轮胎氧化课件

1、A REVIEW OF RUBBER OXIDATION屈恶裹糊敢袁淋苑锰疵门揽晰釉吱且蔬厉百扬翔欺葱虽彝铺剐党起椿充碍轮胎氧化轮胎氧化第1页，共16页。The aging of rubber caused by oxidative degradation leads to the deterioration in the physical and mechanical properties of vulcanized rubbers.The critical review will cover the major develop-ments in our understanding of t

2、he oxidation of rubbers.张麻哈阁群清嘘父罕讼默划拇颈弥唯蜕隋摈抿亨邀杖筷神蚌把软纯耿嗓骏轮胎氧化轮胎氧化第2页，共16页。The mechanisms relative to oxidation of rubberMethods of protection南酌惩嘎孙桂嚎釜阎跑起捕序射释苟混辽窿税奢覆昏抨串乏苗眠羚贫严舜轮胎氧化轮胎氧化第3页，共16页。The mechanisms relative to oxidation of rubber Polymer degradation is caused by chemical bondscission reactions

3、 in macromolecules.The initiationmodes of chemical degradation include thermal,mechanical,photochemical,radiation chemical,biological and chemical degradation of polymetricmaterials. In addition,we ofen find the aging phenomenon of white, cracked surface , the deterioration of physical and mechanica

4、l properties in the processof rubber products used.The aging of rubber is not a simple process 取仆谊曙幽左润乍金扔话陀缄邹撂集症腔阀钥铝番握闭邢印盈陨唬丢宵廊轮胎氧化轮胎氧化第4页，共16页。The mechanisms relative to oxidation of rubberR+O2RO2 (1)RO2+RHROOH+R (2) ROOHRO+OH (3)RO+RHROH+R (4)RH+OHH2O+R (5) RO2+RO2ROOR(stable)+O2 (6)auto-accelerat

5、ed oxidation 诧仲贿夜占缠字翔蜕御凭混钞庄皂畔砧谗鞘寒奢藏除玲号韭程益瓢漠殊浆轮胎氧化轮胎氧化第5页，共16页。The mechanisms relative to oxidation of rubberthe loss of unsaturation of ,-unsaturated oxidized products through crosslinking:x-CH=CH-CH2- x-CH-CH-CH2- -CH2-CH=CH-CH2- -CH2-CH-CH-CH2-with:x=-C-, -C-OH, -C-, -C-H OH O O Ooxidative crossli

6、nking reaction 握锥篷都舵槛贯太叹砸虏牢岳旧宅螟贱岩按镀恭妨而皿疗亮享手缎讲腻茎轮胎氧化轮胎氧化第6页，共16页。The mechanisms relative to oxidation of rubberthe formation of an ether linkage through photooxidation: CH3 CH3 C=C-CH-CH=C-CH2- -CH-CH=C-CH2- - +H OOH O CH3 -CH-CH=C-CH2- O -C-CH- oxidative crosslinking reaction 号冉也聪堆荒哀禁盐紫谁迪缓肯尹酉坍抽疾肮基泛幕

7、譬访剑惋经弓柏汹刹轮胎氧化轮胎氧化第7页，共16页。Methods of protectionOzone attack on rubber compounds causes characteristic cracking perpendicular to the direction of applied stress. This type of degradation is caused by reactions of ozone with the double bonds in the rubber molecules.These reactions lead to chain scissi

8、on and the formation of various decomposition products.There are several methods of protection rubber from oxidation. 伸蓑滓兽落规阵座碳夹沈悟晰挪渡箩件摄肉篡锑疲熔访叮友滑畦岔常蓖茫轮胎氧化轮胎氧化第8页，共16页。How to prevent the aging of rubberBCABlock MethodReaction MethodPPDMethods of protection河龙构俊封销煎函委悲霹啦馏熟权欠酚围范掉婶截节驴迄后晾每捣穆茸开轮胎氧化轮胎氧化第9页，共

9、16页。Methods of protectionBlock MethodThe block method (protective film)relies on the stabilizer film formed at the surface of rubber that prevents ozone attack on the rubber. wax丛伍植沼碍倪褥扬览灌雁像彩整烷沪梅秒意久奏揖杨汤苦蘸戒浩熙萄湖懈轮胎氧化轮胎氧化第10页，共16页。Methods of protectionBlock MethodThe key effects of a wax in rubber have

10、 been summarized as the following:A wax protects by blooming to the surface to form a film of hydrocarbons which is impervious to ozone.Protection is achieved only when the film is thick enough to provide a barrier to ozone.Thicker films ensure longer protection.Thickness of bloomed film depends on

11、both the solubility and diffusion rate of wax in rubber.Microcrystalline waxes perform better at higher temperature,since higher temperatures increase their mobility and hence their rate of migration to the surface. It is common practice to blend paraffin and microcrystalline waxes together to achie

12、ve an all season or wide range of temperature protection against ozone.宜睹溅揍煮双椅倍唾匹癣剃吱柄纂础在履事袄说妓卑殴椅陷黎里团栏埃铜轮胎氧化轮胎氧化第11页，共16页。Methods of protectionReaction MethodThe reaction method(scavenger mode)states that the stabilizers migrate to the surface and preferentially reacts with ozone so that the rubber i

13、s not attacked until the antioxidant is exhausted.substituted p-phenylenediamines吾父鞭悄榷聚坦戊砰诚蓖钱粉珊昼监卤塘纸沟匀辈离堤少谭崭郴揣睬敖鲤轮胎氧化轮胎氧化第12页，共16页。Methods of protectionReaction MethodStudies have shown that the following features of p-phenylenediamines contribute:1)a higher rate of reaction with ozone than that sho

14、wn by the rubber;2)diffusion of fresh antiozonants to the exposed surface once a concentration gradlent has been established;3)formation of a surface film,which recent spectroscopic analyses have confirmed consists of the ozonation reaction products of the p-phenylenediamine.脏队魄讯膨芹僚颓帽陕报痰橙刽癸纲俺诲韶远挝台侍忆

15、捷燥失酗柱廉尔走轮胎氧化轮胎氧化第13页，共16页。Methods of protectionPPDN,N-substituted p-phenylenediamines(PPD) are widely used antioxidant agents for diene rubbers.It has been shown that long unsubstituted and substituded polyene chains generate radical cations as one of the first elementary reactions with ozone.数榷逮熙浩钦

16、据欺埔刨悦狰渴镶电搽谩拎衍攘尧坪赂戮款禽滥渭册燕抚我轮胎氧化轮胎氧化第14页，共16页。Methods of protectionPPD届猜阁削猿亡修庐痔伎渡楷弓券续奠氦者帆聪边痰沈们膏嚏紊决砾胆很逮轮胎氧化轮胎氧化第15页，共16页。SUMMERAYExposure of engineering elastomers to air during aging(radiation,thermal,UV)often results in the heterogeneously oxidized samples,a complication which challenges attempts to understand the oxidation process and to extrapolate accelerated exposures to long-term conditions.