金属离子对脂肪族聚酯降解性能的影响

在土壤培养液中添加不同种类的金属离子,研究了它们对可生物降解聚酯聚乳酸（PLA）、聚丁二酸丁二酯（PBS）膜降解性能的影响。采用傅里叶变换红外光谱仪表征了PLA和PBS膜降解前后的化学结构。结果表明：所有降解后的膜表面均有明显被侵蚀的痕迹;在土壤培养液中的Mg^2＋,Zn^2＋,Ca^2＋对PLA的降解性能有促进作用,对PBS的降解性能则影响不大;降解后PLA膜的玻璃化转变温度有所升高,但PBS膜变化不大。     

可降解塑料聚乳酸(PLA)生物降解性能进展

聚乳酸(Poly(lactic acid),PLA)是1种可由生物质原料发酵产物乳酸聚合而成的生物可降解塑料。PLA因具有良好的生物降解性、生物相容性、无毒及加工性能好的优点,而被广泛地应用在包装、农业、纺织和生物医学材料等领域。基于可循环利用和环境保护的目标,塑料生物降解性能的研究也成为当前研究的1个重要方面。针对近年来的PLA生物降解性能方面的研究进行了详细总结,重点总结了PLA的生物降解方法,包括生物堆肥降解、微生物降解以及酶促降解等方法;对降解后的PLA力学性能的变化进行说明;另外还阐述了PLA的生物降解机制;最后,展望了PLA生物降解性能研究的发展方向。     

液压脉动注射成型聚乳酸力学性能及生物降解性能的研究

在不同振动工艺参数下,研究液压脉动注射成型对聚乳酸(PLA)制品力学性能、结晶性能及生物降解性能的影响.结果表明,与普通注射成型相比,液压脉动注射成型的PLA制品拉伸强度提高了10.6%,冲击强度提高了29.7%,结晶度提高了11.9%.在蛋白酶K催化降解下,其生物降解过程是从表面侵蚀到内部整体侵蚀的逐步演变过程,制品总降解速率比普通注射成型的小.     

聚乳酸/芦苇纤维复合材料降解性能研究

采用熔融共混法制备了不同比例的聚乳酸/芦苇纤维（PLA/RF）共混物,并通过吹塑制备了相对应的薄膜。研究了在蛋白酶K的作用下不同RF含量的PLA/RF薄膜的生物降解性能,同时用差示扫描量热法（DSC）和扫描电子显微镜（SEM）测定了样品降解过程中的结晶行为以及表面形貌变化。结果表明,RF对PLA的酶解降解有促进作用,随着RF含量的增加PLA/RF复合材料的酶解速率提升,其中含有30 %（质量分数,下同）芦苇纤维的PLA/RF薄膜的降解速率最大,16天内可降解81.11 %。研究还表明,加入芦苇纤维可以降低PLA的结晶度,从而影响降解速度。     

PLA/PBAT共混物的降解性能研究

通过双螺杆挤出机和吹膜机组制备不同比例的聚乳酸/聚对苯二甲酸己二酸丁二酯（PLA/PBAT）共混物薄膜,测量共混物的热性能、力学性能,并观察其相形貌,计算共混物在堆肥条件下的生物降解率,研究共混物降解前后的结构、热力学行为和元素的变化。结果表明,PLA与PBAT是不相容体系,加入PBAT后PLA的韧性得到改善;PLA的生物降解率高于PBAT,共混物的生物降解率随着PBAT含量的增加而降低,且在降解初期,PLA的降解产物会促进PBAT的水解;PLA、PBAT及其共混物在堆肥降解前期只是大分子链水解为小分子链的过程,不发生分子链的结构变化;PLA及PBAT的降解会先发生在无定形区,共混物中PLA在无定形区的降解速度受到PBAT的影响而变慢,且共混物中PLA、PBAT的降解行为发生变化,无定形区与结晶区的降解同时发生;共混物在堆肥试验初期的降解以水解为主。     

生物降解材料在水环境中降解性能的研究进展

综述了目前典型生物降解材料在水环境中降解性能的研究现状,详细介绍了聚乳酸（PLA）高分子材料（PLA、PLA共聚物、PLA复合材料等）、聚羟基烷酸酯（PHA）、聚己内酯（PCL）、聚丁二酸丁二醇酯（PBS）、聚（己二酸丁二醇酯?对苯二甲酸乙二醇酯）（PBAT）和CO₂共聚物等在不同水环境中的降解性能;最后总结了生物降解材料未来需要关注的问题和发展方向。     

聚乳酸降解菌的分离鉴定及其产酶和降解特性

以山东潍坊使用聚乳酸/聚己二酸-对苯二甲酸丁二酯共混物(PLA/PBAT)地膜的土壤为样本,采用以聚乳酸(PLA)为惟一碳源的无机盐培养基筛选PLA降解菌。使用形态学观察、生理生化实验、16Sr RNA基因序列分析及构建系统发育树等方法鉴定降解菌。通过水解圈法确认产蛋白酶活性高的降解菌为研究对象,并采用福林酚法结合单因素及响应曲面法对外源营养源与产酶条件进行了优化。采用SEM、FTIR和XRD等方法分析了降解前后PLA的形貌和结构变化,研究了降解菌对PLA的降解情况。结果表明:从土壤中筛选获得了一株产蛋白酶的PLA降解菌(门多萨假单胞菌Pseudomonas mendocina);优化得到的最佳产酶条件为:在100 mL筛选培养基中,加入质量分数为2%的葡萄糖和质量分数为1%的胰蛋白胨作外源营养源,pH为7.4,接种量为1.4 mL,培养温度32℃。在此条件下,蛋白酶活性最高为32.15 U/mL,较未优化前提高约26倍;PLA降解菌产蛋白酶可催化降解PLA材料中的酯键,5 d内PLA降解率可达29.35%。     

聚乳酸的酶促降解研究

采用蛋白酶K对聚乳酸(PLA)薄膜进行酶促降解,考察了溶液起始pH值、降解温度、蛋白酶K浓度、降解时间等因素对薄膜降解率的影响,并研究了后3种因素对溶液pH值变化趋势的影响。利用扫描电子显微镜(SEM)和X射线衍射(XRD)仪观察和分析了薄膜降解前后的形态和结晶情况。结果表明,随溶液起始pH值、降解温度、蛋白酶K浓度的增加,PLA薄膜降解率先增大后降低,随着降解时间的增加,PLA薄膜的降解率先逐渐增大,在6 h后趋于稳定;获得了最合适的降解工艺参数:溶液起始pH值为9.0、降解温度为160℃、蛋白酶K浓度为0.5 mg/mL、降解时间为6 h,在此条件下蛋白酶K对PLA薄膜的降解率可达(94.3±0.8)%。溶液pH值随后3种因素的变化趋势与降解率大体相反,间接反映了PLA薄膜在降解过程中生产了大量单体乳酸。SEM观察到降解后的薄膜表面形成了孔洞及蚀痕。XRD分析结果表明降解后薄膜的相对结晶度降低,晶体区域发生降解。     

PLA降解菌的分离鉴定及其产酶和降解特性

以山东潍坊使用聚乳酸/聚己二酸-对苯二甲酸丁二酯共混物(PLA/PBAT)地膜的土壤为样本，采用以聚乳酸(PLA)为唯一碳源的无机盐培养基筛选PLA降解菌。使用形态学观察、生理生化实验、16S rRNA基因序列分析及构建系统发育树等方法鉴定降解菌。通过水解圈法确认产蛋白酶活性高的降解菌为研究对象，并采用福林酚法结合单因素及响应曲面法对外源营养源与产酶条件进行了优化。采用SEM、FTIR和XRD等方法分析了降解前后PLA的形貌和结构变化，研究了降解菌对PLA的降解情况。结果表明：从土壤中筛选获得了一株产蛋白酶的PLA降解菌(门多萨假单胞菌Pseudomonas mendocina)；优化得到的最佳产酶条件为：在100 mL筛选培养基中，加入质量分数为2%的葡萄糖和质量分数为1%的胰蛋白胨作外源营养源，pH为7.4，接种量为1.4 mL及培养温度32 ℃。在此条件下，蛋白酶活性最高为32.15 U/mL，较未优化前提高约26倍；PLA降解菌产蛋白酶可催化降解PLA材料中的酯键，5 d内PLA降解率可达29.35%。     

改性聚乳酸材料的堆肥降解性能研究

依据GB/T 19277.1—2011测试方法,研究了丙烯腈-丁二烯-苯乙烯(ABS)改性聚乳酸(PLA)材料在受控堆肥条件下的生物降解性能。结果表明:PLA含量为80%以上的PLA/ABS共混材料具有较好的生物降解性能,且经堆肥降解试验后的培养土的挥发性固体含量、pH值与试验前接近。     

高密度聚乙烯复合薄膜生物降解性的研究

将聚乳酸、淀粉分别与高密度聚乙烯(HDPE)共混,制备了具有一定降解性能的HDPE塑料薄膜。研究了聚乳酸和淀粉对HDPE薄膜力学性能、降解性能、降解后的力学性能、结晶、微观结构等的影响。结果表明:聚乳酸和淀粉能提高HDPE薄膜的力学性能,复合薄膜降解30d后力学性能会有一定程度的降低。     

Preparation and properties of successive alkali treated completely biodegradable short jute fiber reinforced PLA composites

The natural fiber reinforced biodegradable polymer composites were prepared with short jute fiber as reinforcement in PLA (Poly lactic acid) matrix. The short jute fiber is successively treated with NaOH at various concentrations (5%, 10%, and 15%) and H₂O₂. The composites were prepared with untreated and treated short jute fibers at different weight proportions (up to 25%) in PLA and investigated for mechanical properties. The results showed that the composite with successive alkali treated jute fiber at 10% NaOH and H₂O₂ with 20% fiber loading has shown 18% higher flexural strength than neat PLA and untreated jute/PLA composite. The flexural modulus of the composite at 25% fiber loading was 125% and 110% higher than that of composites with untreated fibers and neat PLA, respectively. The impact strength of composite with untreated fibers at higher fiber weight fraction was 23% high as compared to neat PLA and 26% high compared to composite with treated fibers. The water absorption was more for untreated jute/PLA composite at 25% fiber loading than all other composites. The composite with untreated fibers has high thermal degradation compared with treated fibers but lower than that of pure PLA matrix. The enzymatic environment has increased the rate of degradation of composites as compared to soil burial. Surface morphology of biodegraded surfaces of the composites were studied using SEM method. POLYM. COMPOS., 37:2160–2170, 2016. © 2015 Society of Plastics Engineers     

Degradation of poly(L‐lactide) by a mesophilic bacterium

A Gram negative, rod‐shaped mesophilic bacterium active for poly(L ‐lactide) (PLA) degradation was isolated through the enrichment culture and clear‐zone method. The isolated strain was identified to be Bordetella petrii PLA‐3 on the basis of 16S rDNA gene sequence analysis. B. petrii PLA‐3 was active not only for the degradation of low‐molecular‐weight PLA but also for the degradation of high‐molecular‐weight PLA. The strain seemed to attack the crystalline part of PLA as well as the amorphous region. The PLA film incubated in compost inoculated with the isolated strain lost its weight more notably and exhibited a lower molecular weight than that incubated in the sterilized compost without living microorganisms. Moreover, the profile of the cumulative amount of CO₂ after 20 days of burial in the sterilized compost and subsequent inoculation of the isolated strain into compost was nearly the same as that of CO₂ evolved from PLA buried in compost with the isolated strain at the very beginning when the time was shifted by 20 days. This indicated that not only the abiotic hydrolysis but also the microbial enzymes of the strain contributed to the initial chain cleavage of PLA molecules and resolved the doubt that PLA molecules should be initially cleaved into very low‐molecular‐weight substances by abiotic hydrolysis to be subsequently absorbed into and biodegraded by microorganisms. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

细菌纤维素/聚乳酸复合膜制备及性能

以聚乳酸(PLA)为原料,利用细菌纤维素(BC)生产菌株发酵制得BC/PLA复合膜。通过对BC/PLA复合膜制备过程中发酵时间、纺膜速率、PLA溶液用量等因素的考察,以BC/PLA复合膜载药率为指标,进行了BC/PLA复合膜制备工艺的优化;利用FTIR、TG、拉力实验、XRD及SEM对BC、PLA及BC/PLA复合膜化学基团、热性能、力学性能、结晶度及表面形貌进行了分析;对BC/PLA复合膜载药及释药过程进行了研究。结果表明,PLA溶液用量对BC/PLA复合膜载药率影响较小,BC/PLA复合膜最优制备工艺为:纺膜速率0.15 mm/s,发酵时间36h,所制备BC/PLA复合膜在15mg/L双氯芬酸钾药液中最大载药率为2.51mg/g。FTIR、TG、拉力实验、XRD及SEM结果表明,BC与PLA可以成功复合,从而改善PLA的热性能及力学性能,所制备BC/PLA复合膜具有三维网状多孔结构。载药BC/PLA复合膜药物释放过程符合一级释放动力学模型。     

Halochromic poly (lactic acid) film for acid base sensor

A novel strategy to engineer biodegradable halochromic film based on poly (lactic acid) (PLA) for pH sensorial substances was presented. The effect of polyethylene glycol (PEG) compositions and dye amount on the efficiency of halochromic pH film was observed. The interactions between PLA, PEG, and dye was evidence by Fourier transform infrared. UV–VIS results indicated the sensitivity of the halochromic film through color changes. Mechanical performance was investigated by tensile testing to assess the potential of the halochromic film. It was found that the halochromic pH film has a clear color response from yellow to purple at pH 3–11 with a rapid response time within a minute. The results also revealed that varying content of PEG showed a significant effect on response time compared with varying dye compositions. PLA/PEG film and dye formed new interactions where PEG increased the free volume of PLA and made it possible for the PEG and the dye to diffuse and entrap between PLA chain. In term of the film strength, the addition of PEG and dye improved the flexibility of PLA film, which enables great potential in many applications such as medical, textile, and packaging.     

PLA/MCC复合材料的制备及其性能

以水稻秸秆经碱解、酸解得到的微晶纤维素(MCC)作为聚乳酸(PLA)的改性材料,通过溶液共混、流延成膜制备了PLA/MCC复合膜,采用傅里叶变换红外光谱仪、差示扫描量热仪、扫描电子显微镜等对其性能进行了表征。结果表明:水稻秸秆中木质素、半纤维素等杂质大部分被有效除去,当NaOH质量分数为5%时,去除率最大,MCC成功制备;当MCC质量分数为8.3%时,可以最大程度改善PLA/MCC复合膜的拉伸性能,MCC与PLA结合最好,而MCC的加入会使复合膜的热稳定性有所降低。     

Synthesis and characterization of polylactic acid-lecithin-starch bioplastic film

Plastic-induced environmental issues could be solved using biomaterials, such as polylactic acid (PLA) film. PLA film is a costly solution suggesting the need to add less expensive starch. However, PLA and starch do not mix due to their diverging water behavior. In this study, we evaluated the impact of lecithin as a compatibilizer in varying ratio of PLA and starch film. The results show that inclusion of lecithin in PLA/starch composite leads to enhanced mechanical properties compared with the composite without lecithin. All films' thermal properties were stable but the thermograph of PLA/starch display two peaks whose distance is impacted by lecithin. In addition, morphology and functional group fingerprints revealed that the addition of lecithin improved the interfacial adhesion between the two polymers. Lecithin influenced the positioning and dispersion pattern of starch granules and distinct transmittance characteristics. The improved compatibility of PLA/starch makes the resulting films less susceptible to water penetration and dissolution. This work demonstrated the possibility of using lecithin as emulsifier between PLA and starch which could expand the application of PLA/starch film especially in packaging industries and bale net wrapping.     

静电纺PLA/丝素-明胶复合纤维膜的性能研究

通过静电纺丝先制备聚乳酸(PLA)纤维膜,在PLA纤维膜上分别喷射不同比例的丝素-明胶纺丝液制得PLA/丝素-明胶复合纤维膜,对复合纤维膜的溶解性能、尺寸稳定性、力学性能及生物性能进行表征。结果表明:与丝素-明胶纤维膜相比,PLA/丝素-明胶复合纤维膜的溶失率明显下降,尺寸稳定性及柔软性得到改善,且经甲醇处理后,复合纤维膜的力学性能提高。将制备的复合纤维膜进行小鼠胚胎细胞(3T3)培养实验,3T3在PLA/丝素-明胶复合纤维膜上能更好地粘附、伸展和繁殖。     

Single Solvent‐Based Film Casting Method for the Production of Porous Polymer Films

A single solvent‐based film casting process for fabricating porous polymer films is developed in this study. The porous film is produced by mixing concentrated polylactic acid (PLA)/chloroform solution (20 wt%) and fresh chloroform solvent is followed by film casting. The average pore sizes of the films produced are seen to increase from 2.1 (±0.1) µm to 6.4 (±0.2) µm with increasing ratio of concentrated PLA solution and fresh solvent from 1:2 to 1:4. Functional groups of PLA after casting into porous film are confirmed via Fourier transform infrared spectroscopy analysis. Cytocompatibility studies (via Alamar Blue assessment) utilizing MG‐63 cells on the porous PLA films reveal an increase in cell metabolic activity up to 8 d postseeding. In addition, these direct cell culture studies show that the porous membranes support cell adhesion and growth not only on the surface but also through the porous structures of the membrane, highlighting the suitability of these porous films in tissue engineering applications.