A study on the photostabilizer additives on the textile fiber reinforced polymer composites: Mechanical,thermal, and physical analysis

The effect of photostabilizers on the mechanical, thermal, and physical properties of textile fiber reinforced polymer (T‐FRP) composites was investigated. In the first phase of this study, the effect of different concentrations of ultra violet absorber (UVA), hindered amine light stabilizers (HALS) and antioxidants (AOs) into T‐FRP composites for unweathering condition are examined. Mechanical tests were performed as well as differential scanning calorimetry (DSC) analysis for thermal properties. According to test results, there is no significant effect of photostabilizers on the mechanical and thermal properties of the T‐FRP composites. In the second phase of the study, the influence of the photostabilizers on the durability performance of T‐FRP composites is focused under the accelerated UV weathering condition by the help of tensile testing, thermal analysis, and color measurements. According to test results, only about 5% loss in mechanical properties (25% loss for composites without additives) can be observed after 240 h of UV weathering with HALS and UVA addition at adequate concentrations. In addition, AOs can be considered as a strong stabilizer on physical properties with lower color change values. This work shows that the efficiency of the photostabilizers is highly dependent on the type, concentration, and weathering time. POLYM. ENG. SCI., 58:1082–1090, 2018. © 2017 Society of Plastics Engineers     

光稳定剂复配对核壳WPC抗紫外老化性能的影响

为探索经济、环保且效果更好的木塑复合材料(WPC)表面耐老化处理方法,采用共挤技术,以不同复配方式将纳米白炭黑、HALS–L944及UV327添加于核壳型WPC壳层。对试样进行紫外光加速老化试验,并对其弯曲性能、表面颜色及化学成分结构进行了测试表征与方差分析。研究结果表明,当壳层加入1%纳米白炭黑与1%UV327复配时效果最好,紫外老化2 500 h后,较之空白样,WPC的弯曲强度保留率提高了14.7%,弹性模量保留率提高了17.4%,保护效果最好,具有一定的协同作用;表面颜色变化较为缓慢,色差下降了44.9%,优于单独添加光稳定剂效果;O/C值增长幅度为9.1%,氧化的碳/未氧化的碳比值增加了11.8%,表面氧化程度最低。说明纳米白炭黑与UV327具有一定的协同作用,能够更好地提高核壳WPC的抗紫外老化性能,降低其光氧化降解程度。     

ABS的耐候老化研究

主要对丙烯腈–丁二烯–苯乙烯塑料(ABS)的不同耐候性能进行了研究,通过人工加速老化试验,对比老化前后色差变化,考察光稳定剂对ABS耐候性能的影响。结果表明,添加光稳定剂能够有效地改性ABS耐候性能;受阻胺光稳定剂与紫外线吸收剂复配使用对ABS有很好的耐候效果;适当地提高受阻胺光稳定剂含量有利于提高ABS的耐候性能。     

Photostabilization of poly(vinyl chloride) by protective coatings

The light stability of poly(vinyl chloride) plates has been substantially increased by protecting their surface with a UV‐cured acrylic clearcoat containing both a UV absorber and a HALS radical scavenger. To ensure a long‐lasting adhesion, the coating was photochemically grafted onto the PVC substrate. The coated PVC sample remained transparent, non‐colored, and glossy upon accelerated QUV‐B weathering for up to 3000 hours. An additional advantage of this method of photostabilization is to improve some of the surface properties of the coated polymer, such as its resistance to solvents, abrasion, and scratching. The method was also successfully used to recover highly photodegraded PVC and make it even more weathering‐resistant than the original polymer.     

Synergistic effect of hindered amine light stabilizers/ultraviolet absorbers on the plasticized PVC during photo-irradiation

Two kinds of piperidine derivatives including a low-molecular weight (Wt. 481, T770) and a high-molecular weight (Wt. 2000–3100, C944) hindered amine light stabilizers (HALS) are added singly or with ultraviolet absorbers (UVA) in combination to plasticized poly(vinyl chloride) (PVC) samples. Digital photos, color changes, attenuated total refection-Fourier transform infrared spectra (ATR-FTIR), and mechanical properties are obtained to investigate the photostable effect of the light stabilizers on the plasticized PVC after artificial aging. PVC samples with HALS perform well at the first 400 h of irradiation in color change, FTIR, and mechanical properties, but at the last 400 h the photostability decreases. Besides, C944 performs better than T770, because C944 is a high-molecular weight UV stabilizer and has good extraction resistance. Plasticized PVC samples with UVA resist discoloring and photooxidation from the photo-irradiation. Excellent synergism is observed between the combination of HALS and UVA. PVC with HALS/UVA performs better than PVC with HALS and PVC with UVA in color differences, FTIR, and mechanical properties. The synergism is due to the different stages of functions between HALS and UVA. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

四溴双酚A双(2,3-二溴丙基)醚阻燃V-2聚丙烯材料光稳定化研究

采用氙灯老化仪对四溴双酚A双(2,3-二溴丙基)醚阻燃V-2聚丙烯材料进行光老化,通过测色仪测试样品色差变化,评估材料的紫外老化性能。系统研究了不同钛白粉、抗氧剂、光稳定剂对材料紫外老化性能的影响。优选最佳配方与国外同类材料进行耐候性能及力学性能变化对比。     

Effects of weathering aging on mechanical and thermal properties of injection molded glass fiber reinforced polypropylene composites

The effect of weathering aging on the degradation behavior of injection molded short glass fiber reinforced polypropylene composites (GFPP) is studied. First, the effect of outdoor weathering on mechanical properties of GFPP composite was investigated by tensile, flexural, and impact tests. Furthermore, to clarify the degradation behavior under natural weathering environments, differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) measurements were carried out to analyze the structural and molecular changes during weathering aging. The results show that weathering aging has a significant influence on changes in mechanical properties, melting temperature and the degree of crystallinity of PG6N1 without added carbon black and UV absorbing agent. Those degradations not only occurred on the surface of GFPP but also proceeded to the inner matrix and interface. However, GFPP GWH42 with added carbon black and UV absorbing agent shows excellent weathering stability.     

Synergistic effect of hindered amine light stabilizers/ultraviolet absorbers on the polyvinyl chloride/powder nitrile rubber blends during photodegradation

The photostability of hindered amine light stabilizer (HALS) and ultraviolet absorber (UVA) on the blends of plasticized poly (vinyl chloride) (PVC) and powder nitrile rubber (NBR) has been studied with a Xenon Test Chamber. The digital photos, color differences, attenuated total refection‐Fourier transform infrared (ATR‐FTIR) spectra and mechanical properties of the blends have been determined. HALS combined with UVA effectively protects PVC/NBR blends from yellowing and restrains the decrease of elongation at break of the blends. The synergistic phenomenon is ascribed to the different photostable mechanisms of HALS and UVA at different photo aging stages. The color of PVC/NBR control sample quickly changes into yellow at the first 400 h of irradiation, due to the polyenes structures that induced by the double bonds of butadiene in NBR. From 400 to 800 h, crosslinking dominates and the amount of polyenes decreases, resulting into the decrease of color change. At the early stage of irradiation, chain‐scission of polymer takes the predominant place, and the tensile strength decreases. But during the latter stage, crosslinking takes the predominant place and the tensile strength increases slightly. HALS and UVA have a little effect on the maintaining of elongation at break of PVC/NBR blends. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Effect of weathering cycle and manufacturing method on performance of wood flour and high‐density polyethylene composites

Wood–plastic lumber is promoted as a low‐maintenance high‐durability product. When exposed to accelerated weathering, however, wood–plastic composites may experience a color change and loss in mechanical properties. Differences in weathering cycle and composite surface characteristics can affect the rate and amount of change caused by weathering. In this study, 50% wood flour filled high‐density polyethylene composite samples were injection molded, extruded, or extruded and then planed to remove the manufacturing surface characteristics. Composites were exposed to two accelerated weathering cycles in a xenon arc weathering apparatus. This apparatus exposed the samples to xenon arc radiation, which is a combination of UV, visible, and IR radiation that is similar to solar radiation. Composites were exposed to radiation with or without water spray. After exposure to radiation and water spray, composites with more wood component at the surface (i.e., planed samples) experienced a larger percentage of total loss in flexural modulus of elasticity and strength after weathering compared with the other composites. Composites exposed to radiation only did not experience as much change in properties as those exposed to radiation with water spray. The results of this study demonstrate that exposing wood–plastic composites to water spray in combination with radiation is more severe than exposing wood–plastic composites to radiation only. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3131–3140, 2006     

紫外老化对聚苯乙烯泡沫性能的影响

采用紫外加速老化方法,研究聚苯乙烯泡沫(EPS)在受到紫外老化后其外观和缓冲性能的变化规律,分析材料内部结构的变化.结果表明,随着加速紫外老化时间的延长,EPS分子链上产生某种显色基团,导致试样表面颜色变黄,EPS的最小缓冲系数值增大,缓冲效率降低;且随老化时间的增加,EPS分子量降低,分子量分布由2.13增大到3.76;分子结构中C元素含量减少,O元素含量逐渐增加,紫外线照射导致EPS表面受到激发并在水和热的共同作用下发生表面氧化,生成C O键、C-OH键等新的官能团;加速老化使EPS结构中大分子断链,化学键重组,导致力学性能下降.研究EPS材料的老化行为是推断其使用寿命和环境的基本依据,为EPS衬垫在运输包装过程中的合理应用提供参考依据.     

Kinetic study of hindered amine light stabilizer photografting in low density polyethylene films under natural weathering conditions

The photografting kinetic of a hindered amine light stabilizer (HALS) was studied in low density polyethylene (LDPE) films under natural weathering conditions. The HALS (PBH‐3) was added to the polymer at a concentration of 0.3% (w/w). The photografting kinetic of polymer bound HALS (PBH‐3) was determined by direct spectroscopic measurements through the absorption band area of the stabilizer centered at 308 nm in the UV spectra and 1605 cm^?1 in Fourier transform IR (FTIR) spectra, which correspond to benzylidene malonate ester and benzylidene malonic groups, respectively. In parallel, measurements were carried out on the free PBH‐3 content after chloroform extraction of the photostabilizer from the polymer matrix by means of UV and gas chromatography methods. The results showed that in natural weathering the grafting of PBH‐3 occurred in the LDPE film after very short exposure times of 127 and 168 h as determined by UV and FTIR, respectively. Moreover, the curves describing both the photografting and the free HALS kinetics exhibited similar profiles. The mechanism of photografting implies a rapid photoreaction between the methylenic double bond of the stabilizer and the macroalkyl radicals of the polymer, resulting in formation of polymer‐bonded aminyl derivatives of the stabilizer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1524–1532, 2002; DOI 10.1002/app.10492     

Improved Ultraviolet (UV) Radiation Stability of the Polypropylene (PP) Films of Woven Jumbo Bags for Outdoor Applications

Several formulations were developed with polypropylene (PP) in combination with antioxidants, calcium stearate, hindered amine light stabilizers (HALS) and ultraviolet light absorber (UVA) for making woven jumbo bags, which will be capable of carrying a load of two tons of materials in outdoor conditions. Thin films of these formulations were extruded followed by stretching to improve mechanical properties. Both stretched and un-stretched PP films were subjected to severe accelerated weathering by ultraviolet (UV) radiation for various periods and it was observed that un-stretched films reached 50% retention of tensile strength (TS) within 500 hours of exposure, while stretched films (tapes) did not reach 50% TS retention even after 10,500 hours of the exposure indicating an improved UV stability of the stretched films of PP.     

Evaluation of dimensional stability,weathering and decay resistance of modified pine wood by in-situ polymerization of styrene

Abstract

In this study, polystyrene modified Scots pine (Pinus sylvestris L.) wood was investigated upon artificial weathering, decay resistance, dimensional stability and water uptake properties. Polystyrene modification was carried out on pretreated wood by immersion of wood into styrene monomer and further polymerization. The resistance of modified wood against cycles of UV and water exposures was examined by artificial weathering test for 672?hours, and decay resistance was evaluated by attacks of Coniophora puteana and Trametes versicolor on the samples. During the artificial weathering, color and surface roughness of the samples, and macroscopic changes were determined periodically. Changes in the surface chemistry and morphology of the weathered samples were investigated by ATR-FTIR and SEM, respectively. It was proven that polystyrene effectively protected pine samples from both fungi even after leaching procedure, but it was more effective in preventing C. puteana attacks than T. versicolor attacks. As a result of artificial weathering, the surface of all samples was darkened. However, changes in color and roughness as well as crack formations of the modified sample surfaces were found less than those of the untreated samples. Polystyrene also provided considerable improvement on dimensional stability, as well as water repellence of wood.     

Synthesis of 5‐sulfosalicylic acid‐intercalated layered double hydroxide and its effects on wood flour/polypropylene composites during accelerated UV weathering

In this study, 5‐sulfosalicylic acid (SA) anions have been intercalated into Mg₃Al‐NO₃ layered double hydroxide (LDH) to synthesize SA‐intercalated Mg₃Al‐NO₃‐LDH (LDH‐SA) by ion‐exchange reaction. Then, the effects of LDH, SA, and LDH‐SA on the photostability of wood flour/polypropylene (WF/PP) composites during accelerated ultraviolet (UV) weathering were investigated. The surface color, surface gloss, and mechanical properties of the composites during weathering were tested, accompanied by characterizations using SEM, ATR‐FTIR, and TG. The results showed that (1) SA anions completely replaced the anions in LDH and the thermal stability of LDH‐SA was considerably enhanced; (2) composites with LDH or LDH‐SA exhibited less color change, fewer surface cracks, better thermal stability, and less losses of mechanical properties than the control group; (3) LDH‐SA showed a long‐term efficiency and alleviated the photo‐oxidation of WF/PP composites successfully; (4) LDH‐SA blocked UV light by physical shield effect of the layer sheets, as well as the chemical absorbability of the interlayer anions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44597.     

Effect of processing method on surface and weathering characteristics of wood–flour/HDPE composites

Wood–plastic lumber is promoted as a low‐maintenance high‐durability product. When exposed to accelerated weathering, however, wood–plastic composites may experience a color change and/or loss in mechanical properties. Different methods of manufacturing wood–plastic composites lead to different surface characteristics, which can influence weathering. In this study, 50% wood–flour‐filled high‐density polyethylene (HDPE) composite samples were injection molded, extruded, or extruded and then planed, to remove the manufacturing surface characteristics. Fourier transform infrared spectroscopy was used to chemically show the difference in surface components. The samples were weathered in a xenon‐arc weathering apparatus for 1000, 2000, and 3000 h and analyzed for color fade and loss of flexural modulus of elasticity and strength. Final color (lightness) after weathering was not dependent on the manufacturing method. However, the manufacturing method was related to mechanical property loss caused by weathering. Composites with more wood component at the surface (i.e., planed samples) experienced a larger percentage of total loss in flexural modulus of elasticity and strength after weathering. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1021–1030, 2004     

Effects of two staining methods on color stability of wood flour/polypropylene composites during accelerated UV weathering

Two staining methods of wood flour/polypropylene composites in an attempt to improve the color stability of wood‐plastic composites (WPCs) were investigated. The first was to dye wood flour (WF) before compounding with polypropylene (PP) to make stained composites. The second method involved mixing pigments directly with WF and PP. Nine groups of composites were weathered in a QUV accelerated weathering tester for 960 h. Their surface color, surface gloss, washing resistance, and flexural properties were tested during weathering. Additionally, the weathered surface was characterized by SEM and ATR‐FTIR. The results revealed that (1) the washing resistance of composites were improved after staining treatments; (2) composites made of dyed WF showed higher surface gloss values and less cracks on weathered surface at the early stage of weathering; while composites containing pigments displayed brighter color, less color change, and less loss of flexural properties during weathering; and (3) weathering resulted in the protrusion of WF and photodegraded lignin on exposed surface. Adding pigments was proven to be more effective staining method for improving composite color stability during weathering. POLYM. COMPOS., 38:1194–1205, 2017. © 2015 Society of Plastics Engineers     

Accelerated weathering properties of compatibilized composites made from recycled HDPE and nonmetallic printed circuit board waste

The main aim of this work is to examine the influence of the contents of nonmetallic printed circuit board (PCB) waste component on the photodegradation of recycled high‐density polyethylene (rHDPE) composites. The properties tested were chemical changes, flexural properties, color stability, water absorption, leaching properties, and crystallinity changes of the composites after exposure to 2,000 h of accelerated weathering. Surface degradation for composites with nonmetallic PCB was less compared to unfilled rHDPE mainly because glass fibers covered almost the whole surface of specimens, acting as a protective layer, thus, slowing down the photodegradation reaction. Incorporation of compatibilizer in rHDPE/PCB composites had played an important role in resisting degradation due to UV exposure. All the composite samples became lighter in the early stages of weathering exposure; however, compatibilized composites showed less lightening and reduction on strength and modulus. Carbonyl index increases with exposure time indicating that the oxidation reaction continuously occurred during the aging process. Incorporation of compatibilizer had successfully reduced the water absorption uptake by the composites and effectively delayed some degradation properties of weathering. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43110.     

Phase Stability and Mechanical Properties of Zirconia and Zirconia Composites

Monolithic zirconia materials (3Y‐TZP, 10Ce‐TZP, and 12Ce‐TZP) and their composites with 30 vol% alumina were produced. Low‐temperature aging degradation (LTAD) and mechanical properties of materials were investigated. For assessment of phase stability in the materials, aging experiments were performed in water at 90°C for 32, 64, and 128 days. The aging phenomenon was characterized and monitored using X‐Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Four‐point bending was used to determine the flexural strength of materials before and after aging treatment in water at 90°C for 2, 4, and 6 months. The aging experiments resulted in different phase transformation rates for the materials studied. The 12Ce‐TZP containing materials showed the highest resistance to low‐temperature aging and 3Y‐TZP containing materials showed the highest bending strength. When compared, no change in flexural strength was observed between the materials not exposed to aging and the aged materials.     

碳纤维增强树脂基复合材料性能的研究

以不同含量的二乙烯三胺(DETA)固化的环氧树脂为基体,制备了碳纤维增强树脂基复合材料。通过扫描电镜和红外光谱分析了T-300型碳纤维表面形貌和基团组成。通过拉伸实验、冲击实验对复合材料的力学性能进行了表征;通过紫外老化实验对复合材料的耐候性进行了表征;通过扫描电镜和热重分析对复合材料的断面形貌和耐热性进行了表征。结果表明:碳纤维增强树脂基复合材料具有良好的耐候性、力学性能、而且还具有质量轻、高比强度等一系列优异的性能。     

Synthesis,characterization, and performance evaluation of novel stabilized TDI‐based polyurethane coatings under accelerated weathering

Some toluene diisocyanate (TDI)‐based polyurethane resins (PURs) for coating applications were synthesized with castor oil and their performance was estimated under accelerated UV weathering with and without a novel UV absorber. Changes in physical properties, chemical structure, and color of the samples were monitored by mechanical property testing, FTIR spectroscopy, and colorimetry, respectively. A stable polyurethane coating was achieved at 0.5% concentration of additive in the host matrix. Mechanical properties were also retained as in the pristine PUR after mixing. Commercial Tinuvin P and benzotriazole‐based novel UV absorbers were found to improve the photoresistance of the PUR coating, and the highest efficiency of the novel UV absorber against weathering was estimated at 0.5 wt% concentration. J. VINYL. ADDIT. TECHNOL. 11:13–20, 2005. © 2005 Society of Plastics Engineers.