關(guān)于混有二氧化鈦的氧化鎂在PVC門窗型材中的可用性研究畢業(yè)論文外文資料翻譯

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1、 外文資料翻譯 A study on usability of magnesium oxide with titanium dioxide in PVC door and window profiles 1. Introduction Polyvinyl chloride is among the most widely used synthetic organic polymer materials. Plasticized polyvinyl chloride compositions are widely encountered as, for instance,vi

2、nyl sheet goods and as objects formed from plastisols.Polyvinyl chloride is commercially available in a variety of grades, some of which are suitable for preparing rigid,plasticizer-free compositions for extrusion . For plastics, prolonged exposure to the sun’s electromagnetic radiation in the ultr

3、aviolet (UV) region can lead to photooxdiation and degradation of physical properties, often manifested by color change and embrittlement. Similarly,the UV component of ordinary fluorescent lighting can degrade polymers and many of the additives used with them. The effective UV radiation that does

4、reach the earth’s surface extends from about 290–400 nm. This range happens to include the highest energy component UV band, and the segment around 300 nm, which is the most distractive to plastics. Some man-made high-energy radiation sources mercury arc lamps, xenon arcs, carbon arcs, and various s

5、un-lamps can emit radiation at wave lengths below 290 nm and these can degrade plastics even more severely than natural sun light. Hence, they are often used for accelerated testing of plastics. The energy content of UV radiation in the 290–400 nm can rupture most of the chemical bonds present in p

6、olymer structures. Not all the polymers are equally affected by UV radiation, and some have a degree of resistance, otably polymethyl methacrylates and fluorocarbons. Others, that in their pure forms could be expected to be resistant to UV, are degraded because of contaminants present that act as si

7、tes for UV energy absorption. Absorption of radiation energy by polymer produces molecular excitations: if the level of absorbed energy is high enough, it can activate a chemical reaction whereby internal bonds (carbon to carbon, carbon to hydrogen, carbon to halogen, etc.) are broken so that polym

8、er degradation results. PVC is damaged by dehydrochlorination (release of hydrogen chloride), autooxidation and echanochemical chain scission. This degradation is caused by the simultaneous sequence of these reactions. Dehydrochlorination, prevailing reaction during processing,leads to increasing d

9、iscoloration. In the course of the proceeding degradation the physical properties are also changed in the direction of increasing embrittlement. PVC of ideal constitution should be thermally stable, which was concluded from investigations with model substances. Therefore, it has to be assumed that t

10、he damage, articularly the dehydrochlorinations, starts from sites of the macromolecule with labile chlorine–carbon bonds. PVC can be degraded by heat and sun lights. The release of hydrogen chloride, which is the indication of PVC degradation in prolonged exposure to the sun’s electromagnetic radia

11、tion in the UV region, is occurred according to the following reactions: The color of PVC-based article is changed from yellow to black according to degrees of the degradation. Once the reaction has started, polymers quickly and progressively experience changes in appearance: surface qualities, g

12、loss, chalking, color, electrical properties, tensile strength and elongation; and can reach the end points of embrittlement and total disintegration. The degradation of polymers exposed to UV, often described as photodegradation and frequently identified as photooxidation, can follow various route

13、s. By absorbing UV radiation directly, a polymer molecule can reach a high-energy excited state where it becomes unstable. If the excess energy can be dissipated in a fashion that does not affect the molecule by making it phosphoresce or fluoresce, or by converting the energy to heat that can be car

14、ried away, or by transferring the energy to another molecule, photochemical reaction does not started and thus, polymer degradation will not happen. However, such actions occur only rarely, since most polymers cannot dispose of the excitation energy without undergoing a chemical reaction that sets o

15、ff a degradative process. In theory, many pure polymers should not absorb UV radiation, and thus, not be subject to photodegradation. However, in practice the most polymers contain impurities such as carbonyl or carboxy groups or hydroperoxides that readily absorb radiation in the 290–400 nm range

16、causing them to break down. Thus, generating sites within the polymer structure where chemical reactions can be initiated and propagated by free radicals. The active groups may be unavoidably present as a result of reactions that occur during polymerization. Similarly, metallic ions are present in m

17、ost polymers as residues from polymerization catalysts, or as constituents of compounding additives such as heat stabilizers, antioxidants, colorants, fillers and others. The metal ions are highly receptive to the absorption of UV radiation, and are efficient in transferring the absorbed energy to t

18、he polymer molecules around them, thus, they act as photo-sensitizers and can promote degradation at the same time that they perform their desired functions. Another contributor to photodegradation of polymers is oxygen, which helps any free radicals that may be liberated by the UV to initiate and

19、propagate oxidation of the polymer, hence, the term photooxidation. Polyvinyl chloride suffers from poor heat stability. Its degradation occurs by autocatalytic dehydrochlorination initiated at the labile sites in the polymer chains. This leads to severe discoloration and loss of mechanical propert

20、ies. The dehydrochlorination most probably proceeds by a chain mechanism involving radical intermediates. Various defect sites in PVC are branching. Inorganic and organic thermal stabilizers are commonly added to protect the polymer from heat degradation. Among the most widely used ultraviolet stab

21、ilizers is titanium dioxide pigment. Filling a polyvinyl chloride composition with this pigment substantially reduces the effective depth of penetration of ultraviolet light into the surface of an article formed from such a composition. Mohamed et al. pointed out that barbituric acid and thiobarbit

22、uric acid are nontoxic organics, thermally stable materials of high melting point. Both contain active methylene groups, and can act as H-donor through their enolic hydrogen groups, which can intervene with the radical species derived from the thermal degradation of PVC. They investigated the possib

23、ility of using barbituric acid and its thioanalogue as thermal stabilizers for rigid PVC. The effective stabilization often requires a combination of antioxidant system in which complementary overlap of different mechanistic pathways involved. This act often referred to as synergism, is the motivat

24、ion for the use of admixing composition of dibutyltin maleate and trinitro and its ester homologues. The stabilization agents of dibutyltin maleate and trinitro esters could retard somewhat the photodegradation of PVC. It is hoped that the total stabilizing effect of this admixed system should be gr

25、eater than the sum of the individual effects when PVC is subjected to an environment where the effects of heat and UV are combined. Turoti et al. investigated the effect of the stabilizing action of admixed mixtures of dibutyltin maleate and trinitro and its ester homologues on polyvinyl chloride ex

26、posed to natural atmosphere. In their study, the degradation and stabilization reactions were monitored by color formation, tensile strength and elongation at break, reduced viscosity as well as determination of time to embrittlement. It is observed that the stabilized PVC sample has an effective re

27、duction in degradation reactions. Titanium dioxide is by far the most important of white inorganic pigments and possesses all-round suitability. While rutile titanium dioxide is highly reflective at visible wavelengths, it is also highly absorptive at ultraviolet wavelengths. However, although tita

28、nium dioxide is a highly effective ultraviolet light stabilizer for polyvinyl chloride compositions, it does have several serious drawbacks. An important disadvantage is the cost of titanium dioxide which has historically tended to be high compared with filler or extender pigments such as calcium ca

29、rbonate and talc. Another significant disadvantage of using titanium dioxide as an ultraviolet stabilizer in unplasticized polyvinyl chloride compositions is that historically titanium dioxide has been periodically in short supply. The relatively high cost of titanium dioxide is an especially signi

30、ficant disadvantage for the manufacture of articles for exterior use from unplasticized polyvinyl chloride compositions because such articles must often have substantially greater dimensions, for structural reasons than the effective penetration depth of ultraviolet light in the articles. Thus, it i

31、s highly desirable to able to reduce the level of titanium dioxide in such a composition without experiencing an accompanying increase in the rate of degradation and reduction in service life. Although it seems to decrease the level of titanium dioxide in the PVC composition will tend to increase th

32、e effective penetration depth of ultraviolet length and will consequently accelerate the degradation of the PVC, the experimental observations do not support such an expectation. Since PVC compositions consist generally of from about 0.5–5 parts by weight of rutile titanium dioxide per hundred parts

33、 by weight of the polyvinyl chloride, there is no guarantee for the bulk of titanium dioxide to locate near the external surfaces of articles exposed to sun lights. In this study, usability of magnesium oxide with titanium dioxide in the PVC compositions for forming of the exterior articles such as

34、 door and window profile is investigated in terms of determining discoloration and some mechanical properties of the articles under accelerated weathering test. 2. Materials and methods PVC compositions widely used to form the exterior articles such as door and window profiles consist essentially

35、of about five parts (by weight) stabilizers, five parts rutile titanium dioxide, five parts fillers, and 0.1-3 parts process aids per hundred parts by weight of the polyvinyl chloride resin. Polyvinyl chloride is subject to thermal degradation by dehydrochlorination. Since many processes for formin

36、g useful objects from polyvinyl chloride compositions, such as extrusion and molding, subject the composition to elevate temperatures, most include thermal stabilizing agents that tend to inhibit thermal degradation of the polymer during processing. Example of commonly employed thermal stabilization

37、 agents includes barium/cadmium and organotins including mercaptides, maleates and carboxylates. Polyvinyl chloride is also subject to degradation by exposure to ultraviolet light. Articles formed from polyvinyl chloride compositions, which are exposed to ultraviolet light such as vinyl siding and

38、vinyl window and window frame components typically include an ultraviolet stabilizer. In this study, five different compositions of PVC were used to fabricate door and window profiles. These profiles are faded under accelerated weathering conditions. Discoloration and some mechanical properties of

39、the profiles are determined to choose the most suitable polyvinyl chloride composition used to form the exterior articles. For window profiles up to nine repeated extrusion processes were investigated. The properties like impact strength, modulus, Vicat temperature, thermal stability, etc. of recyc

40、led window frame profiles from 20 to 25 years old windows are determined, it is shown that such recycled PVC is suitable for reprocessing. The heat impact of PVC bottle materials during the recycling process at 160– 180 ％ was investigated by IR- and UV-spectroscopy and by DSC. The bottle samples are

41、 slightly and considerably affected at these temperatures as shown by determination of the formed decomposition products, colour change, loss of volatile components and peroxide formation in air. However, since these decompositions occurred at about 30 min of experimental time which is about six-fol

42、d of that of real process times, the reclaimed material was found recyclable which makes the use of this material in the production of window sections, profiles, pipes and even bottles possible. Investigations on the mechanical properties of recycled PVC bottle material separated from the postconsu

43、mer waste stream show significant reduction in strength and ductility. It is believed that the main reason for this is the presence of impurities, especially PET, which although present at levels below 0.5% had a large effect on the properties. Also investigated was the degradation that occurs durin

44、g multiple reprocessing of recycled PVC from post-consumer bottles using IR-analysis and molecular weight measurements. Batches of recycled flake and powder as well as pure but processed bottle flake materials were subjected to simulated multiple recycling using a torque rheometer. The results indic

45、ated a rapid degradation of the recycled material compared with purer bottle flake PVC. Multiple recycling of bottle flake mixed with 0.2% polyethylene showed that the PE impurities accelerate the degradation process. Restabilization by adding new bottle flake material surprisingly prevented degrada

46、tion even at small levels of new material (30%) and even after 15 recycling steps. Recycled PVC bottle material can be used successfully in calcium–zinc stabilized PVC foam formulations to produce profiles of saleable quality. Increasing amounts of bottle recyclate had no significant effect on gel

47、ation time, melt rheology or plate-out characteristic and gave rise to an improvement on thermal stability. Foam blends can be extruded to produce profiles of good surface finish and low foam density. Up to 100% PVC bottle recyclate did not affect the density, cell structure or impact properties of

48、co-extruded foam profiles. Foamed PVC recyclate can also be used for inner layers in tubes where densities at about 0.5 g/cm3 arepossible. The reuse of recycled PVC in cable insulations is described in Ref. For this purpose, it is necessary to recover copper and PVC from cable forms originating fro

49、m used motor cars. PVC can be dissolved and separated to be reused in cable and wire insulating. It is reported that cables using 100% recycled PVC have successfully passed preliminary tests. Cable forms with 50% PVC recyclate have been released for the production of new cars by several manufacturer

50、s. Since 1990 PVC floor coverings were collected and recycled in Germany. First results and practical experiences are reported in Ref. Other recycling concepts have been developed for use of recycled PVC packaging or bottle material as core in co-extruded cellular profiles. The products had satisf

51、actory density, foam structure, colour and surface finish. Using up to 100% bottle recyclate did not affect the impact properties of the foam profile.Recycled supermarket trays actually gave an improvement in impact properties, probably due to high levels of impact modifier used in tray formulation.

52、 Also, recovery and reuse of waste PVC coated fabrics is described, extracting PVC with a selected aqueous ethyl methyl ketone solution. This so-called swelling method is a simple procedure with minimum environmental impact. The behaviour of the swelling system and the swelling properties of recover

53、ed components can be characterized by refractive index, swelling degree and the average particle size of recovered PVC. A detailed analysis of the components separated from PVC coated PET fabrics is also described. The recovered PET staple fibre scrap can directly be used to reinforce epoxides or to

54、 form a non-woven fabric on a special machine. 2.1. Materials PVC used in the experiments was obtained from Petkim (PVC S27/R-63). The rutile titanium dioxide (Kronos 2220 TiO2) was supplied by Sayman Chemical Materials. Acrilic polymer used in the experiments as a impact modifier was obtained f

55、rom LG Chemical Ltd (IM 808). TThe tin stabilizer (TIN-41) used in the study was supplied by Kimfor Chemical Ltd. The internal lubricants coded by ESKAY-4 (polyethylene oxide, compound of calcium stearate) and the external lubricants coded by WCBA (polyethylene wax) were also supplied by Kimfor Chem

56、ical Ltd. Magnesium oxide was supplied by MAGOX company. 中文翻譯 關(guān)于混有二氧化鈦的氧化鎂在PVC門窗型材中的可用性研究 1 簡(jiǎn)介 聚氯乙烯是最廣泛使用的合成有機(jī)高分子材料。增塑聚氯乙烯很常見(jiàn)，如乙烯基板材產(chǎn)品和從塑料溶膠中提取的對(duì)象。而市面上的各種聚氯乙烯中還有一些可以用于擠出具有剛性且不含增塑劑成分的產(chǎn)品。 塑料長(zhǎng)期暴露在陽(yáng)光下，陽(yáng)光中的紫外線輻射會(huì)導(dǎo)致其物理性能的下降，這種物理性能的下降可以通過(guò)顏色變化和脆化降解體現(xiàn)出來(lái)。同樣，普通熒光燈的紫外線也可以降解聚合物以及聚合物中所使用的多種添加劑。 地表的有效

57、紫外線輻射波波長(zhǎng)約為290-400納米，對(duì)塑料降解作用最強(qiáng)的波長(zhǎng)為300納米左右的高能紫外線恰好在這個(gè)范圍內(nèi)。而一些人造高能量輻射源如汞弧燈、氙弧燈、碳弧燈以及各種日曬燈能發(fā)出波長(zhǎng)低于290納米的輻射波，這些輻射波對(duì)塑料的降解作用比自然陽(yáng)光更強(qiáng)。因此，它們通常用于塑料的加速試驗(yàn)。 波長(zhǎng)為290-400納米的紫外線所含的輻射能可以使目前聚合物中絕大多數(shù)的化學(xué)鍵斷裂。聚合物對(duì)于紫外線輻射的抗性并不相同，如聚甲基丙烯酸酯和碳氟化合物對(duì)于紫外線輻射的抗性就比較低。另外有一些能夠抗紫外線的純聚合物則由于會(huì)吸收紫外線形成污染源而已經(jīng)被淘汰。 聚合物分子吸收輻射能會(huì)產(chǎn)生躍遷，如果吸收的能量足夠多，達(dá)到化

58、學(xué)鍵斷裂所需要的能量，就會(huì)造成碳碳、碳?xì)?、碳鹵等內(nèi)鍵的斷裂，從而使聚合物降解。PVC的降解是脫氯化氫、自動(dòng)氧化和斷鏈等反應(yīng)共同作用的結(jié)果。 脫氯化氫現(xiàn)象在PVC的加工過(guò)程中普遍存在。在降解的過(guò)程中PVC的物理性質(zhì)會(huì)發(fā)生脆化。通過(guò)實(shí)物模型得到的理想的PVC的結(jié)構(gòu)應(yīng)該是穩(wěn)定的，這就需要假定脫氯化氫的反應(yīng)是從含有不穩(wěn)定氯碳鍵的高分子開始的。熱和陽(yáng)光都可以導(dǎo)致PVC的降解。PVC若長(zhǎng)期暴露在陽(yáng)光中的紫外線下會(huì)根據(jù)下述反應(yīng)方程而釋放出氯化氫： 隨著反應(yīng)程度的加劇，PVC的顏色會(huì)逐漸由黃色變?yōu)楹谏?。一旦該反?yīng)開始，PVC就會(huì)迅速并逐步發(fā)生外觀（如表面質(zhì)量、光澤、粉化、顏色、電性能、拉伸強(qiáng)度和延伸率

59、）上的變化，并最終達(dá)到完全脆化和降解。 聚合物由于暴露于紫外線中而發(fā)生的降解可以按照不同的方式進(jìn)行，這種降解通常被稱為光降解，也經(jīng)常被認(rèn)定為光氧化反應(yīng)。聚合物分子可以通過(guò)吸收紫外線輻射達(dá)到高能量激發(fā)態(tài)而變得不穩(wěn)定。 如果多余的能量通過(guò)一種不影響聚合物分子本身的方式被消耗掉，例如使它發(fā)出熒光或磷光，或者將能量轉(zhuǎn)換成可以被帶走的熱，或?qū)⒒驅(qū)⒛芰哭D(zhuǎn)給另一個(gè)分子，這樣光化學(xué)反應(yīng)就不會(huì)發(fā)生，聚合物降解也就不會(huì)發(fā)生。但是，這種方式很少發(fā)生，因?yàn)榇蠖鄶?shù)的聚合物不能夠不經(jīng)過(guò)發(fā)生降解反應(yīng)過(guò)程就消耗掉激發(fā)能量。 從理論上講，許多純聚合物不應(yīng)該吸收紫外線輻射，因此就不會(huì)產(chǎn)生光降解。然而，在實(shí)踐中大多數(shù)聚合物，

60、如含有羰基或羧基或氫過(guò)氧化物的聚合物，很容易吸收290-400nm范圍內(nèi)的輻射而導(dǎo)致降解。因此，化學(xué)反應(yīng)可以通過(guò)自由基在聚合物結(jié)構(gòu)內(nèi)發(fā)生并擴(kuò)大。聚合反應(yīng)過(guò)程中產(chǎn)生活性基團(tuán)是不可避免的。同樣，金屬離子也會(huì)作為催化劑殘留物，或復(fù)合添加劑（如熱穩(wěn)定劑，抗氧化劑，著色劑，填料和其它助劑）的成分而出現(xiàn)在大多數(shù)聚合物中。金屬離子極易吸收紫外線輻射，并快速將吸收的能量轉(zhuǎn)移給周圍的聚合物分子，因此，金屬離子作為光增敏劑，同時(shí)能促進(jìn)降解。 另一種使聚合物產(chǎn)生光降解的是氧氣。氧氣有助于紫外線產(chǎn)生自由基并傳播氧化作用，因此，氧氣造成的光降解是長(zhǎng)效的。 聚氯乙烯熱穩(wěn)定性很差。其降解以自催化脫氯化氫的方式在聚合物鏈

61、不穩(wěn)定處反應(yīng)。這會(huì)導(dǎo)致嚴(yán)重的變色和力學(xué)性能的降低。脫氯化氫反應(yīng)很有可能是一種連鎖反應(yīng)機(jī)制，反應(yīng)過(guò)程中會(huì)產(chǎn)生自由基中間體。 無(wú)機(jī)和有機(jī)熱穩(wěn)定劑的加入通?？梢云鸬奖Ｗo(hù)聚合物，而使之發(fā)生熱降解的作用。其中最廣泛使用的紫外線穩(wěn)定劑是二氧化鈦顏料。二氧化鈦填充聚氯乙烯，在其表面形成一種色素組合，可以大大降低紫外線有效穿透深度。 穆罕默德等人發(fā)現(xiàn)，巴比妥酸和硫代巴比妥酸是兩種高熔點(diǎn)、無(wú)毒的有機(jī)熱穩(wěn)定性的材料。這兩種材料含有活性亞甲基，可通過(guò)自身的烯醇式氫組提供H-，來(lái)阻止PVC熱降解產(chǎn)生自由基。他們研究了使用巴比妥酸及其硫代物作為硬質(zhì)PVC熱穩(wěn)定劑的可能性。 有效的穩(wěn)定往往需要抗氧化系統(tǒng)的結(jié)合，這涉

62、及到不同機(jī)械作用的互相影響。這種通常被稱為協(xié)同作用的行為，讓他們想到了使用馬來(lái)酸丁基錫和三硝基及其酯類同系物的共混物。馬來(lái)酸和硝基二丁基酯的穩(wěn)定劑可延緩有些PVC的降解。我們希望當(dāng)PVC受到熱和紫外線的共同作用時(shí)，這種穩(wěn)定的復(fù)合穩(wěn)定體系的穩(wěn)定效果比單獨(dú)穩(wěn)定劑的效果總和要好。特羅迪等人研究了二丁基錫和三硝基馬來(lái)酸及其酯類同系物對(duì)自然暴露在大氣中的聚氯乙烯的協(xié)同穩(wěn)定效應(yīng)。他們的研究，通過(guò)顏色的變化、拉伸強(qiáng)度和斷裂伸長(zhǎng)率、粘度的降低和脆裂時(shí)間，對(duì)降解和穩(wěn)定反應(yīng)進(jìn)行了檢測(cè)。 鈦白粉是目前最重要的白色無(wú)機(jī)顏料，具有全面的適用性。金紅石型鈦白粉對(duì)可見(jiàn)光有很好的反射作用，并且能夠高度吸收紫外線。不過(guò)，雖然

63、二氧化鈦是一種高效的聚氯乙烯紫外線光穩(wěn)定劑成分，但它有幾個(gè)嚴(yán)重的缺點(diǎn)。一個(gè)重要的缺點(diǎn)是鈦白粉的成本，與碳酸鹽和滑石粉等填料或顏料相比，其價(jià)格往往要高得多。另一個(gè)使用二氧化鈦?zhàn)鳛橛簿勐纫蚁┳贤饩€穩(wěn)定劑成分的顯著缺點(diǎn)是，歷史上二氧化鈦一直存在周期性供不應(yīng)求的現(xiàn)象。 二氧化鈦是一種成本相對(duì)較高的物品外墻使用硬聚氯乙烯成分，因?yàn)檫@類物品必須經(jīng)常有更大的尺寸大大超過(guò)了在文章紫外線的有效穿透深度結(jié)構(gòu)性原因，制造特別是重大的缺點(diǎn)。 成本相對(duì)較高，是鈦白粉作為制造外墻使用的硬質(zhì)聚氯乙烯物品的添加成分的一個(gè)特別明顯的缺點(diǎn)，因?yàn)檫@類物品由于結(jié)構(gòu)性原因經(jīng)常必須大幅度擴(kuò)大范圍，而不必首要考慮制品的有效紫外線穿透深

64、度。因此，用這樣的組合來(lái)減少太白粉的使用而不增加制品使用壽命退化和減少的的速度是非常好的做法。雖然看起來(lái)減少鈦白粉的使用將導(dǎo)致有效的紫外線穿透深度和長(zhǎng)度的增加而加快PVC的降解，實(shí)際上實(shí)驗(yàn)結(jié)果并不是這樣。由于每百分質(zhì)量的聚氯乙烯中金紅石型鈦白粉的添加量一般約為0.5-5分，沒(méi)有證據(jù)表明暴露在陽(yáng)光下的聚氯乙烯制品的外表面附近聚有大量的鈦白粉。 本項(xiàng)研究，通過(guò)確定變色和某些條件下加速老化試驗(yàn)的力學(xué)性能來(lái)研究混有二氧化鈦的氧化鎂在戶外用PVC門窗異型材制品中的可用性。 2 材料和方法 戶外用聚氯乙烯門窗異型材產(chǎn)品，每百分質(zhì)量的聚氯乙烯樹脂中通常主要添加有5分的穩(wěn)定劑，5分金紅石型鈦白粉，5

65、分填料，0.1-3分的加工助劑。 聚氯乙烯容易因熱降解而脫氯化氫。所以在利用聚氯乙烯加工成可用的制品的諸多過(guò)程（如擠出成型）中，由于加工溫度較高，大部分都加有穩(wěn)定劑以抑制加工過(guò)程中聚合物的熱降解。普遍采用的熱穩(wěn)定劑的有鋇/鎘熱穩(wěn)定體系、有機(jī)錫類熱穩(wěn)定劑等。 聚氯乙烯也會(huì)因?yàn)槭艿阶贤饩€輻射而降解。因此，由于在戶外使而長(zhǎng)期接受紫外線輻射的聚氯乙烯制品，如乙烯基壁板、乙烯基窗和窗框組件等通常都添加有紫外線穩(wěn)定劑。 本項(xiàng)研究，采用5種不同組分的PVC來(lái)制作門窗型材。并在加速風(fēng)化條件下對(duì)這些制品進(jìn)行褪色實(shí)驗(yàn)。以這些制品的變色情況和一些力學(xué)性能為依據(jù)，最終從中選出能夠良好外觀的最適合的聚氯乙烯組分。

66、 對(duì)于窗框來(lái)說(shuō)，調(diào)查顯示至少需要九次的重復(fù)擠壓工藝。對(duì)于已經(jīng)使用了20年到25年的舊窗來(lái)說(shuō)，沖擊強(qiáng)度、模量、維卡溫度、熱穩(wěn)定性等一些性能都是一定的，調(diào)查也表明,這類回收的聚氯乙烯也適合進(jìn)行再加工。我們通過(guò)紅外線和紫外線光譜學(xué)和掃描電鏡等方法對(duì)聚氯乙烯瓶裝材料在加工過(guò)程中180oc的溫度下熱沖擊進(jìn)行研究，瓶子樣品在這樣的溫度下或多或少的受到一些影響，影響程度的大小主要取決于先前產(chǎn)品的分解、變色、揮發(fā)性組分的損失、在空氣中過(guò)氧化物的形成等。 關(guān)于再回收利用聚氯乙烯瓶裝材料機(jī)械性能的調(diào)查表明，使用后的廢液在強(qiáng)度和延展度上有很大的降低。人們普遍認(rèn)為之所以如此，主要是因?yàn)橛须s質(zhì)的存在，特別是聚對(duì)苯二甲酸乙二醇酯，即使它的濃度很低，在0.5%以下，但是聚對(duì)苯二甲酸乙二醇酯對(duì)機(jī)械性能的影響卻是很大。調(diào)查的結(jié)果表明利用回收材料制成的瓶子比用純聚氯乙烯材料制成的聚氯乙烯瓶子更容易分解。如果我們把0.2%的聚乙烯和經(jīng)過(guò)多次加工的瓶子薄片混合在一起，那么會(huì)由于聚乙烯雜質(zhì)的影響加速它的降解過(guò)程。通過(guò)加入新的瓶子薄片材料來(lái)進(jìn)行穩(wěn)定，那么會(huì)非常有效的阻止降解，即使新材料的含量很低（比如30%）、經(jīng)過(guò)了15次循