SEBS-g-MA对R-PET/LLDPE共混物结构与性能的影响

以SEBS-g-MA为相容剂,借助力学性能、DSC、SEM和DMA等表征手段对SEBS-g-MA在R-PET/LLDPE/SEBS-g-MA共混物中的作用进行研究。研究发现,添加质量分数10%的SEBS-g-MA时,共混物的缺口冲击强度和断裂伸长率都得到明显的改善。DSC分析结果表明,LLDPE和PET的熔点都没有发生变化,但PET的熔融峰出现双峰。SEM结果显示,添加10%SEBE-g-MA能够使LLDPE在PET基体中充分分散,过量的SEBS-g-MA会诱导部分PET进入分散相,最终形成Salami结构的聚集体。     

r-PET/TPV/LDPE-g-AA共混合金材料的研究

以动态硫化热塑性弹性体(TPV)为增韧材料,回收聚对苯二甲酸乙二醇酯(r-PET)为基体材料,丙烯酸接枝低密度聚乙烯(LDPE-g-AA)为相容剂,制备r-PET/TPV/LDPE-g-AA共混合金材料。用DMA、DSC、SEM分析TPV及LDPE-g-AA对r-PET玻璃化转变温度、结晶性能、断面相结构的影响,测试了共混合金材料的力学性能。结果表明:加入20%TPV,r-PET/TPV共混材料的熔融温度下降4.85℃,结晶温度提高了2.44℃,断裂伸长率及缺口冲击强度明显提高,弯曲强度和拉伸强度略有下降;加入LDPE-g-AA,r-PET/TPV共混材料玻璃化转变温度向低温方向移动,TPV球状粒子嵌入r-PET基体材料中,相容性提高;含2.5%LDPE-g-AA的r-PET/TPV/LDPE-g-AA共混合金材料,与纯r-PET相比,熔融温度下降7.19℃,断裂伸长率提高133.28%,缺口冲击强度提高59.39%,柔韧性较大幅度提高。     

Nanocomposites of rice and banana flours blend with montmorillonite: Partial characterization

Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films.     

Processing and thermal,mechanical and morphological characterization of post-consumer polyolefins/thermoplastic starch blends

Mixtures of high density polyethylene (HDPE) and polypropylene (PP), both post-consumer polymers were blended with thermoplastic starch (TPS). Corn starch plastification was carried out by extrusion with glycerin addition. The behaviour of TPS produced was investigated in the processing and thermal, mechanical and morphology characterization of post-consumer HDPE/PP blends (100/0, 75/25, and 0/100 wt.%) in different proportions of TPS (30%, 40% and 50% wt.%) by melting flow index (MFI), tensile property measurements, and scanning electron microscopy (SEM), respectively. The addition of TPS reduced the MFI of PP and increased of HDPE and HDPE/PP blends. TPS also decreased the tensile strength and elongation at break, and increased the rigidity of the materials. SEM showed separation of phase between the poliolefins and TPS.     

木薯淀粉/壳聚糖可食共混膜的制备及在草莓保鲜中的应用

以木薯淀粉、壳聚糖为基材,制备用于草莓保鲜的可食共混膜,研究共混比、抗菌剂(柠檬酸)和表面活性剂(吐温60)对共混膜性能及保鲜效果的影响。结果表明:当壳聚糖和木薯淀粉质量比为1:1时,共混膜的拉伸强度为25 MPa,断裂伸长率为10.6%,水蒸气渗透率为160 g/(24 h·m2),其综合性能最佳。当添加质量分数为4%的柠檬酸时,共混膜综合性能较好;当同时添加质量分数为1%的吐温60与1%的柠檬酸时,60 h后的草莓失重率比单独添加质量分数为1%的柠檬酸和1%的吐温60分别降低约20%和15%,说明此时保鲜效果最佳。     

Physical properties and characterization of biodegradable films using nano-sized TiO2/poly(acrylamide-co-methyl methacrylate) composite

In this study, biodegradable films were prepared by using corn starch, PVA, nano-sized poly(acrylamide-co-methyl methacrylate) (PAAm-co-MMA), nano-sized TiO2(P-25)/PAAm-co-MMA composite, and additives which are harmless to the human body, that is, glycerol (GL) and citric acid (CA). Nano-sized PAAm-co-MMA was synthesized by the method of emulsion polymerization. Also, nano-sized TiO2/PAAm-co-MMA composites were synthesized by wet milling for 48 h. The morphology and crystallinty of nano-sized PAAm-co-MMA and TiO2/PAAm-co-MMA composite was observed by the SEM and XRD. The physical properties such as tensile strength (TS), elongation at break (%E), degree of swelling (DS), and solubility (S) of biodegradable films were investigated. The photocatalytic degradability of starch/PVA/nano-sized TiO2/PAAm-co-MMA composite blended films was evaluated using methylene blue as photodegradation target.     

羟基磷灰石的表面改性及其对聚乳酸基多孔支架性能的影响

分别采用柠檬酸和硬脂酸对纳米羟基磷灰石（n-HA）进行表面处理,并利用TGA、FTIR、XPS等研究了不同改性剂的改性效果,发现柠檬酸和硬脂酸能够成功接枝在n-HA表面,但硬脂酸的接枝率更高。将柠檬酸改性的n-HA与聚乳酸（PLA）共混制备复合材料,通过SEM观察发现,制备的n-HA/PLA复合材料在n-HA粉体添加量不超过20wt%时,经处理后的n-HA粉体在基体中分散均匀,两相界面处结合紧密。同时研究了n-HA/PLA复合材料制备多孔骨支架的3D打印成型工艺,并测试了其力学性能,结果表明,采用熔融沉积3D打印技术制备的支架有良好的压缩模量,但达到10%形变时所承受的压缩强度与PLA相比仍然有一定差距。     

Mechanical properties and fracture morphologies of poly(phenylene sulfide)/nylon66 blends—effect of nylon66 content and testing temperature

Poly(phenylene sulfide) (PPS) was melt blended with Nylon66 and the mechanical properties and corresponding fracture morphologies were investigated. The thermal distortion temperature (HDT) of PPS/Nylon 66 blend showed that the inherent thermal stability of pure PPS can be maintained up to 30 wt% Nylon66, but then it started to decrease linearly thereafter to that of pure Nylon66 based on the rule of mixtures relationship. Tensile tests of PPS/Nylon66 blends at testing temperatures of –30, 25, 75, and 150°C showed that the maximum stress decreased up to 30 wt% Nylon66, and started to increase thereafter. Strain at break showed little change at low nylon content regardless of testing temperature, however, a large strain at break increase could be observed at more than 30 wt% Nylon66 and at 150°C testing temperature. At the same testing temperatures, the impact strength of PPS/Nylon66 blends was investigated, and it was found that an impact strength increase at all testing temperatures could be observed at more than 30 wt% Nylon66.     

Amorphous carbon fibres from linear low density polyethylene

Carbon fibres with good mechanical properties have been produced from linear low density polyethylene (LLDPE). The melt-spun LLDPE fibres were made infusible by treatment with chlorosulphonic acid. The cross-linked fibres were pyrolysed at temperatures between 600 and 1100 °C under tension, in a nitrogen atmosphere, within 5 min. Carbon fibres prepared at 900 °C had a tensile strength of 1.15 GPa and a Young's modulus of 60 GPa. The elongation at break was extremely high, up to 3%. The carbon yield of the process was 72 to 75%.     

辐照改性LLDPE及增容增韧作用

采用FT-IR、XRD、SEM和力学性能测试等研究了紫外辐照对线性低密度聚乙烯(LLDPE)的结构与性能的影响,以及辐照改性LLDPE的增容作用。结果表明,通过紫外辐照,在LLDPE分子链上引入了C=O和C-O等基团。辐照改性LLDPE的晶面间距没有发生变化,但是其拉伸强度和断裂伸长率下降。制备了尼龙66/辐照改性LLDPE(90/10)复合材料。辐照改性LLDPE与尼龙66之间的相容性好,辐照改性LLDPE对尼龙66具有较好的增容增韧作用。     

PVA胶带的制备及力学性能研究

目的用水溶PVA薄膜代替不可降解BOPP薄膜作为胶带基材。方法试验分别测试PVA和BOPP薄膜(未涂布)的拉伸强度和断裂伸长率,涂布水性压敏胶的PVA和BOPP薄膜以及涂布热熔胶的PVA薄膜的拉伸强度、断裂伸长率、初粘性和180°剥离强度。结果 BOPP薄膜的拉伸强度为34.32 N/cm,略高于PVA薄膜,但是BOPP薄膜的断裂伸长率低于PVA薄膜;BOPP胶带、PVA热熔胶带、PVA水性胶带的拉伸强度分别为48.38,63.68,32.94 N/cm,BOPP胶带的断裂伸长率同时低于PVA热熔胶带和PVA水性胶带;BOPP胶带的初粘性略高于PVA水性胶带;BOPP胶带、PVA热熔胶带、PVA水性胶带的180°剥离强度分别为1.58,6.48,2.63 N/cm。结论与BOPP胶带相比,PVA胶带的拉伸强度、断裂伸长率、初粘性和180°剥离强度均可满足封箱胶带对力学性能的要求。     

硅灰石填充保鲜膜的性能研究

为增加保鲜膜透气和透湿性能,以LLDPE/LDPE(质量比75∶25)为基材,以硅灰石为填料,制备了不同处理方式和不同添加量的硅灰石保鲜膜。结果表明:随着硅灰石添加量的增加,薄膜的拉伸强度和断裂伸长率逐渐降低,未经处理的硅灰石填充膜的透气和透湿量明显提高,经偶联剂和酸处理的硅灰石能很好地提高与树脂的相容性,薄膜的拉伸强度和断裂伸长率都高于未处理填充膜,且透气系数和透湿系数与空白膜相比也有明显改善。     

花青素-明胶/聚乙烯醇-淀粉复合膜制备与表征

目的 制备花青素明胶/聚乙烯醇淀粉双层复合膜,以期提高花青素单层膜的综合性能.方法 采用流延法分别制备紫薯、紫甘蓝、黑米、黑枸杞、玫瑰、玫瑰茄等6种花青素明胶/聚乙烯醇淀粉双层复合膜,并对比研究膜层的微观组织结构、含水率、力学性能及光学性能.结果 从红外光谱图中可以看出,双层复合膜分子结构没有出现新的特征峰,双层膜结合方式为物理结合,没有新的结构生成,且除紫甘蓝明胶/聚乙烯醇淀粉双层复合膜外,其余复合膜均存在明显的分层界线,2层结合处膜层结构均匀致密,结合良好.不同双层膜的含水率差异显著,而双层复合膜比花青素单层膜的含水率明显降低,不同双层膜的拉伸强度和断裂伸长率差异不显著,与单层花青素明胶复合膜相比,双层复合膜的拉伸强度和断裂伸长率大幅增加,其中紫薯双层膜的拉伸强度增加了75％,断裂伸长率增加了22.9％;所有双层复合膜的透光率相差不大,均在80％以上;与花青素明胶单层膜相比,双层膜的雾度增加了20％左右.结论 制备的双层膜改善了单层膜的力学性能,提高了花青素明胶单层膜的综合性能.     

低缠结超高分子量聚乙烯的制备及其对线性低密度聚乙烯的增强作用

利用单活性位点前过渡金属FI催化剂(Fenokishi-Imin catalyst)进行乙烯的聚合反应,在较低的温度下,制备出具有低链缠结度的超高分子量聚乙烯。经高温凝胶色谱(PL-GPC)测定,产物分子量达到了(2~5)×106;差示扫描量热仪(DSC)检测表明其结晶度达到了70%;流变学研究表明,相对于商业超高分子量聚乙烯,产物链缠结密度大大降低。进一步的力学性能测试显示添加少量的低缠结超高分子量聚乙烯对线性低密度聚乙烯的增强作用非常明显,可使拉伸强度和断裂伸长率大大提高。     

AGING CHARACTERISTICS OF TERNARY BLENDS OF POLYETHYLENES. I

Degradation of a low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE)/high-density polyethylene (HDPE) blend having different weight ratios of LLDPE (10-35 wt%) and HDPE (40-65 wt%) with fixed percentage of LDPE (25 wt%) was studied by aging the film samples at 55, 70, 85, and 100°C in air. Reactions involved in changing the molecular structure and formation of oxygenated and unsaturated groups during thermo-oxidative degradation are discussed. The molecular weight (M_v) showed very little change in the initial hours of aging at different temperatures. Tensile strength was found to increase initially and then decrease with aging time. The increase in tensile strength suggests molecular enlargement, mainly by recombination of alkyl and alkoxy radicals, which produces nonradical products. The thermal stability decreases with increase in aging time and temperature.     

Novel toughened polylactic acid nanocomposite: Mechanical,thermal and morphological properties

The objective of the study is to develop a novel toughened polylactic acid (PLA) nanocomposite. The effects of linear low density polyethylene (LLDPE) and organophilic modified montmorillonite (MMT) on mechanical, thermal and morphological properties of PLA were investigated. LLDPE toughened PLA nanocomposites consisting of PLA/LLDPE blends, of composition 100/0 and 90/10 with MMT content of 2 phr and 4 phr were prepared. The Young’s and flexural modulus improved with increasing content of MMT indicating that MMT is effective in increasing stiffness of LLDPE toughened PLA nanocomposite even at low content. LLDPE improved the impact strength of PLA nanocomposites with a sacrifice of tensile and flexural strength. The tensile and flexural strength also decreased with increasing content of MMT in PLA/LLDPE nanocomposites. The impact strength and elongation at break of LLDPE toughened PLA nanocomposites also declined steadily with increasing loadings of MMT. The crystallization temperature and glass transition temperature dropped gradually while the thermal stability of PLA improved with addition of MMT in PLA/LLDPE nanocomposites. The storage modulus of PLA/LLDPE nanocomposites below glass transition temperature increased with increasing content of MMT. X-ray diffraction and transmission electron microscope studies revealed that an intercalated LLDPE toughened PLA nanocomposite was successfully prepared at 2 phr MMT content.     

Use of rice husks as potential filler in styrene butadiene rubber/linear low density polyethylene blends in the presence of maleic anhydride

In the present study, rice husks filled styrene butadiene rubber (SBR)/linear low density polyethylene (LLDPE) 50/50 blends with a compatibilizer, maleic anhydride (MAH) were prepared using a brabender plasti-corder. Virgin SBR/LLDPE blend was also prepared. The physico-mechanical as well as dielectric properties were investigated. Increasing MAH concentrations in SBR/LLDPE blends resulted in an increase in the tensile strength, elongation at break and hardness. After a certain concentration (2.5 phr), a reduction in these properties was found. On the other hand an increase in the dielectric properties as well as in the mass swell in both toluene and oil with MAH was noticed. After certain concentration of rice husk filler (25 phr) an abrupt increase in permittivity ε′ and dielectric loss ε″ was obtained. These results are supported by the mechanical properties measurements. The scanning electron microscopy (SEM) indicates that the presence of MAH increases the interfacial interaction between SBR/LLDPE blends on one hand and also rice husk filler and the blend on the other hand.     

Effects of carbon nanotube diameter and functionality on the properties of soy polyol-based polyurethane

Soy polyol-based polyurethane (PU) nanocomposites (PUNCs) with 1 wt.% hydroxyl-functionalized multi-wall carbon nanotubes (CNT-OH) were prepared via in situ polymerization. CNT-OH increased the glass transition temperature as well as significantly improved the thermal stability and conductivity of the PUNCs. The PUNC Young’s modulus was much lower than that of neat PU. The tensile strength of the PUNCs with large CNT-OH diameters was slightly higher than that of neat PU. Compared with neat PU, the elongation at break of the PUNCs improved by 30%, 39%, and 45% with increased CNT-OH diameters. Scanning and transmission electron microscopic methods revealed CNT-OH relatively homogeneous dispersion in the PU matrix.     

淀粉氧化改性对可剥离去污膜的性能影响研究

通过对淀粉进行氧化改性,研究了氧化淀粉对以聚乙烯醇为基体的去污膜相关性能的影响。红外光谱分析表明,氧化淀粉在1733cm-1处有羧基吸收峰产生,10%氧化淀粉制备的去污液稳定时间可达到1673h,去污膜拉伸强度为29.32MPa,断裂伸长率为238%,在400~800nm波长范围内透光率可达到85%以上,对不同材质样片的平均去污率可达80%以上。     

Chemically modified fly ash for fabricating super-strong biodegradable poly(vinyl alcohol) composite films

Composite films of poly(vinyl alcohol) (PVA) and chemically modified fly ash (MFA) by sodium hydroxide were prepared by aqueous cast method with 5, 10, 15, 20 and 25 wt% MFA treated with 1 wt% cross-linking agent (glutaraldehyde, GLA). The tensile strengths of the composite films were found to increase proportionally with MFA and the maximum strength attained was 414% higher in the case of 20 wt% MFA than that in neat PVA film. The percentage of strain at break exponentially decreased with addition of MFA. The modulus of the composites was determined to increase proportionally up to a maximum 685% at 20 wt% MFA compared to that of neat PVA film. Interfacial networking between the MFA and PVA was evident from scanning electron microscopy (SEM) images of tensile-fractured surfaces, which was not observed for the unmodified fly ash (FA) system. Atomic force microscopy (AFM) analysis showed that the mean square surface roughness of the composite films of PVA–MFA was 53% smoother than the films with FA.