Enzymatic Degradation of Poly(butylenesuccinate)/Thermoplastic Starch Blend

The degradation of thermoplastic starch blend in the presence of commerciala-amylase and unpurified amylase of microbial origin was investigated.The blends consisting of thermoplastic starch and poly(butylene succinate)have potential use in packaging applications thus,it is essential to establish susceptibility to degradation.Molar mass loss,gravimetric weight loss,and molecular structure were evaluated.The changes in the surface were observed with scanning electron microscopy.It was confirmed that there was a significant difference in gravimetric weight loss between the blends degraded in two different solutions.Unpurified enzymes of microbial origin,produced by Rhizopus oryzae cultures decomposed analyzed materials more efficiently than purified commercial ones.Moreover,it was proved that in applied conditions,the molar mass of PBS fraction did not change significantly.

Improving Polylactide Toughness by Plasticizing with Low Molecular Weight Polylactide-Poly(Butylene Succinate)Copolymer

A low-molecular-weight polylactide-poly(butylene succinate)(PLA-PBS)copolymer was synthesized and incorporated into polylactide(PLA)as a novel toughening agent by solvent casting.The copolymer had the same chemical structure and function as PLA and it was used as a plasticizer to PLA.The copolymer was blended with PLA at a weight ratio from 2 to 10 wt%.Phase separation between PLA and PLA-PBS was not observed from their scanning electron microscopy(SEM)images and the crystal structure of PLA almost remained unchanged based on the X-ray diffraction(XRD)measurement.The melt flow index(MFI)of the blends was higher as the amount of PLA-PBS increased,indicating that the block copolymer did improve the mobility of the PLA chains.Moreover,tensile tests revealed that PLA with greater PLA-PBS copolymer exhibited higher elongation at break and it reached the maximum at 8 wt%of PLA-PBS in PLA,which was around 6 times higher than that of pure PLA.Furthermore,the glass transition temperature,measured by differential scanning calorimetry(DSC),markedly decreased with an increasing amount of the copolymer as it decreased from 61.2℃ for pure PLA to 41.3℃when it was blended with 10 wt%PLA-PBS copolymer.Therefore,the PLA-PBS copolymer was shown to be a promising plasticizer for fully biobased and toughened PLA.

DSC Study of Thermal Properties of Biodegradable Poly(Butylene Succinate-co-terephthalate)

Poly （ butylene succinate ） （ PBS ）, poly （ butylene terephthalate） （PBT） and poly （butylene succirmte-coterephthalate） （PBST）s were synthesized from dimethyl succinate and/or dimethyl terephthalate reacting with 1,4- butanediol through a process of transesterification/ polycondmsation in the presence of a high effective catalyst and characterized by means of GPC and DSC. The investigation was mainly focused on the influence of content of terephthalate units on the molecular weight and thermal properties of resulting polymers. It is revealed that the melting temperature and crystallinity of synthesized polymers decrease first with the increase of terephthalate units, then shift to rise gradually by DSC measurements. The results of Flory equation suggest sequence structure of PBSTs is random.

Construction and evaluation of co-electrospun poly (butylene succinate)/gelatin materials as potential vascular grafts

In this study,a series of poly(butylene succinate)(PBSU)/gelatin composites were prepared by electrospinning.The morphology,physicochemical analysis,biomechanical properties,biocompatibility,and biodegradability of the materials were evaluated.The results showed that the ultimate tensile stress of the vascular PBSU/gelatin grafts at(95/5),(90/10),(85/15),and(80/20)was(4.17±0.54)MPa,(3.81±0.44)MPa,2.94±0.69 MPa and 2.11±0.72 MPa respectively,and the burst pressure was(282.7±22.3)kPa,(295.3±3.9)kPa,(306.8±13.9)kPa and(307.6±9.0)kPa respectively,which met the requirements of tissue-engineered blood vessels.Furthermore,the addition of gelatin improved the hydrophilicity and degradation properties of PBSU,thus enhancing cell adhesion and promoting the inward growth of vascular smooth muscle cells.In summary,the research in this paper provides a useful reference for the preparation and optimization of vascular scaffolds.

Crystallization and Dynamic Mechanical Behavior of Coir Fiber Reinforced Poly(Butylene Succinate)Biocomposites

The crystallization behavior,crystal morphology and form,and viscoelastic behavior of poly(butylene succinate)(PBS)and coir fiber/PBS composites(CPB)were investigated by differential scanning calorimetry(DSC),polarized optical microscopy(POM),X-ray diffraction(XRD)and dynamic mechanical analysis(DMA).The results of DSC measurement show that the crystallization temperature increases with the filling of coir fibers.POM images reveal that the spherulitic size and crystallization behavior of PBS are influenced by the coir fibers in the composites.XRD curves show that the crystal form of pure PBS and CPB are remaining almost identical.In addition,the storage modulus of CPB significantly increases comparing with the pure PBS.This predicted the dimensional stability and improved load-deformation temperature.In conclusion,the addition of coir fibers has a significant effect on the thermal properties of the matrix.

Influencing Factors and Process on <i>in Situ</i>Degradation of Poly(<i>Butylene Succinate</i>) Film by Strain <i>Bionectria ochroleuca</i>BFM-X1 in Soil

This is the first report on the PBS film degraded by any Bionectria ochroleuca fungal strain. The fungal strain BFM-X1 was isolated from an air environment on a vegetable field and was capable of degrading poly(butylene succinate) (PBS). The taxonomic identity of the strain BFM-X1 was confirmed to be Bionectria ochroleuca (showing a 99% similarity to B. ochroleuca in a BLAST search) through an ITS rRNA analysis. The bio-degradation of the PBS film by strain BFM-X1 was studied. Approximately 97.9% of the PBS film was degraded after strain BFM-X1 was inoculated at 28?C for 14 days. The degradation efficiency of BFM-X1 against PBS film under different soil environmental conditions was characterized. The results indicated that 62.78% of the PBS film loss was recorded in a 30-d experimental run in a sterile soil environment indoors. On adding strain BFM-X1 to a soil sample, the PBS degradation rate accelerated approximately fivefold. Furthermore, both temperature and humidity influenced the in situ degradation of the PBS by strain BFM-X1, and temperature may be the major regulating factor. The degradation was particularly effective in the warm season, with 90% of weight loss occurring in July and August. Scanning electron microscope observations showed surface changes to the film during the degradation process, which suggested that strain BFM-X1preferentially degraded an amorphous part of the film from the surface. These results suggested that the strain B. ochroleuca BFM-X1 was a new resource for degrading PBS film and has high potential in the bioremediation of PBS-plastic-contaminated soil

THERMAL PROPERTY, MISCIBILITY AND CRYSTALLIZATION BEHAVIOR OF POLY(3-HYDROXYBUTYRATE-co-3-YDROXYHEXANOATE) AND POLY(BUTYLENE SUCCINATE-ADIPATE) (PHBHHX/PBSA) BLENDS

Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/20 to 20/80 by melt mixing method. Differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMA), polarizing optical microscopy (POM) and wide angle X-ray diffractometer (WAXD) were used to study the miscibility and crystallization behavior of PHBHHx/PBSA blends. Experimental results indicate that PHBHHx is immiscible with PBSA as shown by the almost unchanged glass transition temperature and the biphasic melt.

Miscibility, Crystallization, and Rheological Behavior of Solution Casting Poly（3-hydroxybutyrate）/poly（ethylene succinate） Blends Probed by Differential Scanning Calorimetry, Rheology, and Optical Microscope Techniques

The miscibility and crystallization of solution casting biodegradable poly（3-hydroxybuty- rate）/poly（ethylene succinate） （PHB/PES） blends was investigated by differential scanning calorimetry, rheology, and optical microscopy. The blends showed two glass transition temperatures and a depression of melting temperature of PHB with compositions in phase diagram, which indicated that the blend was partially miscible. The morphology observation supported this result. It was found that the PHB and PES can crystallize simultaneously or upon stepwise depending on the crystallization temperatures and compositions. The spherulite growth rate of PHB increased with increasing of PES content. The influence of compositions on the spherulitic growth rate for the partially miscible polymer blends was discussed.

Nanocellulose: Effect on Thermal, Structural, Molecular Mobility and Rheological Characteristics of Poly(Butylenes Adipate-Co-Butylene Terephthalate) Nanocomposites

The concern with environmental preservation is a very current and relevant topic. Regarding polymers, the search for potentially ecofriendly matters has been the subject of scientific research. In this context, this work aimed to study the effect of adding nanocellulose (nCE) with 1, 3, and 5 wt.% on poly(butylene adipate-co-butylene terephthalate) (PBAT). Thermal, structural, relaxometric, and rheological assessments were carried out. Quantitative evaluation of PBAT copolymer by high field NMR revealed 56.4 and 43.6 m.% of the butylene adipate and butylene terephthalate segments, respectively. WAXD measurement on the deconvoluted diffraction patterns identified that nCE was a mixing of Cellulose I and Cellulose II polymorph structures. At any composition, nanocellulose interfered with the PBAT crystallisation process. Also, a series of new PBAT crystallographic planes appeared as a function of nanocellulose content. PBAT hydrogen molecular relaxation varied randomly with nanocellulose content and had a strong effect on the hydrogen relaxation. PBAT cold crystallisation and melting temperatures (Tcc and Tm) were almost unchangeable. Although Tcc did not change during polymer solidification from PBAT molten state, the sample’s degree of crystallinity varied with composition through the transcrystallization phenomenon. Nanocomposite thermal stability decreased possibly owing to the catalytic action of sulfonated amorphous cellulose chains. For the sample with 3 wt.% of nanocellulose, the highest values of complex viscosity and storage modulus were achieved.

Thermal Behavior and Crystal Transition of Biodegradable Poly(butylenes adipate)Revealed by Two-Dimensional Correlation Spectroscopy

In the present study,thermal behavior and crystal transition of pure poly(butylene adipate)(PBA)upon heating process were investigated by FTIR spectroscopy.To gain further insight into the thermal behavior alteration and the phase transition of PBA,we performed two-dimensional(2D)correlation analysis.We found thatβ-form PBA crystal undergoes not only the melting process but also crystal transition upon the heating process.

Delivery of docetaxel using pH-sensitive liposomes based on D-α-tocopheryl poly(2-ethyl-2-oxazoline) succinate:Comparison with PEGylated liposomes

This study aimed to investigate the ability of the novel materials D-α-tocopheryl poly(2-ethyl-2-oxazoline) succinate(TPOS) to construct pH-sensitive liposomes. TPOS was initially synthesized and characterized by TLC, FTIR, and ~1H-NMR. The buffering capacity of polyethylene glycol-distearoyl phosphatidylethanolamine(PEG-DSPE) and TPOS was determined by acid-base titration, and TPOS displayed a slower downtrend and gentler slope of titration curve than PEG-DSPE within pH 7.4–5.0. Studies on the in vitro drug release demonstrated that TPOS modified docetaxel(DOC) liposomes(TPOS-DOC-L) had a slower drugrelease rate at pH 7.4 similar to PEGylated-DOC liposomes(PEG-DOC-L), whereas the release rate reached approximately 86.92% ± 1.69% at pH 6.4. In vitro cellular uptake assays by microplate reader, and flow cytometry revealed that TPOS modified coumarin 6 liposomes(TPOS-C6-L) had stronger cellular uptake at pH 6.4 than that at pH 7.4( P < 0.01). Conversely, for PEGylated C6 liposomes(PEG-C6-L) and conventional C6 liposomes(C6-L), very similar cellular uptakes were exhibited at different pH values. Confocal laser scanning microscopy images showed that PEG-C6-L and C6-L were mainly located in lysosomes. By contrast, TPOS-C6-L showed broader cytoplasmic release and distribution at 4 h. MTT assay showed that the cytotoxicity of TPOS-DOC-L was similar to that of PEG-DOC-L and conventional DOC liposomes(DOC-L) at the same DOC concentration and at pH 7.4, but was much lower than those at pH 6.4 after 48 h of incubation. The apoptosis of PEG-DOC-L and DOC-L had no remarkable improvement with decreased pH from 7.4 to 6.4. Meanwhile, TPOS-DOC-Lsignificantly induced the apoptosis of HeLa cells with decreased pH. Therefore, TPOS can be a biomaterial for the construction of a pH-sensitive drug delivery system.

Alkylpolyglycoside inducing poly (butylene terephthalate) non-woven graft copolymerization of chitosan

In order to improve the wettability and biocompatibility of the poly （butylene terephthalate） non-woven （PBTNW）, the method of surface modification is used to graft copolymerization of chitosan （CS） onto the PBTNW under alkylpolyglycoside （APG） inducing. The product is thoroughly characterized with the Fourier transform infrared spectroscopy （FrIR）, the electron spectroscopy for chemical analysis （ESCA）, the thermogravimetric （TG） and the scanning electron microscopy （SEM）. It is found that chitosan is successfully grafted onto PBTNW. In addition, the water contact angles, hemolysis tests and cytotoxicity evaluation tests show an improvement in wettability and biocompatihility as a result of graft copolymerization of chitosan. So the CS-grafted PBTNW exhibits greater superiority than the original PBTNW. The CS-grafted PBTNW can be a candidate for blood filter materials and other medical applications.

TRANSESTERIFICATION OF POLY(BISPHENOL A CARBONATE) WITH AROMATIC AND ALIPHATIC SEGMENTS IN BUTYLENE TEREPHTHALATE-CAPROLACTONE COPOLYESTER

In this article, the transesterification of poly(bisphenol A carbonate) (PC) with butylene terephthalate-caprolactone copolyester at a weight ratio 50/50 (BCL(21)) was thoroughly investigated by proton nuclear magnetic resonance spectroscopy ('H-NMR), in conjunction with a model compound. The 1 H-NMR results of the annealed blend PC/BCL(21) show that the formation of bisphenol A-terephthalate ester units is the same as in the annealed blend of PC with PBT, and the transesterification actually occurs between PC and butylene terephthalate (BT) segments in BCL(21). By comparison with the model compound bisphenol A dibutyrate, the new signal appearing at δ= 2.56 in the 1H-NMR spectrum confirms the existence of bisphenol A caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. 1H-NMR analysis of the transesterification rates reveals that the reaction of PC with aromatic and aliphatic segments in BCL(21) proceeds in a random manner. The miscibility of the blend PC/BCL(21) copolyester is favorable for the transesterification of PC with BT segments and CL segments.

Unlocking the Potential of Poly(butylene succinate)through Incorporation of Vitrimeric Network Based on Dynamic Imine Bonds

Poly(butylene succinate)(PBS)exhibits many advantages,such as renewability,biodegradability,and impressive thermal and mechanical properties,but is limited by the low melt viscosity and strength resulted from the linear structure.To address this,vitrimeric network was introduced to synthesize PBS vitrimers(PBSVs)based on dynamic imine bonds through melt polymerization of hydroxyl-terminated PBS with vanillin derived imine containing compound and hexamethylene diisocyanate using trimethylolpropane as a crosslinking monomer.PBSVs with different crosslinking degrees were synthesized through changing the content of the crosslinking monomer.The effect of crosslinking degree on the thermal,theological,mechanical properties,and stress relaxation behavior of the PBSVs was studied in detail.The results demonstrated that the melt viscosity,melt strength,and heat resistance were enhanced substantially without obvious depression in crystallizability,thermal stability,and mechanical properties through increasing crosslinking degree.In addition,the PBSVs exhibit thermal reprocessability with mechanical properties recovered by more than 90%even after processing for three times.Furthermore,PBSV with improved melt properties shows significantly improved foamability compared to commercial PBS.This research contributes to the advancement of polymer technology by successfully developing PBS vitrimers with improved properties,showcasing their potential applications in sustainable and biodegradable materials.

不同拓扑结构聚(丁二酸丁二醇-对苯二甲酸丁二醇)酯的性能

通过溶液流延的方式制备了不同拓扑结构带支链的聚(丁二酸丁二醇-对苯二甲酸丁二醇)酯(PBST-Kx)薄膜,利用^(1)H NMR、GPC、TG、DSC、XRD、流变测试等方法对PBST-Kx的结构及性能进行了研究。实验结果表明,支化剂的引入不会影响PBST-Kx分子链的化学组成、热稳定性和结晶性能,但随支化剂官能度的增加,PBST-Kx的支链数增加,Mn呈减小的趋势,分子量分布变宽。支化结构的引入增加了PBST-Kx的熔体黏度,使其具有更高的弹性和更长的松弛时间,且随着支化度的增加而增大。随支化度的增加,PBST-Kx薄膜的拉伸强度和断裂伸长率降低。

改性磷石膏填充PBAT复合薄膜的制备及性能

为了降低高成本的生物降解树脂用量,采用改性磷石膏(PG-1)填充聚对苯二甲酸-己二酸丁二酯(PBAT),通过挤出吹膜法制备了PBAT/PG-1复合薄膜。通过红外测试、结晶熔融行为分析、X射线衍射测试、扫描电子显微镜表征、水蒸气透过率测试、力学性能等测试,表征了复合薄膜的结构、结晶熔融性能、断面微观形态、阻隔性能和力学性能等。研究结果表明,PG-1的添加使得PBAT/PG-1复合薄膜的结晶和熔融温度都有所提升,结晶度先增加后减小。观察复合薄膜的断面结构发现,PG-1在复合薄膜中分散均匀、与PBAT相容性较好。水蒸气透过率测试结果表明,PG-1的添加有效改善了复合薄膜的阻隔性能。当PG-1的质量分数为20%时,复合薄膜具有优异的力学性能,横、纵向拉伸强度分别提高了94.5%和78.7%,此时断面结构整体平整光滑,无明显团聚现象,水蒸气透过率下降了44.48%,整体性能达到最佳。当PG-1的质量分数高达50%时,复合薄膜仍具有优异的成膜性能,此时的拉伸强度和结晶度仍与纯PBAT薄膜接近。PBAT/PG-1复合薄膜表现出剪切变稀的流变行为,加工性能得到改善。

改性聚己二酸/对苯二甲酸丁二醇酯熔融包覆制备缓释肥的研究

绿色缓释肥的研发可缓解化肥的利用率较低所造成的养份浪费和严重的环境污染。本文使用异丙基三(十二烷基苯磺酰基)钛酸酯(TDBSP)改性可生物降解聚己二酸/对苯二甲酸丁二醇酯(PBAT),降低其熔体流动温度,加入环境友好的乙酰柠檬酸三丁酯(ATBC)进行增塑,进一步提高熔体流动性,使PBAT改性材料能够在120℃下用简单的搅拌工艺对复合肥颗粒进行环境友好的无溶剂熔融包覆,在此基础上填充一定量的疏水钙镁磷肥粉提高缓释效果,得到包膜完整且达到缓释要求的缓释复合肥,并对包膜形态进行评估,对缓释肥料的缓释性能进行了测试。钙镁磷肥粉的填充显著增强了缓释性能,在土柱淋溶实验中,24 h的养份释放低于15%,28 d养份累计释放约为80%,养份持续释放达20 d以上,为经济便捷地制备绿色环保的缓释肥提供借鉴,也为拓展PBAT等可降解塑料的应用领域提供思路。

PLA增强改性PBAT/CaCO_(3)/PEG400复合材料的制备及性能研究

针对聚对苯二甲酸-己二酸-丁二醇酯(PBAT)材料拉伸强度低的问题,通过物理共混法制备聚乳酸(PLA)增强的PBAT复合材料,研究了PLA用量对PBAT拉伸性能、微观相结构、热力学性能及化学组成的影响。进一步加入聚乙二醇400(PEG400)后,将复合材料制备成膜,并对薄膜拉伸性能和微观形貌进行研究。结果表明:随着PLA占比的提升,PBAT/PLA/CaCO_(3)复合材料的拉伸强度先增加后减小,而其断裂伸长率减小;PEG400的加入虽然在一定程度上降低了PBAT/PLA/CaCO_(3)复合材料的拉伸强度,但其提升了PBAT与PLA的相容性,故可显著提升复合材料的断裂伸长率;PLA含量为10%时,PBAT/PLA/CaCO_(3)/PEG400复合材料的拉伸强度和断裂伸长率较纯PBAT分别提升了9.43%和6.94%,使其应用范围得到广泛扩展。

聚丁二酸丁二醇酯的合成工艺与表征

研究了丁二酸酐(SAH)、丁二酸二甲酯(DMS)分别与1,4-丁二醇(BDO)反应合成聚丁二酸丁二醇酯(PBS)的制备方法及基本性能,详细考察了原料配比、酯化/酯交换温度以及缩聚温度等因素对于PBS产品性能以及副产物生成的影响,旨在为工业化连续反应装置的生产提供技术支撑。利用高效气相色谱仪、熔体流动速率仪、安东帕旋转流变仪、分光测色仪对PBS进行了表征,结果表明:以SAH为原料时,最佳工艺条件下制备的PBS的熔融指数为0.516g/min,L值为75.11;以DMS为原料时,最佳工艺条件下制备的PBS的熔融指数为0.514g/min,L值为73.75;PBS呈现明显的假塑性,随着剪切速率的增加,熔体的黏度逐渐降低。

可膨胀石墨-改性稻草纤维@PBAT发泡珠粒复合材料的制备与性能

稻草纤维(RSF)经磷酸和三聚氰胺改性得到了改性稻草纤维(MPRSF),其与可膨胀石墨(EG)进行球磨制备了界面焊料(EG-MPRSF)。采用超临界二氧化碳(scCO_(2))和微波烧结成型技术制备了EG-MPRSF@聚己二酸/对苯二甲酸丁二醇酯(PBAT)发泡珠粒复合材料。采用FTIR、XPS、SEM、EDS、TGA对样品进行了表征,通过硬度、回弹性和压缩强度测试、极限氧指数测试、垂直燃烧等级测试和锥形量热仪测试,考察了EG-MPRSF含量(以PBAT发泡珠粒质量计,下同)对EG-MPRSF@PBAT发泡珠粒复合材料力学性能、阻燃性能的影响。结果表明,EG-MPRSF@PBAT发泡珠粒复合材料烧结后能保留PBAT发泡珠粒原有的泡孔结构,其硬度、回弹性和压缩强度均有较大的提升,且具有阻燃性能。当EG-MPRSF含量为0.20%时,制备的EG-MPRSF@PBAT发泡珠粒复合材料压缩强度、回弹性和硬度分别比PBAT发泡珠粒提升77.8%、16.7%和45.2%,烟气生成速率和总烟释放量分别下降14.9%和24.8%,热释放总量降低17.1%。