PHBV/PLA纤维和其他纤维混合试样的定量分析方法研究

采用化学分析和红外光谱分析相结合的方法研究了生物基聚3-羟基丁酸-戊酸酯/聚乳酸(PHBV/PLA)纤维和其他纤维(涤纶、棉纤维、羊毛、锦纶6)混合的试样(简称多组分混合纤维试样)的定量分析方法。结果表明:首先在常温条件下,采用二氯甲烷溶解多组分混合纤维试样中的PHBV/PLA纤维,得到PHBV/PLA纤维的含量和其他纤维的含量,该方法的绝对误差为-0.5%~0.5%,95%置信界限为(-0.2%,0.2%);然后选定合适溶剂对多组分纤维混合试样中的其他纤维进行溶解得到PHBV/PLA纤维,对PHBV/PLA纤维中的PHBV和PLA的含量采用红外光谱法进行定量分析,将1707.2~1731.8 cm^-1的峰面积和1731.8~2038.8 cm^-1峰面积之比作为PHBV和PLA组分的对应质量比,以此来计算试样中PHBV和PLA的含量,该方法采用经典最小二乘法建立模型,7个校准点拟合的回归方程其线性相关系数为0.9978,校正标准偏差为0.442;10个验证点拟合的回归方程的线性相关系数为0.9943,预测标准偏差为0.617%。     

PLA/PHBV纤维的热学性能

对聚乳酸/聚(3-羟基丁酸酯-co-3-羟基戊酸酯)(PLA/PHBV)纤维进行了热失重分析、差示扫描量热分析、热收缩测试及燃烧性能测试。结果表明:PLA/PHBV纤维的起始分解温度为232℃左右,体现出较好的热稳定性;PLA/PHBV纤维的DSC曲线有两个熔融峰,PLA组分的熔融峰温度为149℃,PHBV组分的熔融峰温度为161.8℃;PLA/PHBV纤维的沸水收缩率为7.5%,表现出了良好的热收缩性能;PLA/PHBV纤维表现出优异的阻燃性能。     

PHBV/PCL共混纤维的结构与性能

采用熔融纺丝法制备聚羟基丁酸戊酸酯(PHBV)/聚ε-己内酯(PCL)生物可降解共混纤维。采用差示扫描量热仪、广角X射线衍射仪、热台偏光显微镜和傅立叶变换红外光谱仪对PHBV/PCL共混体系的相容性和结晶性能进行了表征。结果表明:PHBV和PCL是不相容的;PHBV/PCL共混体系中的PHBV影响了PCL的结晶机制和结晶速率,PCL的结晶形态没有改变;PCL不影响PHBV的结晶机制,降低了PHBV的结晶速率,改变了PHBV的结晶形态。     

PLA/PHBV共混改性研究

采用熔融共混法制备了聚乳酸/聚(3-羟基丁酸-co-3-羟基戊酸酯)(PLA/PHBV)共混物,研究了PLA/PHBV质量比以及滑石粉(Talc)含量对PLA/PHBV共混物性能的影响。结果表明,随着PHBV含量的增加,PLA/PHBV的结晶度先降低后升高,断裂伸长率提高了21.81%,冲击强度提高了35.9%,拉伸强度下降;随着Talc含量的增加,PLA/PHBV/Talc的结晶度增大,冲击强度提高了12.4%,但是断裂伸长率和拉伸强度有所下降;在不显著降低拉伸强度和弯曲强度的前提下,PHBV的含量为20%(质量分数,下同)且Talc含量为1.5%时,复合材料的力学性能最优。     

PHBV共混物纤维制备组织工程支架的研究

利用聚羟基丁酸酯/聚羟基戊酸酯(PHBV)共混材料为基质,通过熔融纺丝、压片成型以及纤维熔结工艺,制得了组织工程用三维多孔支架。研究了PHBV共混材料的吸水率与溶胀比以及支架的熔结温度。结果表明:PHBV共混材料的吸水率较PHBV大为提高,有利于改善PHBV材料的亲水性。其溶胀比较低有助于保持组织工程支架的尺寸稳定性。PHBV共混物纤维的最佳熔结温度在130～140℃范围。采用压片成型/纤维熔结法可制得孔径在300~500μm之间、贯通性好的三维立体支架。降解实验表明:支架材料的降解会引起pH值的微弱下降,支架材料的降解速率较慢。     

扩链剂TMP-6000对聚乳酸/聚（3-羟基丁酸-co-3 -羟基戊酸酯）共混物性能的影响

以扩链剂TMP-6000为增容剂,采用熔融共混制备了聚乳酸（PLA）和聚（3羟基丁酸co3羟基戊酸酯）（PHBV）复合材料,研究了TMP-6000对PLA/PHBV复合材料的结晶行为、微观结构、力学性能的影响。结果表明,无定形PLA的加入抑制了PHBV的结晶,TMP-6000的加入使得PLA/PHBV复合材料的结晶能力变弱,提高了PLA的冷结晶温度,且当TMP-6000含量为0.5 %（质量分数,下同）时,PLA的冷结晶峰开始消失,且适量的TMP-6000使得PHBV的玻璃化转变温度（Tg）升高;TMP-6000的加入使得PHBV均匀分散于PLA基体中,且当TMP-6000含量为0.7 %时,PLA与PHBV的相容性最好;TMP-6000的加入显著提高了PLA/PHBV复合材料的分子量;TMP-6000提高了PLA与PHBV之间的结合力,提高了复合材料的拉伸强度,但断裂伸长率有稍微地降低。     

PHBV增韧PLA的结晶及力学性能研究

采用熔融共混法,以聚(3-羟基丁酸-co-3-羟基戊酸酯)(PHBV)为增韧剂对聚乳酸(PLA)进行改性,得到PLA/PHBV复合材料。研究了PHBV用量对PLA/PHBV复合材料结晶性能和力学性能的影响。结果表明:随着PHBV用量的增加,PLA/PHBV复合材料的结晶度逐渐减小,拉伸强度和弯曲强度逐渐降低,而断裂伸长率则逐渐增大(当PHBV用量为50%时,复合材料的断裂伸长率比纯PLA提高了1.72倍),同时复合材料的冲击强度亦有所提高。由此可见,在不明显降低拉伸强度和弯曲强度的前提下,适量PHBV的添加能够改善PLA/PHBV复合材料的韧性。     

聚乳酸/聚羟基烷酸酯全生物降解共混物研究进展

介绍了聚乳酸(PLA)/聚羟基烷酸酯(PHA)全生物降解共混物研究进展,包括PLA/聚羟基丁酸酯(PHB)共混物、PLA/β-羟基丁酸酯与β-羟基戊酸酯共聚物(PHBV)共混物等,其中重点介绍了其相容性与相态结构、结晶性能、热性能、力学性能、降解性能等方面的研究成果。     

成核剂对PHBV结晶影响的研究

通过熔融共混的方法,分别将成核剂A、成核剂B、氧化锌(ZnO)、二氧化硅(SiO₂)与聚-3-羟基丁酸/戊酸酯(PHBV)进行共混,研究了它们对PHBV结晶性能的影响。利用差示扫描量热仪研究了复合材料的等温结晶和非等温结晶动力学,利用热台偏光显微镜观察了晶体成核和生长过程。结果表明,这些成核剂均可以改善PHBV结晶不完善的情况,使PHBV的熔融峰从2个变为1个;成核剂A和B可改善PHBV的成核效果,提高PHBV的结晶速率,且球晶尺寸明显细化;加入SiO₂后,形成了同心圆球晶,结晶速率获得改善。     

PHBV共混改性研究进展

介绍了聚(β-羟基丁酸戊酸酯)(PHBV)的现有生产状况、性能特点以及存在的不足。简述了PHBV结晶改性的研究成果,总结了PHBV共混改性的研究进展,包括PHBV与聚乳酸(PLA)、聚己内酯(PCL)、聚己二酸/对苯二甲酸丁二醇酯(PBAT)、二氧化碳共聚物(PPC)、淀粉、纤维素及有机黏土等。     

A comparative study on protective properties of electrosynthesized poly(pyrrole)/poly(N-methylpyrrole), poly(pyrrole)/poly(N-phenylpyrrole), poly(pyrrole)/poly(N-methoxyphenylpyrrole) composite coatings

In this study, three sets of different bilayered composite coatings of pyrrole and N-substituted pyrroles were synthesized by a layer-by-layer approach on copper surface and corrosion performances of the synthesized materials were compared. Electrodepositions of poly(N-methylpyrrole), poly(N-phenylpyrrole), and poly(N-methoxyphenylpyrrole) were performed in nonaqueous medium on a poly(pryrrole)-coated copper surface using cyclic voltammetry. The morphologies of the resulting bilayered composite coatings of poly(pyrrole)/poly(N-methylpyrrole), poly(pyrrole)/poly(N-phenylpyrrole), and poly(pyrrole)/poly(N-methoxyphenylpyrrole) were investigated by scanning electron microscopy. Stabilities of a doping-dedoping process of the composites were determined from the cyclic voltammetric study of the bilayer-coated electrodes in a monomer-free solution. Corrosion performances of the bilayer composite-coated and uncoated copper electrodes were investigated in 0.1 M H₂SO₄ solution using open circuit potential–time (E _ocp–t) curves, anodic polarization, and electrochemical impedance spectroscopy. All the investigated bilayered coatings gave significant enhancement in the corrosion resistance of copper, compared to the single poly(pyrrole) coating. Stability and corrosion tests revealed that the composite material poly(pyrrole)/poly(N-methoxyphenylpyrrole) exhibited higher electrochemical stability and corrosion resistant behavior than the other bilayered composite coatings.     

Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(styrene-co-acrylonitrile) and poly(p-methylstyrene-co-acrylonitrile)

The miscibility of poly(methoxymethyl methacrylate) (PMOMA) and poly(methylthiomethyl methacrylate) (PMTMA) with poly(styrene-co-acrylonitrile) (SAN) and poly(p-methylstyrene-co-acrylonitrile) (pMSAN) was studied by differential scanning calorimetry. PMOMA is miscible with SAN having an acrylonitrile (AN) content around 30 wt %. However, PMOMA is immiscible with any of the pMSAN having AN contents between 9 and 36 wt % and with pMSAN having AN contents between 19 and 34 wt %. The miscibility of the blends enables the evaluation of various segmental interaction parameters.     

Flame retardation of poly(ethylene terephthalate) containing poly(4-bromo styrene), poly(vinyl bromide), and poly(vinylidene bromide)

The pyrolysis and gaseous combustion of poly(ethylene terephthalate) (PET) incorporating poly(4-bromostyrene), poly(vinyl bromide), and poly(vinylidene bromide) has been studied using thermogravimetry, flammability limit evaluation, and hydrogen bromide (HBr) evolution techniques. The data obtained have been compared with limiting oxygen index (LOI) flammability data to elucidate flame retardation mechanisms. All the organo bromides studied (applied either via topical treatment or radiation grafting) released HBr on pyrolysis which is capable of inhibiting the gas phase combustion reactions. Condensed phase interactions were also detected which were capable of altering the gaseous pyrolysates. Thermal stability considerations suggest that, although the aliphatic bromides are excellent sources of HBr, they are not ideal flame retardants for PET.     

Miscibility of poly(caprolactone)/chlorinated polypropylene and poly(caprolactone)/poly(chlorostyrene) blends

Poly(caprolactone) (PCL) was blended with poly(chlorostyrene) (PSCI) and chlorinated polypropylene (PPCl). A single glass transition temperature T_g was found for these mixtures, indicating their miscibility. PCL crystallizes in these blends when the chlorinated polymer content is not too high. Otherwise, T_g becomes higher than the melting point of PCL and the high viscosity of the medium hinders the crystallization. The miscibility of PCL/PPCI blends cannot be due to hydrogen bonding between the α-hydrogens of the chlorinated polymer and the carbonyl group of the polyester since PPCI does not have available a large number of α-hydrogens. It is suggested that a dipoledipole ? C?O…Cl? C? interaction is responsible for the observed miscibility phenomenon and that this interaction is probably also responsible for the miscibility between all other polyesterchlorinated polymer mixtures. Finally, it was observed that poly(α-methyl-α-n-propyl-β-propiolactone), poly(α-methyl-α-ethyl-β-propiolactone) and poly(valerolactone) are not miscible with PSCI or PPCl, despite the fact that they are miscible with poly(vinyl chloride).     

Synergetic toughening of poly(phenylene sulfide) by poly(phenylsulfone) and poly(ethylene-ran-methacrylate-ran-glycidyl methacrylate)

Poly(phenylene sulfide) (PPS) is a high-performance super-engineering plastic, but is brittle. In this study, super-tough PPS-based blends were successfully generated by melt blending PPS with poly(ethylene-ran-methacrylate-ran-glycidyl methacrylate) (EGMA) and poly(phenylsulfone) (PPSU) at (56/14/30) PPS/EGMA/PPSU composition, and their toughening mechanisms were investigated in detail. It was demonstrated the interfacial reaction between PPS and EGMA and partial miscibility between PPS and PPSU, both play important synergistic roles on the toughening. The interfacial reaction between PPS and EGMA contributes to the reduction of the PPSU domain size by the increased viscosity of the PPS matrix containing EGMA, and the increased mobility of EGMA chains by negative pressure effect. The partial miscibility between PPS and PPSU contributes to the increased interfacial adhesion between PPS and PPSU, resulting in effective propagation of the impact to the domains, and the increased mobility of not only PPSU chains but also PPS chains, causing a reduction in crystallization.     

Dielectric relaxations in poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate)

A comparative study is undertaken of the dielectric relaxation spectra of poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate), taking into consideration the spectra of the corresponding polymers in the series of the polymethacrylates. The three polymers, PMA, PEA, and PBA, present an α relaxation zone clearly separated from the secondary relaxations. Its shape is not altered with temperature, and it is possible to construct a master curve. With increasing length of the side chain, its distribution of relaxation times broadens and the temperature of the maximum of the relaxation decreases. A β relaxation with decreasing intensity as the length of the side chain increases is clearly perceptible in PMA and PEA, but almost not perceptible at all in PBA. In PEA this relaxation appears split into two peaks. Computer simulation of restricted motions of the side chain discard an origin similar to that of the γ relaxation in PPA or PBA for the lowest temperature component of the relaxation, and suggests the conjunction of two rotation mechanisms in this relaxation for the polyacrylates. For the experimental temperatures of our tests a γ relaxation shows up only in PBA. Its apparent activation energy, higher than in related polymers of the polymethacrylate series, suggests that the tighter packing of monomeric units in polyacrylates leads to a significant increase in the intermolecular contribution to the potential energy barrier responsible for the relaxation.     

Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(vinylidene fluoride)

Summary The miscibility behaviour of poly(methoxymethyl methacrylate) (PMOMA) and poly(methylthiomethyl methacrylate) (PMTMA) with poly(vinylidene fluoride) (PVDF) was examined by differential scanning calorimetry. PMOMA/PVDF blend system was judged to be miscible on the bases of the presence of a single, composition-dependent glass transition for the blend and a pronounced melting point depression of the PVDF component. Furthermore, lower critical solution temperature (LCST) behaviour was observed for all PMOMA/PVDF blends. PMTMA/PVDF blends were found to be immiscible. Based on the melting point depression of PVDF in PMOMA/PVDF blends, the interaction parameter B was found to be -14.5 J/cm³.     

Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(methyl methacrylate)

Summary Poly(n-propyl methacrylate) is known to be immiscible with poly(methyl methacrylate) (PMMA). However, we have found that poly(methoxymethyl methacrylate) is miscible with PMMA, indicating the importance of ether oxygen atoms in achieving miscibility. On the other hand, poly(methylthiomethyl methacrylate) is immiscible with PMMA.     

Temperature-dependent interaction parameters of poly(methyl methacrylate)/poly(2-vinyl pyridine) and poly(methyl methacrylate)/poly(4-vinyl pyridine) pairs

Temperature-dependent interaction parameters (α) of poly(methyl methacrylate)/poly(2-vinyl pyridine) (PMMA/P2VP) pair and PMMA/poly(4-vinyl pyridine) (PMMA/P4VP) pair were obtained from the SAXS profiles at various temperatures, and curve fitting to the random phase approximation theory. For this purpose, symmetric P2VP-block-PMMA and P4VP-block-PMMA copolymers were synthesized anionically. The molecular weights of both block copolymers were controlled to exhibit the disordered state over the entire experimental temperatures. We found that the value of α for PMMA/P4VP was larger than PMMA/P2VP, similar to polystyrene (PS)/poly(vinyl pyridine) pairs. However, the difference between in α between PMMA/P2VP and PMMA/P4VP was much smaller than that between PS/P2VP and PS/P4VP. This might be attributed to the hydrophilic PMMA block compared with hydrophobic PS block. Finally, the order-to-disorder transition temperature for symmetric P2VP-block-PMMA copolymers was determined by small angle X-ray scattering and birefringence methods.