增容剂对竹粉/HDPE复合材料力学性能及流变性能的影响

分别以马来酸酐接枝聚乙烯(MAPE)、马来酸酐接枝聚乙烯-辛烯共聚物(MAPOE)和乙烯-丙烯酸共聚物(EAA)为相容剂,通过熔融共混方法制备高密度聚乙烯(HDPE)/竹粉复合材料。采用万能材料试验机、维卡软化点测量仪和旋转流变仪对该共混物力学性能和流变性能进行详细研究。结果表明,MAPE对竹粉/HDPE复合材料具有很好的增容效果:加入10%MAPE时,复合材料的拉伸强度达到33.3 MPa,提高了50.8%;弯曲强度为46.3MPa,提高了20.0%;缺口冲击强度达到10.22 kJ/m2,提高了95.0%,同时吸水率也得到改善,从0.71%下降至0.62%。流变实验结果表明,MAPE和EAA增容竹粉/HDPE复合材料的黏度较低,而MAPOE体系黏度较高,加工性能变差。     

Nano-CaCO3/HDPE复合材料流变性能的研究

通过熔融共混法制备了纳米碳酸钙/高密度聚乙烯(nano-CaCO3/HDPE)复合材料,使用旋转流变仪研究了复合材料的动态流变性能。结果表明,当nano-CaCO3加入量≤4%(质量分数)时,随着nano-CaCO3含量的增加,nano-CaCO3/HDPE复合材料的储能模量、损耗模量和复数黏度均高于纯HDPE,并逐渐上升。     

PMDI与MAPE复合改性荻草/HDPE复合材料的性能研究

以荻草纤维(SV)、高密度聚乙烯(HDPE)制备复合材料,同时用多苯基甲烷多异氰酸酯(PMDI)与马来酸酐接枝聚乙烯(MAPE)作为改性剂。研究了复合改性对荻草木塑复合材料力学性能、热性能的影响。结果表明,FTIR证明了PMDI的官能团与羟基发生了反应。当SV与PMDI质量比为6:1,SV质量分数为50%,MAPE质量分数为8%时,荻草木塑复合材料的力学性能达到最佳。荻草纤维经过PMDI处理后,促进了纤维的成核剂的作用,但是添加MAPE后,复合材料的结晶度降低。     

离子聚合物改性木塑复合材料的研究

研究了钠离子聚合物(Surlyn 8940)对杨木粉/高密度聚乙烯(HDPE)木塑复合材料的增容和增韧改性效果,并与马来酸酐接枝聚乙烯(MAPE)改性杨木粉/HDPE木塑复合材料相比较。通过万能力学试验机和悬臂梁冲击试验机测试了不同用量的钠离子聚合物或MAPE改性HDPE复合材料的力学性能,以及使用场发射扫描电镜观察钠离子聚合物改性HDPE复合材料的表面和断面形貌。结果表明,当木粉质量分数为40%时,添加4%钠离子聚合物的复合材料的拉伸强度(25.8 MPa)比添加4%MAPE时提高了78.6%;随着钠离子聚合物含量的增加,复合材料的弯曲弹性模量呈现出明显的降低趋势,而添加钠离子聚合物的复合材料的弯曲强度要高于添加MAPE复合材料的弯曲强度,并且发现钠离子聚合物对复合材料有突出的增韧效果,表明钠离子聚合物对于木塑复合材料是较好的增容增韧剂;SEM分析表明添加离子聚合物后,塑料基体对木粉有很好的包覆效果,没有明显的界面缝隙。     

高密度聚乙烯/硅烷偶联剂改性硫酸钙晶须复合材料的制备与性能

以γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）改性的硫酸钙晶须（CSW）为高密度聚乙烯（HDPE）的填料,采用熔融共混法制备了HDPE/CSW复合材料。通过SEM、XRD、TG、DSC表征了KH570改性的CSW对复合材料HDPE/CSW的性能影响。结果表明,改性CSW质量分数为20%时,HDPE/CSW的拉伸和弯曲强度比纯HDPE分别增加9.28%和33.04%,且易产生异相结晶,提升了HDPE/CSW复合材料的耐热性和结晶度。纯HDPE的热降解反应活化能为244.11 k J/mol,改性CSW质量分数为50%时,HDPE/CSW复合材料的热降解反应活化能降到236.99 kJ/mol,表明CSW提升了HDPE/CSW复合材料的热降解反应速率,扩展了复合材料的使用范围。     

异氰酸基改性剂的制备及在木塑材料中的应用

以4,4'-二环己基甲烷二异氰酸酯(HMDI)与十八醇为原料,制备了含异氰酸基的改性剂,并研究其对高密度聚乙烯(HDPE)/木粉复合材料和聚丙烯(PP)/木粉复合材料力学性能及加工性能的影响。结果表明,通过5%改性剂改性以后的木粉,其表面接触角能够达到144.3°。由改性木粉制备的HDPE/木粉复合材料,拉伸强度较未改性最多提高33.9%,断裂伸长率提高74.1%;当改性剂质量分数为3%时,塑化时间从169 s缩短至146 s,平衡扭矩从9.8 N·m减小到8.9 N·m,塑化温度从135.6℃降低至131.9℃。由改性木粉制备的PP/木粉复合材料,拉伸强度较未改性最多提高24.3%,断裂伸长率提高41.8%;当改性剂质量分数为3%时,塑化时间从144 s缩短至102s,平衡扭矩从10.7 N·m减小到7.3 N·m,塑化温度从174.7℃降低至162.7℃     

塑料基体中MAPE/HDPE比例对木塑复合材料力学性能的影响

以高密度聚乙烯(HDPE)和马来酸酐接枝聚乙烯(MAPE)共混物为塑料基体,以木粉为填料,用注塑成型法制备木塑复合材料,研究MAPE/HDPE质量比变化对塑料基体和木塑复合材料力学性能的影响.结果表明:MAPE/HDPE比变化对MAPE/HDPE共混形成的塑料基体强度基本没有影响,但对由该共混物所制得的木塑复合材料的强度影响显著;在相同的木粉含量下,保持配方中MAPE和HDPE的总含量不变,木塑复合材料的拉伸强度随MAPE/HDPE比率增大先迅速增加,然后趋于平缓.冲击强度随MAPE/HDPE比增大逐渐减小.     

废纸／再生高密度聚乙烯复合材料的力学性能研究

以废纸和再生HDPE为原料制备废纸/再生HDPE复合材料.采用红外光谱分析和差示扫描量热法分析手段研究了废纸和再生HDPE的基本特性,同时探讨了废纸用量、增容剂(硅烷偶联剂KH550和马来酸酐接枝聚乙烯MAPE)对复合材料力学性能的影响,并借助扫描电镜观察复合材料的拉伸断面形貌.结果表明:废纸能作为再生HDPE的增强体,且废纸质量分数为15%时,拉伸强度和弯曲强度分别为23.68 MPa、28.78 MPa;增容剂能改善复合材料的界面性质,提高复合材料的力学性能,KH550和MAPE最佳用量分别为1%和4%～6%.     

HDPE/木粉复合材料的性能研究

研究了不同种类的增容剂对高密度聚乙烯(HDPE)木/粉复合材料性能的影响,并研究了增容剂含量、木粉含量对复合材料力学性能及形态结构的影响。结果表明,HDPE木/粉复合材料的拉伸强度、弯曲强度均随马来酸酐接枝HDPE(HDPE-g-MAH)含量的增加而增大;复合材料的缺口冲击强度随甲基丙烯酸缩水甘油酯接枝低密度聚乙烯的增加而提高;复合材料的拉伸强度、弯曲强度随木粉含量的增加而增大;而缺口冲击强度则随木粉含量的增加呈降低趋势。     

连续玻纤增强HDPE复合材料的结晶动力学

采用差示扫描量热(DSC)法分析了不同降温速率下高密度聚乙烯(HDPE)和连续玻纤(GF)增强HDPE复合材料的非等温结晶和熔融行为。使用莫志深法对HDPE和HDPE/GF复合材料的非等温结晶动力学进行研究,得出莫氏方程可以描述其非等温结晶动力学过程。并且采用偏光显微镜(POM)观察结晶形态。结果显示:降温速率越大,聚合物结晶峰越宽、聚合物开始结晶时的温度越低、结晶峰温度越低。GF起到异相成核的作用,使得HDPE/GF复合材料的成核速率高于纯HDPE,但由于纤维对晶体生长具有一定的阻碍作用,使其结晶焓较低。通过熔融曲线分析发现,降温速率和GF的加入对HDPE及HDPE/GF复合材料熔融温度和熔融峰温度的影响并不显著。采用莫志深法的研究结果与由动力学参数得出的结论相一致,HDPE/GF复合材料比HDPE更易结晶。POM等温结晶观察结果表明,HDPE/GF复合材料比HDPE的结晶速率更快,这与DSC和莫志深方程结果一致。     

Correlation between physical bonding and mechanical properties of wood–plastic composites: part 2: effect of thermodynamic factors on interfacial bonding at wood–polymer interface

Abstract

The main objective of this study was to find out if there is any significant correlation between physical properties and interfacial bonding of interphases in wood–plastic composites. To this end, high-density polyethylene (HDPE), mixture of 3% maleic anhydride grafted polyethylene (MAPE) and HDPE (coded as MHDPE) and polylactic acid (PLA) were separately interacted with veneers to identify factors underlying interfaces. Plastics were first melted at 180?°C and dispensed on wood surfaces so that the contact angle (CA) could be directly measured. Wood sanding moderately decreased the CAs of plastics in order of PLA, MHDPE, and HDPE. The treatment of veneers with MAPE comprehensively improved wetting, as the CA of HDPE was significantly reduced on the wood surface after the treatment. Thereafter, the interfacial shear strengths (IFSS) of the wood–polymer interface were determined using the automated bonding evaluation system. PLA had the highest IFSS both for unsanded and sanded veneers. Comparing both parts of this research finally revealed that applying sanding or/and MAPE treatments resulted in lower surface free energy and higher IFSS at the wood–polymer interface. However, our observations support the idea that, at higher temperatures, wetting of composites is mainly influenced by polymer properties rather than interfacial tension at the wood–polymer interface.     

Effect of Coupling Agent Concentration,Fiber Content,and Size on Mechanical Properties of Wood/HDPE Composites

In this study, the influence of coupling agent concentration (0 and 3 wt%), wood fiber content (50, 60, 70, and 80 wt%), and size (40–60, 80–100, and 160–180 mesh) on the mechanical properties of wood/high-density-polyethylene (HDPE) composites (WPCs) was investigated. WPC samples were prepared with poplar wood-flour, HDPE, and polyethylene maleic anhydride copolymer (MAPE) as coupling agent. It was found that the tensile properties and the flexural properties of the composites were improved by the addition of 3 wt% MAPE, and the improved interfacial adhesion was well confirmed by SEM micrographs. It was also observed that the best mechanical properties of wood/HDPE composites can be reached with larger particle size in the range studied, while too-small particle size was adverse for the mechanical properties of wood/HDPE composites. Moreover, the tensile modulus, tensile strength, and flexural strength of WPCs decreased with the increase in fiber content from 50 to 80 wt%; the flexural modulus of WPCs increased with the increase in fiber content from 50 to 70 wt% and then decreased as the fiber content reached 80 wt%. The variances in property performance are helpful for the end-user to choose an appropriate coupling agent (MAPE) concentration, wood fiber content, and particle size based on performance needs and cost considerations.     

甲基化木粉与PE-g-MAH对木粉/HDPE复合材料力学性能的协同作用研究

主要研究了木粉表面甲基化改性和增容剂马来酸酐接枝聚乙烯(PE-g-MAH)对木粉/高密度聚乙烯(HDPE)复合材料力学性能的协同作用.木粉经表面甲基化处理后,与10％PE-g-MAH协同使用,甲基化木粉/PE-g-MAH/HDPE复合材料的拉伸强度、弯曲强度和冲击强度均明显高于未改性木粉/PE-g-MAH/HDPE复合...     

MAPE含量对PE木塑复合材料冲击强度的影响

以高密度聚乙烯(PE-HD)和马来酸酐接枝聚乙烯(MAPE)共混物为塑料基体,以木粉(WF)为填料,采用压制成型法制备了木塑复合材料。研究了MAPE含量对塑料基体和木塑复合材料冲击强度的影响。结果表明,MAPE含量对MAPE/PE-HD塑料基体和木塑复合材料的冲击强度影响显著;保持MAPE和PE-HD的总含量不变时,当木粉含量为30 %时,木塑复合材料的冲击强度随MAPE含量的增大而逐渐减小;当木粉含量为70 %时,木塑复合材料的冲击强度随MAPE含量的增加而逐渐增大。     

木粉疏水改性对HDPE基木塑复合材料性能的影响

采用一种操作简便且易于工业推广的方法对木粉进行疏水改性,具体过程为：将3种可热聚合的单体,即甲基丙烯酸甲酯（MMA）、甲基丙烯酸丁酯（BMA）和苯乙烯（St）均匀喷洒在木粉上,经过预热处理后,与配方中其他组分,如高密度聚乙烯（HDPE）和马来酸酐接枝聚乙烯（MAPE）等通过高速混合机混合均匀,采用双螺杆挤出机造粒后,注射制备木塑复合材料（WPC）样条,测试其力学性能。另外,考察了疏水改性对WPC接触角、维卡软化温度、洛氏硬度、吸水性能、热性能的影响规律。结果表明：疏水改性后WPC的接触角增大,木粉和HDPE的界面相容性改善,力学性能得到明显提高。其中,当MMA、BMA和St的添加量为3%时,WPC的力学性能最好,与疏水改性前相比,弯曲强度分别提高了17.3%、26.3%和27.5%,弯曲模量分别提高了24.4%、24.4%和26.0%,冲击强度分别提高了54.7%、57.7%和60.5%。 此外,疏水改性后WPC的维卡软化温度、洛氏硬度、耐水性和耐热性也得到改善。     

Decorated wood fiber/high density polyethylene composites with thermoplastic film as adhesives

It is difficult for wood fibers/high density polyethylene (WF/HDPE) composites to laminate with poplar (Populus tomentosa) wood veneer due to its nonpolar and imporous surface. In present study, four types of thermoplastic films, include two sorts of chlorinated polypropylene (CPP32 and CPP22) film and a mixture film of maleic anhydride grafted polyethylene (MAPE) and HDPE, were developed to glue poplar wood veneer onto WF/HDPE composite board under heat-pressing. The intermediate layer has well water resistance when used aforementioned films. Optical microscopy and scanning electron microscopy (SEM) results show that CPP32 with higher melt flow rate had the higher permeability into poplar wood and fitness with WF/HDPE surface than CPP22; accordingly, the bonding strength of CPP32 was higher than CPP22. MAPE/HDPE film formed the strongest bonding layer for the high compatibility with the WF/HDPE surface which confirmed using SEM, and the covalent bonding between the poplar veneer and MAPE were confirmed using fourier transform infrared (FTIR). Compared to the high heat-press temperature of MAPE/HDPE, CPP32 has the lower processing temperature and acceptable bonding strength. CPP32 and MAPE/HDPE film both suited as the bonding intermediary to substitute traditional adhesive to manufacture veneered wood-plastic composite boards.     

Rheological properties of teak wood flour reinforced HDPE and maize starch composites

Teak wood flour reinforced high density polyethylene and maize starch composites were prepared by using maleic anhydride grafted polyethylene as a compatibilizer. The mechanical properties (tensile and flexural) of all the composites increased after addition of 10%–40% teak wood flour into HDPE matrix. The complex viscosity (η*) was higher for all the composites at the low frequency, but decreased with increasing frequencies indicating a shear thinning behavior of the composites. The storage modulus and loss modulus increased for the composites compared to the HDPE at low frequencies. Damping factor peak of HDPE and composites showed high below 1 Hz, but the peak start decreasing with increasing above 1 Hz. The relaxation behavior of HDPE and the composites after incorporating teak wood flour, maize starch, and compatibilizer was obtained by Han plot. Biodegradability was enhanced with the incorporation of teak wood flour, maize starch into the composites. Appreciable water uptake and the thickness swelling for the composites indicating it's potential for interior, automobile and packaging applications.     

Thermal,crystallization, and dynamic rheological behavior of wood particle/HDPE composites: Effect of removal of wood cell wall composition

This study investigated the effect of removal of wood cell wall composition on thermal, crystallization, and dynamic rheological behavior of the resulting high density polyethylene (HDPE) composites. Four types of wood particle (WP) with different compositions: native wood flour (WF), hemicellulose‐removed wood particle (HR), lignin‐removed wood particle (holocellulose, HC), and both hemicellulose and lignin removed particle (α‐cellulose, αC) were prepared and compounded with HDPE using extruder, both with and without maleated polyethylene (MAPE). Results show that removal of the hemicellulose improved the thermal stability of composites, while removal of the lignin facilitated thermal decomposition. WPs acted as nucleating agents and facilitated the process of crystallization, thereby increasing the crystallization temperature and degree of crystallinity. The crystallization nucleation and growth rate of αC and HR based composites without MAPE decreased, as compared with WF based one. Composite melts with and without MAPE exhibited a decreasing order of storage modulus, loss modulus, and complex viscosity as αC > WF > HR > HC and αC > HR > WF > HC, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40331.     

Foam extrusion of high density polyethylene/wood‐flour composites using chemical foaming agents

A one‐way analysis of variance and thermal analysis were performed in this study to examine the influences of the contents, types (exothermic vs. endothermic), and forms (pure vs. masterbatch) of chemical foaming agents (CFAs), as well as the use of coupling agents, on the density reduction (or void fraction) and cell morphology of extrusion‐foamed neat high density polyethylene (HDPE) and HDPE/wood‐flour composites. The CFA types and forms did not affect the void fractions of both the neat HDPE and HDPE/wood‐flour composites. However, a gas containment limit was observed for neat HDPE foams whereas the average cell size achieved in the HDPE/wood‐flour composite foams remained insensitive to the CFA contents, irrespective of the foaming agent types. The experimental results indicated that the use of coupling agent in the formulation was required to achieve HDPE/wood‐flour composite foams with high void fraction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3139–3150, 2003     

Effect of highly degraded high‐density polyethylene (HDPE) on processing and mechanical properties of wood flour‐HDPE composites

The influence of highly degraded high‐density polyethylene (HDPE) on physical, rheological, and mechanical properties of HDPE‐wood flour composites was studied. For this purpose, the virgin HDPE was subjected to accelerated weathering under controlled conditions for 200 and 400 h. The virgin and exposed HDPE and pine wood flour were compounded to produce wood flour‐HFPE composites. The results showed that the accelerated weathering highly degraded HDPE. Degradation created polar functional carbonyl groups and also produced extensive cross‐linking in HDPE and consequently poor processibility. The interruptions in the flow characteristics of the degraded HDPE potentially caused processing hurdles when using them for extrusion or injection molding manufacturing as only small part (10%) of virgin HDPE could be replaced by highly degraded HDPE for wood flour‐HDPE composite manufacturing. The mechanical properties of composites containing highly degraded HDPEs were similar to the composites with virgin HDPE and in some cases they exhibited superior properties, with the exception being with the impact strength. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013