增塑剂对生物降解塑料聚乳酸结晶形态的影响

采用熔融共混方法制备了聚乙二醇(PEG)和聚乳(酸PLA)的共混物,并借助差示扫描量热仪和广角X射线衍射仪研究了在80~140℃等温结晶时PEG对PLA结晶形态和熔融行为的影响。结果表明:100℃以上时PLA的结晶度随结晶温度的升高逐渐增加;100℃以下时PLA的结晶度随PEG含量的增加逐渐增大。110℃以下时,晶面间距随结晶温度的升高和PEG含量的增加而逐渐减小;110℃以上时,晶面间距保持不变;当加入15%的PEG时PLA的晶面间距不受结晶温度的影响结,晶生成的是稳定的α晶。     

聚乳酸/聚癸二酸丙三醇酯共混物非等温结晶行为

采用差示扫描量热法对聚乳酸/聚癸二酸丙三醇酯(PLA/PGS)共混物的非等温结晶行为进行研究,并使用Jeziorny法修正了Avrami方程中的结晶动力学常数.结果表明,PGS的加入降低了PLA的结晶温度,结晶度随升温速率的增加而增加.Avrami指数n与升温速率及PGS的含量无关,结晶生长机理为二维方式;修正后的结晶动力学常数随升温速率的增加而增加,PGS的加入对其影响不大.     

纳米二硫化钼对聚乳酸等温结晶行为的影响

采用熔融共混法制备聚乳酸/二硫化钼(PLA/MoS_2)纳米复合材料。通过差示扫描量热法(DSC)研究纳米MoS_2含量对PLA等温结晶行为的影响,采用Avrami方程分析纳米复合材料的等温结晶动力学,并采用X射线衍射(XRD)测试材料的结晶结构。由等温结晶动力学计算结果可知,加入MoS_2纳米粒子后,PLA基体的结晶速率显著提高。例如,当结晶温度(Tc)为110℃,MoS_2含量由0增至2.0%时,试样的结晶半时间(t1/2)可由纯PLA的8.5 min大幅降低至3.2 min。而当Tc为120℃,MoS_2含量由0增至2.0%时,试样的t1/2由纯PLA的11.4 min降低至3.8 min。同时,随着MoS_2含量的增大,PLA基体的最大结晶度也有一定程度增大,说明MoS_2起到异相成核剂作用。PLA/MoS_2试样的Avrami指数在2.6~3.1之间,可知在MoS_2存在下,PLA晶体主要为异相成核和三维生长。     

聚乳酸/1-乙基乙基醚-3-甲基咪唑四氟硼酸盐共混物等温结晶动力学研究

利用差示扫描量热仪(DSC)和偏光显微镜(POM)研究了聚乳酸/1-乙基乙基醚-3-甲基咪唑四氟硼酸盐(PLA/[EOEIM]BF4)共混物的等温结晶行为。由等温结晶动力学分析可知,[EOEIM]BF4含量不同时,共混物的Avrami指数n基本保持在2.5左右,表明[EOEIM]BF4对PLA的成核及生长机理影响不大。然而,共混物的半结晶时间t1/2随[EOEIM]BF4含量的增加而增大,说明[EOEIM]BF4的加入对PLA的结晶有阻碍作用,这可能是由于[EOEIM]BF4与PLA分子间的相互作用所造成的。X射线衍射测试结果表明,所有样品在120℃下等温结晶所得的晶型为α晶型。     

等温冷结晶对PLA/PBAT共混物冲击韧性和耐热性能的影响

通过熔融共混法制备了聚乳酸/聚己二酸-对苯二甲酸丁二醇酯(PLA/PBAT)共混物,并对其微观形貌、热性能、冲击性能和耐热性能进行了研究。结果表明,随着PLA/PBAT共混物中PBAT含量的增加,共混材料的无缺口冲击强度逐渐增大,其中当PBAT含量为30%时,共混材料的无缺口冲击强度达到最大值。再通过等温冷结晶提高PLA/PBAT材料的结晶度,以改善材料的耐热性能。结果表明,等温冷结晶样品的维卡软化温度(VST)明显高于急冷样品,且结晶度越高,VST值则越大;此外,90℃等温冷结晶20 min的样条无缺口冲击强度高于急冷样条,但当等温冷结晶温度提高至130℃时,样条的无缺口冲击强度下降,且低于急冷样条。因此,较低冷结晶温度有利于得到兼具良好耐热性能和冲击性能的PLA/PBAT材料。     

PET/PLA共混物相容性和结晶性能的研究

研究了相容剂钛酸四丁酯[Ti(OBu)4]含量、聚乳酸(PLA)含量对聚对苯二甲酸乙二醇酯(PET)/PLA共混物相容性的影响,探讨了共混物的熔融和结晶行为,并对其结晶形貌进行了观察。结果表明,Ti(OBu)4含量为PLA的4%(质量分数,下同)时,PET/PLA共混物的相容性良好,但当PLA含量超过30%时,共混物出现相分离;PLA的加入使PET的结晶峰变窄,结晶速率增加,且结晶峰温度向高温方向移动;PLA的加入使PET的晶粒尺寸大幅减小,晶粒数目大幅增加,结晶更加完善。     

多元环氧扩链剂对聚乳酸等温结晶行为及力学性能的影响

采用多元环氧扩链剂(ADR)对聚乳酸(PLA)进行熔融扩链改性,得到PLA/ADR共混物。采用差示扫描量热仪(DSC)对共混物的熔体等温结晶行为进行表征和分析。结果表明:在110~120℃温度范围内,ADR的加入提高了PLA熔体的结晶速率;随着ADR用量的增加,PLA等温结晶速率明显提高,半结晶时间缩短。结合熔体流动速率和偏光显微镜分析,从分子运动能力和熔体黏度的角度解释了ADR对PLA等温结晶行为的影响机理。此外,研究了结晶度变化对PLA/ADR共混物拉伸性能和维卡软化温度(VST)的影响。当PLA/ADR(100/1.0)共混物的结晶度由1.7%提高到32.2%时,其拉伸强度由55.6 MPa提高到63.2 MPa,VST由61.9℃提高到156.9℃。结晶度的增大有利于PLA/ADR共混物力学性能和耐热性能的进一步提高。     

聚己内酯对聚乳酸熔融结晶的影响

聚合物共混材料的结晶行为对材料性能有重要的影响,结晶行为是共混材料研究的主要问题。选用聚乳酸(PLA)和聚己内酯(PCL)共混材料,采用偏光显微镜和差示扫描量热仪,对PLA/PCL共混材料的结晶行为进行研究。通过等温结晶动力学,分析PCL对PLA在100和120℃时等温结晶的影响。结果表明,PCL相作为异相成核剂加入PLA相,使得PCL/PLA共混物中异相结晶成核效率提高,晶体直径减小,半结晶时间减小,提高PCL/PLA共混物的结晶能力。随着PCL相的占比增大,PCL/PLA(40/60)试样中出现"海-岛结构",异相成核效率增大,半结晶时间较小,结晶直径减小,结晶度减小。     

PS/PLA共混物的相态结构及其发泡行为研究

采用密炼机制备了聚苯乙烯/聚乳酸(PS/PLA)共混物,以超临界二氧化碳(CO2)为物理发泡剂,采用釜压法制备了PS/PLA共混物泡沫。采用差示扫描量热仪、偏光显微镜和扫描电子显微镜研究了PLA等温结晶行为、PS/PLA共混物的相态结构和PS/PLA共混物泡沫的泡孔结构。结果表明,反应型增容剂使PLA的等温结晶速率提高,晶体尺寸降低;增容剂能够促进PLA在PS中的分散;PLA的加入在发泡过程中能够起到异相成核作用,PLA的结晶有利于气泡的增长和稳定。     

苯乙烯-丙烯酸甲酯共聚物增容对聚乳酸/SBS共混物结晶行为的影响

研究了苯乙烯-丙烯酸甲酯无规共聚物(SMA)增容剂对聚乳酸(PLA)与苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)共混物的结晶行为的影响。通过熔融共混的方法制备了PLA/SBS (m_(PLA)∶m_(SBS)=95∶5)和PLA/SBS/SM A (m_(PLA)∶m_(SBS)∶m_(SM A)=95∶5∶3)共混物,使用扫描电子显微镜(SEM)、差示扫描量热仪(DSC)和偏光显微镜(POM)研究了SM A增容PLA/SBS共混物的形貌、非等温结晶行为、等温结晶行为和晶体形貌。结果表明,SBS的增塑效应和异相成核效应对PLA的非等温结晶和等温结晶行为有促进作用;而SMA的加入起到了降低SBS分散相尺寸的作用,同时阻碍了SBS对PLA结晶行为的促进作用。增容剂SMA阻碍SBS对PLA基体结晶行为促进作用的可能原因在于SMA在PLA和SBS界面处的阻隔作用导致两者接触面积减少,且SMA对PLA的结晶没有促进或抑制作用。     

Dispersion of Poly(phenylene ether) in a Poly(phenylene sulfide)/Poly(phenylene ether) Alloy

We have devised and developed a new method for the preparation of a poly(phenylene sulfide)/poly(phenylene ether) (PPS/PPE) alloy, which has micro‐dispersed PPE in the PPS matrix. PPS was chemically treated to activate the reactivity of the PPS end‐group by extrusion in the presence of diphenylmethane diisocyanate (MDI) in its molten state at 300°C. The reactive processing of the MDI‐treated PPS with maleic anhydride‐modified PPE gave a PPS/PPE alloy with micro‐dispersed PPE in the PPS matrix. The PPS/PPE alloy showed mechanical properties superior to those of PPS at elevated temperature (150°C) and also showed precision‐molding ability superior to that of PPS.     

Poly(ortho-vinylbenzophenone)

This article reports the synthesis and free radical polymerization of ortho-vinylbenzophenone. The glass transition temperature T_g of the homopolymer is 136°C. The products synthesized appeared to be atactic and amorphous. The Mark-Houwink constants for poly (o-vinylbenzophenone) in tetrahydrofuran are K = 4.2 × 10^?2 cm³ g^?1 and a = 0.765. The pre-exponential constant under theta conditions, K_θ, is estimated to be 5.93 × 10^?2 cm³ g^?1. The ratio of unperturbed dimensions of the actual polymer and free rotating analogue chain is 3.93, which is almost double that of polystyrene. The Flory-Huggins interaction parameter for poly $\text{(o-}\text{vinylbenzophenone}\text{)}\text{tetrahydrofuran}$ is 0.48 at room temperature. The $\text{k}{}_{\mathrm{<mtext>p</mtext>}}\text{k}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}_{\mathrm{<mtext>t</mtext>}}$ ratio at 60°C is $\text{1.1 × 10}{}^{\mathrm{?2}}\text{l}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{mol}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}\text{s}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}$. In free radical copolymerizations with styrene at 70°C, r₁ (o-vinylbenzophenone) = 1.216, r₂ = 0.751. This copolymerizations is virtually random.     

苯乙烯—异戊二烯—苯乙烯热塑性嵌段共聚物

简介近年来国外SIS生产状况、生产工艺技术经济评估、SIS的基本性能和应用以及国外技术发展趋势,井对国内SIS产品开发作出预估。     

Poly(alkylnylstannanes)

Summary The synthesis of poly(alkynylstannanes) was achieved by the step-growth polymerization of bisaminostannanes and ,-diynes. This is a new class of organotin polymers containing tin-alkyne linkages in the polymer backbone. The polymers were obtained in good yield, albeit with relatively low molecular weight. The polymers underwent crosslinking on standing to give insoluble material and required stabilization with radical inhibitors. The thermal properties of these materials, and the influence of the group pendent to tin are discussed.     

聚乳酸/聚丁二酸丁二醇酯共混物的研究

通过熔融共混制备了聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)共混物,采用扫描电子显微镜、差示扫描量热仪、旋转流变仪对其相容性、热性能和黏度等进行了研究,并研究了PBS的加入对PLA力学性能的影响。结果表明,PLA和PBS之间是部分相容的,PBS的少量添加并不影响PLA的拉伸强度,且其冲击强度随着PBS含量的增加呈先上升后下降的趋势,当PBS含量为10份时,共混物的冲击强度最好;与纯PLA相比,共混物的黏度有所增加,且随着PBS含量的增加,共混物的黏度逐渐增大;PBS的添加起到异相成核作用,促进了PLA的结晶。     

New Miscible Poly(ether imide)/Poly(phenyl sulfone) Blends

Summary: Blends of PEI and PPSU were prepared directly during the plasticization step of an injection molding process throughout the full composition range. The molded blends were transparent and showed a single glass transition and no dispersed phase by SEM. These characteristics did not allow the presence of a single miscibilized phase to be inferred unambiguously due to the very similar T_gs and refractive indices of the two components of the blends. Miscibility was inferred after close observation of the position, height and area of the enthalpy relaxation peak of the 50/50 blend. The modulus of elasticity and yield stress changed linearly with composition, leading to polymer materials with intermediate characteristics. The linearity was attributed to the lack of decrease in free volume induced by mixing and to the similar orientation of the components before and after mixing. The PPSU presence only slightly reduced the known tendency towards brittle fracture of PEI under notched impact conditions, but the presence of a single amorphous phase led to an expected ductile behavior of the blends close to that predicted by the single rule of mixtures.

Break stress (?) and break strain (○) of PEI/PPSU blends as a function of composition.     

聚羟基烷酸酯改性聚氯乙烯的研究

通过熔融共混的方法分别制备了聚氯乙烯/邻苯二甲酸二辛酯/聚羟基烷酸酯（PVC/DOP/PHA）和PVC/PHA共混物。研究了PHA逐步代替DOP对共混物力学性能和熔体流动性能的影响规律,利用扫描电子显微镜对所制备的试样进行微观结构分析。结果表明,随着共混体系中PHA用量的增加和DOP的等量减少,与PVC/DOP共混物相比,PVC/DOP/PHA共混物的拉伸强度由21 MPa提高至42 MPa,断裂伸长率先增加而后降低,在PHA含量为10.7 %(质量分数,下同)时出现极大值(350 %);在PVC/PHA体系中,PHA含量增加,PVC/PHA共混物的力学性能及熔体流动速率都显著提高,说明PHA可以作为PVC的一种有效的绿色增塑剂和增韧剂。     

聚β-羟基丁酸酯和聚碳酸亚丙酯的共混体系研究

采用溶剂挥发法和熔融共混法分别制备了聚β-羟基丁酸酯(PHB)和聚碳酸亚丙酯(PPC)的共混物,采用DSC、X-射线衍射、扫描电镜、偏光显微镜等手段系统研究了共混物配比对体系热、力学性能、形貌的影响.结果表明,随着共混物中PHB含量的增加,共混物断裂强度增大,PPC的加入可明显改善材料脆性,断裂伸长率增大.PPC的存在可以抑制PHB的结晶过程,降低PHB的熔点,拓宽PHB的熔融加工窗口.上述共混物在可降解塑料领域具有良好的应用前景.     

A Novel Quaternary Blend System of Poly(ethy1ene terephthalate), Poly(trimethy1ene terephthalate), Poly(butylene terephthalate), and Poly(ether imide)

Summary A quaternary blend system composed of three low-T_g semi-crystalline aryl-polyesters namely, [poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poli(butylene terephthalate) (PBT)] and an amorphous high-T_g poly(ether imide) (PEI) was prepared and investigated using thermal and morphology characterization techniques. This study, for the first time, demonstrated miscibility and phase behavior of a quaternary blend comprising four different polymers. A single and composition-dependent T_g was found for each of all quaternary blend samples. In addition, various thermal transition characteristics, single and composition-dependent T_c,c, increasingly suppressed ΔH_c,c at higher PEI contents, are also indication of phase miscibility of the quaternary blend. SEM morphology characterization (3000X) revealed no discernible domains and homogeneous phase morphology in the quaternary blends was also substantiated using optical and scanning electron microscopy results. Received: 14 November 2002/Revised version: 17 February 2003/ Accepted: 22 February 2003 Correspondence to Eamor M. Woo