PLA与官能化的PMMA共聚物相容性的研究

采用无定形DL-PLA与官能化的PMMA熔融共混,采用DSC方法测试共混物的相容性,结果表明其共混物具有良好的相容性     

增塑剂/成核剂对PLLA/PDLA共混熔体流变纺丝性能影响

研究了PLLA/PDLA中加入增塑剂(PEG)和成核剂(TMC-306)的共混样品在不同温度和不同剪切速率下的流变性能以及熔融纺丝制备纤维的热性能分析.结果表明:PEG对PLLA/PDLA共混熔体的流变性能有促进作用,TMC-306对PLLA/PDLA共混熔体的流变性能有抑制作用,而同时加入PEG和TMC-306时,PEG和TMC-306的作用效果相互抵消,使得PLLA/PDLA共混熔体的流变性能与纯PLLA/PDLA的流变性能相近;熔融纺丝制备的纤维中同时加入PEG和TMC-306的样品中sc-PLA的含量最高,耐热性能最好,且纤维的强力和延伸性能都得到提高.     

左旋聚乳酸/右旋聚乳酸无规共聚物的共混纤维的制备与性能

采用右旋聚乳酸-己内酯无规共聚物(PDLA-r-PCL)对左旋聚乳酸(PLLA)进行改性,通过熔融纺丝-牵伸两步法分别制备PLLA、PLLA/PDLA-r-PCL共混纤维;采用差示扫描量热分析、毛细管流变仪、扫描电镜、广角X射线衍射及力学性能测试等方法对共混物及其共混纤维的结晶行为、热性能和力学性能进行研究。结果表明:m(PLLA)/m(PDLA-r-PCL)为95/5、90/10时,共混物具有较好的可纺性,热牵伸3倍后,纤维充分取向结晶,形成结构稳定的纤维;在相同纺丝条件下,PLLA/PDLA-r-PCL共混纤维的强度和韧性高于纯PLLA纤维。     

PET/PA66共混体系的DSC分析及相容性研究

采用溶液法、简单机械共混(熔融法Ⅰ)和存在酯-酰胺交换反应共混法(熔融法Ⅱ)将聚对苯二甲酸乙二酯(PET)与聚酰胺66(PA66)共混,系统地进行DSC分析,并对PET/PA66共混体系的相容性作了一定的探讨。结果表明,PET/PA66共混体系为一热力学不相容体系,共混物的相容性数熔融法Ⅱ共混物的为最佳,溶液法共混物的相容性最差。     

聚合物基底对PEG结晶形貌的影响

为了研究聚甲基丙烯酸甲酯(PMMA)和聚苯乙烯(PS)对聚乙二醇(PEG)结晶形貌的影响,利用偏光显微镜观察了PEG在PMMA和PS两种聚合物基底上的结晶形貌.采用两步成膜的方法分别制备PMMA和PS膜,以其为基底制备PEG膜.当PS为基底时,以乙醇为溶剂,PEG膜热退火后发生去润湿行为;以甲苯为溶剂,PS基底与PEG形成共混物,并发生宏观相分离.当PMMA为基底时,分别以乙醇、甲苯为溶剂,退火后PMMA均与PEG混溶,不发生去润湿行为,且形成羽毛状结晶形貌.实验结果表明:PS与PEG相容性较差,两者的分子链没有发生相互渗透的现象;PMMA与PEG的相容性较好,PMMA分子链渗入到PEG分子链中,影响其结晶速率和结晶形貌.     

不同分子量PCL/PLLA共混物的结晶行为研究

为了研究不同分子量PCL/PLLA共混物结晶行为,文中以二氯甲烷为溶剂对左旋聚乳酸(PLLA)与聚己内酯(PCL)进行溶液共混,制备不同质量比的PCL/PLLA共混物,并利用热台偏光显微镜(POM)和差示扫描量热仪(DSC)对共混物的结晶行为及结晶形貌进行表征与分析。实验结果表明:在PLLA10k中加入PCL2k和PCL10k,PCL的质量分数为10%～20%时对PLLA10k的结晶能力有促进作用;PCL2k/PLLA25k共混物中,随着PCL2k质量分数的增大,促进作用逐渐减小;加入PCL15k后对PLLA25k的结晶能力没有促进作用。POM结果表明,加入PCL后共混物的结晶速率降低,PCL不利于PLLA球晶生长速率的提高,并且PCL10k与PLLA10k共混时会发生宏观的相分离现象。     

PVC/蒙脱土复合材料的制备与性能研究

用乳液聚合的方法制备聚甲基丙烯酸甲酯(PMMA)/蒙脱土纳米复合材料.XRD分析表明PMMA嵌入了蒙脱土层间.使层间距明显扩大.用熔融共混的方法制备PVC/有机化蒙脱土复合材料并对其结构、力学性能、流变性能进行研究,证明该纳米复合材料能有效提高PVC的力学性能.     

双酚A型对位偶氮聚酯/聚碳酸酯共混物的研究

将双酚A型对位偶氮聚酯(p-PBAZO)和聚碳酸酯(PC)进行熔融共混,并使其发生酯交换反应,制备了p-PBAZO/PC共混物.根据p-PBAZO/PC共混物在二氯甲烷中的溶解性研究了酯交换程度,用SEM观察了共混物的形态,结果发现混炼10 min后体系酯交换程度高,p-PBAZO与PC相容性较好.共混物力学性能和光学性能研究结果表明所制备的p-PBAZO/PC共混物具有优异的透明性、光致变色性和力学性能.     

功能化氮化硼纳米片对左旋聚乳酸结晶行为的影响

将羟基官能化氮化硼纳米片(OH-BNNS)与左旋聚乳酸(PLLA)共混,制备PLLA/OH-BNNS纳米复合材料,由于PLLA中羰基和OH-BNNS中羟基存在氢键相互作用,OHBNNS良好地分散于PLLA中。通过各种技术手段研究了OH-BNNS对PLLA的熔融结晶行为,等温结晶动力学,宏观晶体形态、晶体结构的影响。发现添加OH-BNNS能有效加速PLLA的结晶,提高成核密度,导致球晶尺寸变小,结晶度增加,冷却时结晶峰更加明显,二次升温过程中冷结晶行为减弱。低OH-BNNS负载量可以增加α-晶的相对含量,但由于PLLA和OH-BNNS间强的相互作用,在高OH-BNNS负载量下,有序度较低的α′-晶的相对含量增加。     

ABS/PMMA合金性能研究

采用ABS/SAN/PMMA熔融共混的方法制备了不同配比的ABS/PMMA合金,就其组成、加工工艺条件对性能的影响进行了详细地研究.结果表明,ABS中引入PMMA可提高合金的拉伸强度,但在一定程度上降低了缺口冲击强度,当胶含量为12%时,合金产生脆韧转变.同时,注塑工艺条件对其力学性能也有一定影响.     

The Synthesis and Electrorheological Properties of BaTiO_3-coated PMMA Microspheres

Coated-PMMA microspheres consisting of poly (methyl methacrylate)(PMMA) core and barium titanate (BaTiO3) shell were synthesized by the modified sol-gel processing and then adopted as an electrorheological (ER) materials. The structure and morphology of coated powders were characterized by SEM and FT-IR; the shear stress of the suspensions of coated-PMMA particles and pure PMMA particles in silicone oil with a 20 vol% were investigated. The results show that the BaTiO3 coated PMMA microspheres based suspension in silicone oil exhibited typical ER behavior and stronger ER effects.     

Rheology-morphology relationship in polystyrene/poly(methyl methacrylate) blends

The relationship between rheological properties and morphology of immiscible polystyrene(PS)/poly(methyl methacrylate)(PMMA) blends was studied.The blends were prepared using a twin screw extruder.A single screw extruder equipped with a slit die was used to perform shear flow measurements of PS/PMMA blends.Morphological examinations were conducted on the cryogenically fractured and extracted samples by scanning electron microscopy.The results show that the melt viscosity of PS/PMMA blend decreases with increasing shear stress,which is attributed to not only the disentanglement of macromolecules but also the reduction in the domain size and the resultant increase of the interfacial area.The power-law index of the blend melt is lower than any of its component melt,suggesting that deformation and breakup of the dispersed phase increase the dependence of the melt viscosity on the shear stress.The blend whose domain size decreases at a faster rate with increasing shear stress,exhibits a strong shear rate dependence on the melt viscosity.The comparison of the morphologies of samples before and after the slit section of the die indicates that the morphology of the blend has a quick response to shear flow,the coalescence of the dispersed drops is predominant for blends at low shear rates.     

The Synthesis and Eleetrorheologieal Properties of BaTiO3-coated PMMA Mierospheres

Coated-PMMA microspheres consisting of poly （methyl methacrylate）（PMMA） core and barium titanate （BaTiO3） shell were synthesized by the modified sol-gel processing and then adopted as an electrorheological （ER） materials. The structure and morphology of coated powders were chyfecterized by SEM and FT-IR; the shear stress of the suspensions of coated-PMMA particles and pure PMMA particles in silicone oil with a 20 vol% were investigated. The results show that the BaTiO3 coated PMMA microspheres based suspension in silicone oil exhibited typical ER behavior and stronger ER effects.     

Preparation of monomer of degradable biomaterial poly（L-lactide）

1INTRODUCTION Polylactide,oneoftheimportantbiodegrada blematerials,whichhasfavorablebiocompatibility andabsorption[1],hasbeenusedinimplant,chor dasericachirurgicalis,drugcontrolledrelease,boneinternalfixation,tissueengineeringetc[25]. Thepoly(L lactide)(PLLA)withhighrelative molecularmasswasobtainedbyring openingpoly merizationatpresent.Thatis,firsttheintermedi ateproduct(lactide)wasobtainedfromlacticacid, thenthepoly(L lactide)wasobtainedfrominter mediateproductbyring openingpolymer…     

溶剂蒸汽诱导非晶左旋聚乳酸薄膜结晶的原位光谱研究

利用时间分辨的傅里叶变换红外光谱(FT-IR),结合自制实验附件,对室温溶剂诱导左旋聚乳酸(PLLA)薄膜结晶过程中的结构变化进行原位光谱研究,从分子水平上揭示PLLA从无序到有序的结构演变。结果表明:多种溶剂诱导PLLA结晶均形成α′晶型。温度升高时,结晶速率加快,结晶活化能为Ea≈146.1×103 J.(mol.K)-1。除甲苯外,多数溶剂诱导均能诱导PLLA结晶,但其诱导结晶能力不同,其中丙酮可以最有效地加速PLLA结晶。计算所得PLLA的红外结晶度大小顺序为氯仿>丙酮>四氢呋喃>乙酸乙酯>乙醇>甲苯。结晶度较大者对应溶剂的溶度参数与PLLA的溶度参数相近。     

In vitro characterization of PBLG-g-HA/ PLLA nanocomposite scaffolds

The purpose of the present study was to synthesize a new composites scaffold containing poly(γ-benzyl-L-glutamate) modified hydroxyapatite/(poly(L-lactic acid))(PBLG-g-HA/PLLA) and to investigate their in vitro behaviour on bone mesenchymal stromal cells(BMSCs). The results demonstrated that BMSC proliferation was signifi cantly increased on PBLG-g-HA/PLLA scaffolds after 3 and 7 days post seeding when compared to PLLA and HA/PLLA scaffolds. The in vitro osteogenic differentiation also favoured the composite PBLG-g-HA/PLLA scaffolds when compared to controls by signifi cantly increasing Runx2, ALP or osteocalcin mRNA expression as assessed by real-time PCR. The results illustrate the potential of PBLG-g-HA/PLLA scaffolds for bone tissue engineering applications. And the in vivo testing further confi rms the PBLG-gHA/PLLA scaffolds' potentioal for healing critical bone defects.     

Characterization and Saturable Absorption Property of Graphene Oxide on Optical Fiber by Optical Deposition

We prepared graphene oxide(GO) saturable absorber(SA) successfully through optical deposition method, which is a simple but effective approach to deposit various materials onto substrate under the effects of light, and investigated several factors that influence the optical deposition result of GO onto optical fiber end, including poly(methyl methacrylate)(PMMA) concentration, light intensity, light mode, and deposition time. The efficient optically deposited GO preserving its nonlinearity guaranteed by GO/PMMA composite formation was also demonstrated. The GO SA prepared by optical deposition shows superior saturable absorption property with modulation depth and nonsaturable loss of 6% and 40%, respectively.     

Preparation of high viscosity average molecular mass poly-L-lactide

1 INTRODUCTION In recent years, much attention has been focused on biodegradable and biocompatible polymers. Among biodegradable biomaterials, poly-L-lactide(PLLA) is a widely used polymer[1?2]. PLLA is currently used in medicine, including drug delivery systems and hard tissue scaffolds. For hard tissue scaffolds, a certain strength is demanded due to the coordination of strength loss and tissue healing rate to support loading after all degradation of the implant[3]. Many studies on c…     

Melt synthesis and characterization of poly(L-lactic acid) chain linked by multifunctional epoxy compound

High molecular weight(Mw) poly(L-lactic acid)s(PLLAs) were synthesized using multifunctional epoxy compound(Joncryl-ADR4370) as chain extender. The products were characterized by gel permeation chromatography(GPC) and spectroscopy(¹HNMR and FTIR). The results indicated that the Mw of PLLA increased with the increasing of the ratio of epoxy compound and the extending of reaction time. The highest M _w of PLLA reached 360 000 g/mol when the ratio of epoxy compound was 1.5 wt%. However, the reactants turned to cross-linking when the ratio of epoxy compound was over 1.5 wt%. Differential scanning calorimetry(DSC) measurements demonstrated that the glass transition(T _g) and melting temperatures(T _m ) of products increased slightly as the increase of the molecular weight. Analysis of the hydrolytic degradation in vitro showed that the branched PLLA possessed the quicker degradability than that of the linear PLLA.     

Synthesis and characterization of polyepichlorohydrin-based copolymers with biphenyl groups attached thioether unit

Three novel copolymers,poly[1-(4-(benzothiazole-2-thio-alkyloxy)-biphenyl-4'-oxy)2.3-epoxypropane]s,were synthesized by the reaction of polyepichlorohydrin with obtained monomers,4-(benzothiazole-2-thio-alkyloxy)biphenyl-4'-ols,in which the number of methylene unit in substitution group of biphenyl group was 2,4,6,respectively.The structures of obtained compounds were confirmed by elemental analysis and 1H NMR.The decomposition temperatures of copolymers were near 340 ℃.Differential scanning calorimetry(DSC) measurement and polarized optical microscopy(POM) observation showed the resulting copolymers did not exhibit thermotropic liquid crystalline mesomophism and belonged to semi-crystalline substance.