胶粉/聚丙烯热塑性弹性体的研究进展

概述热塑性弹性体(TPE)的分类及用途,重点介绍胶粉/聚丙烯(PP)TPE的研究进展状况。采用胶粉与天然橡胶(NR)并用、过氧化物为硫化剂或相容剂、动态硫化等方法可以提高胶粉/PP TPE的性能,PP的熔融指数、胶粉粒径、螺杆结构和挤出参数等对胶粉/PP TPE的性能均有影响,胶粉部分脱硫以及加入生胶包覆胶粉粒子可以进一步提高胶粉/PP TPE的性能。对胶粉/PP TPE发泡性能及应用的研究具有广泛的经济和社会意义。     

废胶粉填充改性RHDPE增容研究

研究了废胶粉的活化处理、不同种类相容剂对回收高密度聚乙烯/废胶粉(RHDPE/WRP)共混体系的增容效果.结果表明,WRP活化处理对提高WRP界面活性有效果.不同相容剂对提升共混体系性能的影响不同,其中添加10份马来酸酐接枝聚乙烯(PE-g-MAH)相容剂对提升RHDPE/活化WRP体系整体性能最有效,可使RHDPE/WRP共混材料的拉伸强度从简单共混物的18.8 MPa提高到22.5 MPa,缺口冲击强度从37.5 kJ/m2提高到60.9 kJ/m2;热变形温度从55.8℃提高到63.6℃.     

动态硫化法制备EPDM/PP/WRP的初步研究

初步研究了EPDM／PP／WRP共混材料的力学性能和微观结构。结果表明，废胶粉用动态硫化法可以改善EPDM／PP／WRP共混物的机械性能。通过胶料扯断断面的扫描电镜照片的分析，可证明改性后的废胶粉与聚丙烯的界面粘着力增强。     

加相容剂的聚丙烯汽车仪表盘专用料的研制

以聚丙烯（PP）为基础树脂,聚烯烃热塑性弹性体（POE）为增韧剂,马来酸酐接枝聚丙烯（PP－g-MAH)为相容剂,滑石粉为填料制得性能符合汽车仪表盘要求的专用料,并研究了相容剂含量对共混体系性能的影响。结果表明,相容剂的加入能有效地改善聚合物与滑石粉的相容性,增强两相界面的粘结;当相容剂的用量为9份时,共混体系的拉伸强度和冲击强度达到最大值,与未加相容剂的共混体系相比提高20％－30％。相容剂的加入使共混体系的熔体粘度上升,但熔体流动速率有所下降。     

回收高密度聚乙烯/废胶粉共混体系的力学性能研究

探讨了废胶粉（WRP）和回收高密度聚乙烯（RHDPE）共混改性时废胶粉的质量分数、相容剂的种类以及胶粉改性剂对RHDPE／WRP共混体系力学性能的影响。实验结果表明，当废胶粉的质量分数为20％时，体系的综合力学性能最佳。在RHDPE／WRP体系中分别添加EPDM、EVA、EAA时，EVA的增容效果最好，添加5％的EVA能使RHDPE／EVA／WRP体系的冲击强度增加55％。废胶粉经自制表面改性剂ACDI预处理后，其相应的RHDPE／EVA／MWRP体系的拉伸强度和弯曲模量分别增加35％和25％，而对共混物的其它性能影响不大。     

聚丙烯/冷冻胶粉复合材料结构与性能的研究

采用熔融挤出的方法制备聚丙烯（PP）、冷冻胶粉（LGTR）、相容剂及增韧剂的共混物,研究了胶粉用量、相容剂种类和用量及增韧剂对共混体系力学性能和微观结构的影响。结果表明,LGTR的加入会降低PP的力学性能,但随着LGTR用量的增加,共混体系的冲击强度上升;相容剂的使用会增加PP与LGTR的相容性,使力学性能提高;热塑性聚烯烃类弹性体（POE）和三元乙丙胶接枝马来酸酐（EPDM-g-MAH）的使用可以有效提高PP/胶粉共混体系的缺口冲击强度,并且增韧剂的使用可以提高PP与LGTR之间的相容性;高密度聚乙烯（PE-HD）/POE并用做增韧体系时,可以进一步提升共混体系的韧性,提高冲击强度。     

改性胶粉/EPDM/PP热塑性弹性体的制备与性能研究

以乙丙橡胶(EPDM)、聚丙烯(PP)和胶粉等为主要原料,采用动态硫化的方法制备了改性胶粉/EPDM/PP热塑性弹性体,研究了溴化丁基橡胶(BIIR)用量、胶粉的改性剂、热塑性弹性体的硫化剂对改性胶粉/EPDM/PP热塑性弹性体力学性能和耐老化性能的影响,并通过电子扫描电镜观察了热塑性弹性体内部的微观结构。研究结果表明,BIIR用量为12份时,热塑性弹性体的力学性能最优,耐老化性能良好;使用10份松香、6份50%大蒜汁、2份BIIR并用作为改性剂改性的胶粉所制备的热塑性弹性体力学性能最优,耐老化性能良好;使用促进剂TT、硫黄和201树脂并用作为硫化剂所制备的热塑性弹性体力学性能和耐老化性能最优;经过松香、50%大蒜汁和BIIR改性后的胶粉与橡胶基体以及聚丙烯间相界面比较模糊,分散均匀性较好。     

聚氯乙烯/丁腈胶粉共混型热塑性弹性体

将聚氯乙烯与废丁腈胶粉经高温机械共混，制备了动态交联的共混型热塑性弹性体。讨论了共混比，硫化体系及其用量，废胶粉品种（丁腈胶粉，轮胎胶粉）等因素对热塑性弹性体性能的影响，同时将聚氯乙烯／丁腈胶粉与聚氯乙烯／轮胎胶粉制备的共混型热塑性弹性体的性能进行了比较。结果表明，以聚氯乙烯100份（质量份，下同），邻苯二甲酸二辛酯50份，丁腈胶粉80份，丁腈橡胶20份，过氧化二异丙苯0．5份，氧化锌5份及适量其他助剂可制得综合性能较好的共混型热塑性弹性体。扫描电镜结果显示该共混型热塑性弹性体具有较好的相容性。     

相容剂对NBR/PP共混型热塑性弹性体性能的影响

考察了普通氯化聚乙烯（ＣＰＥ）、高氯化ＣＰＥ、马来酸酐接枝聚丙烯及复合氯化聚丙烯（ＣＰＰ）等相容剂对ＮＢＲ／ＰＰ共混体系性能的影响。试验结果表明，复合ＣＰＰ是ＮＢＲ／ＰＰ共混体系的理想相容剂，其最佳用量为６份；以此为相容剂的ＮＢＲ／ＰＰ共混体系具有优良的热塑性，ＮＢＲ／ＰＰ共混型热塑性弹性体可采用热塑性塑料通用的加工方法进行加工。     

PP-g-MAH预浸渍玻璃纤维毡对GMT界面改性的作用

采用含有马来酸酐接枝聚丙烯(PP–g–MAH,简称MPP)的聚丙烯(PP)树脂对玻璃纤维(GF)毡预浸渍,进行增强体改性,通过直接浸渍工艺、增强体预浸渍工艺、累加浸渍工艺等不同工艺制备GF毡增强PP热塑性复合材料(GMT)。对不同工艺制备的GMT界面形态进行了扫描电子显微镜分析,并测定了预浸渍处理后GF的疏水性,研究了预浸渍工艺中MPP的用量对GMT拉伸、弯曲、冲击等力学性能的影响。结果表明:采用含MPP的PP树脂进行增强体预浸渍改性的方法,改性树脂对GF的包覆效果良好,经预浸渍改性法处理的GF,其疏水性增强;并可以获得与PP/MPP改性树脂直接浸渍GF毡时相似的界面改性效果和相近的GMT力学性能;样品界面改性效果相近的情况下,增强体预浸渍改性方法所需的MPP用量明显少于改性树脂直接浸渍时的用量。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.