Thermal,Rheological and Mechanical Properties of Biodegradable Poly(propylene carbonate)/Epoxidized Soybean Oil Blends

Biodegradable poly(propylene carbonate)(PPC)/epoxidized soybean oil(ESO)blends with different component ratios were prepared by melt blending to improve the performance of PPC.The phase morphology,thermal properties,rheological properties and mechanical properties of the blends were in vestigated in detail.SEM exami nation revealed good in terfacial adhesi on betwee n PPC matrix and ESO.According to DSC and DMA,as the content of ESO increased,the glass transition temperature of the PPC component increased,indicating that there was a strong in terfacial in teracti on between the PPC matrix and ESO.The in terfacial in teraction may be caused by rin g-opening reaction between the hydroxyl end groups of PPC and the epoxy groups of ESO,which restricted the chain movement of PPC matrix.The disappearanee of the epoxy groups in FTIR indicated that the in terfacial in teracti on betwee n the two phases was due to the rin g-openi ng reactio n betwee n PPC and ESO.With the addition of ESO,the thermal stabilities were enhanced.With the increasing ESO content,the modulus gradually decreased.However,the stre ngth at yield,the strength at break and the elon gation at break were in creased for the PPC/ESO blends,suggest!ng that the enhancement of the strength and toughness of PPC was achieved by the incorporation of ESO.The rheological measurement revealed that the complex viscosity,storage modulus and loss modulus of PPC were in creased with the increasi ng ESO content at low freque ncy,which indicated that the addition of ESO enhanced the melt strength of PPC in stead of plasticizi ng PPC.

Isothermal Crystallization Behavior of Poly (ethylene terephthalate)/Carbon Black Masterbatch

Poly(ethylene terephthalate) (PET)/carbon black (CB) masterbatch was prepared by melt blending using a separate feeding technique and its homogeneous dispersion morphology was confirmed by transmission electron microscope (TEM). The Avrami and Hoffman-Lauritzen secondary nucleation theories were employed to analyze the effect of high CB content on crystallization kinetics of PET, providing theoretical support for the development of masterbatch with high content of functional components. The Avrami exponents,average values of n,for PET and PET/CB masterbatch are both greater than 3, which indicates three-dimensional growth of crystals. In addition,no significant evidence for regime transition of PET is found applying Hoffman-Lauritzen secondary nucleation theory,though such observations have been reported previously in the literature. Furthermore,appropriate U* value for PET is determined to be 12 800 J/mol. For PET/CB masterbatch,a transition from regime I to regime II around 225℃ is observed with appropriate U* value (12 800 J/mol) . This phenomenon is consistent with a transition point in plot of G versus Tc . The fold surface free energy σe (100. 3 mJ/m 2) of PET is much greater than that of PET/CB masterbatch (48. 3 mJ/m 2) ,which indicates heterogeneous nucleation effect of CB particles.

Biodegradable Poly(propylene carbonate)/Layered Double Hydroxide Composite Films with Enhanced Gas Barrier and Mechanical Properties

Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. A series of poly（propylene carbonate）（PPC）/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient（OP） and water vapor permeability coefficient（WVP） is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.

MISCIBILITY,CRYSTALLIZATION AND MECHANICAL PROPERTIES OF PPC/PBS BLENDS

In this paper, melt blends of poly（propylene carbonate） （PPC） with poly（butylene succinate） （PBS） were characterized by dynamic mechanical analysis （DMA）, differential scanning calorimetry （DSC）, tensile testing, wide-angle X-ray diffraction （WAXD）, polarized optical microscopy and thermogravimetric analysis （TGA）. The results indicated that the glass transition temperature of PPC in the 90/10 PPC/PBS blend was decreased by about 11 K comparing with that of pure PPC. The presence of 10% PBS was partially miscible with PPC. The 90/10 PPC/PBS blend had better impact and tensile strength than those of the other PPC/PBS blends. The glass transition temperature of PPC in the 80/20, 70/30, and 60/40 PPC/PBS blends was improved by about 4.9 K, 4.2 K, and 13 K comparing with that of pure PPC, respectively; which indicated the immiscibility between PPC and PBS. The DSC results indicated that the crystallization of PBS became more difficult when the PPC content increased. The matrix of PPC hindered the crystallization process of PBS. While the content of PBS was above 20%, significant crystallization-induced phase separation was observed by polarized optical microscopy. It was found from the WAXD analysis that the crystal structure of PBS did not change, and the degree of crystallinity increased with increasing PBS content in the PPC/PBS blends.

Synthesis and Properties of Poly(butylene carbonate-co-spirocyclic carbonate)

Poly(butylene carbonateXPBC) has significantly promising applications as a degradable material in the field of polymers, while its poor thermal performance and low crystallization rate are its main defects. To overcome these shortcomings, a series of poly(butylene carbonate-co-spirocyclic carbonateXPBSC) copolymers were synthesized from diphenyl carbonate, 1,4-butanediol and spiroglycol via two-step polycondensation reactions, using magnesium oxide as a catalyst. Differential scanning calorimetry(DSC) results indicated that the glass transition temperature(Tg) values of PBSC copolymers were enhanced from -19℃ to 56℃ with rising the spiroacetal moiety content. Thermogravimetric analysis(TGA) results showed that the resulting PBSCs have a higher thermal stability than that of poly(butylene carbonate). Wide angle X-ray diflraction(WXRD) patterns were characterized to investigate the crystallization behaviour of PBSCs. Tensile testing demonstrated that copolymerization of spiroacetal moieties into PBC chains imparted PBSC with favourable mechanical performance. Typically, PBSC 30 had a tensile modulus of (1735±430) MPa, a tensile strength of (42±5) MPa and an elongation of 504%±36%.

EFFECT OF NANO-FILLER DISPERSION ON THE THERMAL,MECHANICAL AND WATER SORPTION PROPERTIES OF GREEN ENVIRONMENTAL POLYMER

Partially exfoliated nanocomposite （2） has been synthesized by intercalation of poly（propylene carbonate） （PPC） into commercial clay, Cloisite 20B （PPC/C-20B）. Nanocomposite 2 was characterized phiso-chemically and exhibited high thermal, mechanical and anti-water sorption properties as compared to PPC and intercalated nanocomposite （1） of PPC/C- 20B having same amount of clay. TGA results revealed that the thermal decomposition temperature （Td, 50%） of 2 increased significantly, being 40 K and 17 K higher than that of pure PPC and 1, respectively, while DSC measurements indicated that the nano-filler dispersion of 2 increased the glass transition temperature from 21℃ to 31℃. Accordingly, 2 showed high elastic modulus, hardness and anti-water absorption capacity. These thermal, mechanical alad anti-water absorption improvements are of great importance for the application of PPC as packaging and biomaterials.

聚碳酸亚丙酯(PPC)加工热稳定性研究

可降解聚碳酸亚丙酯(PPC)加工热稳定性较差。采用高压毛细管流变仪、傅里叶红外光谱仪(FT-IR)、热失重仪(TG)、拉力机和色差仪对工业级PPC的加工热稳定性进行了系统测试和分析。结果表明,使用高压毛细管流变仪可以较好地评估PPC的加工热稳定性。热失重法可以评估PPC的加工热稳定性,但评估不同加工条件下或不同加工配方的PPC热稳定性灵敏度不高。其它方法均不适宜于评估该材料。本研究对PPC的加工有一定的指导作用,并为今后提高PPC加工热稳定性的研究提供技术支持。

不同分子量聚丙撑碳酸酯的封端及热分解

采用不同封端剂对聚丙撑碳酸酯(PPC)进行了封端,并研究了封端前后PPC的热降解动力学。结果表明封端极大地提高了PPC的热降解温度,未封端PPC同时按多种机制进行热降解,而封端PPC在整个降解过程中只按无规断链机制降解。不同分子量的PPC的热重结果表明未封端PPC的起始降解温度随着分子量的提高而提高,而封端PPC的热降解温度与分子量的关系不大。

环境友好材料-聚碳酸亚丙酯热降解和稳定性研究进展

聚碳酸亚丙酯（PPC）是由二氧化碳和环氧丙烷合成的一类新型高分子材料,具有透明性、生物降解性和生物相容性等特点,可以用作包装材料、气体阻隔材料、生物医用材料等方面.但是,由于PPC的热稳定性较差,在150-180℃的范围内就会出现降解,这样使其应用受到限制.另外,由于在工业生产中大部分高分子材料的加工温度高于150℃.在这样的加工条件下,PPC会发生明显的降解,从而导致共混效果差.因此,关于提高热稳定性的研究一直是PPC改性的研究重点.综述了聚碳酸亚丙酯的热降解机理及其影响因素,并对目前提高PPC热稳定性的方法及研究成果进行了简要介绍.

聚碳酸亚丙酯/聚乙烯醇共混复合材料的性能

采用熔融共混挤出的方式制备了可生物降解的聚碳酸亚丙酯(PPC)/聚乙烯醇(PVA)复合材料。运用差示扫描量热仪(DSC)、热失重分析仪(TGA)、扫描电子显微镜(SEM)和万能试验机分别研究了复合材料的相容性、热稳定性、微观形态以及力学性能。结果表明:复合体系中材料的相容性较好,改性PVA的引入提高了复合材料的热稳定性和拉伸强度,当改性PVA的质量分数为50%时,拉伸强度达到39.2 MPa,提高了约177%。

异氰酸酯接枝改性淀粉/聚碳酸亚丙酯共混物及性能

为提高淀粉(Starch)与聚碳酸亚丙酯(PPC)的界面作用力,在淀粉颗粒与PPC复合时加入二苯基甲烷二异氰酸酯(MDI),进行反应性共混改性,通过FTIR、DSC、TGA、SEM、拉伸测试等手段对共混物进行表征,验证了接枝作用的发生,同时讨论了在熔融状态下,MDI对共混物接枝改性的作用效果。结果表明:有PPC大分子接枝到淀粉颗粒表面上。正是接枝的PPC在两相间充当兼容剂,提高了其相容性,增强了PPC相与淀粉颗粒之间的界面粘接力,使得形态结构稳定化,从而使得力学性能和热稳定性得到有效改善。

聚碳酸亚丙酯/凹凸棒纳米复合材料制备与热稳定性研究

通过溶液共混法制备了聚碳酸亚丙酯/凹凸棒纳米复合材料。利用FT-IR、XRD和SEM表征手段研究了复合材料的结构。研究表明有机改性的凹凸棒在聚碳酸亚丙酯中分散均匀,平均粒径为70nm。利用TG研究了聚碳酸亚丙酯/凹凸棒纳米复合材料的热稳定性,结果发现纳米尺寸凹凸棒的引入能够显著提高聚碳酸亚丙酯的热稳定性,其中凹凸棒含量为0.5%的复合材料热稳定性最好,其5%、50%和最大热分解温度分别为273℃、291℃和289℃,相比PPC分别提高了63℃、53℃和52℃。

生物降解PPC/HA复合材料的制备与性能研究

将羟基磷灰石(HA)用硅烷偶联剂KH570处理,然后与聚碳酸亚丙酯(PPC)进行共混,制备了一种可生物降解、生物相容性好的PPC/HA复合材料,研究了其在不同混合比例时的力学性能、玻璃化转变温度及其内部结构。该复合材料力学强度介于塑料和橡胶之间,具备良好的力学回复特性和一定的形状记忆效应,HA为20％(质量分数,下同)时,断裂伸长率达到315％,弹性回复率可达98％。DSC分析表明,复合材料的玻璃化转变温度受HA的影响不大,在35℃左右,随HA含量的不同略微有一些变化。SEM观察到在拉伸过程中,复合材料内部出现一种板块与微纤复合结构,这种结构对材料的力学性能变化有一定影响,可能也是力学回复特性产生的原因。

聚氯乙烯/聚丙撑碳酸酯共混体系研究

聚合物共混物相容性影响其性能.加入非反应性的共聚物、反应性聚合物及低分子量化合物等可使共混物的增容,或通过熔融反应就地形成接枝共聚物.聚丙撑碳酸酯(PPC),是由二氧化碳和环氧丙烷聚合而成的新型含端羟基脂肪族聚碳酸酯,是一种粘性体,可作为 PVC 的长效增塑剂.

聚甲基乙撑碳酸酯热降解动力学研究

利用热重分析法,在不同升温速率下,对聚甲基乙撑碳酸酯热分解动力学进行研究.采用Kissinger,Flynn-Wall-Ozawa和Coats-Redfern等方法对其动力学数据进行分析.结果表明,聚甲基乙撑碳酸酯具有高的热稳定性能,确定其热反应机理函数为Mampel power法则,活化能E≈108kJ.mol-1.PPC的热降解反应遵循R1一维的相边界反应动力学机理,热降解反应首先发生在样品表面,并逐渐向内部推进.

PPC/SPI复合膜的制备与性质

以大豆分离蛋白(soy protein isolate,SPI)、聚丙撑碳酸酯(poly(propylene carbonate),PPC)为原料,甘油为增塑剂,采取挤压成膜的方法制备PPC/SPI复合膜,并研究PPC与SPI的质量比对复合膜的力学性质、不透明性、耐水性(吸水性和水溶性)的影响以及分析复合膜的热特性和结构。结果表明:随着PPC与SPI质量比(1.0∶1、1.5∶1、2.0∶1、2.5∶1、3.0∶1)的增加,复合膜的柔韧性增强,不透明度增加,吸水率成下降趋势,膜的质量损失率显著降低;同时PPC/SPI复合膜具有良好的热稳定性和稳定、致密均一的结构。

端羟基聚碳酸亚丙酯的MDI扩链及热稳定性

用4,4′-二苯基甲烷二异氰酸酯(MDI)对端羟基聚碳酸亚丙酯(PPC)进行扩链改性,考察了实验条件及MDI用量对反应的影响。用凝胶渗透色谱法对产物进行测试发现,随着MDI用量的增加,产物的数均分子量增加,相对分子质量分布变窄。通过对产物进行红外光谱测试,从峰的变化可看出MDI和端羟基发生了反应,生成了预期产物。通过对产物的热重分析发现,w(MDI)分别为0.5%,1.0%,2.0%时,最大分解温度由扩链前的257.64℃分别提高至274.40,278.22,279.49℃,热稳定性得到改善;且热降解方式由解拉链式降解逐渐变为主链无规断链降解。

全生物降解聚乳酸/聚碳酸亚丙酯共混物研究进展

介绍了完全生物降解的聚乳酸(PLA)/聚碳酸亚丙酯(PPC)共混物的研究进展,重点介绍了共混物的相容性、熔融及结晶行为、力学性能、流变性能及加工性能等方面的研究成果。

聚碳酸亚丙酯／聚甲基丙烯酸甲酯复合材料热降解动力学研究

利用溶液共混法制备聚碳酸亚丙酯/聚甲基丙烯酸甲酯(PPC/PMMA)复合材料,采用热重分析法研究PPC/PMMA热性能,结果表明PMMA的加入可以有效提高PPC的热稳定性能。以多升温速率法对PPC/PMMA热降解动力学进行研究,利用Friedman法、Kissinger法、Flynn-Wall-Ozawa法、Coats—Redfem方法对热降解动力学数据进行分析,确定PPC/PMMA热分解反应机理函数为Avrami-Erofeev方程,遵循一种热降解机理。

PHBV/PPC反应共混物的热性能与动态力学性能及形态结构

将甲基丙烯酸缩水甘油酯接枝的聚(β-羟基丁酸酯-co-β-羟基戊酸酯)(PHBV-GMA)与马来酸酐封端的聚碳酸亚丙酯(MA-PPC)反应性共混。采用差示扫描量热仪、动态力学分析仪和偏光显微镜分别研究了共混物的热性能、动态力学性能和形态结构。结果发现,通过反应接枝,MA-PPC降低了PHBV的结晶度,阻碍了PHBV的结晶,PHBV部分扩散进入MA-PPC相区。PHBV球晶尺寸降低,PHBV和MA-PPC共混组分的相容性得以改善。