的氢键,降低淀粉/PLA共混物的结晶度;在淀粉/PLA共混物中加入ATBC可提高PLA与淀粉的界面结合力,改善其相容性,进而改变淀粉/PLA共混材料的结构与性能。ATBC不影响共混材料的热稳定性,但能降低淀粉/PLA共混物的玻璃化转变温度(Tg)和熔点(Tm),改善加工性能;ATBC能显著提高淀粉/PLA共混材料的柔韧性,含20%ATBC的淀粉/PLA共混材料的断裂伸长率可达到365%。     

茶多酚对壳聚糖/聚乙烯醇复合膜性能的影响

目的以茶多酚为改性剂对壳聚糖/聚乙烯醇复合膜进行共混改性,制备一种综合性能良好的绿色包装材料。方法采用溶液共混法制备不同茶多酚质量分数的壳聚糖/聚乙烯醇复合膜,并对其进行红外光谱分析,以及力学性能、水溶性、气体阻隔性、抗氧化性能的测试。结果茶多酚与壳聚糖/聚乙烯醇基质间发生了分子间相互作用,当茶多酚的质量分数为2%时复合膜的综合性能最好,拉伸强度提高了4.99%,且可保持较高的断裂伸长率,水溶性、水蒸气透过率和氧气透过率分别降低了82.43%,51.40%和72.77%,抗氧化能力增强了58.54%。结论添加适量的茶多酚能够提高壳聚糖/聚乙烯醇复合膜的力学性能和耐水性,并改善其气体阻隔性和抗氧化性能。     

SiO2含量与粒径对PLA/SiO2复合膜性能的影响

目的 为了提高聚乳酸材料的力学性能和气体阻隔性,选择二氧化硅为共混材料,通过改变二氧化硅的粒径和含量,研究SiO2对SiO2/PLA复合膜性能的影响.方法 用流延法制备二氧化硅/聚乳酸(SiO2/PLA)复合膜.采用力学性能测试、结晶性测试、热稳定测试和透氧、透水蒸汽测试等分析手段对制备的复合膜进行力学性和阻隔性的表征.结果 在PLA材料中添加适量的SiO2对复合膜的拉伸强度和弹性模量会有增强作用,并且粒径越小,增强效果越明显;粒径为50 nm,质量分数为2％时复合膜表现出更佳的力学性能.同时,随着SiO2含量的增加,氧气透过系数呈先降低后升高的趋势,在SiO2质量分数为2％时透过系数最小,复合膜的氧气阻隔性最好;不同粒径不同含量的SiO2透湿性测试结果表明,SiO2粒径为50 nm,质量分数为2％时复合膜的阻隔性效果最好.结论 二氧化硅的加入能够提升聚乳酸的弹性模量和阻隔性,并且二氧化硅的粒径和不同添加量对复合膜的性能有很大影响.     

改性二氧化硅对SiO2/PLA复合膜性能的影响

目的研究改性二氧化硅对聚乳酸力学性能、氧气透过性能和水蒸气透过性能的影响。方法选择粒径为50nm的工业级二氧化硅为添加剂,使用KH570硅烷偶联剂对其进行改性,然后通过溶液浇铸法将改性后的二氧化硅与聚乳酸共混制备成膜。测试分析拉伸性能、透氧性能和透水蒸气性能,表征复合膜的力学性和阻隔性能。结果与纯PLA膜相比,改性复合膜的拉伸强度和弹性模量分别提高了18.65%和19.91%;玻璃化转变温度比纯PLA膜高11℃左右,热稳定性得到增强。与纯PLA膜相比,改性复合膜的氧气透过系数和水蒸气透过系数分别降低了29.89%和43.76%,阻隔性明显提高。结论经KH570硅烷偶联剂改性的二氧化硅对聚乳酸材料性能的增强效果更佳,为聚乳酸材料在包装领域的应用提供了依据。     

ATBC/PLA-TP复合片材的制备及性能研究

目的制备具有抗氧化性的增韧聚乳酸(PLA)基片材。方法采用乙酰柠檬酸三丁酯(ATBC)、聚乳酸与茶多酚(TP)共混制备复合片材,差示扫描量热分析(DSC)探究试样的热力学性能,采用力学性能测试片材的抗拉强度和断裂伸长率,通过傅里叶红外光谱(FTIR)判断材料内部作用,采用水接触角和透湿性测试衡量片材的亲水性和阻湿性,采用DPPH法测试片材抗氧化性。结果断裂伸长率最高提升了108.7%,而试样的抗拉强度无规律变化;通过红外测试得出C=O向低波数移动。ATBC和TP的加入可以有效促进PLA结晶。水接触角测试表明改性前后的PLA表面疏水,而加入了TP后,材料表面显著亲水,且含有TP的试样水蒸气阻隔性变差。抗氧化性测试结果表明,加入质量分数为1%的TP后的片材抗氧化性显著提升,其抗氧化能力相当于质量浓度约为300mg/L的L-抗坏血酸(Vc)。结论 ATBC/PLA-TP复合片材性能良好且具备发展潜力。     

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。     

Synthesis and characterisation of starch/agar nanocomposite films for food packaging application

In the present work cassava starch/agar Ag and ZnO nanocomposite films were prepared by the solution casting method. The structural, physical and antimicrobial properties of the nanocomposite films were studied as a function of the concentration of Ag and ZnO nanoparticles. The results of the thermogravimetric analysis showed 8–15% degradation of both the nanocomposite films at 150°C endorsing the thermal stability of the films. Scanning electron microscopic analysis reveals the uniform blending of Ag and ZnO nanoparticles with a starch/agar matrix with tiny waves like appearance on the surface. The incorporation of Ag and ZnO nanoparticles in the film was found to reduce the moisture content, water solubility and water vapour permeability with increase in the concentration of Ag and ZnO nanoparticles. The growth kinetics study of Pseudomonas aeruginosa and Staphylococcus aureus in the presence of Ag and ZnO blended nanocomposite films showed promising results especially against Gram‐negative P. aeruginosa. Thus, the film synthesised in the present study bears the potential to be used as active packaging material to prevent food from bacterial contamination and spoilage.Inspec keywords: casting, microorganisms, scanning electron microscopy, nanoparticles, food preservation, solubility, thermal analysis, zinc compounds, food processing industry, food products, thermal stability, permeability, antibacterial activity, food packaging, contaminationOther keywords: water vapour permeability, food packaging, solution casting method, structural properties, physical properties, antimicrobial properties, water solubility, agar nanocomposite film, starch nanocomposite film, Pseudomonas aeruginosa, Staphylococcus aureus, bacterial contamination prevention, spoilage prevention, scanning electron microscopic analysis, thermogravimetric analysis, temperature 150.0 degC, Ag, ZnO     

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.     

POSS对壳聚糖膜的阻湿与拉伸性能的影响

目的研究以四甲基铵基笼形聚倍半硅氧烷(Octa TMA POSS)为填料,制备壳聚糖基复合膜,对壳聚糖薄膜的水蒸气阻隔性能和力学性能进行改善。方法采用溶液共混流延法制备复合膜,测定其水蒸气透过系数、表面接触角、溶胀度、溶解度、吸附等温曲线、拉伸性能、成膜液流变性能、微观形貌和X射线衍射等。结果笼形聚倍半硅氧烷的加入可提高复合膜对水分子的阻隔性,尤其是质量分数为3%时,其水蒸气透过系数下降了15.9%。同时,壳聚糖薄膜的力学性能也得到改善,在质量分数低于5%时,壳聚糖薄膜的抗拉强度、弹性模量可同时得到提高。结论四甲基铵基笼形聚倍半硅氧烷的加入可改善壳聚糖薄膜的阻湿性能和力学性能,可大大提升其在食品包装领域的应用潜力。     

Bio-nanocomposites based on derivatized potato starch and cellulose, preparation and characterization

The use of native starch as a thermoplastic polymer is limited by its fragility and high moisture absorption. Native potato starch was derivatized using different agents in order to reduce its hydrophobicity. A reduction in starch mechanical properties was also found as a side effect of derivatization treatments. The addition of nanocellulose allows to considerably improve mechanical properties of biopolymers as well as to maintain their inherent biodegradation capability. Cellulose nanofibers were added to native and modified starch in order to improve the mechanical properties. The mechanical properties of starch/cellulose nanocomposite films were evaluated, finding that they considerably improved with the addition of cellulosic nanofibers. This contribution demonstrates a new approach in order to produce bioplastics with combined effect: improved moisture and heat resistance (due to the chemical treatment) and high mechanical properties (after the addition of nanocellulose).     

偶联剂对玻璃纤维增强淀粉/聚乳酸复合材料性能的影响

分别以马来酸酐、KH550、KH560和KH570为偶联剂对玻璃纤维进行预处理,再与淀粉、聚乳酸(PLA)复合,通过熔融挤出法制备玻璃纤维增强淀粉/PLA复合材料。研究了偶联剂种类对玻璃纤维增强复合材料熔融指数、力学性能、热性能和熔融流变性能的影响。实验发现马来酸酐、KH550、KH570、KH560处理玻璃纤维增强淀粉/PLA复合材料的熔融指数和力学性能都依次增大,表明KH560处理玻璃纤维增强淀粉/PLA复合材料的界面黏结作用最强。对热性能进行表征发现,马来酸酐、KH550、KH570、KH560处理玻璃纤维增强淀粉/PLA复合材料玻璃化转变温度、重结晶温度、结晶度和热稳定性均依次提高。受玻璃纤维与淀粉/PLA基体界面黏结效果的影响,马来酸酐、KH550、KH570、KH560处理玻璃纤维增强淀粉/PLA体系的储能模量和复数黏度依次增大。