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

Poly(butylene succinate) (PBS),poly(butylene terephthalate) (PBT) and poly(butylene succinate-co-terephthalate) (PBST)s were synthesized from dimethyl succinate and/or dimethyl terephthalate reacting with 1,4-butanediol through a process of transesterification/polycondensation 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.

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.

Nonisothermal Crystallization Kinetics of Poly(butylene adipate-co-terephthalate) Copolyester

Nonisothermal crystallization behavior of poly(butylene adipate-co-terephthalate)(PBAT) synthesized via direct esterification and polycondensation reactions was investigated by the differential scanning calorimetry(DSC).The Avrami equation modified by Jeziorny and the Z.S.Mo equation were employed to describe the non-isothermal crystallization kinetics of copolyester samples.The test results showed that the Avrami equation was successful in describing nonisothermal crystallization process of PBAT copolyesters.PBAT copolyester could give birth to secondary crystallization.The crystallization parameter(Zc) increased with an increasing cooling rate and the Avrami exponent(n) was around 2.3.For a given cooling rate,the value of Zc demonstrated a sagging trend with an increase in adipic acid(AA) content.The equation proposed by Z.S.Mo was successful in describing the nonisothermal crystallization kinetics of PBAT copolyesters.

Preparation and Properties of a New Type of Poly(butylene-terephthalate)with Layered Silicate Nanocomposites

In this paper, poly(butylene-terephthalate)-layered silicate of clay nanocomposites (NPBT) are reported. Their thermal properties, heat distortion temperature (HDT) and crystallization nucleation are investigated. NPBT samples have apparent viscosity over 0.85, HDT of 30℃ to 50℃ higher than that of poly (butyleneterephthalate) (PBT) for clay load from 1.0% to 10.0% (by mass), and higher capability to accommodate clay than other polymers. The nonisothermal crystallization experiments indicate that the better thermal degradation behavior and crystallization rate of NPBT are 50% higher than PBT, and its injection mould processing temperature is lowered from ll0℃ to 55℃. NPBT samples are characterized by several techniques. X-ray shows an original clay interlayer distance enlarged from 1.0 nm to 2.5 nm, while both TEM and AFM indicate an average size from 30nm to 100nm of exfoliated clay layers, and 3%(by mass) of particle agglomeration being phase separated from PBT matrix, which are factors on some mechanical properties decrease of NPBT. The disappearance of spherulitic morphology in NPBT resulted from layers nucleation is detected. Improving NPBT properties by treating clay with long chain organic reagent and controlling the way to load it is suggested.

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.

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.

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

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 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.

Enhanced Crystallization of Poly(butylene adipate-co-terephthalate)by a Self-assembly Nucleating Agent

Poly(butylene adipate-co-terephthalate)(PBAT)is a promising biodegradable flexible polymer but suffers from slow crystallization rate,making it less attractive for some applications like the injection-molded products in comparison with low-density polyethylene(LDPE).This work aimed to accelerate the crystallization of PBAT by adding a self-assembly nucleating agent octamethylenedicarboxylic dibenzoylhydrazide(OMBH).PBAT/OMBH composites with various OMBH contents(0 wt%,0.5 wt%,0.7 wt%,1 wt%,2 wt%,3 wt%and 5 wt%)were prepared through melt-mixing.The effect of OMBH on the crystallization behavior,morphologies and mechanical properties of PBAT was investigated.The highest nucleation efficiency value of 59.6%was achieved for PBAT with 0.7 wt%OMBH,much higher than that of 22.7%for PBAT with 0.7 wt%talc.Atomic force microscopy results showed that OMBH formed fine fibers and induced the formation of transcrystalline layers of PBAT.Fourier transform infrared spectroscopy(FTIR)combined with two-dimensional correlation spectra suggested that the intermolecular dipole-dipole N—H…O=C interactions but not hydrogen bond between OMBH and PBAT promoted the crystallization of PBAT in the initial period of crystallization.The presence of OMBH did not change the crystal form of PBAT but had positive contribution in enhancing its crystallinity and mechanical properties.This work is essential for preparing PBAT with high crystallization rate,enhancing its potential applications in injection-molded products.

淀粉的改性及其对淀粉/PBAT/碳酸钙复合材料结构和性能的影响

采用甘油、六偏磷酸钠(SHMP)和聚乙二醇(PEG)改性木薯淀粉并制备改性淀粉/聚己二酸对苯二甲酸丁二醇酯(PBAT)/碳酸钙复合材料,采用傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、差示扫描量热仪(DSC)、热失重分析仪(TG)等对改性淀粉和复合材料进行分析,研究改性淀粉对复合材料结构和性能的影响。结果表明,甘油的外增塑作用和PEG、SHMP的内增塑作用使淀粉化学结构改变、无定形成分增加,淀粉颗粒由饱满的圆球状变成了不规则的大颗粒,250℃前稳定性提高,250℃后稳定性降低,有利于使用加工和热分解,不同改性剂改性淀粉结晶熔融行为存在差异;复合不会改变PBAT、碳酸钙和淀粉的原有晶型,但相容性的差异导致复合材料热性能和力学性能的差异,改性淀粉增加了复合材料的韧性,甘油、SHMP和PEG的协同改性使淀粉与PBAT、碳酸钙的相容性最佳,复合材料的综合性能最好。

木质素在合成可降解高分子材料中的应用研究进展

简述了木质素的结构、特性和分类情况,并综述了近年来国内外使用木质素来增强和改善聚对苯二甲酸-己二酸丁二酯、聚乳酸、聚己内酯和聚丁二酸丁二酯等合成可降解高分子材料性能的研究进展。指出木质素与合成可降解高分子材料复合可以赋予复合材料多种功能特性,如紫外屏蔽、抗菌、阻隔等,并能改善材料的生物降解性能,同时实现降本增效的目标。最后提出当前木质素与合成可降解高分子材料复合材料工业化生产应用存在的问题,并对木质素基全生物降解复合材料的未来研究趋势进行展望。

静电纺丝HNTs/PBST复合纳米纤维膜的制备及其空气过滤性能研究

采用静电纺丝工艺,以可生物降解的聚丁二酸丁二醇-共-对苯二甲酸丁二醇酯(PBST)为原料,改性埃洛石纳米管(HNTs)为驻极体,制备了HNTs/PBST复合纳米纤维膜,探讨了HNTs对PBST纳米纤维膜的形貌、结构及空气过滤性能的影响。实验结果表明,改性HNTs添加量为10%(w)即可使PBST纳米纤维直径细化,协同增强了纳米纤维膜的物理筛分效应及静电吸引能力,显著提升了材料的综合过滤性能,HNTs/PBST复合纳米纤维膜对PM0.3的过滤效率高达96.67%,且过滤阻力仅为90.5 Pa。

界面强化增容反应程度对PLA/PBAT共混物结构和性能的影响

通过熔融共混法将具有不同环氧含量的界面增容剂(Joncryl ADR-4400和Joncryl ADR-4468)引入聚乳酸(PLA)/聚对苯二甲酸-己二酸丁二醇酯(PBAT)共混物中,并采用转矩流变仪、傅里叶红外光谱仪、差示扫描量热仪、动态热机械分析仪、流变仪、电子万能试验机和扫描电子显微镜等仪器研究界面增容反应程度对PLA/PBAT共混物微观分子链行为及宏观性能的影响。结果表明,界面增容剂结构中的环氧基团通过与PLA和PBAT的羟基或羧基反应,在两相界面处形成微交联结构,增强两相界面的相互作用,最终提高共混物的力学性能。材料的宏观性能测试表明,与环氧当量较高的ADR-4400相比,ADR-4468的引入形成了更加完善的微交联结构,界面相互作用更强,使PLA/PBAT/ADR-4468共混物中PLA的玻璃化转变温度提高至54.7℃。当ADR-4468添加量为0.75%时,PLA/PBAT/ADR-4468共混物拉伸强度达36.4 MPa,断裂伸长率达302%,缺口冲击强度可达9.6 kJ/m^(2),较未改性PLA/PBAT分别提高18%、560%和69%,材料刚韧平衡性优良。

硅油/PBAT复合材料的制备及耐热性能研究

聚己二酸-对苯二甲酸丁二醇酯(PBAT)作为生物可降解材料在包装领域应用广泛,但存在耐热稳定性差、易受环境影响发生老化等问题。本文采用熔融共混的方法,制备了不同添加比的端羟基硅油(SO)/PBAT复合材料,探讨耐热添加助剂对PBAT热稳定性和可降解性能的影响。结果表明,复合材料具有更好的耐热性,当SO质量分数达0.6%时,最终分解温度提高到411.02℃,热分解速率较纯PBAT降低了10.34%。SO的添加显著延缓了PBAT的热氧老化,SO/PBAT降解稳定性得到提升,热氧降解30 d后0.6%SO/PBAT的拉伸强度保持率较纯PBAT提高了27.48%,质量损失率较纯PBAT降低了20.78%。此外,复合材料的分子量下降幅度减缓,低场核磁反演曲线说明SO的添加并未改变PBAT的热氧老化机理。

PBAT/纤维素复合材料发泡行为研究

利用熔融共混法制备了己二酸丁二醇酯和对苯二甲酸丁二醇酯的共聚物(PBAT)/纤维素复合材料,将其压板后,以超临界CO_(2)为物理发泡剂,利用间歇式釜压升降温发泡方法,制备了PBAT/纤维素发泡材料。对复合材料的结晶性能,流变性能,发泡材料的发泡性能,压缩回弹性能进行研究。结果表明,纤维素的加入可以促进PBAT样品结晶,随着纤维素含量的增大,PBAT样品冷结晶峰先右移后左移,同时提升了复合材料的储能模量和复数黏度;发泡后,随着纤维素含量的增大,发泡样品的发泡倍率先增大后减小,而泡孔密度先减小后增大再减小;以PBAT-G-GMA为相容剂改善PBAT与纤维素的相容性,发泡样品泡孔形态稳定,纤维素的增加可以增加发泡样品的韧性;发泡样品在130℃浸泡2 h降温泄压后,随着泄压温度的升高,发泡样品的泡孔密度减小,泡孔尺寸及发泡倍率增大;当泄压温度为80℃,纤维素粉含量为10份时,发泡倍率达到13.06倍,泡孔密度为0.37×10^(10)个/cm^(3)。

酰肼类成核剂己二酸二苯基二酰肼对PBS复合材料性能的影响

聚丁二酸丁二酯(PBS)是近些年兴起的一类绿色环保高分子材料,具有良好的生物可降解性和生物相容性,是最具发展潜力的环境友好材料之一。然而PBS冲击强度较低,结晶性能较差,限制了其进一步的发展和应用。针对以上不足,采用酰肼类成核剂己二酸二苯基二酰肼(TMC-306)对PBS树脂进行改性,研究了酰肼类成核剂的添加量对PBS复合材料力学性能、结晶性能、加工性能以及微观形貌的影响。结果表明,TMC-306的引入明显改善了PBS/TMC-306复合材料的力学性能和结晶性能,当TMC-306添加量为15份时,PBS复合材料的冲击强度从41 J/m提高至102 J/m,提升了149%,结晶度从48.40%提高至62.01%,提升了28.12%。X射线衍射测试结果表明,成核剂TMC-306使复合材料晶面的衍射峰面积略微增大,与纯PBS晶型基本一致。流变测试结果发现,随着成核剂添加量的增加,PBS复合材料的储能模量、损耗模量和复数黏度均逐步增大,熔体强度得到了提高,这说明成核剂同时也改善了复合材料的加工性能。扫描电子显微镜测试结果表明,随着TMC-306的增加,PBS复合材料的断面由平整光滑变为“阶梯”式结构,且在添加量为15份时最为明显,这与力学测试结果相一致。