橡(xiang)膠是指具(ju)有可逆形變(bian)的(de)(de)高彈性(xing)聚(ju)合(he)物(wu)材料，在(zai)(zai)室溫(wen)(wen)下富(fu)有彈性(xing)，在(zai)(zai)很小的(de)(de)外力作用下能產生較大形變(bian)，除去外力后能恢(hui)復原狀。橡(xiang)膠屬于完(wan)全無定型聚(ju)合(he)物(wu)，它的(de)(de)玻璃化轉變(bian)溫(wen)(wen)度（T g）低，分子量往(wang)(wang)往(wang)(wang)很大，大于幾(ji)十萬。

橡(xiang)(xiang)(xiang)膠(jiao)分為天(tian)然橡(xiang)(xiang)(xiang)膠(jiao)與合成(cheng)橡(xiang)(xiang)(xiang)膠(jiao)二種。天(tian)然橡(xiang)(xiang)(xiang)膠(jiao)是從橡(xiang)(xiang)(xiang)膠(jiao)樹、橡(xiang)(xiang)(xiang)膠(jiao)草等(deng)植物(wu)中提取膠(jiao)質后加(jia)工制成(cheng)；合成(cheng)橡(xiang)(xiang)(xiang)膠(jiao)則由各種單體經聚合反應(ying)而得。橡(xiang)(xiang)(xiang)膠(jiao)制品(pin)廣泛應(ying)用于工業或生活各方面(mian)。

通(tong)用(yong)型橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)的綜(zong)(zong)合(he)(he)性(xing)(xing)(xing)(xing)能(neng)(neng)較好(hao)(hao)(hao)，應用(yong)廣泛(fan)。主(zhu)要有：①天(tian)然橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)，從三葉(xie)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)樹的乳膠(jiao)(jiao)(jiao)制得(de)(de)，基(ji)本化(hua)學成(cheng)分(fen)為順(shun)(shun)- 聚(ju)(ju)(ju)(ju)異(yi)(yi)戊(wu)二(er)烯(xi)(xi)。彈性(xing)(xing)(xing)(xing)好(hao)(hao)(hao)，強度(du)高，綜(zong)(zong)合(he)(he)性(xing)(xing)(xing)(xing)能(neng)(neng)好(hao)(hao)(hao)。②異(yi)(yi)戊(wu)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)，全名(ming)為順(shun)(shun)-1，4-聚(ju)(ju)(ju)(ju)異(yi)(yi)戊(wu)二(er)烯(xi)(xi)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)，由(you)異(yi)(yi)戊(wu)二(er)烯(xi)(xi)制得(de)(de)的高順(shun)(shun)式合(he)(he)成(cheng)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)，因其(qi)(qi)結構(gou)和性(xing)(xing)(xing)(xing)能(neng)(neng)與天(tian)然橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)近似，故又(you)稱(cheng)合(he)(he)成(cheng)天(tian)然橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)。③丁(ding)(ding)(ding)苯橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)，簡(jian)稱(cheng)SBR，由(you)丁(ding)(ding)(ding)二(er)烯(xi)(xi)和苯乙烯(xi)(xi)共聚(ju)(ju)(ju)(ju)制得(de)(de)。按生產方法分(fen)為乳液聚(ju)(ju)(ju)(ju)合(he)(he)丁(ding)(ding)(ding)苯橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)和溶液聚(ju)(ju)(ju)(ju)合(he)(he)丁(ding)(ding)(ding)苯橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)。其(qi)(qi)綜(zong)(zong)合(he)(he)性(xing)(xing)(xing)(xing)能(neng)(neng)和化(hua)學穩定性(xing)(xing)(xing)(xing)好(hao)(hao)(hao)。④順(shun)(shun)丁(ding)(ding)(ding)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)，全名(ming)為順(shun)(shun)式-1，4-聚(ju)(ju)(ju)(ju)丁(ding)(ding)(ding)二(er)烯(xi)(xi)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)，簡(jian)稱(cheng)BR，由(you)丁(ding)(ding)(ding)二(er)烯(xi)(xi)聚(ju)(ju)(ju)(ju)合(he)(he)制得(de)(de)。與其(qi)(qi)他通(tong)用(yong)型橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)比，硫化(hua)后的順(shun)(shun)丁(ding)(ding)(ding)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)的耐(nai)寒(han)性(xing)(xing)(xing)(xing)、耐(nai)磨性(xing)(xing)(xing)(xing)和彈性(xing)(xing)(xing)(xing)特別優異(yi)(yi)，動(dong)負荷下發熱少，耐(nai)老化(hua)性(xing)(xing)(xing)(xing)能(neng)(neng)好(hao)(hao)(hao)，易(yi)與天(tian)然橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)、氯(lv)丁(ding)(ding)(ding)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)、丁(ding)(ding)(ding)腈橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)等(deng)并用(yong)。⑤氯(lv)丁(ding)(ding)(ding)橡(xiang)(xiang)(xiang)膠(jiao)(jiao)(jiao)，簡(jian)稱(cheng)CR，由(you)氯(lv)丁(ding)(ding)(ding)二(er)烯(xi)(xi)聚(ju)(ju)(ju)(ju)合(he)(he)制得(de)(de)。具有良好(hao)(hao)(hao)的綜(zong)(zong)合(he)(he)性(xing)(xing)(xing)(xing)能(neng)(neng)，耐(nai)油、耐(nai)燃、耐(nai)氧化(hua)和耐(nai)臭氧。但其(qi)(qi)密度(du)較大，常(chang)溫(wen)下易(yi)結晶變硬，貯存性(xing)(xing)(xing)(xing)不好(hao)(hao)(hao)，耐(nai)寒(han)性(xing)(xing)(xing)(xing)差。