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回收塑料材料注射成型英文文献和中文翻译

时间:2018-06-09 19:35来源:毕业论文
With society focusing more and more on environmental issues, the recycling of materials of all types has become an important concern. As a result of previous processing and usage, the properties of recycled materials are often significantly

With society focusing more and more on environmental issues, the recycling of materials of  all  types  has  become  an  important  concern.  As  a  result  of  previous  processing  and usage, the properties of recycled materials are often significantly  inferior when compared to  their  unrecycled  counterparts.  Recycled  polymeric  materials,  for  example,  have  lowered  molecular  weights  caused  by  previous  thermal  and/or  shear  histories.  Thus,  the scope  of  application  for  recycled  materials  has  traditionally  been  very  limited.  With  the aid  of  a  new  processing  concept  known  as  vibration-assisted  injection  molding  (VAIM),the  mechanical  properties  of  products  containing  recycled  polymeric  materials  could  be dramatically  improved.  The  current  paper  presents  the  results  of  an  initial  experimental investigation  into  the  application  of  VAIM  for  recycled  polystyrene  (Recycled-PS)  products. A number of recycled/new material blends were studied, and in all cases significant product mechanical property enhancements were realized through the use of VAIM. It was concluded  that  VAIM  molded  products  containing  as  much  as  50%  low-grade  recycled material  could  be  made  stronger  than  products  made  using  traditional  molding  with
100%  new  polymer.  Detailed  results  are  presented  in  the  paper,  along  with  some  insight into the likely fundamental mechanism underlying the utility of the VAIM technique.
Introduction 23979
The recycling of plastic materials, which has been explored for a  long  time  for  ecological  and  economical  reasons,  has  been  accomplished to some degree . A strong demand exists, however,for  much  more  success  in  this  area.  Recycling  can  reduce  the quantity  of  municipal  solid  waste (MSW) that  requires  further treatment  and  ultimate  disposal,  and  regulating  bodies  across  the U.S. have adopted goals for the amount of MSW to be recycled in an  effort  to  reduce  the  dependence  on  landfills   and  incinerators.
In  general,  recycled  materials  are  considered  to  be  of  lower quality than their unrecycled counterparts . This is because the properties of  materials(later  to  be  recycled ) deteriorate  during processing  and  usage.  The  major  causes  of  quality  losses  in  recycled polymer materials are UV exposure and degradation due to thermal,  chemical,  and  shear  history.  Depending  on  the  chemical structure and existing degradation condition, polymers degrade by chain  scission.  This  can  occur  randomly  along  the  chain,  at  the chain  midpoint,  and/or  at  the  chain  end. The  net  result  is  that  the fundamental polymer chains are broken, the molecular weight becomes lower, and hence the associated material properties are reduced.
Recycled  polymers can  be categorized into two types—postindustrial  and  postconsumer  plastics.  Post-industrial  recycled plastics  are  usually  runners  and  sprues  resulting  from  injection molding processes. These recycled plastics are used frequently by blending  them  in  with  new  or  virgin  polymer.  Typical  virgin/recycled  material  blends  utilize  recycled  plastic  levels  of  up  to 30%  by  weight.  The  major  reasons  for  using  recycled  materials during  injection  molding  are  better  flo w,  lower  cost,  and  a  minimization  of  final   material  waste  levels.  Better  flow   into  molds  is achieved  because  recycled  polymers  usually  have  lower  viscosities  than  their  unrecycled  counterparts.  The  lowered  viscosity  is the result of fewer entanglements associated with the lowered molecular  weight.  While  this  can  have  a  beneficial   effect  as  far  as mold filling  is concerned, it likewise reduces the mechanical performance  of  the  final   products.  In  the  case  of  general-purpose polystyrene  materials,  lower  molecular  weights  lead  to  more brittle  behavior  and,  hence,  a  loss  of  material  toughness. 回收塑料材料注射成型英文文献和中文翻译:http://www.751com.cn/fanyi/lunwen_17270.html
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